Bi-Amping with Different Watts - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 15 Old 11-06-07, 01:34 AM Thread Starter
 
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Bi-Amping with Different Watts

I was just wondering if anyone has tried bi-amping a speaker using different watts? Since everything under 80hz LFE goes to my PC13-U, would it be noticeable if I used 400w for the Mids/Tweets and only 140w for the woofer (Axiom m80)?
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post #2 of 15 Old 11-06-07, 04:04 AM
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Re: Bi-Amping with Different Watts

The problem with bi-amping with different amplifiers is that it could be difficult to adjust the two amplifier gains to reproduce an homogeneous sound. You don't want the mids/highs to be louder than the lows (or the opposite).

You should also ensure that the two amplifiers have the same kind of sound and imaging. I have heard of people using one tube amplifier for the mids/highs and another transistor-based amplifier to the lows. It sounds logical for getting the best out of the two worlds but it is harder to find a good match and tune it all.

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post #3 of 15 Old 11-06-07, 12:15 PM
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Re: Bi-Amping with Different Watts

Hmm,... well, kinda. I had bi-amped my mains by using the "surround back" amps on my 3805 and connecting them to the low frequency terminals on my speakers, then assigning control to Zone 3. I know this is not really bi-amped, but it was an interesting experiment. By adjusting the Zone 3 level up or down I could boost or cut the lows,.... the high side of the speakers were still connected to the L/R mains. Kinda sorta like what you are asking about???

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post #4 of 15 Old 11-06-07, 12:37 PM Thread Starter
 
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Re: Bi-Amping with Different Watts

It was more of a question then anything. My mains are 4ohm and the rest of my speakers are 8ohm, so I was thinking of buying two different amps for the system. Probably two channel for the front and 5 channel for the rest. I was also thinking about a 5 channel amp and just bi-amp the mains and use the last channel for the center.
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post #5 of 15 Old 11-06-07, 03:01 PM
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Re: Bi-Amping with Different Watts

Oh, I see. Sorry, I misunderstood you completely ! I thought that you wanted to use two different amplifiers on the same speakers. My bad !

Having a separate power amplifier for the front speaker i quite common in high-quality audio systems. Typically in this case, people want a very good dedicated 2-channel system which can perform well in surround mode too.

Buying a powerful power amp for the front and using a receiver (+ optional dedicated surround amplifier) for the other speakers is one easy way to go. It's often relatively cheap too. Most modern receivers have room equalization and auto-setup which will setup the correct gain for each channel. You don't have to worry about impedance ...

Another solution, as you noted, is to buy a powerful 5/7 channel power amp to power all your speakers. It's simpler but you loose the flexibility of having a better 2-channel system than the surround system. On the other side, you can always use the unused channels to bi-amp your front speakers (and that's a cheap upgrade!)

To the end, it all depends on what you truly want to achieve and how large your budget is.

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post #6 of 15 Old 11-13-07, 05:42 PM Thread Starter
 
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Re: Bi-Amping with Different Watts

I've read a few posts where people have used a 5 Channel Amp to feed their front three (Bi-amp Mains, Center) and just run the receiver for the rear/surround channels. That way, the receiver would only be running 2 channels and the amp would be feeding the power to the front sound stage speakers.

After reading that and listening to some DVD's, I find that there's not always sound coming from the surrounds as there are from the main three. This could be another possibility as well. I think that I'm going to have to see for myself.
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post #7 of 15 Old 11-13-07, 09:39 PM
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Re: Bi-Amping with Different Watts

A lot of people don't put stock in audible improvements due to passive bi-amping, myself included (and I have tried it). You also can't use less watts unless you get rid of the internal crossover. If you perform the electrical circuit analysis, which Audioholics has done, and you can do even a simple model on a piece of paper, the signal that the drivers actually see should be basically the same.

Active bi-amping with no internal crossover would, however, let you use less power for the more sensitive drivers and utilize the individual amps over a smaller frequency range, both of which could result in less distortion. The problem is you need to know what the correct crossover should be, and account for any effects on phase or impedance that the speaker was designed with. Which means purchasing a speaker that was supposed to be actively bi-amped, or designing one on your own.
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post #8 of 15 Old 11-13-07, 10:03 PM Thread Starter
 
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Re: Bi-Amping with Different Watts

Quote:
Josuah wrote: View Post
A lot of people don't put stock in audible improvements due to passive bi-amping, myself included (and I have tried it). You also can't use less watts unless you get rid of the internal crossover. If you perform the electrical circuit analysis, which Audioholics has done, and you can do even a simple model on a piece of paper, the signal that the drivers actually see should be basically the same.

Active bi-amping with no internal crossover would, however, let you use less power for the more sensitive drivers and utilize the individual amps over a smaller frequency range, both of which could result in less distortion. The problem is you need to know what the correct crossover should be, and account for any effects on phase or impedance that the speaker was designed with. Which means purchasing a speaker that was supposed to be actively bi-amped, or designing one on your own.
So, what did you think or what results did you notice when you bi-amped your speakers? Was it a noticeable difference and was it worth the money to try and attempt it?
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post #9 of 15 Old 11-14-07, 07:03 PM
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Re: Bi-Amping with Different Watts

I don't put any stock in audible improvements due to passive bi-amping.
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post #10 of 15 Old 11-14-07, 09:16 PM Thread Starter
 
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Re: Bi-Amping with Different Watts

So, are you saying that you wouldn't recommend doing the bi-amping then?
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