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Discussion Starter · #1 ·
I got a 120MW x 5 stand alone power amp. That's meant each channel can work individually. I would like to know IN THEORY,


option 1) for each stereo channel, using 1 to 2 RCA from pre amp to power amp, using a pair of cable from power amp to LF of speaker and the other pair to HF i.e. a sense of bi-amp for each speaker: or


option 2) just bridge 2 power amp channels into 1 and makes 320MW x 2 output to both speaker.


which option is better IN THEORY, bi-amp or more power ?? Thanks!
 

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Depending on your speakers, I wouldn't bridge the channels to get more power. By bridging the channels, you are summing two channels to get one more powerful one. As a result, the load the bridged amplifier sees is half. So if your speakers are 8 ohms nominal, they will now present a 4 ohm load to the bridged amp. Because many speakers can dip below their nominal rating, you are in danger of exceeding the current capacity of the bridged amp. The result is distorted output.
 

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I would go with running each channel to each individual input on your speaker. Your speaker most likely has at least two pairs of binding posts that have two different crossover networks or you wouldn't be asking about biamping versus bridging. So pick a channel on your five channel amp and wire that to your woofer and another channel to your mid/tweeter. Depending on the outputs of your preamp, you may need to get a splitter to increase the number of outputs from 2 to 4. Some multichannel amps can be setup to biamp by using "jumper" interconnects between available preouts on the amp to the input of another channel. As far as I'm concerned, the method of using a multi channel amp to biamp is akin to horizontal biamping. Your multi channel amp most likely has a shared power supply among all the channels. This isn't the most optimal setup for biamping. I have two identical amps in my setup to do vertical biamping. This increases power capacity by dividing the load the woofer puts on the amplication system to two separate power supplies. The remaining channel on each amp is left to drive the mid/tweeter which isn't as power hungry as the woofers.


To further expand on the biamp concept, you'll need to add either a passive or active crossover before the amp(s). Introduction of a line level crossover helps to further increase the efficiency of what biamping can offer by only directing the operating frequency of the driver to the specific amp power it. This eliminates wasted energy in amplifying a full range signal for a driver that is only reproducing a part of it.


Don't get me wrong here. I am currently running a setup that you propose. I have found that there has been definite sonic benefits that I can hear with biamping without a line level crossover. But I do intend on adding an active crossover sometime in the future to further realize the benefits of biamping. But of course to do it right all the way, I'll have to remove the passive crossovers at the speakers and directly wire them to the amps. But that's more trouble than I would want to get into.
 

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I forgot to add one other thing concerning multi channel amps. So far, the Bryston 9B-SST is the only amp I've found that has five discrete amplifiers in one chassis. The five channels are on individual cards with their own power supplies that mount into the main housing. If you have this amp you're in good shape.
 

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Discussion Starter · #7 ·
My power amp is a Chinese made power amp which is famous in Hong Kong and China for its quality vs its prices! And I have also known that its export version in Japan costed around 1800 USD! Anyway, thanks for the information and advise from WongHung. The information is really a good reference for me to consider whether I have to buy 2 1 to 2 splitters and 2 paris of speaker wire for the bi-amp trial!! Cause as U may notice that my speakers are 4 ohm, and I had known before that 120MW is not power enough to push them in good shape! Thus why I have to use bridge method!
 

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Won, you should keep in mind that if you use an active (ahead of amp) crossover, you should go into your speakers and bypass the internal crossover sections, to avoid interactions between the different crossover frequencies. Otherwise, you'll be losing a frequency band somewhere that corresponds to the two different crossover frequencies.
 

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Larry,


Thanks for the reply. Yes, I'm aware of the issues with running a crossover ahead of the amp and interactions with the passive crossovers in the speakers. What I plan to do is to run the crossover points on the active crossover at points that are beyond those of the passive units in the speaker. In essence, creating a curve that encompasses the passive crossover points. Then I'll let the passive crossovers in the speakers refine the signal down further. I know this isn't the best way and ideally I should have only the active crossover filtering the signals, but I really don't like the idea of butchering up my speakers. Also, if I were to directly couple the speakers to the amps, I would have to look at tri-amping. And that possibility is more money than what I want to deal with.
 

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Why not just Biwire? That's what I do with my Wharfedales. According to them, biwiring will at least reduce the stress on the crossover improve the overall sound.
 
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