Bi-Amping with a receiver, is it worth it?

[PENG]

Of course, I would not be surpised if I did not understand your question

- Rich

Thanks for not being surprised, LOL!!

You said:

It will not get louder but the bass is the most likely to clip creating harsh distortion in the high-frequencies.
However, in this case, the tweeter will remain unaffected as it has its own amp will not be clipping.

I responded:

Rich: Your example of bass clipping won't affect the treble sounds good but don't you think the preamp may clip anyway in some of those scenarios?

So I agreed and thought what you said was a great point, but while the "independent" power amp should not clip the high frequency signal, I questioned whether the preamp, that is not independent unless you bi-preamp it instead of using a Y-connector, could also clip the signal if the volume is cranked above its capability. I assume you are using just one preamp with a Y connector, so in that case the preamp has to amplify the full signal and output the same signal to both independent mono power amps via the Y-connector.

If the preamp could in fact clip, then both "independent" power amps would be amplifying a clipped signal to begin with, that's what I questioned, and I do not have a definitive answer. I do know in my applications my preamps and power amps will always operate well within their limits. I hope I have not further confused you, if I did I quit anyway.

 

[PENG]

"Forces" the current type to flow only through those wires that are hooked up? Pretty sure doesn't work like that. That would be like saying you could control the type of water that went through each of two different hoses hooked up via Y connector at the faucet. Regardless of what the tweeter is "using", the amp is still amplifying the whole signal that was sent to it.

At least they did not claim there was any proven audible difference.

John, I can assure you that circuit theory dictates that it does work like that, but of course not 100% (I don't think the author implies 100% effect either) because as we all know filter circuits are not brick walls, so some LF signals will still flow through the HF pair of speaker cable. You are correct about the amp is still amplifying the whole signal (I just said the same to Rich in my post rereamp), but the output of the amp has the choice of two pair of wires now, each as a filter at the other end, though again filters are not brick walls.

I am not a believer at all on any claims of audible difference from biwiring, but I feel the urge to defend the author of that article when he/or she presented something that is in accordance with EE circuit theory.

 

[RichB]

Thanks for not being surprised, LOL!!

If the preamp could in fact clip, then both "independent" power amps would be amplifying a clipped signal to begin with, that's what I questioned, and I do not have a definitive answer. I do know in my applications my preamps and power amps will always operate well within their limits. I hope I have not further confused you, if I did I quit anyway.

I am not a EE but at one time so this is they way I understood it.

I was going to get a 7 channel ATI or Outlaw amp so I asked this very question of ATI, Outlaw, and Marantz.
All three responsed that the Marantz would have no problem driving two amps because it is effectiving halving the input impedance of the amp which were sufficiently high to pose a problem for the Marantz.

- Rich

 

[PENG]

I am not a EE but at one time so this is they way I understood it.

I was going to get a 7 channel ATI or Outlaw amp so I asked this very question of ATI, Outlaw, and Marantz.
All three responsed that the Marantz would have no problem driving two amps because it is effectiving halving the input impedance of the amp which were sufficiently high to pose a problem for the Marantz.

- Rich

I suddenly think I know which part you misunderstood me so I am not going to quit yet. May be you thought I have been questioning about whether the preamp would clip due to driving two power amps. No, as I said I never doubted that a typical/well built preamp should have no issue at all feeding two power amps via Y-connectors.

My question is only about whether a preamp could also clip if pushed, the same way you cited when a power amp is cranked beyond its limit with heavy bass content. My question has nothing to do with driving one power amp or two. In fact I meant a preamp that drives just one power amp, so if the bass could cause a power amp to clip if cranked beyond its limit, wouldn't the same happen to a preamp? A preamp is still an amp, just handling lower level signals, right?

 

[RichB]

I suddenly think I know which part you misunderstood me so I am not going to quit yet. May be you thought I have been questioning about whether the preamp would clip due to driving two power amps. No, as I said I never doubted that a typical/well built preamp should have no issue at all feeding two power amps via Y-connectors.

My question is only about whether a preamp could also clip if pushed, the same way you cited when a power amp is cranked beyond its limit with heavy bass content. My question has nothing to do with driving one power amp or two. In fact I meant a preamp that drives just one power amp, so if the bass could cause a power amp to clip if cranked beyond its limit, wouldn't the same happen to a preamp? A preamp is still an amp, just handling lower level signals, right?

This may be the blind leading the blind but I believe that because the impedance is so high on an amp it takes very little current to drive them.
So like an amp, it has to be able to supply the current to maintain the voltage and not clip.
Most folks told me that so long as the input impedance is 10x of the output impedance there will be no clipping or drop in voltage that would cause roll-off.
Since the AV8801 output impedance is 220 ohms then the amp should be 2.2K. So even the Outlaw 7900 at 10K should not have a problem.
Most amps have even higher impedance.

Here is the response for Jeff at ATI about splitting the XLR signal:

</SPAN></SPAN>
Assuming the output impedance of your Marantz is relatively low, there will be no problems. Even if the output impedance is a little high, this will only cause a small high frequency droop--say .3 dB or so at 20 kHz which is probably not audible.</SPAN>

I think this answers it, but if it doesn't we need a more knowledgeable AH to jump in

- Rich

 

[PENG]

Amplfier Clipping

This may be the blind leading the blind but I believe that because the impedance is so high on an amp it takes very little current to drive them.
So like an amp, it has to be able to supply the current to maintain the voltage and not clip.
Most folks told me that so long as the input impedance is 10x of the output impedance there will be no clipping or drop in voltage that would cause roll-off.
Since the AV8801 output impedance is 220 ohms then the amp should be 2.2K. So even the Outlaw 7900 at 10K should not have a problem.
Most amps have even higher impedance.

Here is the response for Jeff at ATI about splitting the XLR signal:



I think this answers it, but if it doesn't we need a more knowledgeable AH to jump in

- Rich

I don't think what you cited are too relevant, may be to some extent it is though. I am an EE but not specialized in audio so while I understand the underlying theories and principles I cannot do a convincing job in this kind of topic. There is always Dr. Google, a quick search yielded the following.

As to more knowledgeable AH, here's one, post #7.

http://forums.audioholics.com/forums/amps-pre-pros-receivers/85369-amplifier-voltage-gain-matching-your-preamp-amplifier.html

Other's expressed similar opinion in:

post#10

http://forums.audioholics.com/forums/amps-pre-pros-receivers/85523-amp-clipping-issue.html

A good pdf file here but I don't know how to link to download the file.

http://www.google.ca/url?sa=t&rct=j&q=audio pre amplifier clipping&source=web&cd=10&ved=0CHUQFjAJ&url=http://www.zedaudiocorp.com/Technical/Amplifier-Clipping.pdf&ei=S9CvUbzLCoWNqQGD74GQAQ&usg=AFQjCNEn4kWok1v8ebLR8GawimyUACN8Zw

but you can read it here:

Amplfier Clipping

I just have to repeat one more time to be clear. A well design preamp, or amp, is not going to clip when used within their limits, but I am wondering if not used within their limits, wouldn't a preamp clip in similar ways, or differents ways that power amps do. That's all, not much to ask and not much not to believe, I hope.‎

 

[Swerd]

Interesting (Objective) piece on bi-wiring.

What effect does Bi-wiring have? : Empirical Audio

This article tries to give the appearance that it says something, but it makes no observations or conclusions whether or not we can hear bi-wiring.

It shows a graph with two different traces comparing frequency responses from bi-wiring (blue) and double wiring (red).

1. This graph came from a simulation, not a real measurement of speakers.
2. The differences in the red and blue curves only become apparent above 100 kHz.
3. Below that graph it says:

The graph above shows that in the bi-wired version, the frequency response to the tweeter is increased from 478 KHz to 1.762 MHz over the double-wired version.
​

Few people hear as high as 20 kHz, so I am not at all sure what is meant by that. 478 kHz to 1.76 MHz are absurdly higher than anything audible to humans. I am certain that no tweeters or recorded music go anywhere near as high as that.

Below that is an equally absurd effort to show bi-wiring also affects phase:

In the graph above, the double-wired version has a phase shift of 2.5 degrees at 20KHz. The bi-wired version, however, has a phase shift of only 0.5 degrees at 20KHz at the tweeter.
​

Again, its a simulation, not a real measurement made from a speaker. There is little agreement among acoustics and audiology experts on the subject whether humans detect even large phase shifts in reproduced sound. This article avoids all that and assumes that not only are large shifts in phase response audible, but tiny shifts of 2.5° or less are also capable of being heard.

By showing scientific looking simulated data that was extended to absurdly high frequencies, this article tries to get readers to believe bi-wiring makes an audible difference. To me, that borders on dishonest.

If anything, it demonstrates that bi-wiring cannot be heard.

 

[fmw]

Interesting (Objective) piece on bi-wiring.

What effect does Bi-wiring have? : Empirical Audio

So that we understand, speakers with two sets of terminals for biwiring have one terminal attached to the top of the crossover and one to the bottom. The problem is that the crossover still connects all the drivers so, electrically, the scheme doesn't change anything except for adding more wire. Just as bi-amping done properly can have an audible effect, bi-wiring would have to have the drivers electrically separated from each other to have an audible effect. In other words you would have to cut the crossover network in half and run the unwanted part of the signal for each driver to ground. Nobody but an audiophile does biwiring. Bi amplifying is easier.

 

[j_garcia]

So that we understand, speakers with two sets of terminals for biwiring have one terminal attached to the top of the crossover and one to the bottom. The problem is that the crossover still connects all the drivers so, electrically, the scheme doesn't change anything except for adding more wire. Just as bi-amping done properly can have an audible effect, bi-wiring would have to have the drivers electrically separated from each other to have an audible effect. In other words you would have to cut the crossover network in half and run the unwanted part of the signal for each driver to ground. Nobody but an audiophile does biwiring. Bi amplifying is easier.

That depends on the network and it would be assumed that the network in question actually DOES separate the HF and LF so that when the jumper is removed from the terminals that they do not share signal.

 

[PENG]

That depends on the network and it would be assumed that the network in question actually DOES separate the HF and LF so that when the jumper is removed from the terminals that they do not share signal.

That was the point I was trying to make and defended that author, on that point only. If the crossover network is not separable into two halves then that speaker is not really biwireable. If it is not bewireable then it is not biampable either.

 

[fmw]

That depends on the network and it would be assumed that the network in question actually DOES separate the HF and LF so that when the jumper is removed from the terminals that they do not share signal.

An easy way to find out is to remove the jumpers and put just one wire on either of the terminal pairs. You will know immediately if that is the case.