Bi-amp configuration

So I’m reading more and more about the merits of going for a bi-amp setup using a pair of power-amps where, for example, one power-amp does the treble/mid and the other bass. It all sounds logical and I can understand the reasoning around this. Anyway I was wondering on the consensus.

Cheers :slight_smile:

Naim have traditionally been advocates of active systems, and if you really want to do biamping properly, have money to spend, and don’t mind having lots of boxes, that’s the way to go. Passive biamping is a much cheaper and easier alternative, and can still work well, but I would always want to weigh up the advantages against a single, higher spec amp at a similar price.


I’ve heard that it can sometimes be an advantage in going for a more powerful power amp for the bass. For example a 250DR for mid/treble and a 300DR for the bass. Rubbish or sensible?

You can read a bit more about Naim’s position regarding biamping (passive and active) here:

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This may sound totally counterintuitive, but the consensus appears to be that if you use two different power amps, the more powerful one should go on the tweeter, not the bass.


I was, perhaps naively, thinking the bass needs more oomph than the mid/treble - not correct then?

In a passive bi-amp situation it probably makes little or no difference, however, with active bi-amping the better amp usually gives best performance on the HF.


Cheers… :slight_smile:

Further to Richard’s comment, there is little to be gained by simply bi-amping, as both amps are still processing both the LF and HF signals, and you still need the passive crossover in the speakers.

However using an active crossover to separate the signals before the power amps, does have significant advantages.

The theory goes how the change in impedance when you get a bass note affects the higher frequencies. So splitting the drive helps this. Anyway this is what I read (ATC forum as it happens).

That’s a gross oversimplification. The complex impedance of the load (i.e. the loudspeaker) doesn’t change!

To understand the instantaneous voltage / current relationship in the output structure of the amp you need to analyse using complex numbers and vector arithmetic for the load, the output structure of the amp and the feedback loop. If you do this for the case of simple bi-amping and also for a crossover before the power amp, the advantages of the latter become clear, as do the quite limited benefits of the former.

The increased control of the system interaction through the crossover region offered by a small signal active crossover is a further substantial advantage.

Thanks… yes oversimplified I know. I read this on the ATC forum last week from one of their tech bods but I’ve been struggling to find the post now! :frowning:

For what it’s worth, and from a completely non technical viewpoint, I did try bi-amping some years ago, (the thread should be searchable on the Forum archive), and found the resulting sound to be heavy and oppressive … and several other contributors at the time said that “oppressive” exactly described their feelings too.

This was using non DR’d 250 and 300.

Well this all started from a comment by the AD so I’ll broach the idea that he lends me another power amp plus cables.

Is it not possible to run two stereo power amps as two mono amps ?

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Yup, you just run one channel of each stereo power amp.

The other Forum members have given very good advice why technically passive biamping isn’t preferred.

In addition (and biamping was a subject periodically raised on the old forum) I recollect that only two speaker manufacturers have categorically come out in favour of biamping; B&W and Neat Acoustics.

I certainly think that the money is better spent on a better power amp (rather than adding another amp) if you feel that your current one is in some way deficient.

Seems silly that many speakers still offer the option with two sets of terminals if they don’t openly recommend it.

Agreed, and then you have to replace the questionable links they come with, with some half-decent jumper cables.

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I’m fairly certain that just by replacing the cruddy links that come with so many bi-wireable speakers, much of the perceived gain of bi-wiring is achieved.

I remember a few years ago when I was given some big B&W floor standers and I decided too try them out in the main listening room. The initial results were pretty disappointing really with a rather congested sound and an amorphous low end that was oddly detached and ill defined. The simple expediant of removing the metal links and replacing with some RS hook up wire brought a big improvement if not quite a total transformation to the sound.