To bi-amp or tri-amp is two use two or three amplifier channels for each loudspeaker. To bi-wire is to use one amplifier and two speaker cables for each loudspeaker. The two are very different in concept and performance results. Let’s start with bi-amplifying.
Bi-amping or tri-amping requires the preamplifier’s output signal to be shared by the amplifier inputs; either two or three depending on which you are doing. Let’s stick with bi-amping to keep the words fewer. Instead of connecting the preamplifier’s RCA or XLR output directly to the input of a single power amplifier channel, as is traditionally the case, we now split the signal into two: one going to each of the two power amplifiers we need for bi-amping. The output of each amplifier is connected by its own speaker cable to the loudspeaker: one amp powers the tweeter, the other the woofer (in a two-way).
There are several words of caution when bi-amping speakers. First, the input signals must be identical. You cannot use the preamp’s RCA output for one amp, the XLR output for the other (for multiple reasons, not the least of which is the 6dB gain difference). If the preamplifier has only one of each, which is typical, use a patch cord signal splitter. Secondly, the power amplifiers themselves must be gain matched–and closely. Some purists insist the power amplifiers themselves must be matched as well, but I think that philosophy ignores some of the potential benefits of the practice.
Once requirements have been met, the system should work the same as before, except now we have one power amplifier dedicated to the tweeter, another to the woofer.
So, what are the benefits and what are the downsides? Much depends on how and why you are doing this–and there can be a number of reasons.
Tomorrow we’ll start with understanding the traditional reason for bi-amplification. We’ll then move on to more exotic reasons that may make more sense.