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bri1270
06-01-2005, 11:29 AM
Can I bi-amp a 340C with 400W into 2, so 200 a piece?

bikeman
06-01-2005, 12:00 PM
Can I bi-amp a 340C with 400W into 2, so 200 a piece?

This is from an earlier thread. This was Dave F's response. Hope it helps.

David



Thanks James... here is a better approach There seems to be some confusion regarding bi-amping so I thought I will present an accurate explanation…

I have noticed that bi-amping seems to have two definitions lately, both similar, but with very dramatic differences as to how to achieve it and what benefits (if any)

From an engineering perspective, we define bi-amping as using different amplifiers (usually 2) each dedicated to reproducing a different frequency range. In reality, when you are using an AVR with the speakers set to small, and a powered subwoofer you are already bi-amping. The amplifier in your receiver is dedicated to a frequency range of, for example, 80 Hz to 20 kHz, while the amp in your sub is dedicated to 80Hz and below. This is achieved by using active high and low pass filters. Active meaning that the signal processing (filtering) is done on the low level signal (pre-amp level), before it is amplified, thus resulting in an amplifier only reproducing a portion of the bandwidth.

To achieve this type of bi-amping with a loudspeaker (which has many proven benefits), one would have to design an active crossover for the speaker and bypass the internal, passive (high level) crossover… This type of beneficial bi-amping is simply NOT possible with typical loudspeakers that are bi-wire capable. You can not bypass the internal crossover of the speaker. Using 2 amplifiers (each one dedicated to a different frequency range) will have no benefit and can hurt performance.

In fact, even if you were able to bypass the internal crossover, and use an electronic crossover to separate highs and lows thus sending them directly to the tweeter and woofer, I would NOT recommend it. Reason for this, at least in our crossovers, there are many optimizations and impedance compensation circuits designed to contour and control the response and dispersion of the speaker, not just send the highs to the tweeter and the lows to the woofers. Naturally, bypassing our crossover would also bypass these circuits, thus critically hampering the performance of the loudspeaker….

Where confusion seems to develop is that many people now define bi-amping simply as using more than one amplifier feeding the same signal into the speaker. This can be done with our CMT-340 series speakers, however, there is much to be considered before attempting this..

It is critically important to use the exact same amplifier. As you know, not all amplifiers sound the same or have the same gain… In fact, there are probably as many different amps as there are speakers. Imagine using an amplifier that sounds different from another, and one of those amps is feeding the tweeter while the other feeds the woofer. Do you think the loudspeaker would perform within specification? Certainly not, plus, different impedances of the amplifiers could greatly affect how the crossover “blends” the tweeter response with the woofer response. Crossover point might be moved higher or lower, the delicate phase alignment might be thrown off.. All greatly hurting the performance…

Some receivers offer a “bi-amping” feature so that if you are not using that 3rd pair of speaker outputs (7.1) you can run another set of cables from that output to the speaker. This used to be called “amplifier bridging” and I guess the marketing geniuses decided that bi-amping is a more exciting term, even though it is technically incorrect. This type of bi-amping can present a slight performance improvement in power and dynamics only. However, keep in mind that all the amplifiers in your receiver are running off the SAME power supply so technically speaking, the benefits you might achieve in added power and dynamics are severely limited by. It is NOT the same as using two separate amplifiers…


I hope this explains what bi-amping truly is… thanks for your time!
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Good Sound To You!

David Fabrikant
www.ascendacoustics.com (http://www.ascendacoustics.com/)

bri1270
06-02-2005, 03:12 AM
Great stuff, thanks Bike - I guess I would be "bridging" then, but it doesn't really seem worth it. I knew it was mostly mumbp jumbo, but I have an extra free channel so I figured what the heck, might as well put it to use.

bri1270
06-10-2005, 03:21 AM
Just to clarify - If I use two channels from the same amp...ie. one, two channel amp, to feed the 340C I should be okay. Like I said, I have an extra channel, and If I use the amp in bridged mode I'm looking at 500W total as opposed to 205W using one channel.

curtis
06-10-2005, 04:01 PM
yeah...you should be fine....but as far as the 340c is concerned, I do not think you are going to benefit from it, and you have to make sure in implement it properly, if not, you could hurt the speaker. Make sure you feed each amp the exact same signal.

bri1270
06-10-2005, 06:40 PM
That's not a problem, I'll feed the amp the center channel signal to both sides. I'm confused though, why wouldn't there be much benefit? It's virtually doubling the power to the speaker. Specs say that it can handle 240W, power from the Amp will be about 400W, but I would never run it that hot, I'm only interested in the added headroom, particularly for HT.

I always thought it was better to run the speakers on an amp that can provide more than enough power to prevent clipping.

curtis
06-10-2005, 06:46 PM
yeah.....but the 340's are not power hungry speakers.....200 watts is already more then necessary. Try it, and let us know if you hear a difference.....good or bad.

You do realize, that at normal levels, the speakers never see anything close to 200 watts.

bri1270
06-11-2005, 03:15 AM
I sure do, but I thought with movie tracks there were peaks that could approach that level.

bikeman
06-11-2005, 06:06 AM
I sure do, but I thought with movie tracks there were peaks that could approach that level.

True enough. I've played around with this and can't detect a difference. My RS meter can but it's not enough for me tell a difference. One thing to keep in mind. We're not discussing music or voices with these peaks. They're usually sounds related to action movies. I can already get these to ear damage levels without the bi-amp so getting a tad bit more isn't adding anything of value for me. It may add some clarity to these sounds but I can't vouch for that.

David