Author Topic: Interesting find comparing AVR trim to sub volume adjustment  (Read 504 times)

Online KenMasters

Interesting find comparing AVR trim to sub volume adjustment
« on: December 07, 2018, 10:18:00 AM »
I always make sure that the AVR level settings are in the negative figures (if I can't hit 0). Though with my most recent receiver the minimum volume at which I can set the subs without the AVR having to increase the volume during autocal results in a pretty significant volume reduction of -9.5 and -7.5 for the left and right subs respectively - which from my understanding shouldn't be a problem (volume setting on the subs is at a quarter at this point).

Yesterday I found myself thinking about this and thought I'd play around with the volume. I took a measurement of the system as is, then I set the levels for the sub on the AVR to 0, then turned down the volume on the subs themselves until their readings corresponded to those of the AVR's settings.

I then compared them measured together with my initial reading:



So that worked out well enough. Then I took a look at the spectrogram and waterfall charts - setting the volume on the subs and leaving the AVR at neutral seems to have had an unexpectedly positive effect:

AVR Volume Control


Sub Volume Control


Any thoughts as to why this might be?
« Last Edit: December 07, 2018, 10:25:32 AM by KenMasters »

Offline Jason Willemse

Re: Interesting find comparing AVR trim to sub volume adjustment
« Reply #1 on: December 07, 2018, 02:55:54 PM »
VERY interesting result! Now I'm keen to apply the same at home, as my AVR settings are very similar to what you had indicated. Were you able to note any changes without the spectrogram and waterfall info, as in audible difference?

Online KenMasters

Re: Interesting find comparing AVR trim to sub volume adjustment
« Reply #2 on: December 07, 2018, 04:09:51 PM »
VERY interesting result! Now I'm keen to apply the same at home, as my AVR settings are very similar to what you had indicated. Were you able to note any changes without the spectrogram and waterfall info, as in audible difference?

I only went through content after I was done taking readings and looking at the graphs, so can't say with certainty that any differences I noted aren't psychological. I do feel that there is a less oppressive, cleaner character to the bass in certain sections of content, such as the heartbeat in the intro to Daredevil.

Whether I do hear it, or am just comforted by pretty graphs, I'm pleased either way. Though more than anything else, I'm curious to know whether the signal from the AVR's or the sub's amps are the cause. I took readings multiple times with both settings with the same results, so rule any anomalies there as the culprit. I would guess it's the sub's amplification that's behind it,  I had to reduce the volume by almost half of its original setting - less distortion at lower volume perhaps? I'm no expert on these matters.

Offline jvr

Re: Interesting find comparing AVR trim to sub volume adjustment
« Reply #3 on: December 07, 2018, 05:14:49 PM »
I concur. I did the same thing quite a while back, that is setting the AVR's sub setting to zero and compensating with the sub's volume, and it sounded much better to my ears. I think I posted something about it at the time.
Lend me your ears

Offline windshear

Re: Interesting find comparing AVR trim to sub volume adjustment
« Reply #4 on: January 07, 2019, 12:08:19 AM »
Hi Ken, I don't see any difference in the graphs. If what you are looking at is the spectrogram at 42Hz and 78Hz then I would call that at 25dB down from the original an external anomaly that gave you a false improvement when it was measured. This normally becomes apparent when measuring at too low a level that external sources are able to falsely give an impression of what is going on (noise floor impinging). If you did indeed measure them both at the level with a calibrated Umik-1, then for interests sake repeat the process with your master volume set at 5 or even 10db louder and see if its repeatable.

Online KenMasters

Re: Interesting find comparing AVR trim to sub volume adjustment
« Reply #5 on: January 07, 2019, 04:29:45 AM »
Hi Ken, I don't see any difference in the graphs. If what you are looking at is the spectrogram at 42Hz and 78Hz then I would call that at 25dB down from the original an external anomaly that gave you a false improvement when it was measured. This normally becomes apparent when measuring at too low a level that external sources are able to falsely give an impression of what is going on (noise floor impinging). If you did indeed measure them both at the level with a calibrated Umik-1, then for interests sake repeat the process with your master volume set at 5 or even 10db louder and see if its repeatable.

Multiple readings for each adjustment were taken during the same session with a Umik-1 (volume set as per the standard -12dB REW Generator and SPL meter method). Having thought on it further though, perhaps the difference comes down to the levels set for each sub possibly not being a precise match to those of Audyssey. There is quite a difference between the behaviour of the left and right sub, perhaps it's a result of the tipping of balance...

Okay, tested out the theory, that's indeed what's happening. Just one click up on one sub and there's a marked difference. The left sub needs to be set quite a bit lower than the right in order to level match the two, just a click either way on the left makes quite a difference. Sub volumes are low, 10 and 14 respectively out of a possible 80 points. It's an odd shaped room with no parallel walls, an alcove, recesses and protrusions.
« Last Edit: January 07, 2019, 04:33:15 AM by KenMasters »