Subwoofer volume knob vs receiver gain?

[yepimonfire]

I've discovered that setting the volume knob at 1/2 and calibrating the sub at -3dB on the receiver (75dB SPL) causes clipping on the output stage of the receiver at 0 dB on the receivers volume control ( reference volume for film). If I crank the knob all the way up and set the gain in the receiver to -13dB I crank crank it all the way to +12dB without the clipping problem.

I have no idea what the input impedance or input sensitivity is on the sub or the output voltage on the receiver but I'm positive the sub is asking for more voltage at 1/2 volume than the receiver can give.

Is there any reason why cranking the gain on the sub to max would be a bad thing?

Sent from my SM-G360T1 using Tapatalk

 

[WaynePflughaupt]

A powered sub is similar to a stand-alone amplifier, especially the pro-audio kind that has on-board gain controls. An amplifier is a two-stage device comprised of the input stage and the amplification stage. The input section is a line level-device that takes the incoming signal and regulates it to a usable level (via the aforementioned gain controls) for the amplifier section.

Thus it’s no issue setting the sub’s gain anywhere that’s needed to accommodate the level (strong or weak) of the incoming signal. That’s what it’s there for.

Regards,
Wayne A. Pflughaupt

 

[ski2xblack]

Shouldn't be any problem. In your particular case you've discovered it's necessary.

Ideally, you would set the pre-outs to be as hot as possible while also avoiding clipping. You may have a bit of wiggle room to go back in the other direction slightly if you want to play around with it, but that's probably not necessary.

 

[William Lemmerhirt]

The other thing you might find is if the avr is at -13 it might not activate the auto on.

 

[j_garcia]

I start with the sub at 50% and see where it calibrates. Then see how much adjustment is needed to get it close to zero (+/- 1-2 dB) on the receiver without having the gain on the sub at 100%.

 

[Pogre]

I start with the sub at 50% and see where it calibrates. Then see how much adjustment is needed to get it close to zero (+/- 1-2 dB) on the receiver without having the gain on the sub at 100%.

Slightly off topic... My receiver will go to +20, but I've never had it even to 0 for fear of blowing something up. I'll run it at -10 pretty often though. I guess my question is, is it fairly common to push it to 0 and play at that volume? Would I be endangering anything? I have no idea where the threshold is for clipping.

*Edit: It actually goes up to +6.5. I paused and tried for the first time.

 

[William Lemmerhirt]

Slightly off topic... My receiver will go to +20, but I've never had it even to 0 for fear of blowing something up. I'll run it at -10 pretty often though. I guess my question is, is it fairly common to push to 0 and play at that volume? Would I be endangering anything?

I don't think it's uncommon at all. In my case if I'm any lower than -7, it won't turn my subs on until the volume is turned up. Then I have to turn it back down. I usually shoot for around-5 to -3. Then I have some room if I want to trim up. I run a few hot so that's not usually a thing. What I've read is that if you're avr gets into the + range, that's when you can see distortion in the signal. Never verified this but makes sense so I just stay below. You shouldn't blow anything up unless you trim super high and the MV is really high also.

 

[Pogre]

I don't think it's uncommon at all. In my case if I'm any lower than -7, it won't turn my subs on until the volume is turned up. Then I have to turn it back down. I usually shoot for around-5 to -3. Then I have some room if I want to trim up. I run a few hot so that's not usually a thing. What I've read is that if you're avr gets into the + range, that's when you can see distortion in the signal. Never verified this but makes sense so I just stay below. You shouldn't blow anything up unless you trim super high and the MV is really high also.

Audyssey trimmed everything back -3 to -5db (-5 being a surround). I'm going to -10 and sometimes want some more, but I'm afraid of frying my speakers. I've wondered why it would trim ALL of my speakers that much?

A rule of thumb being 0 as the threshold for distortion sounds right to me too. Let's see if anyone else chimes in.

 

[William Lemmerhirt]

Audyssey trimmed everything back -3 to -5db (-5 being a surround). I'm going to -10 and sometimes want some more, but I'm afraid of frying my speakers. I've wondered why it would trim ALL of my speakers that much?

A rule of thumb being 0 is the threshold for distortion sounds right to me too. Let's see if anyone else chimes in.

The reason it sets them to minus values is their sensitivity. For example, speakers in the 87db range might be trimmed at +3 while ones in the 92db range might be trimmed at -3. Sensitivity and distance are the biggest factors there. The sub is trimmed based on where the gain is set, as opposed to, but similarly how the sensitivity effects the regular channels.

 

[Pogre]

The reason it sets them to minus values is their sensitivity. For example, speakers in the 87db range might be trimmed at +3 while ones in the 92db range might be trimmed at -3. Sensitivity and distance are the biggest factors there. The sub is trimmed based on where the gain is set, as opposed to, but similarly how the sensitivity effects the regular channels.

So if I were to bump all of the trim numbers up 1 or 2db for each speaker I could get more volume without turning the knob as far, thus giving me illusion I'm not getting close to 0?

*Edit: Or just leave it, stop being a pussy and go to 0. I'll stop derailing the thread. My apologies to the op.

 

[j_garcia]

That's what I mean by starting with 50% on the sub - see where it calibrates, as in is it higher or lower than zero. Not every room and sub will get you close to zero. If it is WAY off, then your hopes of getting close to zero are obviously a lot lower. My current config with the sub at about 75% gain gives me +1dB from zero, and that seems about right. With my old sub, it was more like -5dB.

 

[Pogre]

That's what I mean by starting with 50% on the sub - see where it calibrates, as in is it higher or lower than zero. Not every room and sub will get you close to zero. If it is WAY off, then your hopes of getting close to zero are obviously a lot lower. My current config with the sub at about 75% gain gives me +1dB from zero, and that seems about right. With my old sub, it was more like -5dB.

Thanks J. I think I got it sorted out in my head. yepimonfire has a different issue. Though my issue was more just a question centering around the volume control of my avr.

William, I just cranked it to 0. Holy crap! It got frighteningly loud with no distortion. Phew! That was intense. I've never heard my system that loud before. It was plenty. I now have no fear of creeping close to 0 any more... except hearing loss.