# 1 pre out channel to multiple amp channels?



## chewie (Oct 26, 2011)

I am not exactly sure if I am wording this correct, so please bear with me. I would like to bi, and possibly later tri, amp my Linn Ninka's and Ekwal. Can I use 1 pre out on my surround processor to go to multiple channels on external amplification? For example from Front-L channel on the surround processor to 2-3 channels on an external amp in order to achieve the bi or tri amping I desire?

Thanks in advance guys!


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## tonyvdb (Sep 5, 2007)

Hi there, yes it is doable however Im not sure what your thinking the advantage is in doing so?
Each time you "y" the output you will loos a little bit of level so you would need to increase the output level of the receiver.I only recommend splitting the signal once.


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## chewie (Oct 26, 2011)

Well, I was not sure whether this would be akin to bi-wiring or whether it would really degrade what I am hearing. 

I see what your saying about splitting, so if I am going to go to external amplifiers then maybe I get 2 5 channel amps so I can bi amp my mains and center and then use the remaining 4 channels for surround and surround back?


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## tonyvdb (Sep 5, 2007)

That would work, just make sure that you use the same length cables for the bi-amping.


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## chewie (Oct 26, 2011)

Thanks Tony!


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## phreak (Aug 16, 2010)

Hi chewie, one other thing to consider here. What are you using for crossover and level matching? Many people see zero benefit to bi-amping if you are amplifying the full range signal to each driver. I would personally only consider it if the Pre-out went to a crossover, with the signal being split properly to each amp for the frequency range the driver can handle. Level matching is sometimes possible with the amp gain control, but not all amps have one. Food for thought. Sometimes it's better to just get a more powerful amp, and depend on the crossover within your speaker, rather than 2 amps and an active crossover.


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## Kal Rubinson (Aug 3, 2006)

phreak said:


> Hi chewie, one other thing to consider here. What are you using for crossover and level matching? Many people see zero benefit to bi-amping if you are amplifying the full range signal to each driver. I would personally only consider it if the Pre-out went to a crossover, with the signal being split properly to each amp for the frequency range the driver can handle. Level matching is sometimes possible with the amp gain control, but not all amps have one. Food for thought. Sometimes it's better to just get a more powerful amp, and depend on the crossover within your speaker, rather than 2 amps and an active crossover.


Amen. What the OP proposes is doable but not an effective use of resources.


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## chewie (Oct 26, 2011)

Ahh...very good point guys. I had not really considered that. The setup I was considering was an Onkyo 5509 (When I can get one) going to a pair of NAD T955 amps to let me do the bi amping, but I think you may have saved me some money since I am not planning to cross each channel. I will probably just get a single T975 instead and bi-wire my mains and center as I do today.

Thanks a lot for the good advice guys!


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## Kal Rubinson (Aug 3, 2006)

Biwiring is benign but pointless.


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## chewie (Oct 26, 2011)

Hehe, yeah, it is amazing how vehemently people differ on that point. I personally have never noticed a difference in bi wiring versus non, but man, to some people its a religious debate.


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## jackfish (Dec 27, 2006)

> Many people see zero benefit to bi-amping if you are amplifying the full range signal to each driver.


If a channel of an amplifier is directed to the high or low frequency section of a loudspeaker in a biamp configuration it does not have to amplify the full range signal due to the impedances involved. Hence, the amplifier would be, for the most part, only amplifying the frequencies that section is producing. You are repeating a common misconception of passive biamping.


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## phreak (Aug 16, 2010)

jackfish said:


> If a channel of an amplifier is directed to the high or low frequency section of a loudspeaker in a biamp configuration it does not have to amplify the full range signal due to the impedances involved. Hence, the amplifier would be, for the most part, only amplifying the frequencies that section is producing. You are repeating a common misconception of passive biamping.


Not to be argumentative here, but to further my own education in the matter, I don't understand this at all. I understand that I speakers impedance can change with frequency, and that the impedance affects the current output of the amplifier. What I don't get is how the amp does not amplify the portion of the signal that the driver is not reproducing. I would appreciate an explanation of that phenomenon, or a link to threads expounding on the issue, as I have not been aware of this "misconception of passive bi-amping", having not previously being exposed to the controversy.


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## jackfish (Dec 27, 2006)

Sorry, I was trying to over simplify it. Yes, those frequencies are still amplified, but due to the speaker crossover it is at such high impedances that there is little load presented. So for all intents and purposes it is as if those frequencies were not being amplified. The "misconception" which is oft repeated it that passive biamping wastes power, which is "burned off" by the crossover as heat in the frequencies that particular speaker section is not producing. This implies that there is significant power required from the amplifier for the frequencies not produced which is untrue due to the impedances involved and the resulting lessened current draw.

In addition, there is often more to a speaker's crossover than just separating frequencies. Baffle step compensation and other "shaping" of the signal is often employed by the speaker designer to achieve the desired sound. If one employs an electronic crossover in an active biamping configuration and does not provide altering the signal to reflect these other circuit considerations in the original speaker design, the speaker will have to sound different, often not for the better. Even changing the crossover slope can destroy a speaker's intended sound.

My main point is that those who say that passive biamping is a waste of time and active biamping only provides benefit may not be aware of all the considerations involved with each method.


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## Kal Rubinson (Aug 3, 2006)

jackfish said:


> If a channel of an amplifier is directed to the high or low frequency section of a loudspeaker in a biamp configuration it does not have to amplify the full range signal due to the impedances involved. Hence, the amplifier would be, for the most part, only amplifying the frequencies that section is producing. You are repeating a common misconception of passive biamping.


That is so but is there an audible benefit over a similar but higher-powered single amp?


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## Anthony (Oct 5, 2006)

Back when I was doing a lot of speaker design and testing, I would bi amp or tri amp designs to test individual crossover components separately. In some cases it was just to isolate the sound to see what was best, in others it was to make sure the passive components measured the way I wanted them to (before I wired everything together).

It sounded fine and allowed for much better tuning of the overall gain between sections to balance the sound. I prefer single wiring speakers for simplicity and the ability to move them between systems (give them away as gifts  ) and so on, but biamping does have its place.

As Jay said, though, there are a lot of other crossover components that do things like shaping, notch filtering, impedance flattening, BSC, etc that just adding an extra amp or electronic crossover will not replace directly. 

It's a complicated dance to get the sound right and one solution does not fit every speaker design or installation (or budget).


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## Kal Rubinson (Aug 3, 2006)

Yes, I agree with that. When I was designing/building speakers, all my initial builds were multiamped simply because the independence made analysis and tweaking easier. OTOH, the last part was to translate it into a passive single-wire implementation.


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## chewie (Oct 26, 2011)

So based on this thread, it sounds as though the majority of you are in the "bi-amping/bi-wiring does not provide the benefit to justify the cost" camp.


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## jackfish (Dec 27, 2006)

Depends.


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## Jungle Jack (Jul 28, 2009)

chewie said:


> Hehe, yeah, it is amazing how vehemently people differ on that point. I personally have never noticed a difference in bi wiring versus non, but man, to some people its a religious debate.


Hello,
I too have never noticed any difference with Bi or Tri Wiring. Unlike most AV Forums, we really do try to not let things turn negative even on subjects where consensus is not possible.
Cheers,
JJ


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