Sub volume level question.............

EricH

I was wondering if there is any benefit to turning up the volume level on my sub while turning down the LFE level on my AVR. At this time, I have the sub volume set on 1 1/2, and the AVR sub volume at 0 +/-. Won't the sub sound better with it's amp running at a higher level, say a volume setting of 3 or 4? At the same time I'd be lowering the LFE channel volume level from the AVR to match the previous output. Or does all of this make no difference at all?

Thanks, Eric.

HK AVR 630
RTi70 mains
CSi40 center
CSi30 side surrounds
RTi38 rear surrounds
Velo CHT-15 sub

Dr. Spec

The opposite generally holds true. Sub pre-outs tend to have higher levels of THD than the other pre-outs at anything over the 0 setting.

Keep the sub pre-out level set around -5 (on a scale of -10 to +10), and you'll be sending the sub amp a cleaner signal.

EricH

Yes, that's what I meant. Reduce the pre-out volume while increasing the remote volume control on the sub. My AVR can indeed be reduced to a max of -10. I will try this tonight. Thanks for the help

Still, I guess my main question is this: Does turning up the volume on the sub itself from 1 or 2, to 4 or 5, then decreasing the pre-out volume improve sound quality? More power is being sent to the woofer from the sub's self contained amp, correct?

wlrandall

This is exactly what I did to eliminate clipping with my PSW350s. Amp volume is about 60%, AVR output is set at -5dB. Seems to work a lot better driving the sub with the amp instead of driving the amp with a hot signal.

Dr. Spec

Still, I guess my main question is this: Does turning up the volume on the sub itself from 1 or 2, to 4 or 5, then decreasing the pre-out volume improve sound quality? More power is being sent to the woofer from the sub's self contained amp, correct?

Yes, it will improve the SQ. You will have a lower distortion signal, and also improve the dynamics of the signal.

If you adjusted the pre-out up to +10, THD would be quite high and the waveform would showed some clipping.

EricH

Originally posted by Dr. Spec
Yes, it will improve the SQ. You will have a lower distortion signal, and also improve the dynamics of the signal.

If you adjusted the pre-out up to +10, THD would be quite high and the waveform would showed some clipping.

Thanks for your input Dr. and wlrandall. Both responses have helped me out on this issue. I understand the idea of a lower distortion LFE signal at lower pre-out levels, but am still wondering about the sub amp sound quality per volume applied. What if the LFE pre-out was always a perfectly clear signal at any level. Would I still see a benefit adjusting these levels?

EricH

Went home at lunch. Set LFE pre-out to -5, increased volume on sub to 3. Popped in The Two Towers. Helm's Deep-wall breach scene. It works! Less distortion, cleaner sound. Thanks again for the help.

Dr. Spec

Originally posted by EricH
What if the LFE pre-out was always a perfectly clear signal at any level. Would I still see a benefit adjusting these levels?

First, your scenario is hypothetical and would never happen in real life; all output devices become non-linear at some point along their operating curve.

Second, the subwoofer plate amp will have its worst S/N ratio at the minimum gain setting. You need to adjust the setting so it provides a decent amount of gain to the signal and gets it up above the noise floor of the amp.