Novice attempting to bi-amp. Help

Vertical bi-amplification will work "better" if you have speakers that are a benign load on the higher frequencies and you have an abundance of power in both channels. Since the highs are relatively "coasting" in terms of power draw, the "excess" power that the supply is capable of is now available as reserve to help feed and control the much more demanding woofers. However, i must point out that this is NOT true if the amp that you are running is of true "dual mono" design since each channel has its own dedicated transformer and filter caps. As such, the supply is not being "shared" so one channel could not draw from the other. This method is more convenient than it is anything else, as it allows the amp to be placed closer to the speakers should one desire to do so.

If you have speakers that are reactive on top and multiple and / or low impedance woofers down low, each section of the speaker is pulling equally hard on the power supply. In this instance, horizontal bi-amping may provide greater benefits as you have a dedicated power supply that can cope with the demands of each frequency range on their own. This minimizes sagging of the supply for both frequency ranges simultaniously and presents a more stable stereo image. This is not to mention that this can result in less clipping being seen by the high freq drivers, which is a good thing in terms of reliability. I say this because the woofers would no longer have the capabilities to starve the power supply feeding the mids and tweeters, thus assuring them of always having adequate power to reproduce the signal.

If you gain a drastic amount of channel separation by vertically biamping, something is wrong with the design of your power amp. I say this because horizontal bi-amping is theoretically the same as running a single amp in normal stereo mode. The benefit is that you now have a dedicated power supply to each frequency range rather than to each channel. If you can hear a very noticeable difference in channel seperation using vertical over horizontal, your amps are simply poorly designed, lack channel seperation and are high in crosstalk between channels. If you are able to obtain excellent channel separation and imaging in stereo mode with one of these amps, you should be able to do the same with two of them in horizontal mode.

Obviously, the one drawback to vertical bi-amping is that you obviously need two identical amps to do this. One can horizontally bi-amp with two different amps, so long as their gain is relatively matched.

Obviously, the ultimate set-up would be to bi or tri-amp using monoblocks. This allows dedicated power supplies for not only each channel, but for each frequency range used. Channel separation and dynamic headroom are no longer part of the equation as you should have achieved the best possible in such a situation. That is, if the amps were selected so as to easily provide enough power under any conditions to each of the drivers it is connected to. It is possible to use a dedicated amp for each driver and still starve the driver IF the amp was too small to start off with to achieve the desired listening level. Sean
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Choose wisely, Luke Skywalker! That's the best advice for bi-amping. I would NOT use Carver amps at all for anything except maybe Sub Bass. Why? Because they are not particularly low in distortion or pleasing in subjective quality to my ears...

Having said that, I agree with Sean about the relative merits of "vertical" vs. "horizontal" amp application.

You can check your crosstalk by putting a dummy load on one
channel of your amp, the speaker on the other, play the signal ONLY into the one channel with the dummy load at normal listening levels, and see what you hear (if anything) from the speaker. That's your crosstalk in practical terms.

It should be >30-40dB down worst case.

I'd try to find a very high quality amp for the top end... since that's whats going to effect the overall quality of the sound that you hear. The highs have an inordinate contribution to what you perceive out of a speaker...

If you bypass the crossover in the speaker, and go with an electronic crossover, you might be pleasantly surprised at how much better the ribbons can sound without the Carver
parts in there... Since the ribbons themselves without the xover are almost completely resistive, it is a very easy load to drive, so you only need a sweet sounding amp, not one that is both sweet and can drive wierd loads!

similarly, I'd swap out the caps if they are not already Polypropylenes in the HP section immediately regardless...

If you do decide to use the internal crossover, I'd set up a little box with a 1st order high pass (a cap and some resistors) to feed the HF amps (or do it internally) so that that section sees a 6dB/oct rolloff from about 1 octave below the Carver's crossover point. This will keep all the LF energy out of those amps. Automatically less intermodulation, no matter what.

Regardless, look for some nice sounding amps for the ribbon part of the speaker, imho.

Thanks to all for the in depth advice. I believe I understand the set up to do the horizontal bi amp,
how would the hook up for vertical bi amping differ as
this is the set up most use with the carver amazing speakers
according to my research on the Audioreview site?
Thanks again for all the imput.

Mar4004

Bear, good idea about the dummy load and listening for "bleed through". Simple and quite effective. Do you think that removing the interconnect from the input of the "dead" channel and using something along the lines of a Cardas cap be of any further assistance while doing this test ?

While i have never done any "controlled" testing and taken measurements, i would think that -30 to -40 db's "should" be pretty easy to achieve. What are some figures of amps that you would consider to offer good to excellent channel separation ?

I agree with getting the passive crossovers out of there. It is amazing how much even a single "high grade" cap in a simple 6 db crossover can destroy the sound of a speaker.

I also agree with your comments regarding the Carver amps. Those speakers are capable of performance well beyond those specific amps, especially if the passive crossovers are bypassed.

Mar, in vertical bi-amping, let's say that we have amp A and amp B. You would hook up amp A to one speaker and amp B would go to the other. Amp A's right channel would drive the woofers and the left channel would drive the ribbons. Amp B's right channel would drive the woofers on the other speaker with the left channel driving the ribbons.

Obviously, i selected left / right channels just for demonstration purposes as one channel should be the same as the other and they don't have preferences as to what they drive. Sean
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Sean, the unused channel should probably be grounded, although that doesn't actually simulate operating conditions. So, I'd suggest alternately terminating the interconnect with another bit of local gear (like the output of a CD player not playing but on...

In lab tests the other channel is usually grounded.

Obviously the best separation is going to be a set of monoblock amps with separate supplies and chassis. That should be nearly infinite. Everything else is less.

I don't have any figures at hand for commercial amps, but they should be close to the noise floor unless there is a problem modulating the power supply at high loads (there can be). But this should not show up until you really suck some power. Or, on occasion there is radiation due to the current drawn through a conductor.

(you can make a nifty thing using a loop of wire as a transmitter, like around the room, and an inductor on the input of a preamp fed to an earphone - you can "broadcast"
directly on audio that way)