Novice attempting to bi-amp. Help

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
>

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)

I would think that shunting the input should negate all but the highest levels of crosstalk. After all, the input is where the "leakage" would have the most chance to be picked up and amplified as that is where the circuitry would offer the most gain. Shorting the input jack to ground would in effect shunt the "leakage" to ground at the same time, making the test far less realistic in terms of real world operating conditions. That is why i thought a Cardas Cap might be worthwhile, as you would only hear the "internal leakage" within the amp itself with minimal influence from outside sources.

One other thing just came to mind. I would guess that someone with HIGHLY sensitive speakers might hear more "crosstalk" simply due to the fact that the speakers allow more to be heard with less amplitude signal sent to them. As such, someone with K-Horns, K.A.R's, etc... may think that their otherwise "excellent" amp is "leakier" than someone with an amp that is actually much poorer with a pair of 86 db speakers. I guess that is why it is "good" to have test equipment and dummy loads to document such things. You at least end up with consistent and repeatable conditions that can be used from component to component. This allows one to have a specific baseline to work from. Sean
>

even if you have 2 amps of the same model, I would still be weary of a vertical setup, unless they are a monoblock pair sold as such, or at least factory matched.

amps are like people, to a certain extent, it's a nature/nurture kinda thing.

IF you've got 1 amp that is used 12 hours a day, hard, and another amp that is used only for 30 minutes on weekends, it doesn't matter that they are sequential serial numbersa, they are going to be different sounding (to some extent).

With a Horizontal setup, the highs will sound the same from right to left, and the lows will sound the same from right to left.

With a vert setup, one speaker would be getting the benefit of a more broken in amp, while the other speaker would suffer comparatively from the newer amp.

Some manufaturers will match the amps, output wise for a fee.

Unless the amps were a pair of monos, or had been factory matched, I'd still use the horizontal setup, basically for right to left continuity and consistency.

How to perform a gain match two amp if they are the same made but different model has different power output? However both of them have output control L/R too.