Custom Sub Arrived

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chargedmr2

Re: Custom Sub Arrived
« Reply #20 on: 23 Mar 2013, 05:52 pm »
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.

chargedmr2

Re: Custom Sub Arrived
« Reply #21 on: 23 Mar 2013, 05:54 pm »
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:

chargedmr2

Re: Custom Sub Arrived
« Reply #22 on: 23 Mar 2013, 06:09 pm »
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. 

rajacat

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Re: Custom Sub Arrived
« Reply #23 on: 23 Mar 2013, 06:37 pm »
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

neekomax

Re: Custom Sub Arrived
« Reply #24 on: 23 Mar 2013, 08:04 pm »
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

ctviggen

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Re: Custom Sub Arrived
« Reply #25 on: 23 Mar 2013, 08:05 pm »
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. 

TJHUB

Re: Custom Sub Arrived
« Reply #26 on: 23 Mar 2013, 09:27 pm »
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. 


Austin08

Re: Custom Sub Arrived
« Reply #27 on: 23 Mar 2013, 10:06 pm »
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.

chargedmr2

Re: Custom Sub Arrived
« Reply #28 on: 23 Mar 2013, 10:41 pm »
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.

chargedmr2

Re: Custom Sub Arrived
« Reply #29 on: 23 Mar 2013, 10:45 pm »


+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. 

TJHUB

Re: Custom Sub Arrived
« Reply #30 on: 23 Mar 2013, 11:22 pm »
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.   

chargedmr2

Re: Custom Sub Arrived
« Reply #31 on: 24 Mar 2013, 12:51 am »
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!):


And here is the original graph with 1/3 smoothing applied (this had the mains running as well):


TJHUB

Re: Custom Sub Arrived
« Reply #32 on: 24 Mar 2013, 03:07 am »
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. 


TJHUB

Re: Custom Sub Arrived
« Reply #33 on: 24 Mar 2013, 03:16 am »
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. 


chargedmr2

Re: Custom Sub Arrived
« Reply #34 on: 24 Mar 2013, 03:30 am »
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. 

TJHUB

Re: Custom Sub Arrived
« Reply #35 on: 24 Mar 2013, 03:42 am »
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. 

chargedmr2

Re: Custom Sub Arrived
« Reply #36 on: 24 Mar 2013, 07:28 pm »
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.

Saturn94

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Re: Custom Sub Arrived
« Reply #37 on: 24 Mar 2013, 07:38 pm »
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.


Hmmmm...can't see the pic. :scratch:

chargedmr2

Re: Custom Sub Arrived
« Reply #38 on: 24 Mar 2013, 07:53 pm »
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...

Saturn94

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Re: Custom Sub Arrived
« Reply #39 on: 25 Mar 2013, 12:04 am »
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: