sub volume level (1 Viewer)

[Vince Maskeeper]

We need to be clear that this is specific to the PE amplifiers, as I've seen a hundred cases which work with other products. My advice on calibration has been pretty common on this forum for more than 3 years- and I have seen many many people come back and not only be able to calibrate just fine, but prefer the sound of their system after doing so.

Today I calibrated a system using an Advent 505s which has a Carver Sunfire plate amplifier, and ran the sub essentially full bore (this sub for some reason hummed once you hit the top 5% of the volume knob- something funky in the pot I guess, so it's at 95%) and the system was still easily able to be calibrated.

I would say that we should be careful to be clear, just because one particular plate amplifier would be too high at full level- doesn't necessarily mean this is an absolute. I have seen many (and read about even more) that worked fine.

-V

 

[Ryan Schnacke]

Ryan, can you expand on this desire a little. I'm curious the reasoning for not wanting to run the receiver at the bottom of the range-- my first Pioneer HT receiver showed measurable clipping on bass peaks at -1 on the sub output!

What does -1 mean? If the range was -20 to 0 and you were driving up to reference levels then I'm impressed you could push it up so high. On my receiver the sub level range is like -30 to +10 so -1 is about 3/4 of the way up. And I never turn it up past 5dB below Ref so that's 5dB of headroom right there.

I agree with you whole-heartedly about keeping the signal below clipping. That's definately the way to go. And assuming you're not pushing into clipping, I can see two advantages to running the receiver's sub out above minimum. The first advantage is keeping your plate amp from automatically shutting down in the middle of a movie. The second is signal to noise ratios.

If I'm running a 50mV signal to the sub and I pick up 2mV of noise along the way that's 4% of the whole signal. But if I'm running a 100mV signal to the sub and pick up 2mV of noise that's only 2% of the whole. Then I can use the sub's gain control to cut that signal in half and get 50mV of signal and 1mV noise.

BTW, I haven't tried it but I doubt I could run the plate amp on my SVS wide open and still calibrate.

 

[Vince Maskeeper]

If I understand correctly the power on/off feature is based upon a signal input, and I would assume it is post sub preamp stage (since I think you mentioned above turning the sub volume up made the power on/off more sensitive).

This would seem to operate on the same priciple you applied above- no matter how the combination of sub output/sub input- in two situations where you have the exact smae voltage coming in- it shouldn't matter if it's pushed by the receiver or the sub preamp stage...

And in terms of S/N ratio- this is an element- however on material band limited at 125hz (and most mising under 80hz)- the appearance of noise is a whole different beast- and certainly not nearly an issue as a full range signal (in fact, that's why the LFE signal can boosted 10db without worry of boosting the noisefloor of the playback format).

Again- there are pluses and minuses to almost any configuration- and I would suggest there are serious pluses to the config I've mentioned in several configurations. So, the best bet is to try it. If it doesn't work- well feel free to throw it out the window.

-Vince

 

[Ryan Schnacke]

I meant to say that I have 5dB more headroom than a guy who listens at ref because I never turn it up that loud. I knew that wasn't real clear when I wrote it but I didn't bother to elaborate. Sorry.

And in terms of S/N ratio- this is an element- however on material band limited at 125hz (and most mising under 80hz)- the appearance of noise is a whole different beast- and certainly not nearly an issue as a full range signal

Good point. I hadn't thought of it that way. You're right - most of the noise picked up along the way will be higher frequencies that get filtered out by the low-pass filter.

 

[Wayne A. Pflughaupt]

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