Axiom Home Page Forums General Discussion Advice from Axiom Owners SQ8 Question?

I have a Denon 3808ci. The Zone 2 terminals on this amp are configurable to be Zone 2, Rear Surrounds, or Bi-Amping. You connect a set of wires from the Zone 2 terminals, to the second set of terminals on the speakers, then you configure them as Bi-Amp. According to where I bought it, and to Denon it is supposed to help make them sound a little smother/fuller. Now just adding a second set of wires is Bi-wiring, and that is of course a completely different thing. But the way I have it is supposed to make a difference. Night and day, no, but I feel better about it.

Marketing says it's supposed to make a difference. I suspect 7.1 would make more of a difference.

...to two different outputs on the same receiver or same amp with a single, common power supply... (Which is how nearly every receiver is designed.)

To expand upon what he's saying. The amp in the receiver is rated for x Watts into n channels. That isn't so much because of the design of the output stage of the amps as it is the power available in the power supply.

Running the full frequency output of one channel to both the high and low range of a speaker will provide the same amount (actually for most content, more) of power to the speaker as pushing two channels with full frequency content into a split, passive cross-over network of the same speaker (and thus turning the unplayed part of the content to heat).

The only way a single amp/power supply can gain anything by bi-amping is to remove the cross-overs from the speaker and perform active crossing-over before the signal is amplified.

Don't believe us? Get an SPL meter, play a passage a good volume level, where you think you'd be getting a benefit from having two amps. Record the peak value. Now remove the bi-amping, don't touch the position on the volume control, and play the same passage again. If the bi-amping was doubling your power you should lose 10 dB. You won't. You shouldn't lose anything it may actually end up a little louder--if you were being current limited by running the same content through twice as many amps.

Actually if I remove the Bi-amping, I will loose all the base from Fronts. You remove the bridging bars from the back of the speakers. Also by your logic you would gain nothing by adding additional speakers, since they all go back to the same amp, I mean if you are talking volume, and not definition. Maybe I am misunderstanding what you are saying.

This is from Denon's FAQ's
Bi-amping and bi-wiring are different. But they’re often confused because both bi-amped and bi-wired systems have two sets of speaker cables running from amplifier(s) to a speaker. However, it’s what happens to the audio signal before it gets sent to the speaker that really distinguishes these two techniques. The only way we can answer your question is to dive into the details. So, here they are
Traditionally speaking, bi-amping means the use of two separate amplifier channels connected directly (no passive crossover in the signal path at all!) to individual loudspeaker drivers optimized to reproduce a particular frequency range. For example, one amplifier channel would be connected directly to a tweeter for high frequency reproduction, another to a woofer for bass reproduction.
Bi-amping requires an electronic crossover to divide the wide range audio signal from a preamplifier before that signal ever gets to the amplifiers. The advantages of traditional bi-amping are significant. Damping factor (a measure of the amplifier’s ability to control the back-and-forth motion of the driver) increases, intermodulation distortion goes down, and effective amplifier power is increased dramatically.

Thing is, you're not doing traditional bi-amping, as they call it, since removing the bars from the back of the speakers does not remove the internal passive crossover. So while their explanation is correct, it's not what their receivers do.

But hey, it hurts nothing to do it the way you do, other than the lack of 7.1.

...and I meant when disabling the bi-amping to replace the bars.

[quote=ClubNeonIf the bi-amping was doubling your power you should lose 10 dB.[/quote]
Just a quick note to say that halving/doubling the power will result in a ~3dB change, not 10dB.

Just trying to learn, so hang with me. My speaker manual says how to Bi-amp, and how to Bi-wire both, and my Studio 60's can be Bi-amped according to the manual. I would agree that it would not make any real difference if I was just running a second set of wires. I am pretty sure that when you configure the Denon for Bi-amp, it only sends the low freq stuff out of those speaker terminals.

I guess if you are correct, then it is just a useless function they have built into this receiver.

Just a quick note to say that halving/doubling the power will result in a ~3dB change, not 10dB. [/quote]

I am not sure that is correct either. Every 3 db is double the volume correct? But as you go up it takes more power to increase another 3db. So it takes a lot more power to go from 75db to 78db than it does from 6 db to 9db. Once again maybe I don't understand, but that was the way it was always explained to me.

Smitty, does the manual specify which terminal to hook which output to? If not, then it's not doing any active crossovering. (No, that's not a word...) Also, if there's no way to specify the bi-amp crossover, it's probably not doing it, and if it is, it's not doing it well.

I'd advise you swap terminals, but that might or might not prove anything. I don't think it would be detrimental to the speakers (since the internal, passive crossover network is still working)