Setting speaker levels with Avia question

[GlocksRock]

When I use Avia to set the speaker levels, I get different results from the test tones. What I mean is that there are two different places on the disc that have full bandwidth pink noise for me to set levels, so if I use one set of pink noise and set the levels I get one result, but when I go to the other place on the disc that has pink noise, I get different results, are the levels on the disc not the same? This is also the case when I use the built in test tones on the receiver (Yamaha RX-V1600), the main difference is in the left and right front channel and center. Then if I switch to a different setup disc, I would think that since I calibrated the system with one disc, that it should yield similar results with another disc, even the the volumes may not be the same between the different discs, I would expect all the speakers to read the same SPL, am I wrong for expecting this?

 

[Buckle-meister]

How large is the difference in values?

Regards

 

[GlocksRock]

a couple db, probably not enough of a difference that I would notice, but I still expect some consistency.

 

[Buckle-meister]

a couple db...

'Tis what I thought.

Were the differences found from tones at quite high frequencies? Because you will find that even moving your body a little will cause the needle to be affected.

Regards

 

[GlocksRock]

It was the wide bandwidth pink noise, and it was at ~72 - 75 db.

 

[mtrycrafts]

Then if I switch to a different setup disc, I would think that since I calibrated the system with one disc, that it should yield similar results with another disc, even the the volumes may not be the same between the different discs, I would expect all the speakers to read the same SPL, am I wrong for expecting this?

Not all set up DVD discs use the same -30dB FS signal, that would result in a 75dB spl tone. Avia, I think, uses a -20dB FS signal, same as for a mastering sound stage, resulting in a 85dB SPL tone. 75 was used for homes because 85 was just too loud in homes.

 

[GlocksRock]

I understand that, but regardless the difference I'm seeing is that when I switch between either avia, or another setup disc, and the receiver's test tones, it seems as though I have to adjust the level of one of the front speakers. I should be able to put in either disc, or use the built in tones and have all the speakers play at the same db once I've calibrated them regardless of the overall volume.

 

[MDS]

If the discs are each recorded at a different level, how can you expect them to play at the same volume? A Barry Manilow CD won't be recorded as hot as an Iron Maiden CD and for the same position of the volume dial on the receiver, the Iron Maiden CD is going to be louder.

The receiver tones are at -30 dBFS and AVIA is at -20 dBFS. The maximum level that can be recorded is 0 dBFS - so receiver tones are 30 dB below maximum and AVIA is 20 dB below maximum. AVIA is hotter from the start.

If you calibrate to 75 dB using the receiver tones, you get 105 dB when the signal is max (a peak in the recording). If you calibrate using AVIA, you get 105 dB when the signal is max. So it doesn't matter which you use. As Mtrycrafts said, 85 dB is very loud, so the receiver uses a slightly lower test signal so you only have to calibrate to 75 dB, which isn't quite as annoying to your ears.

Measuring with one disc and then switching to another that is recorded at a different level is not comparing apples to apples. If you calibrate with one disc and then do it again with the same disc but are off by 1 or 2 dB, that is normal. Other variables in the environment such as the position of your body as you hold the meter, background noise, etc can change the reading slightly.

If you have DVE, compare that to the receiver's internal tones. They are both at -30 dB.

 

[mtrycrafts]

I understand that, but regardless the difference I'm seeing is that when I switch between either avia, or another setup disc, and the receiver's test tones, it seems as though I have to adjust the level of one of the front speakers. I should be able to put in either disc, or use the built in tones and have all the speakers play at the same db once I've calibrated them regardless of the overall volume.

I would rely on one of the DVD discs before the quality of the tones in a receiver. But, if you level match with one DVD disc and test again with another, if I understand you correctly, one of the front speakers will be off by a few dB? And the same happens when you level match to the other then retest with the first disc? Is it always the same speaker? Not sure why this would happen, if my understanding is correct.

 

[GlocksRock]

Yes, it always seems to be the same speaker. I understand that the overall volume level will be different between different discs, and the internal receiver test tones, but once calibrated, I would think that the speakers should stay calibrated regardless of what discs test tones I use.

 

[mtrycrafts]

I would think that the speakers should stay calibrated regardless of what discs test tones I use.

Since only one channel/speaker has this issue, I am at a loss why the other channels don't change relatively from disc to disc but one does. Curious.

 

[GlocksRock]

That's what I'm trying to figure out. When I get my new center channel I'll recalibrate everything and see if the problem is still there.

 

[mtrycrafts]

That's what I'm trying to figure out. When I get my new center channel I'll recalibrate everything and see if the problem is still there.

Is it your center speaker giving you the problems as you are replacing it?
If it is a horizontal MTM speaker, maybe that is the issue? Horizontal MTM types have severe lobing issues in the horizontal direction.

 

[GlocksRock]

No, the center wasn't the problem, I just decided to upgrade from the Polk CS1 to the Polk CS2, basically the same speaker, it just uses 6 1/2" woofers instead of the 5 1/4" woofers.