Setting up your sub - Signal to noise



Heard something the other day that seemed to make a lot of sense so, from that, Ill pass it on and also ask a question to your real audiophiles out there!

When setting your sub up always leave the DB gain level on the processor/amp at +/-0db. Never, tune it down via the amps channel level screen. In doing this you increase the signal to noise ratio. In short, leave the processor at the 0db level and use the subs on-board amp to set it to reference level.

Sounds obvious, but I never thought of it before. Sub level now at 0 and subs volume adjusted accordingly!

Question: If this signal to noise ratio exists with the A/V to sub, does this also apply when you connect a power amp to your A/V.

For example, I have connected my Arcam P-25 to my Denon 3802. With all channel levels set to 0, the Arcam registers at around 81-83db and thus I need to tune down the Arcam levels (via the Denon) by around 4db a channel.

Is this then causing a higher signal to noise ratio and, in short, providing a slightly (even if not audibly) worse sound quality?


Distinguished Member
If there is a difference, can you hear it?

To get all your channel levels at 0 you would have to move your speakers nearer or further away from you (depending on room size/speaker position). Unless you happen to be jammy and have speakers positioned so that at your listening position all channels are set to 0 on the channel levels whilst balanced to 75db.

Certainly the case with me, all channels are at - figures (FL -3, C -2, FR -3 etc etc). Couldn´t get the sub volume much lower to be honest, its at 3 on the sub with the amps SW channel level at -7. If I set the SW channel level to 0, I´d have to turn the subs volume almost to off!!

I´ve tinkered around with the channel level settings for the Stereo mode, at the moment they´re at FL -3, FR -3. I changed them to 0 and couldn´t hear any difference, that´s not to say there isn´t a difference, just that I couldn´t hear one.

Dom H

I thought it was recommended to have the amp set to it's lowest value and adjust on the sub, my 3802 SW is at -12dB


Active Member
The kind of S/N level differences we are talking about here on the sub output are probably insignificant and inaudible. From a practical point of view its probably best to set the sub volume to something that is easily reproducible (mid-point say) and adjust final level at the processor. That way you can quickly get back to your known reference point if the sub is ever moved to another system or otherwise disturbed for some odd reason.



Originally posted by Dom H
I thought it was recommended to have the amp set to it's lowest value and adjust on the sub, my 3802 SW is at -12dB
Setting to -12 only leaves you the option of altering the subs volume if needs be via the sub, depending on the subs location not always ideal. Then there's the setting up of the sub channel level, is it not more convienent to do it from the listening position than having to get up and down trying to get the volume right.

Also depends on the sub itself I would have thought, I have had a sub in the past that if I had set the LF on the amp to -12 and set the subs at full volume I know it would have had trouble reaching the 75db required.


I have the subs at mid-point, just in case someone changes them, as Allan sujests, and the AV at 0 level, a bit of a coincidence, but I had to use the 0db inputs instead of the +12db on the subs...

Does it make a difference... :confused:

I had this heird experience with my TAG, it would sound better with all channel levels 10db up, and volume less 10db, then the opposite, I asked them, and they said I am crazy, it doesn´t matter with digital gear...

But I know it did matter with analog, and the subs are analog, you had less S/N with the volume control too low or too high...

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