"Vertical" biamping

Some have suggested the use of vertical biamping - two amps of the same model/brand powering all four inputs of my biwireable speakers. I'm curious to hear feedback from those that have attempted it.

It has also been suggested that it might not be worth it if your preamp doesn't support 2 pairs of outputs.

I'm curious to hear from those that have tried vertical biamping in general or possibly even modified their preamp to have multiple outputs in pursuit of this vertical biamping idea.

I'm using a Threshold FET 2 pre amp and a CJ/Sonographe SA250 that I would most likely buy one more of if I pursued this.


Phil: The best way to biamp is with an active cross-over and bi-pass the speaker's crossover. I have done this to great effect. I have Martin Logan's which benefit tremendously by separating the bass and panel demands on an amplifier. With the active cross-over, you don't have to worry about having only one pre-out. If you can't go with an active cross-over, your results will vary depending on the speakers. In most cases, it will improve things, but to a varying degree, and in some cases not worth the extra $$, which might be better spent on just upgrading the amplifier. Hard to tell which is best without knowing what speakers you are driving.
Hi all,

Just to clarify, I am using Proac 1.5's.

I have used vertical biamping a little. I did it because I bought two of the same amplifier. They sounded good and weren't real expensive. It was a way for me to get more power with out spending a lot of money. I found that I had less separation loss if I were to do horizontal biamping. I am using this configuration now. My preamp now has two sets of outputs. I am looking to upgrade to an older conrad johnson preamp. Some of them have to sets of outputs, and some do not. I have to have two, becase creating a "y" off one output is a pain, and won't sound as good as if I had two outputs.

FYI, I hear that some of the anthem preamps that have two sets of outputs is nothing more than a "y" off the main output for a second set of main outs. I am saying this because I would assume someone with some electrical knowledge could take their preamp and do the same thing. Happy listening!
I was going through similar issues with VT100s and my ProAcs, so for an extra data point, I asked the US dist. He recommended horizontal, passive bi-amping. Never got around to tho', since I ended up with a new pair of Martin Logans.
I have been using a vertical bi-amp on my Vandersteen's for about a year. I found it to be one of the most worthwhile improvements that I have EVER made. Vandersteen recommends the vertical biamp over the horizontal. Only one channel of the amp reproduces low frequencies freeing the other channel up for better mids and highs because the power supply of the amp is not bogged down so bad. There is also some benifit to this "unbalancing" of the amps power supply. The only caveat with this is the amps need to be identical with the same input sensitivity(as with any biamp) Vandersteen also recommends NOT using different cables for the upper and lower sections. I can't say if all of this is specific to the Vandersteen speakers. I can say that if anyone feels Vandersteen speakers are layed back and soft sounding(which I hear regularly on this sight), then they haven't heard them set up like this properly. It was amazing what biamping did!
I do not have two of the same amps, so I have to go the horizontal route.
I have two Krell stereo amps. Dan D'Agostino prefers vertical biamping.
I am using The Krell KBX active crossover with my B&W800's and the improvement over just using one amp is staggering! But, remember, I am actively bi-amping which requires alteration to the speaker (Dan D'Agostino designed the change). This was a very expensive upgrade, but worth every cent!
I would consider improving your speakers BEFORE going to expense of an electronic x-over.
Just my opinion
I use it with my Legacy Classics and a Sunfire Theater Grand amp. It really helped out the sound and the detail. Probably the biggest change was on the low end where the difference in sound was huge. I have tried several times to go back, but can't make myself do it after hearing the biampped version. I would highly recommend it.

You can use an active crossover without removing the passive crossover. If you get an active crossover like Bryston offers where you can set the cutoff point for the upper and lower points separately, you keep most of the unwanted signal from reaching the amplifier, whcih is the approach I would use rather than making mods to the speakers which reduce their value and marketability.