Two Subs...Gain Matching vs Level Matching - Page 7 - AVS Forum
Forum Jump: 
 5Likes
 
Thread Tools
Old 12-24-2013, 12:34 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by toofast68 View Post

Ok, so quick verification....

I gain matched all three subs (identical) with the mic a few inches away.

Then placed all three in final resting place and re-ran setup and it actually found my subs to be at 78 db, I left it alone.

When all done, the trim was set at -2 db for the subs.

So if I want them a bit HOTTER, I should modify the trim vs. the level on the subs correct ?
What receiver do you have? What "setup" does it have?

Are your subs all Y'd off the same subwoofer output?

When you measured 78 dB, what signal did you use to measure it?

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Sponsored Links
Advertisement
 
Old 12-24-2013, 12:36 PM
Advanced Member
 
toofast68's Avatar
 
Join Date: Nov 2007
Location: NorthEast Ohio, USA
Posts: 938
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 19
Quote:
Originally Posted by craig john View Post


What receiver do you have? What "setup" does it have?

Are your subs all Y'd off the same subwoofer output?

When you measured 78 dB, what signal did you use to measure it?

Craig

 

Onkyo 809

 

It has an 8 seating position setup

 

I have 3 subs at the moment, 2 sets of pre-outs - fronts are y'd

 

the AVR measured 78 db

 

thanks for helping!

toofast68 is offline  
Old 12-24-2013, 12:58 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by toofast68 View Post

Onkyo 809

It has an 8 seating position setup
Audyssey XT, right?
Quote:
Originally Posted by toofast68 View Post

I have 3 subs at the moment, 2 sets of pre-outs - fronts are y'd
According to the manual, (filedepot.onkyousa.com/Files/own_manuals/TX-NR809_En_web.pdf), you only have one subwoofer output, correct? So all subs are Y'd off one subwoofer output?
Quote:
Originally Posted by toofast68 View Post

the AVR measured 78 db
Was that in the step in Audyssey where you measure the subwoofer SPL, just before the test tones run? You weren't measuring that afterwards using an SPL meter and the test tones, right?

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 12-24-2013, 01:02 PM
Advanced Member
 
toofast68's Avatar
 
Join Date: Nov 2007
Location: NorthEast Ohio, USA
Posts: 938
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 19
Quote:
Originally Posted by craig john View Post


Audyssey XT, right?
According to the manual, (filedepot.onkyousa.com/Files/own_manuals/TX-NR809_En_web.pdf), you only have one subwoofer output, correct? So all subs are Y'd off one subwoofer output?
Was that in the step in Audyssey where you measure the subwoofer SPL, just before the test tones run? You weren't measuring that afterwards using an SPL meter and the test tones, right?

Craig

Yep XT correct....

 

Mmmm, I have 2 sub pre-outs, but I think internally they might just be y'd of course.

 

Yes the step was just before the test tones were run.

toofast68 is offline  
Old 12-24-2013, 01:11 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by toofast68 View Post

Yep XT correct....

Mmmm, I have 2 sub pre-outs, but I think internally they might just be y'd of course.

Yes the step was just before the test tones were run.
On closer inspection of the manual, you are correct... 2 sub pre-outs, internally Y'd. Therefore all your subs are receiving the exact same signal. This is good for the way you've set your gain-matching. It seems you've done things correctly. However, one important step remains... setting the single subwoofer "Distance" setting in the receiver for an optimal result. If your subs are different physical distances to the listening position, you'll want to experiment with the subwoofer Distance setting in the pre/pro to see if Audyssey got it correct or if it can be improved. Do you have any measurement gear?

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 12-24-2013, 01:14 PM
Advanced Member
 
toofast68's Avatar
 
Join Date: Nov 2007
Location: NorthEast Ohio, USA
Posts: 938
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 19
Quote:
Originally Posted by craig john View Post


On closer inspection of the manual, you are correct... 2 sub pre-outs, internally Y'd. Therefore all your subs are receiving the exact same signal. This is good for the way you've set your gain-matching. It seems you've done things correctly. However, one important step remains... setting the single subwoofer "Distance" setting in the receiver for an optimal result. If your subs are different physical distances to the listening position, you'll want to experiment with the subwoofer Distance setting in the pre/pro to see if Audyssey got it correct or if it can be improved. Do you have any measurement gear?

Craig

Ok, I will experiment with that..

 

As for measurement gear, I just have a old no name SPL meter, seems to work, but not integrated, etc. with anything. Assume if I bought some stuff I could really do a better job?  I just get so confused on exactly what is needed.

toofast68 is offline  
Old 12-24-2013, 02:34 PM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Download a freeware copy of REW.

A USB measuring microphone to connect to your laptop.

A patch cord to connect your computer headphone out to the RCA, stereo, front faceplate connectors on the AVR.

A digital sound meter from Radio Shack.
BeeMan458 is offline  
Old 12-24-2013, 04:08 PM
AVS Special Member
 
raynist's Avatar
 
Join Date: Dec 2002
Location: Pittsburgh
Posts: 1,455
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
Liked: 344
Quote:
Originally Posted by BeeMan458 View Post

Download a freeware copy of REW.


A USB measuring microphone to connect to your laptop.

A patch cord to connect your computer headphone out to the RCA, stereo, front faceplate connectors on the AVR.

A digital sound meter from Radio Shack.

Do you need the sound meter from radio shack if you have a calibrated USB mic? I don't remember needing or using one.

3 - JTR 228's LCR (game room)
4 - DIY Sound Group V-8 Coaxials in slanted boxes (game room)
4 - PSA Triax's (game room)
3 - DIY Sound Group V-8 Coaxials in Ported Boxes for LCR's
2 - SVS SB13+'s (living room)
1 - SVS SB12-NSD (bedroom)
raynist is offline  
Old 12-24-2013, 04:11 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by toofast68 View Post

Ok, I will experiment with that..

As for measurement gear, I just have a old no name SPL meter, seems to work, but not integrated, etc. with anything. Assume if I bought some stuff I could really do a better job?  I just get so confused on exactly what is needed.
If you have multiple subs, some type of measurement gear is almost a requirement if you want to get optimal response from them. I use XTZ, (http://store.acousticfrontiers.com/Acoustic-Measurement/XTZ-Room-Analyzer-II-Standard.html) It's really easy to setup and use... basically "Plug 'n Play."

Here is an example of an XTZ measurement and how it aided me to optimize my setup, (which is very similar to yours: 3 subs, all Y'd off one subwoofer output, gain-matched and calibrated with Audyssey XT.) It shows the the problem that can occur with an incorrect subwoofer Distance setting:



The only difference between those two traces is a 4.5 ft. adjustment of the subwoofer Distance. Audyssey can often get this setting wrong, especially in multi-subwoofer systems.

The difference in the sound was astonishing. The bass went from being weak and thin to being strong, powerful and full. I never would have known what the problem was, or how to fix it, without XTZ. Other programs can do the same thing. REW, as recommended by Beeman is one of them, OmniMic is another: http://www.parts-express.com/dayton-audio-omnimic-v2-precision-measurement-system--390-792 It doesn't matter so much what you use... it matters that you use it. smile.gif

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 12-24-2013, 04:20 PM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by raynist View Post

Do you need the sound meter from radio shack if you have a calibrated USB mic? I don't remember needing or using one.

I have three sound meters. Two from Amazon and one from Radio Shack. We have a calibrated measuring microphone. It's a mixed bag if one needs a sound meter or not. In my opinion, yes, one "NEEDS" a sound meter. Others will disagree. I find a sound meter to be convenient and can be used at anytime to measure output. Measuring microphones need to be set up and connected to a computer to be able to see what's being measured. Also, the sound meter is used to calibrate REW.

I can't imagine not having a sound meter.

-
BeeMan458 is offline  
Old 12-24-2013, 05:09 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by raynist View Post

Do you need the sound meter from radio shack if you have a calibrated USB mic? I don't remember needing or using one.
An SPL meter is a very general tool that can't give you any information about the frequency of the sound it is measuring. It can only tell you the "Sound Pressure Level" of the sound. While that is interesting, and helpful for calibration, the more important and useful information is SPL by frequency, and SPL decay in the time domain. A simple SPL meter can't tell you anything about those parameters.

If you have single frequency test tones, you can get information about SPL by frequency, but the measurements are very tedious and time consuming. It's far easier to get these data with frequency sweeps and software capable of analysis.

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 12-24-2013, 05:23 PM
AVS Special Member
 
raynist's Avatar
 
Join Date: Dec 2002
Location: Pittsburgh
Posts: 1,455
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
Liked: 344
Quote:
Originally Posted by craig john View Post

An SPL meter is a very general tool that can't give you any information about the frequency of the sound it is measuring. It can only tell you the "Sound Pressure Level" of the sound. While that is interesting, and helpful for calibration, the more important and useful information is SPL by frequency, and SPL decay in the time domain. A simple SPL meter can't tell you anything about those parameters.

If you have single frequency test tones, you can get information about SPL by frequency, but the measurements are very tedious and time consuming. It's far easier to get these data with frequency sweeps and software capable of analysis.

Craig

Thanks.

I don't remember needing to use the SPL meter to calibrate my calibrated sub mic - I could be wrong, it was a few months ago.

3 - JTR 228's LCR (game room)
4 - DIY Sound Group V-8 Coaxials in slanted boxes (game room)
4 - PSA Triax's (game room)
3 - DIY Sound Group V-8 Coaxials in Ported Boxes for LCR's
2 - SVS SB13+'s (living room)
1 - SVS SB12-NSD (bedroom)
raynist is offline  
Old 12-24-2013, 06:05 PM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by raynist View Post

I don't remember needing to use the SPL meter to calibrate my calibrated sub mic - I could be wrong, it was a few months ago.

You're using the sound meter to calibrate REW, not the microphone.

In our case, I use the sound meter to level match our subwoofers at the MLP so as to be able to run Anti-Mode and XT. Doing it this way, one doesn't have to pull out the computerized measuring gear. One simply matches the levels at the MLP, hits the EQ go buttons and it's a done deal. In my opinion, much more convenient and just as accurate when done this way.

-
BeeMan458 is offline  
Old 12-24-2013, 06:31 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by BeeMan458 View Post

You're using the sound meter to calibrate REW, not the microphone.

In our case, I use the sound meter to level match our subwoofers at the MLP so as to be able to run Anti-Mode and XT. Doing it this way, one doesn't have to pull out the computerized measuring gear. One simply matches the levels at the MLP, hits the EQ go buttons and it's a done deal. In my opinion, much more convenient and just as accurate when done this way.

-
Please define "accurate." Yes...if "level-matching" is the final goal, doing it the way you describe will yield accurately "level-matched" subs. rolleyes.gif

However, IMO, "gain-matching" is the more beneficial approach, as I've stated throughout this thread, especially if you have identical subs, and you have any desire to push the subs close to their limits. I even suggested it to you a few days ago in your other thread. Nonetheless, if "convenience" is more important than max headroom, or if relative calibration is the only "endpoint," then level-matching is fine.

For me, I want to optimize the full capabilities of all my subs. I also want the maximum *system* output AND I want the deepest frequency extension. Gain-matching of identical subs is the best, and only, way to achieve those goals.

Merry Christmas.

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 12-24-2013, 06:49 PM
AVS Special Member
 
Join Date: Mar 2003
Posts: 4,509
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 610
Hey CJ,

Once in a while I glance at this thread but never seem to have the time to post in it.

Q: Exactly how does one level match differently placed multiple subs? If using the AVR rumble tone, all subs would have to have exactly the same response or use of an SPL meter would be in vain. Since all subs will likely never have the same response, how is level matching accomplished?

Of course, gain matching is the only method that makes sense. I believe in driving the entire system with a single amplifier because it eliminates the need to tape the floor and close mic. smile.gif

The only rap against gain matching seems to be that the nearer sub would be locatable. If a sub (or whatever # of subs) is locatable, the calibration is off. If the calibration is off (in nearly every case that means the sub is 'hot'), the subs will be localizable by a far greater # of listeners regardless of placement or method of calibration.
bossobass is offline  
Old 12-24-2013, 06:52 PM
AVS Special Member
 
raynist's Avatar
 
Join Date: Dec 2002
Location: Pittsburgh
Posts: 1,455
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
Liked: 344
Quote:
Originally Posted by BeeMan458 View Post

You're using the sound meter to calibrate REW, not the microphone.

In our case, I use the sound meter to level match our subwoofers at the MLP so as to be able to run Anti-Mode and XT. Doing it this way, one doesn't have to pull out the computerized measuring gear. One simply matches the levels at the MLP, hits the EQ go buttons and it's a done deal. In my opinion, much more convenient and just as accurate when done this way.

-

I have the UMIK-1 and set it up according to their website. Didn't use a separate SPL meter that I can remember.

http://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew

3 - JTR 228's LCR (game room)
4 - DIY Sound Group V-8 Coaxials in slanted boxes (game room)
4 - PSA Triax's (game room)
3 - DIY Sound Group V-8 Coaxials in Ported Boxes for LCR's
2 - SVS SB13+'s (living room)
1 - SVS SB12-NSD (bedroom)
raynist is offline  
Old 12-24-2013, 09:57 PM
AVS Special Member
 
Gooddoc's Avatar
 
Join Date: Oct 2004
Posts: 4,180
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 589 Post(s)
Liked: 389
Quote:
Originally Posted by BeeMan458 View Post

You're using the sound meter to calibrate REW, not the microphone.

Quote:
Originally Posted by raynist View Post

I have the UMIK-1 and set it up according to their website. Didn't use a separate SPL meter that I can remember.

http://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew

The UMIK-1 comes calibrated for SPL out of the box. There is no need to calibrate SPL with a separate SPL meter. It's plug and play with REW just like Omnimic.
Gooddoc is online now  
Old 12-25-2013, 05:25 AM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by Gooddoc View Post


The UMIK-1 comes calibrated for SPL out of the box. There is no need to calibrate SPL with a separate SPL meter. It's plug and play with REW just like Omnimic.

This is the sound meter I use.

One is calibrating REW, not the microphone and yes, REW does have a SPL calibration page. Then there's the unwritten about convenience not having to haul the measuring gear out to do a simple level/gain match and Audyssey calibration run.

(here, I have the flint and dry moss. confused.gif Wouldn't it be easier just to use this lighter?)

Our last calibration run, the subs/speakers were positioned, subs level matched at the MLP, Anti-Mode was run, Audyssey XT was run, AVR parameters were adjusted and voila, the system was up and running with all the measuring gear, still safely tucked away in their prior appointed locations.

Cops are very kind, they give a perp the choice, hard or easy. In my younger days, I would choose hard. In my older days, I choose easy. tongue.gif

(i even have a calibration device, to calibrate the sound meter. No idea how to calibrate the calibration device.....it could be lying ya know)

...tongue.gif

Sound meter calibration device.

Backup sound meter.

Radio Shack sound meter

...tongue.gif

Did I mention, in my opinion, sound meters are a very important part of the EQ'g process and one should not EQ without one?

-
BeeMan458 is offline  
Old 12-25-2013, 06:19 AM
AVS Special Member
 
Gooddoc's Avatar
 
Join Date: Oct 2004
Posts: 4,180
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 589 Post(s)
Liked: 389
I agree that if using a condenser mic with phantom power that requires calibration of REW with a separate SPL meter, then it is far easier to just use that separate SPL meter for simple SPL measurement. But my point was that REW SPL does not have to be calibrated with a separate SPL meter when using the UMIK like it does if you use a condenser mic. So, unlike the condenser mic setup, a dedicated SPL meter is not necessary and it's hard to justify the cost of getting one. It also makes taking an SPL measurement about as easy as using a dedicated meter. It's just a USB cable into the laptop.

Of course, the dedicated SPL meter is still an option if plugging in a USB is too much hassle. I just wouldn't recommend someone buy one if they go with the UMIK, that's all. biggrin.gif
Gooddoc is online now  
Old 12-25-2013, 06:36 AM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by Gooddoc View Post

...and it's hard to justify the cost of getting one.

(Three JTR Noesis 212HTs, complimented by two S2s et al and for the price of a sound meter, he posts of cost justification?)

confused.gif This is a hobby. No justification is required. tongue.gif

-
BeeMan458 is offline  
Old 12-25-2013, 08:18 AM
AVS Special Member
 
Gooddoc's Avatar
 
Join Date: Oct 2004
Posts: 4,180
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 589 Post(s)
Liked: 389
Quote:
Originally Posted by BeeMan458 View Post

(Three JTR Noesis 212HTs, complimented by two S2s et al and for the price of a sound meter, he posts of cost justification?)

confused.gif This is a hobby. No justification is required. tongue.gif

-

Can't deny any of that... tongue.gifbiggrin.gif
Gooddoc is online now  
Old 12-25-2013, 08:22 AM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
...biggrin.gif

Hopefully, later next month, our next add will be a Denon 4520ci.

(but honey, the amplifier section is to die for as well as it has XT32 and SubEQ HT installed)

Can I get a "justify?"

-
BeeMan458 is offline  
Old 08-01-2014, 08:23 PM
Advanced Member
 
ahblaza's Avatar
 
Join Date: Nov 2007
Location: Pittsburgh Steeler Country
Posts: 790
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 332 Post(s)
Liked: 339
Guys, I know this is an old thread, but I have four identical down firing subs and I would like to gain match all four. When I place each sub in the center of my room to gain match it should I turn the sub on it's side so the driver is facing forward or just measure with it down firing with the mic the same distance from each sub? TIA

j_nordi
ahblaza is offline  
Old 08-01-2014, 09:16 PM
AVS Special Member
 
tvuong's Avatar
 
Join Date: Dec 2000
Posts: 1,736
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 175 Post(s)
Liked: 118
Measure them exactly how they sit-down firing. The point is to get same spl at the same spot with all subs.
ahblaza likes this.
tvuong is offline  
Old 08-01-2014, 09:51 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by ahblaza View Post
Guys, I know this is an old thread, but I have four identical down firing subs and I would like to gain match all four. When I place each sub in the center of my room to gain match it should I turn the sub on it's side so the driver is facing forward or just measure with it down firing with the mic the same distance from each sub? TIA
It doesn't matter, as long as you are consistent from one IDENTICAL sub to the next. Place each sub in exactly the same spot, in the same orientation, with the same mic, placed exactly the same distance relative to each sub. Play the same rumble tone signal, and set the gains on all subs so the SPL meter reads the exact same SPL... and you'll end up with them all perfectly gain-matched.

Craig
ahblaza likes this.

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 08-02-2014, 10:21 PM
Advanced Member
 
ahblaza's Avatar
 
Join Date: Nov 2007
Location: Pittsburgh Steeler Country
Posts: 790
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 332 Post(s)
Liked: 339
Quote:
Originally Posted by craig john View Post
It doesn't matter, as long as you are consistent from one IDENTICAL sub to the next. Place each sub in exactly the same spot, in the same orientation, with the same mic, placed exactly the same distance relative to each sub. Play the same rumble tone signal, and set the gains on all subs so the SPL meter reads the exact same SPL... and you'll end up with them all perfectly gain-matched.

Craig

Craig, excuse my ignorance but when you say play the same rumble tone signal are you referring to the AVR's pink noise tone generator? Also what gain level should I shoot for on the SPL meter (dB level). Does it matter at what distance I have the mic relative to each sub as long as it is the same for each sub and each sub is in the exact same position as the first? In other words what SPL reading should I try to achieve for each sub, I don't have a clue what decibel level to try and achieve with each identical sub. Do you then reco that I run Audyssey XT, because that's all I have. Someone else said to do (after gain matching) a one mic spot Audyssey run to test what Audy sets the sub's trim level at, the desired level is according to him is between -5 to -8 and then run a full auto calibration, he said it is important to try and get that initial -5 to-8 dB trim level. Thank you so much for taking the time to answer this query, greatly appreciated my friend. TIA.
Cheers Jeff

j_nordi

Last edited by ahblaza; 08-02-2014 at 10:32 PM.
ahblaza is offline  
Old 08-02-2014, 10:33 PM
Advanced Member
 
ahblaza's Avatar
 
Join Date: Nov 2007
Location: Pittsburgh Steeler Country
Posts: 790
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 332 Post(s)
Liked: 339
Quote:
Originally Posted by tvuong View Post
Measure them exactly how they sit-down firing. The point is to get same spl at the same spot with all subs.

Thanks for taking the time to answer my question, it means a lot to me.
Cheers Jeff

j_nordi
ahblaza is offline  
Old 08-03-2014, 10:10 AM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,389
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Liked: 363
Quote:
Originally Posted by ahblaza View Post
Craig, excuse my ignorance but when you say play the same rumble tone signal are you referring to the AVR's pink noise tone generator?
That tone should work. It's generally a 40 to 80 Hz "noise" tone. As long as you use the same tone, at the same level, for all the subs, it'll be fine.

Quote:
Originally Posted by ahblaza View Post
Also what gain level should I shoot for on the SPL meter (dB level).
If you have 4 identical subs, you want to use a level for *each* sub that results in a *combined* level of 72 to 78 dB when all the subs are placed back in their in-room positions. This will allow the combined subwoofer system to be properly calibrated with the speakers within the range of most receivers and pre/pro's. More below...

Quote:
Originally Posted by ahblaza View Post
Does it matter at what distance I have the mic relative to each sub as long as it is the same for each sub and each sub is in the exact same position as the first? In other words what SPL reading should I try to achieve for each sub, I don't have a clue what decibel level to try and achieve with each identical sub. Do you then reco that I run Audyssey XT, because that's all I have. Someone else said to do (after gain matching) a one mic spot Audyssey run to test what Audy sets the sub's trim level at, the desired level is according to him is between -5 to -8 and then run a full auto calibration, he said it is important to try and get that initial -5 to-8 dB trim level. Thank you so much for taking the time to answer this query, greatly appreciated my friend. TIA.
Cheers Jeff
In my room, I find that a nearfield setting, (with the mic 2" from the middle of the driver), of 88 dB results in a combined level of 76 dB when each of the subs is placed back in its' in-room position. However, I have 3 dual opposed subs, (6, 15" drivers in 3 cabinets), distributed unevenly around my room. That same 88 dB setting may, or may not, work for you with 4 downfiring subs, and without knowing their in-room placements.

My suggestion for you is to start by having all the subs in their in-room positions, set them all to the same gain setting, and then measure their combined output at the Primary Listening Position, (PLP). If they're higher than 78 dB, lower them all the same amount until the combined SPL reads 72 - 78 dB. If they're lower than 78 dB, raise them all the same amount until the combined SPL reads 72 - 78 dB. If they are all set to the same gain setting, and you're confident that the identical gain setting results in them being gain-matched, you're done. However, some subs will have variations in the gain at identical gain settings on the amps. In that case, if you want to be more precise about it, you can proceed to the next step.

Start by moving one sub to the middle of the room. Lay it on its' side and place the mic/SPL meter 2" from the driver. Play the subwoofer test tone and measure the SPL. Mark the exact location of that sub on the floor with masking or painters tape. Without moving the mic, move that sub out and the next sub into the exact same position and adjust the gain until it reads the same SPL as the 1st sub. Then repeat that process with the other 2 subs. Then move each sub back into it's in-room position and measure the combined output at the PLP. It should be within the 72-78 dB range. If not, adjust each sub by the exact same amount until their combined response is within that range.

From that point, you can continue with your Audyssey XT calibration. It's not terribly important to have a -5 to -8 trim setting in the receiver after running Audyssey, but I personally prefer it. It allows for the ability to add some input signal to the subs to run the system a little "hot" without exceeding the "0" trim setting. Some sub amps can be overdriven with an excessively high input signal. Staying below "0" ensures you won't overdrive the input of virtually any subwoofer amp.

However, you may not be done yet. With 4 subs, if they end up being different physical distances from the PLP, you most likely need to do the Audyssey subwoofer "Distance" tweak, as written by Keith Barnes here:
https://dl.dropboxusercontent.com/u/...Oct%202013.pdf

Good luck!

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
Old 08-03-2014, 05:47 PM
Advanced Member
 
ahblaza's Avatar
 
Join Date: Nov 2007
Location: Pittsburgh Steeler Country
Posts: 790
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 332 Post(s)
Liked: 339
Thank you Craig for the detailed and informative reply, I feel a little better now and not so intimidated by all of this, I can't convey my appreciation for all that you have done, again many thanks my friend.
Sincerely, Jeffrey

j_nordi
ahblaza is offline  
Old 08-03-2014, 06:24 PM
AVS Special Member
 
caloyzki's Avatar
 
Join Date: Jan 2010
Location: New York
Posts: 2,159
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 163 Post(s)
Liked: 46
Quote:
Originally Posted by craig john View Post
That tone should work. It's generally a 40 to 80 Hz "noise" tone. As long as you use the same tone, at the same level, for all the subs, it'll be fine.


If you have 4 identical subs, you want to use a level for *each* sub that results in a *combined* level of 72 to 78 dB when all the subs are placed back in their in-room positions. This will allow the combined subwoofer system to be properly calibrated with the speakers within the range of most receivers and pre/pro's. More below...


In my room, I find that a nearfield setting, (with the mic 2" from the middle of the driver), of 88 dB results in a combined level of 76 dB when each of the subs is placed back in its' in-room position. However, I have 3 dual opposed subs, (6, 15" drivers in 3 cabinets), distributed unevenly around my room. That same 88 dB setting may, or may not, work for you with 4 downfiring subs, and without knowing their in-room placements.

My suggestion for you is to start by having all the subs in their in-room positions, set them all to the same gain setting, and then measure their combined output at the Primary Listening Position, (PLP). If they're higher than 78 dB, lower them all the same amount until the combined SPL reads 72 - 78 dB. If they're lower than 78 dB, raise them all the same amount until the combined SPL reads 72 - 78 dB. If they are all set to the same gain setting, and you're confident that the identical gain setting results in them being gain-matched, you're done. However, some subs will have variations in the gain at identical gain settings on the amps. In that case, if you want to be more precise about it, you can proceed to the next step.

Start by moving one sub to the middle of the room. Lay it on its' side and place the mic/SPL meter 2" from the driver. Play the subwoofer test tone and measure the SPL. Mark the exact location of that sub on the floor with masking or painters tape. Without moving the mic, move that sub out and the next sub into the exact same position and adjust the gain until it reads the same SPL as the 1st sub. Then repeat that process with the other 2 subs. Then move each sub back into it's in-room position and measure the combined output at the PLP. It should be within the 72-78 dB range. If not, adjust each sub by the exact same amount until their combined response is within that range.

From that point, you can continue with your Audyssey XT calibration. It's not terribly important to have a -5 to -8 trim setting in the receiver after running Audyssey, but I personally prefer it. It allows for the ability to add some input signal to the subs to run the system a little "hot" without exceeding the "0" trim setting. Some sub amps can be overdriven with an excessively high input signal. Staying below "0" ensures you won't overdrive the input of virtually any subwoofer amp.

However, you may not be done yet. With 4 subs, if they end up being different physical distances from the PLP, you most likely need to do the Audyssey subwoofer "Distance" tweak, as written by Keith Barnes here:
https://dl.dropboxusercontent.com/u/...Oct%202013.pdf

Good luck!

Craig
Hi Craig. What about if i have two mismatched sub? Can i stil do like what you said above?thanks.
caloyzki is offline  
 

Tags
Outlaw Audio Lfm 1 Ex
Thread Tools


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off