Level Matching

[psbfan9]

I read something interesting, but also confusing. Well, to me anyway. I was reading about level matching whne running two subs. The article said that the best way was to set up the mic. 1m in front of one sub, then take it out, put the other sub in the same spot as the first, then run the test tones again. Then set subs up in their permanent positions.
My listening position is more than 1m from the sub, so I why wouldn't I set the mic at the listening position? I'm not running a sub right now ( it went Boom!, and not in a good way) but wanted to get as info as could so when I can afford another sub I'll be prepared.

Does this one meter distance also apply to setting up mains and surrounds, or should that be done from the listening position?

Here's the text;

Mark a spot on your floor. For each subwoofer you want to level match, you need to position it precisely in the same spot. Make sure all controls are set similarly - crossover out, EQ1 (if it has a EQ control), Q=0.7 (if it has Q control), etc. Place a SPL meter 1 m in front of the subwoofer. Set it to the 80 dB range. C weighting. With just one subwoofer, and receiver's sub out at 0 dB, adjust the level on the subwoofer to get a nice balance. Set all subwoofers to about this level.
Put the first subwoofer in the spot. Set volume to where it sounded good in your system. Play a 50 Hz tone and adjust the volume on your receiver to get a 80 dB reading. If you have two subwoofers to match, lower the volume on the subwoofer to get 75 dB. If you have four subwoofers you want to match, adjust the volume on the sub to get 70 dB.
Move the sub out and place the second sub in the same location. Play the same test tone and adjust the sub's volume control to get the same dB reading. Repeat this for the rest of the subwoofers. Now they are all level matched. Do not touch their volume control again after this or they will not be level matched.

 

[Steve81]

You're talking about gain matching; the idea behind it is that with such a setup, one sub won't run out of steam before the other.

 

[AcuDefTechGuy]

why wouldn't I set the mic at the listening position?

For Audyssey or other automatic room setup, you do place the microphone at the listening positions.

But you want each subwoofer to output the same volume BEFORE you apply Audyssey.

Now if each sub were identical, you just simply turn the volume knob at the back of each sub to 50% (or all the same level). Then apply Audyssey.

 

[Steve81]

Under this system, you don't necessarily want Audyssey messing with the relative levels either. If Sub#1 sub is bumped up by 10dB relative to the other by Audyssey, its going to run out of steam much earlier than Sub #2, potentially wasting Sub #2's remaining output capabilities as Sub #1 distorts badly, chuffs, etc.

 

[psbfan9]

You're talking about gain matching; the idea behind it is that with such a setup, one sub won't run out of steam before the other.

That part I get. I was confused by not setting the mic at listening position.

For Audyssey or other automatic room setup, you do place the microphone at the listening positions.

But you want each subwoofer to output the same volume BEFORE you apply Audyssey.

Now if each sub were identical, you just simply turn the volume knob at the back of each sub to 50% (or all the same level). Then apply Audyssey.

I assumed the article was written with using identical subs in mind. I may be wrong though.

Under this system, you don't necessarily want Audyssey messing with the relative levels either. If Sub#1 sub is bumped up by 10dB relative to the other by Audyssey, its going to run out of steam much earlier than Sub #2, potentially wasting Sub #2's remaining output capabilities as Sub #1 distorts badly, chuffs, etc.

I was thinking the same thing.

 

[Steve81]

That part I get. I was confused by not setting the mic at listening position.

I expect the key part is making sure the location of the sub and the location of the mic aren't variables when taking the measurements. Of course, having a mic at 1m might make things a bit easier to read vs the listening position.