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Simple Biamp question

I know there have been dozens of biamp threads, but my question is so simple that I'm sure someone can answer it instantaneously.
I have a preamp with 2 pairs of outputs and 2 identical stereo amps than cannot be bridged into mono status. So I wish to biamp my speakers (Allison 4s with biwire posts)
1. Can I vertically biamp with the left leads of both outputs going to one amp and the left speaker and vice versa with the right leads? I have heard from some Audio people that I cant do this. Why? Something to do with crossovers and imaging and soundstage....
2. Is it better to horizontally biamp witjh both amps sending single wires to lower frequencies and both amps sending single wires to upper frequencies?

I would prefer the verical, as it's neater and easier, but are therte drawbacks? Is there a reason both left and right outputs from the preamp cannot go into one amp and use it as a mono?

Amps : TAD 60
Prreamp: TAD 150 Signature

Thanks very much for your help.
springbok10
almarg's avatar
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almarg
9,670 posts
 
Why would the absence of independent crossovers make them unsuitable for biamping?
It is conceivable that if the speaker is not designed to be biamped its design could be such that it would short the two amplifier channels together, either directly or through some low impedance circuit path. That could be unhealthy for both the amp and the speaker.

In that situation the risk of damage would be reduced somewhat by the fact that both amplifier channels will be putting out signals that, to a close approximation, are identical. But if you don't have a manual for the speakers, or if the manual does not address biamping, it would be prudent to do some Googling to see if others have biamped that speaker successfully.

Regards,
-- Al
ssglx
203 posts
 
Vertical biamping works wonderfully with my Monarchy SM70 Pro amps. Sounds much better this way than using them as mono-blocks, for some reason. I am very happy with the setup.
springbok10 OP
711 posts
 
Al, I think that's at my repair guru implied - I misquoted him about stereo vs mono- so I am afraid of blowing up both amp and speaker by shorting the 2 channels. I have just asked in a new thread whether anybody has biamped Allison 4s. Thanks again for your input.
springbok10 OP
711 posts
 
Because the Allisons are not made any more, it's difficult to find out what the crossovers look like, so Larry, my consultant repair guru, is just not sure how safe it is, but not based on any knowledge of the schematics, as he has not seen them. Hopefully someone will answer affirmatively , otherwise I may have to skip this experiment!
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almarg
9,670 posts
 
Take a look at the rear panel of your speakers, and see if there is a statement indicating "remove both links for biamplification."

I found this writeup, which shows such a statement on the rear of what is probably the Allison One, although the Four is also mentioned in the text. See the third photo from the top. If that statement appears on your Fours, you're good to go!

Strangely, though, I also found several rear panel photographs of Fours, which only showed a single pair of binding posts (as well as a three-position switch to control "acoustic power balance"). Perhaps there were multiple versions of the Fours.

Regards,
-- Al
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