SongTowers FR Question (not flat from 1k-20khz) with RoomEQ

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audiocrazy

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #20 on: 10 Jun 2009, 05:28 am »
Frankly, if I were Audiocrazy, I would feel a little ganged up on at this point.  I'm sure he's following the measurement instructions as best he can, and he's getting results that look problematic.  So I really want to be as constructive as possible.  I would be very interested to see separate measurements of each ST in the same position.   That should at least cast light on the tweeter polarity issue.   That leaves the droop in the response at higher frequencies.   Audiocrazy--where are you located?  I would be happy to send you a small, light 2-way that you could measure to see whether you get results anything like mine.  It's difficult to make any progress unless there is a known reference point
Dennis I'm located in Minneapolis, MN.
Sorry I did not mean to start a flame  :oops: but I'm trying to figure out if there is something wrong in my setup.
I took measurments of speakers individually and here is the graph.
I'll add more details tomorrow morning. Gotta go to work.

Red Line is Right Speaker
Green line is left speaker


fsimms

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #21 on: 10 Jun 2009, 01:18 pm »
I have trouble believing that chart.  It shows the SongTowers have a peak at 18 Hz!!!!  I didn't know they were that good!  :lol: :lol: :lol: 

A flat speaker would bedown about 10 db at the listening position at 20 kHz.  According to Jim's chart the SongTowers are down 5 db at 20 kHz.  The chart shows a drop of 20 db which is about 5 db worse than would expected.

Edit.  I expect the chart is shifted to the left due to the speed of your computer.  You are probably seeing the drop at the right at 30 or 40 kHz.

DMurphy

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #22 on: 10 Jun 2009, 01:28 pm »
Frankly, if I were Audiocrazy, I would feel a little ganged up on at this point.  I'm sure he's following the measurement instructions as best he can, and he's getting results that look problematic.  So I really want to be as constructive as possible.  I would be very interested to see separate measurements of each ST in the same position.   That should at least cast light on the tweeter polarity issue.   That leaves the droop in the response at higher frequencies.   Audiocrazy--where are you located?  I would be happy to send you a small, light 2-way that you could measure to see whether you get results anything like mine.  It's difficult to make any progress unless there is a known reference point

Ok Dennis, time to "gang up" on you.  :P

I may be wrong, but I don't think it's possible to reverse the polarity of one tweeter and have it cancel out the other tweeter above say...3kHz?  Audiocrazy's measurement should have nothing to do with tweeters out of phase.

I certainly wasn't trying to "gang up" on him, but I'm telling you without any doubt that his REW setup is not correct.  I'd suggest he post that graph pic on hometheatershack and let the pros (Bruce and Wayne) get audiocrazy fixed up.  I can assure you that his measurement will look as it should and all the speculation contained in this thread can be concluded.  :wink:

Hoooookay--time to gang back.  I wasn't claiming one tweeter would cancel out another.  Reversing the polarity on one tweeter, or both, will cause a suckout in the crossover region, because the woofer and tweeter are supposed to be perfectly in phase at that point.  if you flip the polarity, they cancel in the region of 2-3 khz, which is why I suggested there might be a problem.  I wasn't referencing the droop further up.  That looks more like a mic calibration problem. 

DMurphy

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #23 on: 10 Jun 2009, 01:36 pm »
Dennis I'm located in Minneapolis, MN.
Sorry I did not mean to start a flame  :oops: but I'm trying to figure out if there is something wrong in my setup.
I took measurments of speakers individually and here is the graph.
I'll add more details tomorrow morning. Gotta go to work.

Red Line is Right Speaker
Green line is left speaker


[/quote]

Hmmmmmm.   Thanks for doing that, but it's difficult to believe you have the speakers in the same position.  There are just too many differences in the specific and overall frequency response to be explained by crossover issues or driver variation.  If you do have them in the same position, then I would have to agree with others that there is something off in the calibration or measuring technique.

TJHUB

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #24 on: 10 Jun 2009, 03:23 pm »
Frankly, if I were Audiocrazy, I would feel a little ganged up on at this point.  I'm sure he's following the measurement instructions as best he can, and he's getting results that look problematic.  So I really want to be as constructive as possible.  I would be very interested to see separate measurements of each ST in the same position.   That should at least cast light on the tweeter polarity issue.   That leaves the droop in the response at higher frequencies.   Audiocrazy--where are you located?  I would be happy to send you a small, light 2-way that you could measure to see whether you get results anything like mine.  It's difficult to make any progress unless there is a known reference point

Ok Dennis, time to "gang up" on you.  :P

I may be wrong, but I don't think it's possible to reverse the polarity of one tweeter and have it cancel out the other tweeter above say...3kHz?  Audiocrazy's measurement should have nothing to do with tweeters out of phase.

I certainly wasn't trying to "gang up" on him, but I'm telling you without any doubt that his REW setup is not correct.  I'd suggest he post that graph pic on hometheatershack and let the pros (Bruce and Wayne) get audiocrazy fixed up.  I can assure you that his measurement will look as it should and all the speculation contained in this thread can be concluded.  :wink:

Hoooookay--time to gang back.  I wasn't claiming one tweeter would cancel out another.  Reversing the polarity on one tweeter, or both, will cause a suckout in the crossover region, because the woofer and tweeter are supposed to be perfectly in phase at that point.  if you flip the polarity, they cancel in the region of 2-3 khz, which is why I suggested there might be a problem.  I wasn't referencing the droop further up.  That looks more like a mic calibration problem.

Ha ha!  :D  Thank goodness I was misunderstanding you because for a little while there, I was really disappointed in you. :P

Again, audiocrazy's REW setup is not correct.  The mic calibration is definitely wrong and the sound card calibration looks strange as well.  I wish I could help, but the bad thing about REW is that it is far from easy to setup your first time through.  I've set it up twice now and each time it's like starting all over again.  I want a new laptop, but the fact that I'd have to reinstall REW makes me live with what I've got.  Seriously!

Audiocrazy:

I think you should start by downloading the latest mic calibration file from hometheatershack for your ECM8000 and load it into your REW software.  That calibration file you have right now looks way off.  I wouldn't worry too much about the soundcard calibration for now.  It really doesn't affect the issue you've got going on right now anyway.   

jsalk

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #25 on: 10 Jun 2009, 03:57 pm »

I think you should start by downloading the latest mic calibration file from hometheatershack for your ECM8000 and load it into your REW software. 

Keep in mind that the ECM8000 calibration file on that site is a generic one.  To be accurate, each individual ECM8000 requires a calibration file for that individual mic.  The generic file will get you close, but it will not be totally accurate.

- Jim

TJHUB

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #26 on: 10 Jun 2009, 04:46 pm »

I think you should start by downloading the latest mic calibration file from hometheatershack for your ECM8000 and load it into your REW software. 

Keep in mind that the ECM8000 calibration file on that site is a generic one.  To be accurate, each individual ECM8000 requires a calibration file for that individual mic.  The generic file will get you close, but it will not be totally accurate.

- Jim

That is true Jim, but there is no way the generic file is as far off as what audiocrazy's graph is showing.  I'm fairly certain all of the mics tested for the calibration file proved pretty close (or close enough for home use).  We're not discussing a few db's here, we're talking over 20db.  It is obvious to me what the issue is, apparently not so for the rest of you...

Good luck with findings audiocrazy, I'm fairly certain everything is just fine with your speakers and you should sit back and enjoy your Salk's by listening to music instead of frequency sweeps.


audiocrazy

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #27 on: 10 Jun 2009, 06:33 pm »
Hmmmmmm.   Thanks for doing that, but it's difficult to believe you have the speakers in the same position.  There are just too many differences in the specific and overall frequency response to be explained by crossover issues or driver variation.  If you do have them in the same position, then I would have to agree with others that there is something off in the calibration or measuring technique.
Dennis you are right I took the measurement at listening position and did not move the speaker to same location.  I'll do that when I get a chance. I'm tied up at work and will be travelling.

Keep in mind that the ECM8000 calibration file on that site is a generic one.  To be accurate, each individual ECM8000 requires a calibration file for that individual mic.  The generic file will get you close, but it will not be totally accurate.
- Jim
Jim you are right I should get my mic calibrated to get accurate results.

I agree that REW graphs does not tell the full story and I've confirmed that when I added SVS AS-EQ1. The REW graph looked almost similar to what I had using Audyssey EQ. But it sounded much different. Nevertheless I've followed the REW instructions to the T and have consulted BruceK and Wayne several times when I was learning to use REW.

Jim and Dennis I really apologize if I have offended you in anyway  :oops:. My intent was trying to figure out if there was any issue in my setup.
All in all I am very happy with my ST's :inlove:. I value the efforts and dedication Jim and Dennis :thankyou: takes in building such nice speakers.

DMurphy

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #28 on: 10 Jun 2009, 07:37 pm »
Hmmmmmm.   Thanks for doing that, but it's difficult to believe you have the speakers in the same position.  There are just too many differences in the specific and overall frequency response to be explained by crossover issues or driver variation.  If you do have them in the same position, then I would have to agree with others that there is something off in the calibration or measuring technique.
Dennis you are right I took the measurement at listening position and did not move the speaker to same location.  I'll do that when I get a chance. I'm tied up at work and will be travelling.

Keep in mind that the ECM8000 calibration file on that site is a generic one.  To be accurate, each individual ECM8000 requires a calibration file for that individual mic.  The generic file will get you close, but it will not be totally accurate.
- Jim
Jim you are right I should get my mic calibrated to get accurate results.

I agree that REW graphs does not tell the full story and I've confirmed that when I added SVS AS-EQ1. The REW graph looked almost similar to what I had using Audyssey EQ. But it sounded much different. Nevertheless I've followed the REW instructions to the T and have consulted BruceK and Wayne several times when I was learning to use REW.

Jim and Dennis I really apologize if I have offended you in anyway  :oops:. My intent was trying to figure out if there was any issue in my setup.
All in all I am very happy with my ST's :inlove:. I value the efforts and dedication Jim and Dennis :thankyou: takes in building such nice speakers.

I'm certainly not offended.  I'm just a little frustrated to see results that bad and not have a better grasp of what might be going on.  I'm still a little concerned about the 2-2.5 k suckout on one of the speakers.  That wouldn't be a calibration issue.  But I'll wait until I see the results when you do both from the same position.   

BradJudy

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #29 on: 10 Jun 2009, 08:52 pm »
That is true Jim, but there is no way the generic file is as far off as what audiocrazy's graph is showing.  I'm fairly certain all of the mics tested for the calibration file proved pretty close (or close enough for home use). 

Yes, at one point I compared the calibration files for multiple ECM8000 mics purchased at different times, by different people.  While each was unique, the variations were very small (+/- 1db range) and within the bulk of the range, they were within a fraction of a db of each other. 

For home use, a calibration file shouldn't be needed with the ECM8000 and the mics are not consistent enough to make using a generic file worthwhile IMO.

Nuance

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #30 on: 10 Jun 2009, 09:13 pm »
Audiocrazy - can you measure the speakers individually, but when placed in the exact same listening position?  This will rule out a crossover or driver issue.

I assume the two measurements above vary because they were measured individually from where they reside rather than when placed in the exact same spot.

Jeff B.

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #31 on: 10 Jun 2009, 09:30 pm »
It actually seems fairly obvious to me also, but unfortunately, I don't think my appraisal is going to agree entirely with TJHUB's conclusion, so you guys can do whatever you like with my comments here.

After reading through everything in the thread and looking all of the plots over I am seeing essentially what I would expect to see based on what I have read (with one exception, which I will get to in a minute).

First, regarding the mic calibration file, the Behringer ECM8000 is a fairly flat mic to begin with. Even to use it without a calibration file will not result in these apparent discrepancies, in fact I doubt you would notice the difference. Rather, I think the explanation is much simpler -

From what I gather, these are in-room response measurements measured at the listening location ( I did not see the actual distance specified, unless I missed it somewhere). If this distance is 8-10 feet then I would expect to see:

....room gain in the lowest octaves
....boundary cancellation and peaks due to the room response
....and a falling top two octaves due to directivity and absorption

And this appears to be exactly what we see. There is a difference between the two speaker, but he commented that he did not move them to the same location, so that can easily explain these differences too (at least partly).

Now, about the falling top-end response - I do not know how well the mic is set-up on the tweeter axis. If it is off-axis much it will contribute to an even greater drop, so this is something to consider as well.

I always check my speakers in my room using an RTA with pink noise to see how the balance looks in-room. When the balance is very flat at one meter it will still show a significant loss in top octave energy at 8-10 feet, but it doesn't sound that much different, because at that distance we are hearing a greater proportion of the speaker's power response, which the mic does not pic up. Again, what I see in these graphs correlates well with what I see in listening position measurements in my own room, with one exception.....

The dip at 2kHz in the one speaker should probably not be present in one and not the other. If his measurments were vertically off-axis (from the tweeter axis) then I could see picking up the beginning of a null in the lobing along this axis, but the top-end should be more rolled off if this were the case. Based on this, I tend to agree with Dennis, I think the tweeter in that speaker may be connected with the wrong polarity compared to the other speaker. Otherwise, I don't have much of any issue with what I am seeing here.

Jeff Bagby

TJHUB

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #32 on: 10 Jun 2009, 11:21 pm »
Seriously guys, please look at this:

Here is the graph I posted earlier in this thread.  The black line in this graph is the Behringer ECM8000 mic's calibration line.  In the blue circle, note which way the line goes and at what frequency.



Now look at audiocrazy's graph.  Again, the black line in this graph is the mic calibration line.  In the blue circle, note that the line is WAY off from where it should be.



I could be wrong, but I'm almost certain that the mic calibration file that audiocrazy is using is subtracting from the actual mic readings from 3kHz and up when it should be adding from 10kHz and up.  This in turn would cause his upper frequency measurement to be skewed way down.  Hmm...

There is no doubt that the 2kHz dip Dennis has noted shouldn't be affected by the mic calibration and there certainly could be an issue there, but it doesn't change what I'm trying to get you guys to see.

For grins, here is the in-room response of my HT2-TL's at my seating position.  The speakers are running full-range and are about 11.5' apart and just under 14' from my listening position.  The blue line is the left speaker and the red line is the right.  The low end peak is from my room.  Every speaker and subwoofer I've had in my room has that 38Hz peak and weird behavior around 60Hz.  I have no room treatments whatsoever. 








DMurphy

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #33 on: 10 Jun 2009, 11:57 pm »
Seriously guys, please look at this:

Here is the graph I posted earlier in this thread.  The black line in this graph is the Behringer ECM8000 mic's calibration line.  In the blue circle, note which way the line goes and at what frequency.



Now look at audiocrazy's graph.  Again, the black line in this graph is the mic calibration line.  In the blue circle, note that the line is WAY off from where it should be.



I could be wrong, but I'm almost certain that the mic calibration file that audiocrazy is using is subtracting from the actual mic readings from 3kHz and up when it should be adding from 10kHz and up.  This in turn would cause his upper frequency measurement to be skewed way down.  Hmm...

There is no doubt that the 2kHz dip Dennis has noted shouldn't be affected by the mic calibration and there certainly could be an issue there, but it doesn't change what I'm trying to get you guys to see.

For grins, here is the in-room response of my HT2-TL's at my seating position.  The speakers are running full-range and are about 11.5' apart and just under 14' from my listening position.  The blue line is the left speaker and the red line is the right.  The low end peak is from my room.  Every speaker and subwoofer I've had in my room has that 38Hz peak and weird behavior around 60Hz.  I have no room treatments whatsoever. 






That's very interesting.  Thanks for the comparisons.  I'm having trouble getting my mind around the mic calibration plots you're showing.  Where do they come from?  Are you showing the generic correction file for Audiocrazy's set up?  If so, I would interpret it the way you do--the correction should add high treble. 

Jeff B.

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #34 on: 11 Jun 2009, 12:24 am »
Hmmmmm.....well, your graphs do make a good point worthy of consideration. We will see how this resolves itself.

Thanks, Jeff



Seriously guys, please look at this:

Here is the graph I posted earlier in this thread.  The black line in this graph is the Behringer ECM8000 mic's calibration line.  In the blue circle, note which way the line goes and at what frequency.



Now look at audiocrazy's graph.  Again, the black line in this graph is the mic calibration line.  In the blue circle, note that the line is WAY off from where it should be.



I could be wrong, but I'm almost certain that the mic calibration file that audiocrazy is using is subtracting from the actual mic readings from 3kHz and up when it should be adding from 10kHz and up.  This in turn would cause his upper frequency measurement to be skewed way down.  Hmm...

There is no doubt that the 2kHz dip Dennis has noted shouldn't be affected by the mic calibration and there certainly could be an issue there, but it doesn't change what I'm trying to get you guys to see.

For grins, here is the in-room response of my HT2-TL's at my seating position.  The speakers are running full-range and are about 11.5' apart and just under 14' from my listening position.  The blue line is the left speaker and the red line is the right.  The low end peak is from my room.  Every speaker and subwoofer I've had in my room has that 38Hz peak and weird behavior around 60Hz.  I have no room treatments whatsoever. 





TJHUB

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #35 on: 11 Jun 2009, 12:38 am »
Jeff:

Thanks.  I have a hard time getting my point across sometimes.  I'm glad you are now seeing what I'm trying to communicate.  Until audiocrazy gets his REW running correctly, I wouldn't worry too much about anything else.  There may be other issues, but you cannot draw any solid conclusions from his graphs.

The first graph is mine to show the correct ECM8000 mic calibration plot (the black line).  I can only assume that the mic reads low above 10kHz and the calibration file adds to the actual measurement.

The second graph is audiocrazy's to show that his mic calibration file is the opposite direction.  I can only assume that his calibration file is subtracting from the actual measurements thus causing the poor looking graph.

I'm at work right now and can't play with things to completely understand what's going on here.  If I wasn't working 13-15 hours days, I could be of more help.  I haven't even turned on my setup to listen to my Salks now since weekend before last.  :(



I could graph his data for him if he send me the data file.  I've done that with other forum members in the past to show them things.   


idiotec

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #36 on: 11 Jun 2009, 02:54 am »
Interesting thread.  I must say, it makes me very happy to have neither measuring equipment nor an EQ.  :P

Nuance

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #37 on: 11 Jun 2009, 05:13 am »
So the Behringer doesn't measure flat up to 20KHz?  Hmm...that stinks.  That was the mic I was going to purchase.

BradJudy

Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #38 on: 11 Jun 2009, 10:49 am »
So the Behringer doesn't measure flat up to 20KHz?  Hmm...that stinks.  That was the mic I was going to purchase.

I just double-checked the cal file for mine and it measured +/- 1.1db from 20-20kHz.  As I said, the cal files I have compared were all pretty flat and not consistent enough to warrant the use of someone else's cal file. 

I hadn't noticed the extreme calibration used in these examples - definitely stop using the cal file and then see how it graphs. 

turkey

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Re: SongTowers FR Question (not flat from 1k-20khz) with RoomEQ
« Reply #39 on: 11 Jun 2009, 01:49 pm »
Now, about the falling top-end response - I do not know how well the mic is set-up on the tweeter axis. If it is off-axis much it will contribute to an even greater drop, so this is something to consider as well.

I always check my speakers in my room using an RTA with pink noise to see how the balance looks in-room. When the balance is very flat at one meter it will still show a significant loss in top octave energy at 8-10 feet, but it doesn't sound that much different, because at that distance we are hearing a greater proportion of the speaker's power response, which the mic does not pic up.

With most speakers, people don't normally listen on-axis, so the on-axis response doesn't mean much. (It's a very small part of the overall output of the speaker.)

What is far more important is the off-axis response and power response. What are these like in the various Salk models? I've seen some of the graphs on the web site, but they were only at one angle and weren't anything special anyway.