AudioCircle
Industry Circles => Salk Signature Sound => Topic started by: chargedmr2 on 21 Mar 2013, 02:15 am
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Hi guys,
Quite some time ago I asked Jim if he would build me a custom subwoofer. It had to meet my wife's approval which meant that it would double as an end table (no dedicated listening room for me). At first I wasn't sure exactly what I wanted, but I settled on a design to accommodate the LMS Ultra 5400. Jim was very helpful and built the sub just as I needed for our space (I think we exchanged more than 100 emails!). I have not been able to get the sub fully integrated yet, but so far, I am very impressed. This thing puts out very very CLEAN bass. I will be applying EQ to flatten the response in the near future, but even as it is, the difference is quite noticeable with music and especially movies (in fact, I am now on the hunt for room rattles that need to be eliminated). After I get it well integrated with my SongTowers, I will post back with some more detailed impressions. For now, I figured I'd post a few pictures and mention some of the details about the sub design:
Dimensions: 21x21x25 (including spikes)
Weight: 209lbs (I actually weighed this beast on our scale)
Volume: 3.3 cu ft
Finish: Ziricote with Ziricote hardwood inserts on all four vertical edges
Base: 3/8" steel plate powder coated black (thanks to Oregondv who did the metal work)
Binding posts: Jim's Cardas premium posts (bottom mounted for discrete look)
And the pictures from arrival to getting it into place...
I was at work, but the driver agreed to leave the delivery in front of the garage.
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3394_zps5fd466a9.jpg)
I dragged the pallet into the garage for unpacking.
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3397_zpsed910681.jpg)
Almost there!
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3400_zps93675db5.jpg)
And the fist glimpse (all Salk owners know that Jim's work must been seen in person for full appreciation).
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3401_zps148a4e8b.jpg)
I placed some styrofoam back on for protection and rolled it in with a dolly.
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3404_zps94a9888c.jpg)
And here it is on its side awaiting spike installation (notice the binding posts).
(http://img.photobucket.com/albums/v442/chargedmr2/IMG_3405_zps16b69bc1.jpg)
And finally, here it is in its final place.
(http://img.photobucket.com/albums/v442/chargedmr2/SubPlacement_zps256b121c.jpg:original)
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That's one of the nicest subwoofers I've ever seen! You have a beautiful home as well, by the way.
What will you be using to apply PEQ to the subwoofer? Do let us know if we can help out.
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Thanks Nuance. Jim really does very nice work!
I'm not sure what to use for EQ. I was thinking about a balanced miniDSP but I'm not sure if that's the best option. I read (on another forum) that it may clip the input signal if you're dealing with a hot sub out, though I think my AVR will be OK with it. What do you use/recommend? I'm hoping to creat a flat response that goes pretty low.
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I noticed you mentioned room rattles in your post. In my exprience, when room rattles are easily heard over the bass, it can sometimes be a sign of cancellation issues. Try a few different placement options........ if you're allowed :lol:
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I would pick up one of these to power your sub. You can also get a pro amp with built in EQ and Xover from Crown or several others. Pro amps work great for sub applications, lots of power and low cost. Fan noise is a problem for some but the PE amp does not have a fan. I'd get the PE amp. There are more expensive options but I think they might be overkill.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-811
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I noticed you mentioned room rattles in your post. In my exprience, when room rattles are easily heard over the bass, it can sometimes be a sign of cancellation issues. Try a few different placement options........ if you're allowed :lol:
Well, as you might imagine, the bad news is that placement alternatives are not an option. :duh: But the good news is that the rattles are not heard from the LP, but when I get up and walk around the room. Even better, I've determined that the rattle is coming from one of the HVAC vents in the ceiling.
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I would pick up one of these to power your sub. You can also get a pro amp with built in EQ and Xover from Crown or several others. Pro amps work great for sub applications, lots of power and low cost. Fan noise is a problem for some but the PE amp does not have a fan. I'd get the PE amp. There are more expensive options but I think they might be overkill.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-811
I've already got the amplification taken care of (a true 2.4Kw RMS), but I don't have an amp with DSP built in (which may have been a nice option). And I agree with you that it's overkill for average use, but its definitely not overkill for the sub, which can easily take everything this amp has. I really wanted to be sure that there was plenty of headroom (at reasonable movie watching levels) for EQ to remedy the below 30Hz roll-off. For music, there is plenty of bass and after getting this sub, I'm reminded of how well the SongTowers do all on their own in the low frequency region. So far, I still prefer the SongTowers without sub for two-channel listening. Once I get the sub properly integrated (within my limits), I'll reevaluate.
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Thanks Nuance. Jim really does very nice work!
I'm not sure what to use for EQ. I was thinking about a balanced miniDSP but I'm not sure if that's the best option. I read (on another forum) that it may clip the input signal if you're dealing with a hot sub out, though I think my AVR will be OK with it. What do you use/recommend? I'm hoping to creat a flat response that goes pretty low.
Based on what you said about clipping the input signal I have an option for you but it'll require having the necessary tools to measure your room. If you're cool with that I highly recommend the Behringer DSP1124p. It's ugly as can be, but if you hide the thing it's probably the best option for the money IMO. You can even use it to set the input level on your receiver so you never clip the signal. Again, though, you'll need to have a mic and soundcard paired with software (like REW) to measure your room first. If that's something you're not willing to venture then the miniDSP is a great option. I don't know that you'll be able to use it to adjust the input level on your receiver, though. The reason you can use the Behringer to adjust the input level of the receiver is because it has the meters on the front, and before you apply EQ you put it into a bypass type mode in order to display the receiver's input signal.
Regarding integrating the subwoofer, taking in-room measurements will be a great asset. I used my ears and REW to integrate my subs and couldn't be happier. With that said, being placement limited is definitely your Achilles Heal.
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Based on what you said about clipping the input signal I have an option for you but it'll require having the necessary tools to measure your room. If you're cool with that I highly recommend the Behringer DSP1124p. It's ugly as can be, but if you hide the thing it's probably the best option for the money IMO. You can even use it to set the input level on your receiver so you never clip the signal. Again, though, you'll need to have a mic and soundcard paired with software (like REW) to measure your room first. If that's something you're not willing to venture then the miniDSP is a great option. I don't know that you'll be able to use it to adjust the input level on your receiver, though. The reason you can use the Behringer to adjust the input level of the receiver is because it has the meters on the front, and before you apply EQ you put it into a bypass type mode in order to display the receiver's input signal.
Regarding integrating the subwoofer, taking in-room measurements will be a great asset. I used my ears and REW to integrate my subs and couldn't be happier. With that said, being placement limited is definitely your Achilles Heal.
Thanks for the advice Nuance. I will look into the DSP1124p and get back with questions (which I'm sure I'll have). I have measurement gear (Tascam 144, mic calibrated to 5Hz, REW, SPL meter), so I'm good to go there. Yeah, in my situation, the best I can do with placement is move the sub a few inches forward or backward, or rotate it in any direction (sad, I know). And just maybe I can work in some room treatments.
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Thanks for the advice Nuance. I will look into the DSP1124p and get back with questions (which I'm sure I'll have). I have measurement gear (Tascam 144, mic calibrated to 5Hz, REW, SPL meter), so I'm good to go there. Yeah, in my situation, the best I can do with placement is move the sub a few inches forward or backward, or rotate it in any direction (sad, I know). And just maybe I can work in some room treatments.
If you already have REW set up and ready to go then using something like the 1124p to apply PEQ and set the input level of your receiver will be a piece of cake. I am here to help if you have any questions.
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Hey Nuance,
Can the 1124p be used to adjust below 20Hz? I'm sure this is not a huge issue, but I'd like to get everything I can out of this sub for HT use. Now that I think about it, I'm not sure if the miniDSP can do this either?
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Hey Nuance,
Can the 1124p be used to adjust below 20Hz? I'm sure this is not a huge issue, but I'd like to get everything I can out of this sub for HT use. Now that I think about it, I'm not sure if the miniDSP can do this either?
Neither can, no. Room gain should easily get you flat to 15Hz, though, if not lower. Have you measured the room/sub yet? If so, do you have issues getting below 20Hz?
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I have a pair of 18" LMS Ultra subs, and they tend to roll off a little above 20Hz. I use an 1124P to EQ them, and I use a wide 20Hz filter to boost them. I'm flat to about 14Hz.
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Nuance, TJHUB -
Thanks for the replies. I have to take some new measurements since I wasn't clear on how the "direct" mode works with Denon AVRs. I believe I had "double" bass going on (Denon seems to ignore all base management for the mains in this mode). The initial measurements were certainly not flat under 20Hz (or anywhere else for that matter!). There seems to be some roll-off that starts at about 30Hz in my room.
However, if I can get flat to 15Hz or so with the 1124P, then that should probably do it. I don't think I can expect anymore than that without going to dual (or more) subs.
Do you guys have any noise issues with the 1124P? Does it produce a pretty clean signal?
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From your pictures, look like the sub is right next to you. You should have a very nice measurement curve. Hum, did you try to move your sofa a bit and see if thing get smoother.
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The 1124p is nice and quiet in both my and TJ's system. Post up some measurements when you have a chance.
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Austin -
I can't move the couch too much, maybe about 6" further back. I'll try to measure around the LP to see what I get and then decide if it's worth moving. Or were you suggesting to get some more space between sub and couch?
Nuance -
Great to hear that noise isn't an issue. I'll try to get some measuring done tomorrow and will post up the findings for advice.
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Austin -
I can't move the couch too much, maybe about 6" further back. I'll try to measure around the LP to see what I get and then decide if it's worth moving. Or were you suggesting to get some more space between sub and couch?
Nuance -
Great to hear that noise isn't an issue. I'll try to get some measuring done tomorrow and will post up the findings for advice.
6 inches can make or break a response in some cases. Have fun experimenting, and I look forward to seeing your measurements.
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Look like EQ is your best option since sub placement and moving furniture is limited. Be careful, EQ is a great tool in your case but too much EQ do more harm than good. I just ran across a thread from Brian of Rythmik and though it is a very interesting find.
Dynamic EQ
I have another customer, Jack, has a FV15HP-550 and he cannot even play his past -30db without the sub generating sound like it is bottoming out. He traced the problem to DynamicEQ and his AVR is Denon2310.
Here is the problem of DynamicEQ. DynamicEQ is implemented in DSP (digital domain processing). It has a fixed number of digits in the digital domain (whether it is crude 16bit, or more advanced 24bit, or the ultra high resolution 32bit), the objective is to make best use of the more significant bits. If we say don't use the top 3 bits in a 16bit digital system, we literally degenerate the system into a 16-3=13bit digital sytem which is not good. So we need to know the fact that the more significant bits are already being used. Next, dynamicEQ is implemented in digital domain processing, not analog domain. If we boost the signal in digital domain, we need to increase the digital representation of the signal. In another words, we multiply the signal by a factor. If we multiply by a factor of say 4x (which is 12db), that shifts the number upward towards the MSB by 2 bits. The risk of such operation is "over-flow". Over-flow is the MSB are truccated. Signal reversal is common in this case. That is different from analog clipping which is saturation (not signal reversal). So in short, it is not a wise thing to do. Increasing the sub channel level is far less problematic because it is done by a digital potentiometer and it almost achieves the same result.
So in short, if you don't have to turn on DynamicEQ, please don't. Why, one may ask, the problem was not a problem on El cheapo subs? Because those subs have limited resolution, it sounded broken already. Any additional anomaly will be masked (vastly).
After Jack fixed the problem (along with other problems he also uncovered in this process), he is now able to play THX Life test at reference level and the entire room feels like the epic center of the earthquake when the mushrooms is on the screen.
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very nice, looks like high end furniture :D
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Look like EQ is your best option since sub placement and moving furniture is limited. Be careful, EQ is a great tool in your case but too much EQ do more harm than good. I just ran across a thread from Brian of Rythmik and though it is a very interesting find.
Thanks for the tip. I don't use dynamic EQ, but this is very informative since I am using a Denon AVR. I will probably mess around with Audyssey later today if I have time, but I'm a little worried that it might try too hard to boost some dips that I have. Any advice in this regard? I'll post my sad looking frequency response in a few minutes.
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very nice, looks like high end furniture :D
Credit for the furniture selection goes to my wife. I'm just lucky that I was able to choose the speakers! :green:
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Ok, I did some measuring today and as I suspected, things aren't looking too good. This is not surprising given my untreated room and limited placement. Below are measurements taken with my AVR set to cross to the sub at 80Hz. Looks like moving the couch back a foot or so will not really help me out. Things are still not good, and actually a little worse when I do this.
Something else that I noticed (and also have noticed in the past), is that measuring in the upper frequencies is difficult. Well, not difficult, but frustrating in the sense that slight movements seem to produce large changes in the overall frequency response (an inch to the left, or a few inches back, seems to change things dramatically). This would seem to indicated that slight movements by the listener (during actual listening) could alter the experience notably. But in practice, I don't notice these dramatic differences that seem to emerge in my graphs. Almost feels like measuring in the upper frequencies requires a bit of voodoo, some wishful thinking, and crossed fingers. I should mention (as if it's not obvious!) that I'm a complete amateur when it comes to REW and measuring. So while a little frustrating, it is fun to learn.
Enough rambling...here is the graph with no smoothing applied. Is this a hopeless situation or can some EQ help? :cry:
ETA: Not sure why the image is so small, but the center line is 75bd and it is displaying 5db increments. And this is 9Hz though 200Hz.
(http://img.photobucket.com/albums/v442/chargedmr2/submeasurement-80hzcrosstomains_zpsce039fcb.jpg)
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Perhaps you need more subs to help equalize the response throughout the room. Maybe a couple more smaller subs, discreetly placed, would eliminate the need for extensive and intrusive room treatments.
One vs Multiple Subs and why? http://www.audiocircle.com/index.php?topic=106756.0
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I'm a noob where this is concerned, as well... but if I'm seeing this correctly, we're talking 30+ db swings in response, meaning some frequencies are more than 3x as loud as others? Is that right? :o
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Perhaps you need more subs to help equalize the response throughout the room. Maybe a couple more smaller subs, discreetly placed, would eliminate the need for extensive and intrusive room treatments.
One vs Multiple Subs and why? http://www.audiocircle.com/index.php?topic=106756.0
Even multiples subs will be helped with room treatments. I always thought about trying to hide subs, but that turns out to be much harder than anticipated. Possible, but hard.
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Things are getting a little exaggerated here. First of all, the measurement isn't all that bad. How many of you have ever measured your rooms? And room treatments for frequencies below 200Hz are tough to say the least.
chargedmr2: don't worry about upper frequency measurements. Just worry about your sub for the time being. I could easily work with that. A BFD with a few filters would fix that right up. I'm a little surprised, and then again not so much, by the dip at around 28Hz. That must have something to do with your sub and listening position being in the middle of the room. I must say I haven't seen that before.
Would you be willing to take a measurement of just the sub playing, and also one of just the sub about 1 foot from the driver?
I'd also like to see that original measurement with 1/3 smoothing if you could.
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Things are getting a little exaggerated here. First of all, the measurement isn't all that bad. How many of you have ever measured your rooms? And room treatments for frequencies below 200Hz are tough to say the least.
chargedmr2: don't worry about upper frequency measurements. Just worry about your sub for the time being. I could easily work with that. A BFD with a few filters would fix that right up. I'm a little surprised, and then again not so much, by the dip at around 28Hz. That must have something to do with your sub and listening position being in the middle of the room. I must say I haven't seen that before.
Would you be willing to take a measurement of just the sub playing, and also one of just the sub about 1 foot from the driver?
I'd also like to see that original measurement with 1/3 smoothing if you could.
+1. Why there is a deep in around 30hz. I think this is a null spot. Also try place the sub next to the orange chair or between the other 2 chair on the opposite side and face toward LP.
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Things are getting a little exaggerated here. First of all, the measurement isn't all that bad. How many of you have ever measured your rooms? And room treatments for frequencies below 200Hz are tough to say the least.
chargedmr2: don't worry about upper frequency measurements. Just worry about your sub for the time being. I could easily work with that. A BFD with a few filters would fix that right up. I'm a little surprised, and then again not so much, by the dip at around 28Hz. That must have something to do with your sub and listening position being in the middle of the room. I must say I haven't seen that before.
Would you be willing to take a measurement of just the sub playing, and also one of just the sub about 1 foot from the driver?
I'd also like to see that original measurement with 1/3 smoothing if you could.
TJ - Thanks for the encouragement here. I've been taking lots of measures with minor tweaks to see what happens. I even rotated the sub to face backwards (not easy given the weight and spike/wood floor combination). Surprisingly, doing simple things like opening vs. closing doors makes a measurable difference. But, nothing I have done yet has really shored up the major concerns, so I'm probably back to dealing with the curve that I posted here already. I have a few more small things to try, but I doubt any major differences will be achieved.
I'll take your advice and ignore the upper frequencies for now--all of this measurement almost has my head spinning.
I'm going to reposition the sub to face forward again and then I will take the two requested measures and post them here shortly, along with the original measure with 1/3 smoothing applied.
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+1. Why there is a deep in around 30hz. I think this is a null spot. Also try place the sub next to the orange chair or between the other 2 chair on the opposite side and face toward LP.
Austin,
There isn't as much room as there might seem near the orange chair, but the other location you mentioned is a potential possibility. I think I might be able to convince my wife that it would "look much better" over there if I can't get this original location to work out.
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I would try to find a position that first works best for the room, then one that might minimize any of the dips. Did any of the test positions affect the 28Hz dip at all? I'm really hoping that's the sub rolling off and not room cancellations.
Do you have any idea of what the internal volume of that sub is? And are you certain the amp you are using to drive the sub doesn't have some sort of subsonic filter implemented? What amp are you using BTW?
Again, what you initially measured isn't all that bad. The 28Hz dip and the 70Hz peaks are the only things I don't like very much. I've seen MUCH worse.
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Ok, I've taken some more measurements, but let me address the other questions real quick. I'm using a SpeakerPower amp (2400 watts RMS) that only has one filter for subs (30-80Hz), but I am not using it. I did engage the filter real quick and it showed as it should in the measure that followed. So, I'm pretty certain the amp is running full frequency (and the AVR is taking care of the crossover). The internal volume of the sub after accounting for bracing and the subwoofer is just over 3.25 cu ft.
After taking the measures that you requested, it's looking like there is definitely a problem with the sub location. In fact, with the sub only and no mains, the 28Hz dip now looks much more like a null to me. I guess even with the crossover set to 80Hz, the roll-off was such that the mains still helped reduce the dip at 28Hz.
Also, when the sub was facing backwards, the 28Hz dip still had a serious presence.
Here's the graphs. Sorry again that the pics aren't turning out to great.
Sub Only - Mains disconnected - Measured at the LP and 1 foot in front of sub (I guess it's pretty obvious which is which!):
(http://img.photobucket.com/albums/v442/chargedmr2/subonly-nomainslpandclosemeasures_zps36ce220f.jpg)
And here is the original graph with 1/3 smoothing applied (this had the mains running as well):
(http://img.photobucket.com/albums/v442/chargedmr2/submeasurement-80hzcrosstomains-onethirdsmoothing_zps52aa17b0.jpg)
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Bummer that you are dealing with a null at 29Hz, but at least now you know.
Do you have the distance settings correct on your AVR? Not that it is the issue, it's just good to know that's not part of the issue. Also, try reversing the polarity on your sub just for grins.
My guess is that you've picked a spot for your sub that's just not going to work. The only real issue is the null you have. For me, that would be extremely unacceptable. Take some time and see if you can come up with an alternative position that might work.
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A thought...
Could you test the sub just to the right of your right main speaker? If not something you can do permanently, it will at least show if the 29Hz null is more sub placement or listening position.
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If I can get wife approval, I have three potential alternative spots that I might be able to use, but one will require some creative cabling (it would be a LONG run up into the attic and back down to reach the back wall, but there is a place that the sub would at least fit). It would be a tight fit to place the sub at the front right where you suggested, but I can definitely try it out as you suggest. I'm starting to wish this thing came with wheels rather than spikes! I can also place the sub between the two chairs over at the right side of the room (basically the other side of the chair from what you recommended).
I double checked the sub distance setting and it was off by a foot (measuring from front center of the woofer to LP). The mains and center are spot on. I'll try to reverse the polarity to see what that does (I'm guessing not much since the sub was running on its own).
If I have the time, I'll try another location tomorrow.
Thanks for the help so far.
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It's good you have other spots you can try. You don't have to try the one I suggested as much as you just need to try something else.
Good luck tomorrow.
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OK, I've done quite a bit of experimentation with measuring today. Before I undertake a complete relocation of the sub to the other side of the room, I though I'd post the following graph to show what happens when I simply rotate the sub to face in toward the side of the couch. These measures are only with the sub running (mains are disconnected) and the AVR crossover is set to 80Hz. There are three measures, one taken at each of the seating positions on the couch. The measure with no dip in the 30Hz region is taken closet to the sub, and the other two measures with dips appearing in this region are taken in the center seating position and the last remaining position.
(http://img.photobucket.com/albums/v442/chargedmr2/SubMeasures-FacingCouch2_zpsb96956c9.jpg:original)
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OK, I've done quite a bit of experimentation with measuring today. Before I undertake a complete relocation of the sub to the other side of the room, I though I'd post the following graph to show what happens when I simply rotate the sub to face in toward the side of the couch. These measures are only with the sub running (mains are disconnected) and the AVR crossover is set to 80Hz. There are three measures, one taken at each of the seating positions on the couch. The measure with no dip in the 30Hz region is taken closet to the sub, and the other two measures with dips appearing in this region are taken in the center seating position and the last remaining position.
(http://www.dpreview.com/galleries/407830083/download/2482510)
Hmmmm...can't see the pic. :scratch:
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Sorry about that. I think it would have been way too large had it shown. I edited the post above to include the pic. I was looking for a better place to host them, since they turn out really blurry when I upload to photobucket. But at least it should be visible now.
ETA: Let me know if that current pic is too big. It shows up fine on my laptops, but it's way too big on my iPad...
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Sorry about that. I think it would have been way too large had it shown. I edited the post above to include the pic. I was looking for a better place to host them, since they turn out really blurry when I upload to photobucket. But at least it should be visible now.
ETA: Let me know if that current pic is too big. It shows up fine on my laptops, but it's way too big on my iPad...
Thanks. Can see it now. A bit big on my iPad mini, but can scroll back and forth to see the whole thing. :wink:
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Thanks for posting your measurements. Based on what I see I do highly recommend experimenting with other locations (the sub and your couch). Placing the subwoofer near the center of the room has always made for difficult integration in my experience, as does placing the listening position there. The bass response will just about always be the worst it can be if you're sitting in the center of the room. It would be best to place the subwoofer near a side wall boundary, but not necessarily in the corner (corners are okay, though). Try behind the LP to the left of the desk (near where the angled wall meets the back wall), or try the front right corner near. Posting a couple other pictures so we can see the rest of the room would be helpful.
I recommend measuring how far your couch is from the front and back wall. If it is close to the center of the room then it's time to bargain with the wife and move it back a bit. Ideally you want to be around 1/3 the length of the room from either the front or the back wall. In your case I'd recommend 2/3 from the front wall and 1/3 from the back wall. I realize this may not be doable, but being near the center of the room will almost always produce a poor response.
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Nuance,
Thanks for the comments. TJHUB has been helping me out via PM and I have made some good progress. For now, the sub is no longer next to the couch. After many (many) measures, I have located it between the two white chairs on the opposite side of the room near the windows. I'm not sure this is the best location, but it's much better (Austin also recommended this spot). I could hear the difference immediately. The null/dip just under 30Hz is completely gone and the peaks in the 70-80Hz range have come down as well. My wife isn't overjoyed about this new spot, since it displaced another end table that she really liked, but she's surprisingly agreeable and I think she will live :thumb: I might be able to move the couch back a little more, but I'm not sure I'll get noticeable improvements, though I will definitely check (I can only move back about 6" before crowding the desk behind it). I'll be ordering a BFD DSP1124p this week, though it seems that they may have been discontinued? Can't wait to see what I can do with some EQ applied.
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That's great news! Your new location is ideal, as it's not directly in a corner but is along a boundary - very cool. Do you mind posting measurements?
I didn't realize the 1124p was discontinued. They usually sell for $50 used, which is a bargain in my opinion. Try to snatch a used one up if you can. When it arrives I'd be happy to walk you through the input level setup with the receiver, not to mention anything else. I am sure TJHUB would be more than happy to assist as well.
You're well on your way to achieving a great blend and awesome bass!
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Nuance,
Here is the last measure that I took. This is the sub only (mains disconnected), with the crossover set to 80Hz. There is no smoothing applied. Obviously not a good frequency response as is, but hopefully one that can now be tamed with some EQ (unlike my first measures). Also, I need to measure with my mains running again to see what happens in the crossover region. I'm hoping the nulls above 80Hz in the graph posted here will be less problematic once the mains are factored in--we'll see.
(http://img.photobucket.com/albums/v442/chargedmr2/sub-locatedbetweenchairsbywindows_zpsea5580fb.jpg:original)
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On the EQ, you mentioned earlier in the thread you were running a Denon AVR, although not which model. Some Denon AVRs (4311 for sure, don't know about others), have an option to bypass Audessey to the left and right spreaker. For stereo sources this would only EQ the SUB, not the mains. I ran this way quite a while with good results. If you happen have the 4311, Audessey XT32 is quite good for subwoofer EQ.
Just something to try, since it may not cost you anything if your AVR has that function.
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Gzerro,
Thanks for the tip--I was wondering about that exact issue. I was thinking that I could try out Audyssey for the sub only, but wasn't sure if/how that was possible. Unfortunately, I have a lower line Denon AVR (3312) and it has XT, but not XT32. I'll double check to see if there is a way to disable Audyssey settings for my mains. In the end, the BFD is a reasonably priced EQ option, so that is what I'll plan to do for the long term solution.
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I have a denon 2113ci. I think DIRECT mode disables all processing and sends signal only to L/R (no subwoofer). PURE DIRECT is the same but turns off all video circuits. STEREO mode sends L/R and sub and applies processing (multieq and dynamic eq) unless you specifically go through some menus and turn it off.
Also keep in mind that the processing can normalize to a few curves - but the default is NOT flat.
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I have a denon 2113ci. I think DIRECT mode disables all processing and sends signal only to L/R (no subwoofer). PURE DIRECT is the same but turns off all video circuits. STEREO mode sends L/R and sub and applies processing (multieq and dynamic eq) unless you specifically go through some menus and turn it off.
Also keep in mind that the processing can normalize to a few curves - but the default is NOT flat.
That sounds correct to me. I currently use stereo mode with all processing disabled if I want the sub engaged. Otherwise, I use direct mode which disables all processing and bass management (i.e., the crossover). It's a quick and easy way to hear my SongTowers running full range without the sub. Hit the stereo button and the sub comes back to life with the crossover engaged.
Sounds like defeating the Audyssey settings for the L,R only isn't an option on this AVR (despite the type of curve that it applies). No big deal, for me. I'm pretty set on dedicated EQ for the sub.
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Gzerro,
Thanks for the tip--I was wondering about that exact issue. I was thinking that I could try out Audyssey for the sub only, but wasn't sure if/how that was possible. Unfortunately, I have a lower line Denon AVR (3312) and it has XT, but not XT32. I'll double check to see if there is a way to disable Audyssey settings for my mains. In the end, the BFD is a reasonably priced EQ option, so that is what I'll plan to do for the long term solution.
The 3312 does have the option to apply bypass Audyssey to the left and right mains - see advanced audyssey settings of your manual. Your graph is looking pretty good with the new placement. I think you might be surprised at the improvement.
That said, in the long run I can understand why you would want a stand alone solution, especially if you are considering an upgrade your front end electronics. It will open up alot of options for you.
Good luck!
Tom
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Wow - that is a much better in-room response curve! That will be easy to work with. As you mentioned, add in the speakers and measure again up to 200Hz and then you'll know where you add the EQ filters in REW. Speaking of which, I always manually add filters, as REW recommends way too many. The less filters the better. Based on your above response you should be able to get away with 3-5. You should be able to play with your current measurement in REW and manually add filters to follow the 24dB poctave response curve. Obviously you don't want to follow that curve when you add the speakers in, though, as it is meant to be EQd to only for the subwoofer running on its own. With the speakers added in it'll ideally be a nice straight line or a slight downward curve as you move higher in frequency.
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Hey, you might look into the Dspeaker Anti-mode Dual Core. I'm picking up a used one this week! :D
Here's the big AC thread, in case you missed it: http://www.audiocircle.com/index.php?topic=110377.0
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The 3312 does have the option to apply bypass Audyssey to the left and right mains - see advanced audyssey settings of your manual. Your graph is looking pretty good with the new placement. I think you might be surprised at the improvement.
That said, in the long run I can understand why you would want a stand alone solution, especially if you are considering an upgrade your front end electronics. It will open up alot of options for you.
Good luck!
Tom
Tom,
Thanks for this info--I haven't messed with Audyssey much, but I will check this out at least in the interim.
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Wow - that is a much better in-room response curve! That will be easy to work with. As you mentioned, add in the speakers and measure again up to 200Hz and then you'll know where you add the EQ filters in REW. Speaking of which, I always manually add filters, as REW recommends way too many. The less filters the better. Based on your above response you should be able to get away with 3-5. You should be able to play with your current measurement in REW and manually add filters to follow the 24dB poctave response curve. Obviously you don't want to follow that curve when you add the speakers in, though, as it is meant to be EQd to only for the subwoofer running on its own. With the speakers added in it'll ideally be a nice straight line or a slight downward curve as you move higher in frequency.
I definitely breathed a sigh of relief after measuring in the new location. It was a lot of work moving that sub around and given my limited flexibility, I was pretty worried that I would be stuck with some horrible nulls in the frequency response. I'll do some more measuring this coming weekend and I'll post back for advice.
Thanks
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Hey, you might look into the Dspeaker Anti-mode Dual Core. I'm picking up a used one this week! :D
Here's the big AC thread, in case you missed it: http://www.audiocircle.com/index.php?topic=110377.0
Thanks for the link--I've not seen this product, so I'll take a look when I get a chance.
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Wow - that is a much better in-room response curve! That will be easy to work with. As you mentioned, add in the speakers and measure again up to 200Hz and then you'll know where you add the EQ filters in REW. Speaking of which, I always manually add filters, as REW recommends way too many. The less filters the better. Based on your above response you should be able to get away with 3-5. You should be able to play with your current measurement in REW and manually add filters to follow the 24dB poctave response curve. Obviously you don't want to follow that curve when you add the speakers in, though, as it is meant to be EQd to only for the subwoofer running on its own. With the speakers added in it'll ideally be a nice straight line or a slight downward curve as you move higher in frequency.
Nuance & TJHUB -
I finally got around to measuring my sub in its new location along with both of the mains. As you can see there is a pretty notable dip around 110Hz and just before 200Hz there is a huge dip. Are these dips less serious from practical listening standpoint than, say, a large dip around 30Hz (like I used to have in my first sub location)??
Nuance, I didn't quite get what you were saying the first time I read your comments here, but I now see that I can use REW to predict my frequency response should certain filters be applied. I still don't know how to do that, but I will do some more learning soon.
(http://img.photobucket.com/albums/v442/chargedmr2/subplusmains-subbetweenchairsbywindows_zpsbb050bfa.jpg)
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^ Send me your mdat file (your REW file) and I'll work it to show you the predicted response. I can also tell you the exact filters I used so that when you do get your EQ you can just enter them in, remeasure and see what you think.
The dip between 100 & 200Hz seems to be present in most measurements I've seen. Perhaps it is the floor/ceiling bounce that occurs? My measurements show the same thing, but like yours the dip is narrow so I wouldn't worry too much about it.
PM me and I'll give you my E-mail if you do want to send the mdat file.
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Thanks Nuance. I'll be home shortly and will forward the file along tonight. I appreciate your willingness to help out :thumb:
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Thanks for sending the file. This is a general idea of what you can achieve with REW and your EQ...
The top line is the original, the bottom is the predicted response:
(http://i401.photobucket.com/albums/pp94/iviustang50h/eqd_zps765e7fb2.jpg)
This is a snapshot of the EQ filters I applied:
(http://i401.photobucket.com/albums/pp94/iviustang50h/EQFilters_zps926f43cb.jpg)
And this is the predicted response again but also includes the predicted waterfall plot (it's hard to see the predicted vs. the actual because the graph used the same color):
(http://i401.photobucket.com/albums/pp94/iviustang50h/FR15-200_zpsf6986774.jpg)
You'll notice once the EQ has been applied the bass response is a bit quiter than the response above the crossover. All this means is that once you're finished applying the EQ and achieving the frequency response you desire you'll have to use the subwoofer output in the receiver (or the subwoofer gain on the sub itself) and turn it up a bit. Some people like the bass just as flat as the rest of the FR, but some prefer it a little hot; I fall into the latter camp, with my bass being 3-4dB hot for movies and music (below the crossover).
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If I may, I would suggest possibly leaving that response alone. The only thing I might consider doing to taking a few db off the 63Hz hump if and only if I heard an issue. If I did EQ the 63Hz area, I'd also add a wide 20hz filter to boost 20Hz for movies.
A lot of us with the TC Sounds drivers tend to run them a little hotter because they are so amazingly transparent. If you find yours is not ultra defined and transparent, you need to feed it a better signal.
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At the very least I would pull down the peaks at 37 and 63Hz. You need to be careful boosting down low, even if it isn't a null, but if your amplifier is powerful enough you should be fine. Just use caution.
Here is what it would look like with just 2 filters to pull down those peaks, and then one wide bandwidth filter to boost at 20hz (+7dB and 12 bandwidth):
(http://i401.photobucket.com/albums/pp94/iviustang50h/boost_zps0b6dd0ce.jpg)
You can obviously tweak to your hearts desire, but this gives you a rough idea of what you can achieve. The cool thing is use can use a variety of different methods in order to get where you want to be. :thumb:
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Guys,
Thanks so much for the help here. This has been a great learning experience, and I realize that there is so much more to study up on.
I have now figured out how to use the EQ filters in REW (thanks Nuance). What a great feature. I can also see that there are a number of ways to adjust the curve.
TJHUB - Do you feel that further processing the signal (via PEQ) is not necessarily worth the payoff of a flatter frequency response (in this case)? I realize that frequency response is somewhat overrated as compared to other issues caused by the room, but I'm curious to know just a little more about your thoughts here.
Would it be possible to bypass the EQ entirely for music, but engage it for movies? I like the idea of not having the signal go through multile rounds of DAC, but I will have to see how things turn out I guess.
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I wouldn't bypass the EQ for music at all. Not only will applying the PEQ filters flatten the response (which will be very noticable when listening), but it'll also reduce ringing/decay times. Win win.
TJHUB and I will agree to disagree on this one. :) Definitely pull those peaks down, and if your amp can handle it, experiment (with caution) with a boost at 20Hz. You won't regret it.
Edited for poor grammar.
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He's just flat out wrong! :)
I suppose the pun was intended :)
Well, I guess I will just have to experiment and see what works. I'm sure I will try out a bunch of different EQ options and from what I understand, the 1124p can save presets, so presumably I could have one curve for music and another for movies, etc?
Back to the EQ options...have either of you (or anyone else) heard much about the FBQ1000? It seems very similar to the 1124p, but I can't find much feedback (and there really is no pun intended here!) on it.
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I suppose the pun was intended :)
Well, I guess I will just have to experiment and see what works. I'm sure I will try out a bunch of different EQ options and from what I understand, the 1124p can save presets, so presumably I could have one curve for music and another for movies, etc?
Back to the EQ options...have either of you (or anyone else) heard much about the FBQ1000? It seems very similar to the 1124p, but I can't find much feedback (and there really is no pun intended here!) on it.
LOL - you caught my pun. :)
Yes, you can definitely have a curve for music and one for movies, which is one of the great things about getting a dedicated PEQ. You can apply whatever "curve" you want, or you can just EQ it flat and then adjust the subwoofer gain or subwoofer output on the receiver to your desired level. You'll have many options with a PEQ unit.
Regarding the difference between the 1124p and the FBQ1000, here is what Behringer said:
"Thank you for the enquiry.
The FBQ1000 and DSP1124P are basically the same, the FBQ1000 being the newer version to supersede the DSP1124P.
In parametric mode you can setup filters manually and fine tune the standard ISO frequency within a tuning range of 1/3 octave (in 1/60-octave steps), so you can have frequencies fairly close.
Hope that helps.
Kind regards,
Eddie
Your MUSIC Group Support Team"
SO it sounds like the FBQ is the DSP1124p's replacement. I say get the FBQ1000. Don't forget to pick up enough RCA to mono adapters when you're ready to connect it.
(http://www.knowzy.com/Images/American_Recorder-1-4_Inch_Male_Mono_To_Female_RCA_Adaptor.jpg)
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Perfect...that clears things up nicely. Thanks for inquiring.
I'm currently running an RCA to XLR cable to my amp, so I assume that I could just purchase a second very short XLR -> XLR cable to connect everything up.
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One more thought for those that EQ their sub(s). Has anyone given consideration to the Symetrix 551e? It's been long discontinued, but used ones are around (it seems to be recommended over at HTS forum). It's an analog PEQ with 5 bands and it has the ability to set filters as low as 10Hz.
Speaking of 10Hz, I was noticing how my measured response drops off sharply at 10Hz. I'm guessing that Denon uses a high pass filter? I don't think it's my amp.
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A $2500 sub and a good one at that being fed a signal that's run thru a Behringer. Why not just buy a booming sub and save yourself a lot of money. In other words. Good sub ruined by a piece made for the "pro" segment is the fastest road to regret. Good speakers and sub but S@@@ for electronics. Makes no sense to me. But, it's your money. Spend it as you see fit. Remember you get what you pay for.
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...You'll notice once the EQ has been applied the bass response is a bit quiter than the response above the crossover. All this means is that once you're finished applying the EQ and achieving the frequency response you desire you'll have to use the subwoofer output in the receiver (or the subwoofer gain on the sub itself) and turn it up a bit. Some people like the bass just as flat as the rest of the FR, but some prefer it a little hot; I fall into the latter camp, with my bass being 3-4dB hot for movies and music (below the crossover).
Hi Nuance. Didn't want to hijack the thread so I sent you a PM. Sorry for the odd subject line....my goof.
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A $2500 sub and a good one at that being fed a signal that's run thru a Behringer. Why not just buy a booming sub and save yourself a lot of money. In other words. Good sub ruined by a piece made for the "pro" segment is the fastest road to regret. Good speakers and sub but S@@@ for electronics. Makes no sense to me. But, it's your money. Spend it as you see fit. Remember you get what you pay for.
Of course I understand the principle that you raise, but are you speaking from experience? If so, can you elaborate on the sub and Behringer EQ that you have tested? What effect did it have on the sound quality, specifically?
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A $2500 sub and a good one at that being fed a signal that's run thru a Behringer. Why not just buy a booming sub and save yourself a lot of money. In other words. Good sub ruined by a piece made for the "pro" segment is the fastest road to regret. Good speakers and sub but S@@@ for electronics. Makes no sense to me. But, it's your money. Spend it as you see fit. Remember you get what you pay for.
With all due respect, your statement is ridiculous, and it doesn't match my and many other's experience. You have some sort of agenda here, and I recommend everyone just ignore it.
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I have an agenda? What would that be? :roll:
And from what I have read so far, I bet you don't hear any difference in components all things being equal.
The first thing I do to even out low end response is to buy two or more subs depending on the situation. Then if need be I go to dsp. As far as a flat response curve goes I wouldn't be boosting a 20hz signal as it requires the driver to make massive movement thus the x-max may run out of linear motion, bringing on high levels of distortion. Plus it makes hugh demands on your amp, consinquently shortening its life.
I would suggest a Dspeaker product 8033. I think the price is around $400 new. Sometimes they show up on A-gon used. A suggestion to the OP. Instead of moving your sub around ,try putting the sub as close to the listening spot or right in the chair and walk around the room to listen for the better/best place it sounds to you. Can save you a lot of time.
Btw, has the OP talked to Jim Salk about your problems. He may be able to be of immense help. Just a thought.
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I have an agenda? What would that be? :roll:
And from what I have read so far, I bet you don't hear any difference in components all things being equal.
The first thing I do to even out low end response is to buy two or more subs depending on the situation. Then if need be I go to dsp. As far as a flat response curve goes I wouldn't be boosting a 20hz signal as it requires the driver to make massive movement thus the x-max may run out of linear motion, bringing on high levels of distortion. Plus it makes hugh demands on your amp, consinquently shortening its life.
I would suggest a Dspeaker product 8033. I think the price is around $400 new. Sometimes they show up on A-gon used. A suggestion to the OP. Instead of moving your sub around ,try putting the sub as close to the listening spot or right in the chair and walk around the room to listen for the better/best place it sounds to you. Can save you a lot of time.
Btw, has the OP talked to Jim Salk about your problems. He may be able to be of immense help. Just a thought.
Harley,
I'm aware that two subs is generally better than one for in-room response, but I had a tough enough time convincing my wife that even one sub was necessary. So, I will be working with only one for now. My placement is also limited for similar reasons, but I tried all sorts of variations on the options I have. The current location is probably the best I will get, and actually isn't too bad from what I can tell so far. So, at this point I need to address my remaining issues with DSP, and live with the best result that I can get. No need to bother Jim, as I don't have any "problem." I'm just learning the best way to integrate this sub into my room with the help of others (probably the standard experience of sub owners...at least those that actually try to do it right).
My amp should be plenty capable of boosting the 20Hz range (within reason of course). In addition, I believe that this sub can also take the additional demand of boosting in this region (I think its reputation alone should put this concern to rest). Again, keeping in mind that I wouldn't try to add excessive boost to begin with.
The 8033 does like a nice product, but I was not really looking for an "automatic" solution (not that automatic is a bad thing). I'd prefer the additional flexibility afforded by other options, though I wouldn't mind trying one out at all.
Do you use one and have you had the chance to compare it to other options? I did find some good reviews over at Home Theater Shack.
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I have an agenda? What would that be? :roll:
And from what I have read so far, I bet you don't hear any difference in components all things being equal.
The first thing I do to even out low end response is to buy two or more subs depending on the situation. Then if need be I go to dsp. As far as a flat response curve goes I wouldn't be boosting a 20hz signal as it requires the driver to make massive movement thus the x-max may run out of linear motion, bringing on high levels of distortion. Plus it makes hugh demands on your amp, consinquently shortening its life.
I would suggest a Dspeaker product 8033. I think the price is around $400 new. Sometimes they show up on A-gon used. A suggestion to the OP. Instead of moving your sub around ,try putting the sub as close to the listening spot or right in the chair and walk around the room to listen for the better/best place it sounds to you. Can save you a lot of time.
Btw, has the OP talked to Jim Salk about your problems. He may be able to be of immense help. Just a thought.
Well, when you make a statement in the manner you did, with the tone you did, it makes it seem like you have an agenda. In this case, what could easily infer that this is your agenda: "Hey everybody, look at me. I need attention, and I am smarter than everyone so listen to me." :) If that wasn't how you intended to come across, perhaps you should have thought things through before posting. And then when you make foolish statements claiming I can or can't hear the difference between components...well, it's easy to write you off as someone with intentions to cause mischief. Again, it was your approach.
We already know you can smooth out the response with multiple subs. If you read the thread, you'd already know that the OP did have the sub in close proximity to the LP, and the low end response was poor. He tried different locations and found the best one to work with. There is nothing wrong with applying EQ below the Schroeder Frequency, something Floyd Toole and Sean Olive themselves are proponents of. It also doesn't matter that the Behringer is used in the pro audio arena. It does what it needs to and doesn't add additional noise or distortion to the signal chain.
Again I'll say, if you had actually read the thread you see that I warned the OP about boosting at 20Hz using a wide bandwidth filter, explaining it can cause amp clipping and possible driver damage. He is, however, using one of the best drivers available paired with a powerful amplifier. I know people who are boosting over 10dB at 20Hz using the same LMS driver with weaker amps in a larger room that have zero issues at reference levels. Circumstances are different for everyone, so experimentation is key. It is very possible that chargedmr2 will run into issues by using a wide bandwidth boost at 20Hz, but it is also possible he'll have no issues. Remember, he isn't boosting a null. So hey, why don't we let chargedmr2 weigh his options and make his own decisions, eh?
The 8033 is a decent unit, but it's not worth the extra $300 over the Behringer or MiniDSP unit. It won't sound any different between 20 and 100hz either.
Finally, in this audio hobby you most certainly do not always get what you pay for, so your statement is incorrect. I respect your opinions, but when you state them as fact and then make back handed critical comments towards others you come across as a troll. Calm down and share your options in a respectful manner, just like the rest of us.
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Well, when you make a statement in the manner you did, with the tone you did, it makes it seem like you have an agenda. (snip)
The 8033 is a decent unit, but it's not worth the extra $300 over the Behringer or MiniDSP unit. It won't sound any different between 20 and 100hz either.(snip)
Finally, in this audio hobby you most certainly do not always get what you pay for, so your statement is incorrect.
Your savings scenario has conveiniently left out the expense to buy all the other equipment you must also have on hand to incorporate the Behringer into your system.
For myself, I would have to buy a laptop plus a soundcard, if my laptop didn't have the correct inputs, plus a spl meter and then a microphone just to get started. Then after a few (hundred) hours of tweaking fun I might be able to get close to what my 8033 did duting the fifteen minutes I was in the shower. :P
For me the extra money for the DSpeaker was worth every penny.
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Your savings scenario has conveiniently left out the expense to buy all the other equipment you must also have on hand to incorporate the Behringer into your system.
For myself, I would have to buy a laptop plus a soundcard, if my laptop didn't have the correct inputs, plus a spl meter and then a microphone just to get started. Then after a few (hundred) hours of tweaking fun I might be able to get close to what my 8033 did duting the fifteen minutes I was in the shower. :P
For me the extra money for the DSpeaker was worth every penny.
Thanks for the info. Which particular 8033 are you using?
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Your savings scenario has conveiniently left out the expense to buy all the other equipment you must also have on hand to incorporate the Behringer into your system.
For myself, I would have to buy a laptop plus a soundcard, if my laptop didn't have the correct inputs, plus a spl meter and then a microphone just to get started. Then after a few (hundred) hours of tweaking fun I might be able to get close to what my 8033 did duting the fifteen minutes I was in the shower. :P
For me the extra money for the DSpeaker was worth every penny.
I agree but there are some point that others may argue.
1. A lot of people already got a laptop.
2. Is there a way to see the outcome before and after the work of the 8033???
3. Maually adjustment - The feature that a lot of guys find usefull.
Enough to said, I love auto ARC and really want to try the new dsp 2.0 for the sake of convenience but for the cost and the ability to maually adjust of the Behringer and Rew combo is still hard to beat.
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Your savings scenario has conveiniently left out the expense to buy all the other equipment you must also have on hand to incorporate the Behringer into your system.
For myself, I would have to buy a laptop plus a soundcard, if my laptop didn't have the correct inputs, plus a spl meter and then a microphone just to get started. Then after a few (hundred) hours of tweaking fun I might be able to get close to what my 8033 did duting the fifteen minutes I was in the shower. :P
For me the extra money for the DSpeaker was worth every penny.
True, but in this instance the OP already has all of that, which I already knew, hence my recommendation. After all, he did take and post measurements, so we already knew he had REW and all the hardware necessary. For an all-in-one solution there are better options than the MiniDSP or Behringer, of course. 100's of hours of tweaking is a bit of an exaggeration; it's more like 2 hours.
I am glad the 8033 is working well for you. :thumb:
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True, but in this instance the OP already has all of that, which I already knew, hence my recommendation. After all, he did take and post measurements, so we already knew he had REW and all the hardware necessary. For an all-in-one solution there are better options than the MiniDSP or Behringer, of course. 100's of hours of tweaking is a bit of an exaggeration; it's more like 2 hours.
I am glad the 8033 is working well for you. :thumb:
Can you help me with the better options for an all-in-one solution?
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Does the Velodyne SMS over on Agon for 250 work for this option. I may have missed somethings, but at 250, could be a steal and a low cost fix. Feel free to berate me..or flog..
Jon
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Thanks for the info. Which particular 8033 are you using?
I have the 8033SII.
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I have the 8033SII.
Thanks "bob". 8)
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In case anyone is interested here is the unit that I will experiment with first, and hopefully keep if all goes well.
(http://img.photobucket.com/albums/v442/chargedmr2/image_zps7b2907f2.jpg)
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Nice, it would be better if it has phase adjustment.
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I don't know if you can adjust the input level of your receiver with that, but it looks pretty nice.
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Austin08 - I figured I will try to adjust for phase issues in the crossover area by using the distance settings on the AVR. Maybe it's more complex than this?
Nuance - were you thinking I might run into issues where the signal is clipped by the EQ or just that the signal from the AVR may not be strong enough for the EQ?
Actually, I keep going back and forth about what I want to try out, but will likely try more than one EQ in the end and stick with the best solution.
I read an really interesting EQ myth document put together by Rane and it suggests that proper EQ requires more than just creating a flat response with a few filters (maybe the five filters of the PE17 is not enough for my situation) Here is a quote from their site:
"MYTH #6: An ideal equalizer would add no phase shift when boosting or cutting.
Phase shift is not a bad word. It is the glue at the heart of what we do, holding everything together. That it has become a maligned term is most unfortunate. This belief stands in the way of people really understanding the requirements for room equalization.
The frequency response of most performing rooms looks like a heart attack victim's EKG results. Associated with each change in amplitude is a corresponding change in phase response. Describing them as unbelievably jagged is being conservative. Every time the amplitude changes so does the phase shift. In fact, it can be argued that phase shift is the stuff that causes amplitude changes. Amplitude, phase and time are all inextricably mixed by the physics of sound. One does not exist without the others.
An equalizer is a tool. A tool that allows you to correct for a room's anomalies. It must be capable of reproducing the exact opposite response of the one being connected. This requires precise correction at many neighboring points with the associated phase shift to correct for the room's opposing phase shift. It takes phase shift to fix phase shift. Simple as that.
One way people get into trouble when equalizing rooms is using the wrong type of equalizer. If an equalizer is not capable of adding the correct amount of phase shift, it will make equalizing much more difficult than it has to be. The popularity of the many constant-Q designs has come about because of this phenomenon. Equalizers that produce broad smooth curves for modest amounts of boost/cut make poor room equalizers, and good tone modifiers. They lack the ability to make amplitude and phase corrections close together. Lacking the ability to make many independent corrections with minimal interference to neighboring bands restricts their usage primarily to giving a shape to an overall response rather than correcting it. Serious correcting requires sharp constant-Q performance, among many other things.
Only by adding many precise, narrow phase shift and amplitude corrections do you truly start equalizing a system's blurred phase response. You do not do it with gentle smooth curves that lack the muscle to tame the peakedness of most rooms. Broad smooth curves do not allow you to correct for the existing phase shift. Its just that simple, you must pre-shape the signal in both amplitude and phase. And that requires narrow filters that preserve their bandwidths at all filter positions."
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chargedmr2,
What I meant was, if the subwoofer output on the receiver is set too high and clips, that clipped signal will be sent all the way down the chain to the subwoofers. Not good. The point of setting the input level of the receiver is to prevent this.
I just PM'd you the process.
As to the phase topic, the article tidbits you quoted sound correct to me. The nice thing about REW is it shows the phase changes when you apply EQ. That's why I prefer to use it paired with something like the MiniDSP or Behringer 1124p or 2496; the options and features are almost limitless. 8)
Edit: Others have expressed interest in how to set the input level of the receiver/preamp using the Behringer EQ's, so I will post the link here publicly. Scroll down to the section that states "Setting The Input Levels On The BFD."
http://www.hometheatershack.com/forums/bfdguide/
The point of this is to prevent sending a clipped signal from the receiver to the subwoofers. Once setting the input level is complete, you'd apply EQ. After that is finished you'll likely need to raise the subwoofer output level because it'll be a lot quieter than what it was. You need to use the gain knob on the subwoofer amp in order to do this; do notadjust the subwoofer output using the receiver or preamp, as you will be nullifying the process you just completed of setting the input level of the receiver/preamp.
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Nuance,
That's basically what I thought you were referring to and it does make good sense. The Rane has an adjustable input and output that can be set via sliders. After looking at the spec sheet, I don't think there will be concern over clipping the input. Here is a link to the specs--let me know what you think: http://www.rane.com/pdf/old/pe17dat2.pdf (http://www.rane.com/pdf/old/pe17dat2.pdf)
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^Sweet! Keep us posted.
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My EQ should arrive on Friday, so it should be an interesting weekend! I did mess around with Audyssey for automatically EQing the sub (but then disabling Audyssey for the mains). I really did not like what it did. It fixed some issues but created a curve that was overall unacceptable.
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I figured I'd post a brief update about the Rane EQ that I ended up purchasing. First, I ended up with a damaged unit on the first time around, but the seller replaced it and all is well at this point. The unit is fully analog, so the adjustments all take place via dials which makes precision a little difficult, but with patience it works quite well. To make adjustments, I eliminated the room effects by looping the output of the unit back into the mic input of my extreranl soundcard. I used this method to set each filter to the precise frequency needed. After that I adjusted bandwidth and cut/boost according to the dials and did some measuring, followed by fine tuning. I was able to produce a much better frequency response below 80Hz.
I did run into one problem, which has nothing to do with the EQ or the sub. I was not able to eliminate my peak (fully) that occurs around 63Hz. Turns out this is caused by my SongTowers, despite the fact that they are crossed over at 80Hz. I still need to reduce this peak by about 5dbs, but am at a loss as to what, if anything, I can do. I measured around my listening position, and also moved my STs within the limits I have and the peak remains. Any ideas for a solution? Large bass traps are not an option either. Also, I'm not sure if running an EQ on the mains is a good idea. I wish the crossover was steeper, as that might have been enough to further reduce the peak as the STs roll off to the sub. I may just have to live with it for now.
Otherwise, I find that the sound is definitely improved in the lower frequencies. Overall, the bass is a little less boomy and doesn't appear to overtake/drown out upper frequencies as much as before. Hard to explain really, but I like the changes as opposed to leaving the signal untreated. And this EQ adds zero perceived noise to the signal and no issues with buzz/hum either.
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I have two possible suggestions for the peak. I am not sure how well the Master Set procedure works as even though I use it my self. I haven’t taken the measurements to confirm their effect. I know that subjectively it seems to work for me. Speaker movements as small as ¼” in the placement of the speakers seem to have large effects on the peaks and dips. I would think that getting the SongTowers as flat as they can be before you use your equalizer might be of benefit. Looking at your pictures, the master set position should be near where your speakers already are.
http://www.audiocircle.com/index.php?topic=64320.0 (http://www.audiocircle.com/index.php?topic=64320.0)
http://www.audiocircle.com/index.php?topic=65908.0 (http://www.audiocircle.com/index.php?topic=65908.0)
Another possibility that you might try that would be easier would just be to plug up the bass ports on the SongTowers. Just another guess.
Bob
Edit: Salk speakers are designed to sound great without toe in so the last master step procedure is probably not necessary.
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I figured I'd post a brief update about the Rane EQ that I ended up purchasing. First, I ended up with a damaged unit on the first time around, but the seller replaced it and all is well at this point. The unit is fully analog, so the adjustments all take place via dials which makes precision a little difficult, but with patience it works quite well. To make adjustments, I eliminated the room effects by looping the output of the unit back into the mic input of my extreranl soundcard. I used this method to set each filter to the precise frequency needed. After that I adjusted bandwidth and cut/boost according to the dials and did some measuring, followed by fine tuning. I was able to produce a much better frequency response below 80Hz.
I did run into one problem, which has nothing to do with the EQ or the sub. I was not able to eliminate my peak (fully) that occurs around 63Hz. Turns out this is caused by my SongTowers, despite the fact that they are crossed over at 80Hz. I still need to reduce this peak by about 5dbs, but am at a loss as to what, if anything, I can do. I measured around my listening position, and also moved my STs within the limits I have and the peak remains. Any ideas for a solution? Large bass traps are not an option either. Also, I'm not sure if running an EQ on the mains is a good idea. I wish the crossover was steeper, as that might have been enough to further reduce the peak as the STs roll off to the sub. I may just have to live with it for now.
Otherwise, I find that the sound is definitely improved in the lower frequencies. Overall, the bass is a little less boomy and doesn't appear to overtake/drown out upper frequencies as much as before. Hard to explain really, but I like the changes as opposed to leaving the signal untreated. And this EQ adds zero perceived noise to the signal and no issues with buzz/hum either.
So you mean the peak is there when xover at 80hz and with not sub?
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So you mean the peak is there when xover at 80hz and with not sub?
Same question from me. If the peak is being caused by the speakers it should go away (or at least be able to be EQ'd down) when crossed to the subs, unless you're still running them full range and you don't know it, or if the slope is not steep at all. It is possible to run the mains full range and also add in the subs; I just don't recommend doing that with SongTower's. Double check to ensure the high and low pass are actually in effect.
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Unfortunately the filters are in effect. At first, when I began measuring and adjusting the EQ for the sub, I thought the EQ just wasn't cutting the frequency enough. The peak did come down, but not by the amount that it should have based on the settings. Further cutting made no difference. This is when I measured the STs without the sub (with the 80hz crossover engaged-not full range) and found that they were the cause of the remaining peak. The crossover has a common 12/24 slope, which I assume is fine in most situations, but it doesn't seem effective when you have a giant peak just 10-20Hz below the crossover point (if I remember correctly, this slope would be down 12db by 40Hz, but only around 3-6db between 60 and 70Hz).
I'll try to post some graphs later to show what is happening visually.
It's not an option at the moment, but in the future when I run a separate amp for the mains, would putting an inline crossover before the amp input be a bad idea for the mains. I'm not sure if these would be transparent enough, or what a good one would even cost. Just thinking out loud...
Edit to add: I just took a look at my Denon 3312's EQ options. I didn't like what Audyssey did when I experimented with it a while back, plus I really don't want to EQ my mains. I did notice, however, that there is an Audyssey setting for "manual" EQ. Does anyone know what this function does? I know that it allows me to cut and/or boost certain preset frequencies, but does this engage any other Audyssey based corrections? It just so happens that one of the frequencies available for adjustment is 63Hz. That is almost exactly where my peak occurs (63.4Hz). Any thoughts as to whether this would be a good solution? Are there any concerns that I should be aware of? I'll try to dig up some info on Audyssey "manual" mode.
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So you have a peak at 63Hz even with the subwoofer off when the crossover is set and engaged at 80Hz? How does that work? It sounds like the crossover isn't working.
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try pluging the port of the mains to see if the ports are not causing a room mode.
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Ricardojoa- My STs are front ported, so it would be a bit unsightly to plug them. I'll experiment to see what happens though.
Nuance- Maybe something is up with the crossover, but I think the peak is just a room effect showing through. If I'm understanding the way the crossover should be working, it means the mains begin to roll off at 80Hz. The slope of the crossover is such that the mains should be down 12db by 40Hz. Since the peak is at located between 63-70Hz, the mains are down by less than 6db at this point. Thus, the peak is reduced by the crossover, but in this case, not by enough to eliminate it. Am I thinking about this correctly? Actually, the crossover, might be down 3db at 80Hz and then slopes further down from there, but I can't remember for sure.
At any rate, let me know what you think based on the graph below:
No Smoothing, top line has sub engaged, bottom line is just the ST's with the crossover set to 80Hz and engaged (unless something mysterious is happening).
(http://img.photobucket.com/albums/v442/chargedmr2/60to70hzpeakissue_zps638b9d03.jpg~original)
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I see. You could still cover the ports for testing and eliminate all the possibilities. Keep in mind that though the fronts are HP, there would still be bass comming from the ports.
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I see. You could still cover the ports for testing and eliminate all the possibilities. Keep in mind that though the fronts are HP, there would still be bass comming from the ports.
It's a room mode and messing with the ports will do nothing positive. Besides, I'm fairly certain the ports are tuned far below the 63Hz area, so plugging them makes no sense.
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The response is quite different between 60 and 80Hz when comparing each graph, so the crossover and subwoofer integration is working. Try reversing phase and see if anything happens (it'll likely effect nearer to 80Hz, but it's worth a shot). Is the slope adjustable?
Room modes can be EQ'd, so something is still amiss. Are you sure you're applying a 80Hz crossover and not a 60? What is the bandwidth of the cut filter you applied to the 63Hz peak? I'd use a 24dB slope if you aren't already and I'd try reapplying the EQ cut after you've ensured the slope and crossover frequency. Setting the crossover alone doesn't mean peaks will automatically go away, but then you should be able to apply PEQ to the subwoofer at that frequency once the crossover transition is applied successfully.
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Nuance - I did try reversing phase as an earlier solution, but the change did not affect the peak. Also, I'm using a Denon 3312 for the mains and it doesn't have an adjustable crossover (that I'm aware of). So I'm stuck with the 12db slope for now.
I agree that the room mode can be EQed, but since it's caused by the mains, my sub EQ is of no use. It's already set to cut the maximum amount (15dbs) at 63.4Hz. I will try using the graphic EQ that is built into my AVR to see if that can help. I was able to confirm that when Audyssey is set to manual mode, it simply acts as a graphic EQ and does not apply any of the Audyssey corrections from the measurement procedure. If this works out I'll repost the frequency response.
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It's a room mode and messing with the ports will do nothing positive. Besides, I'm fairly certain the ports are tuned far below the 63Hz area, so plugging them makes no sense.
There is nothing wrong to plug the port for the SAKE of TESTING. Pluging the ports can make the fronts to roll much ealier naturally, essentially taking unwanted bass. Chargedm2 could try or not, Im just giving a suggestion. And by the way, even if the port are tuned far below 63hz, doesnt mean there is no information comming from them, even if it is HP.
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Nuance - I did try reversing phase as an earlier solution, but the change did not affect the peak. Also, I'm using a Denon 3312 for the mains and it doesn't have an adjustable crossover (that I'm aware of). So I'm stuck with the 12db slope for now.
I agree that the room mode can be EQed, but since it's caused by the mains, my sub EQ is of no use. It's already set to cut the maximum amount (15dbs) at 63.4Hz. I will try using the graphic EQ that is built into my AVR to see if that can help. I was able to confirm that when Audyssey is set to manual mode, it simply acts as a graphic EQ and does not apply any of the Audyssey corrections from the measurement procedure. If this works out I'll repost the frequency response.
Bummer.
So how is it that the peak is higher/larger with the subwoofer engaged than without it? If I look at the response from 90Hz and above it appears you didn't change the volume, so if the peak was caused only by the speakers why did it increase when you put the subwoofer into the mix? They shouldn't be overlapping that much at 63Hz unless the mains are still running full range. Weird...
It is possible that all the positions you've tried the speakers in are still causing the peak. Try measuring the speakers full range with no crossover engaged, then set the crossover and measure them again. Don't change anything but the crossover implementation, then post the graph here. Your Denon should allow differing crossover points, so try 90 or 100Hz as well and see if you're able to EQ the peak. If not then something is wrong. Oh, and this might go without saying, but be sure your speakers are set to "small" on the receiver.
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What is the distance from your floor to your ceiling? Keep in mind that at the frequencies involved, you are not only measuring the speakers, but the room as well (you probably knew this).
- Jim
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Bummer.
So how is it that the peak is higher/larger with the subwoofer engaged than without it? If I look at the response from 90Hz and above it appears you didn't change the volume, so if the peak was caused only by the speakers why did it increase when you put the subwoofer into the mix? They shouldn't be overlapping that much at 63Hz unless the mains are still running full range. Weird...
It is possible that all the positions you've tried the speakers in are still causing the peak. Try measuring the speakers full range with no crossover engaged, then set the crossover and measure them again. Don't change anything but the crossover implementation, then post the graph here. Your Denon should allow differing crossover points, so try 90 or 100Hz as well and see if you're able to EQ the peak. If not then something is wrong. Oh, and this might go without saying, but be sure your speakers are set to "small" on the receiver.
I'll give this suggestion a try--I think I did this already, but I didn't save the graph. I also tried different crossover points up to 120Hz and the peak decreased a couple db, but did not disappear entirely.
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What is the distance from your floor to your ceiling? Keep in mind that at the frequencies involved, you are not only measuring the speakers, but the room as well (you probably knew this).
- Jim
Hi Jim,
The ceilings are 10ft high.
Yes, this is definitely all room effects. I did take some close-up measures of my sub and the response looks absolutely perfect. And it's been a while, but I have also taken close-up measures of my SongTowers--of course they too measure beautifully. So, I hope I am not detracting from Salk speakers by posting the effects of my room on them. I should also mention that things are sounding very good, and I'm really enjoying the learning and experimentation.
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OK, I applied a 6db cut at 63Hz to my main speakers (via my AVR in manual EQ mode). As I expected, this solved the problem. Here are my latest measurements, all taken with my mains crossed to the sub at 80Hz, just as before (Nuance, I didn't take the measures you were looking for since things appear better now):
No smoothing applied (+/- 3db from 10Hz through 80Hz):
(http://img.photobucket.com/albums/v442/chargedmr2/subfrequencies-finaleqapplied-nosmoothing_zps71425b46.jpg~original)
Same measure with 1/6 smoothing applied:
(http://img.photobucket.com/albums/v442/chargedmr2/subfrequencies-finaleqapplied-1-6smoothing_zps9044df91.jpg~original)
And here is the full range measure with 1/3 smoothing applied:
(http://img.photobucket.com/albums/v442/chargedmr2/fullrangemeasure-eqsuccessfullyapplied_zpse81ce449.jpg~original)
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15-200Hz looks fantastic now - congrats! I would leave it alone and move your focus to the area between 300 and 5000Hz. Although, I still think something is wrong if even moving the crossover to 100Hz didn't do anything. It still seems as if the crossover simply isn't working, but if it looks and sounds good...
I know you probably don't want to use EQ on the speakers above the Schroeder Frequency, and I am not a proponent of it, but if moving the speakers around a bit doesn't fix 300Hz-5KHz, you may want to give it a shot and see if it sounds better (it should).
Happy listening!
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Although, I still think something is wrong if even moving the crossover to 100Hz didn't do anything. It still seems as if the crossover simply isn't working, but if it looks and sounds good...
I agree that my results aren't immediately intuitive. The peak actually was reduced by small amounts when moving the crossover progressing from 80 to 120Hz, so the crossover was doing something for sure. But I see your point...why would the peak remain at all if the crossover was moved up substantially? I'll find some time to take more measures and solve this mystery once and for all.