2. amps-preamps
  3. 1427697016

clipping and max rated watts/max volume

Does clipping and max power/max volume usually occur before the volume knob is turned all the way to it's maximum full rotation? What point is typically full power unclipped / max volume? i.e. -Volume knob around half to 3/4 way to max rotation?
labguy
almarg's avatar
almarg
9,670 posts
 
Peter (Csontos), keep in mind that what the preamp puts out is what goes into it plus its gain (which is defined based on its volume control being at max) minus the amount of attenuation the volume control is set to provide.

And what goes into the preamp depends on both the source component and the source material.

So if the amp clips when its input reaches 2 volts, the position of the volume control that will result in the preamp putting out 2 volts will depend on the source component, the source material, and the gain of the particular preamp.

All of those factors can vary widely. So the bottom line is as Ralph (Atmasphere) & ZD stated.

Best regards,
-- Al
csontos
1,311 posts
 
Sure, I get that. I'm just surprised the op wasn't given consensus in terms of typical circumstances. It's usually the case in my collection, low and high level recordings being the oddball. I thought pre amps were built to max out the average amp right around half way on the dial. This has been my experience, I think. Except for my Oppo BDP95 at 2v out direct to my LSR&D monos with 2.4v in. But I can get the clipping indicators on the amps to flash. Why would that be? Wrong specs?
almarg's avatar
almarg
9,670 posts
 
I'm just surprised the op wasn't given consensus in terms of typical circumstances.
OK, I'll give it a shot, while reiterating that all of the following can vary widely. Assumptions:

1)All interconnections are single-ended/unbalanced.
2)Onset of clipping occurs at 1.5 volts into the power amp.
3)Source is a CD player.
4)Maximum output of the CD player is 2 volts (which is about 2.5 db greater than the 1.5 volt clipping threshold of the amp).
5)Preamp gain is 12 db. (Note that some widely used preamps, such as some Conrad Johnson models, have gains that are far higher, e.g. 25 db. And many are significantly lower than 12 db).
6)Volume control attenuation (in db) as a function of position is as shown here. (I realize this is a passive preamp, but I couldn't readily find a comparable db-calibrated volume control illustration for an active preamp).
7)Musical peaks on the source material drive the CDP to its 2 volt max output.

Based on those assumptions, the volume control would need to provide 12 + 2.5 = 14.5 db of attenuation to output a level on musical peaks that corresponds to the clipping threshold of the amp. That in turn corresponds to about the 2 o'clock position on the illustrated volume control, which just happens to coincide with what Kijanki said in the initial response above :-)
... my Oppo BDP95 at 2v out direct to my LSR&D monos with 2.4v in. But I can get the clipping indicators on the amps to flash. Why would that be? Wrong specs?
Could be. The manual for the BDP95, btw, indicates 2.1 volts max output. And keep in mind that the difference between 2.1 volts and 2.4 volts is only 1.16 db. Arguably, to use an expression, "good enough for government work." :-)

Also, I'd expect that the exact clipping point may vary somewhat depending on speaker impedance (lower impedance = lower clipping point, for typical class AB amplifiers having unregulated power supplies), on AC line voltage, on whether the amp is being driven hard continuously or just on occasional peaks, etc.

Best regards,
-- Al
csontos
1,311 posts
 
Thank you Al. The Kappa 9s are the culprit. They dip below 1ohm at 30hz and 7khz. It was Foxy Lady.
almarg's avatar
almarg
9,670 posts
 
The Kappa 9s are the culprit.
Wow! It's quite a testament to the late Professor Leach that his amp can handle those speakers. As I'm sure you're aware, they are widely known as being "amp killers."

Best regards,
-- Al
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