Two Subs...Gain Matching vs Level Matching - Page 7 - AVS Forum
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post #181 of 202 Old 12-24-2013, 11:34 AM
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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?

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post #182 of 202 Old 12-24-2013, 11:36 AM
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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!

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post #183 of 202 Old 12-24-2013, 11:58 AM
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Quote:
Originally Posted by toofast68 View Post

Onkyo 809

It has an 8 seating position setup
Audyssey XT, right?
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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?
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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?

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post #184 of 202 Old 12-24-2013, 12:02 PM
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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.

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post #185 of 202 Old 12-24-2013, 12:11 PM
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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?

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post #186 of 202 Old 12-24-2013, 12:14 PM
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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.

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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.
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post #188 of 202 Old 12-24-2013, 03:08 PM
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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.

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post #189 of 202 Old 12-24-2013, 03:11 PM
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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

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post #190 of 202 Old 12-24-2013, 03:20 PM
 
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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.

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post #191 of 202 Old 12-24-2013, 04:09 PM
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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

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post #192 of 202 Old 12-24-2013, 04:23 PM
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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.

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post #193 of 202 Old 12-24-2013, 05:05 PM
 
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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.

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post #194 of 202 Old 12-24-2013, 05:31 PM
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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.

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post #195 of 202 Old 12-24-2013, 05:49 PM
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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.
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post #196 of 202 Old 12-24-2013, 05:52 PM
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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

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post #197 of 202 Old 12-24-2013, 08:57 PM
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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.

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post #198 of 202 Old 12-25-2013, 04:25 AM
 
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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?

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post #199 of 202 Old 12-25-2013, 05:19 AM
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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

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...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

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(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

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...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?"

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