How do I bi-wire and bi-amp?

Bi-wiring is just running separate speaker cables from the single terminal on your amp to the two sets of terminals present on bi-wire compatible speakers. Doesn't have to be special "bi-wire" cable--you can run two sets of normal speaker cables if you want and just stack up the spade connectors on the amp end. (There is usually a jumper plate connecting the two sets of terminals on the speakers that should be removed).

Bi-amping is running the separate terminals (generally representing the "high" drivers and the "low" drivers for the speaker) on the speaker off separate amplifiers.

In the former case, the "split" occurs after the amp and before the speaker. In the latter case, its a line level split after the preamp and before the amps. If you bi-amp, you can do it horizontally (one stereo amp for the low end, one stereo amp for the high end) or vertically (one stereo amp for the Left, one stereo amp for the right). Maybe I have that backwards, but you get the idea.

Jim, for the record, you don't necessarily *need* an active crossover to bi-amp--I'm bi-amping a pair of ML Prodigy speakers without an active crossover b/c, while MLs are set up for bi-amping, ML strongly counsels *against* active x-overs. For Bigthistle's info, there is a metaphysical debate as to whether I'm getting the full benefits of bi-amping. The debate (I'm simplifying) being balancing putting another active component in the signal path (passive bi-amping) versus allowing your amps to function better by having them only responsible for a smaller bandwidth of freqs. to deal with (active bi-amping).

I can attest, however, that I do get some benefits--I can hear them.

If you aren't using an active x-over, you need two sets of line level outs to feed the two sets of amps. Some pre-amps have two sets. For pre-amps that don't, you can get specialty line level Ys that create two. Or, you can get a funny solid metal block (for RCA connections) that turns one female RCA into two. That's what I've done.

Patrick--the LF part of the signal going to the "High" input gets filtered out by the internal XO in the speaker. Same with the HF part of the signal going to the "Low" input of the speaker.

In my situation, the internal speaker XO can't be taken out of the path, nor does ML recommend use of an active XO, b/c the internal XO is really part of the ML Force Forward design. I gather there are some phase issues that go haywire with an active XO.

Perhaps I should have just bought "bigger" amps. But, I started with one that I had, and got a real good deal on the second one, so reality enters the picture (i.e., buy another VT100Mk III for $3K, or sell my one VT100MkIII for $3K and dump at least $6K beyond that on a pair of VTM200s). I can't bridge them to mono, and, even if I could have, I gather there may be bad issues with bridging resulting from halving the effective impedence seen by the amp, especially aggravated by complex low impedence loads like ESLs.

My rig sounds better now to my ears. Maybe that is because the loads presented to the two amps are easier to drive, even without bi-amping with an active XO. I have to believe the load presented by a high pass filter and an ESL panel is significantly easier for an amp to deal with than the load presented by a XO networked to an ESL and a conventional driver.

Jim-

The ML XO is in the speakers. I'm not using an XO prior to the amps... Being a tech dilettante, I assumed that a bi-wire capable speaker meant that the internal speaker XO is a high pass filter and a low pass filter that get split when you remove the jumper from the speaker terminals. That may be oversimplification and confusing. But, there are no filter or XO elements I use outside the speaker--pre goes to amps, each amp goes direct to a speaker terminal on the MLs.

As long as the gain of the amps matches, you don't need the same number of "watts" on the high and low side if you horizontally bi-amp... I was actually thinking of switching from from horizontal bi-amping with two ARC VT100s (100WPC tube) to a single ARC VT100 for the ESL (high) part, and an ARC D400 (200WPC SS) for the dynamic driver on the bottom. Since they are both ARC amps, the gain is the same, so the relative volumes for top/bottom won't change.