How do I bi-wire and bi-amp?

Edesilva- I'm not at all familiar with your ML's, but am curious about how you cross over before the signal gets to the amps. If passive, are you able to adjust slope and balance? How do you then run speaker wire separately to the LF and HF drivers? From what you seem to be saying, you somehow do a XO before the amps, then run speaker wires to the ML's XO, which sort of sounds like a hybrid bi-amp/bi-wire arrangement. Perhaps you could describe your set-up? I have a pair of Maggies that I'm looking to experiment with bi-amping and would like to consider all options.

Patrick- One of the other advantages of bi-amping is that you can use amps with less power as both amps work more efficiently within their narrower bandwidth. Typically, the amp for HF is around half of the power of the LF amp as LF's suck alot of power. A 200 watt LF amp with a 100 watt HF amp plus the XO may outperform and play louder than one 300 watt amp.

Regards
Jim

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.

Edesilva- THanks. I'm a little lost, but it's probably because I'm not familiar with the speaker. Sounds like it's a little closer to a bi-wire with with an amp for each wire pair?? I'll find a dealer and take a peek....

Jim

Like Edesilva, I also run ML speakers (I wish mine were also Prodigy's, but I am still very happy with the smaller Ascent's) with a passive bi-amplification setup. (Obviously, by default, if you bi-amp you are also bi-wiring.) I chose to use a vertical passive bi-amp, meaning that I use one amp, L & R channels, for the right speaker, and a second amp for the left speaker. My pre-amp has 2 sets of outputs, so I connect both "right" pre-outs to both inputs on the amp for the right speaker, and both "left" pre-outs to both inputs on the left speaker. I then use one channel of the right amp to drive the LF section of the ML's (using the internal XO), and the other channel to drive the panel. Likewise on the left side. Even though both amps are being fed a full range signal, and amplifying the full signal, the channel connected to the LF section "sees" the XO on the other end of the speaker cable, and the impedance is essentially infinite at frequencies above the cutoff frequency, so the current flowing through that cable is only at the lower frequencies. The same effect occurs with the channel driving the panels. The impedance for frequencies below the cutoff freq for the high pass section of the XO is essentially infinite, so the current flowing in the cables only carries the higher frequencies. This is the underlying theoretical benefit of bi-wiring, since it prevents the LF signals in your speaker cables from degrading the HF signals via magnetic interaction.

IMO, one of the biggest advantages of the vertical passive bi-amp is that each speaker gets its own amplifier, similar to using mono bloc's, so even though you are using both channels on each side, you only have the right channels music signal in the right channel amp, and vice versa. Therefor, no inter-channel crosstalk, the power supply for each channel is not stressed my large dynamic peaks on the other channel, etc... Further, I get significantly better sound with this setup than I did using the 2 amps bridged mono w/ bi-wire. This, like Edesilva mentioned, may have something to do with the electrical characteristics of bridging amplifier circuits and the difficult impedance characteristics of an ESL panel, all I know is it sounded very constrained when the volume started moving up. Dynamic constraint is DEFINITELY NOT a problem anymore.

One caveat for the vertical passive bi-amp, you MUST have identical amplifiers for both sides. If you want to use tubes for the highs and SS for the lows, or a more powerful amp for the lows, you have to go with a horizontal bi-amp (which I haven't tried yet, because I like the sound I am getting right now).

I you have 2 identical stereo amps, and 2 sets of speaker cable (these don't have to be identical), I would at least give a vertical passive bi-amp a listen. Again, I don't know which has a greater impact, the bi-amp effect or the bi-wire effect, but the end result sounds really good (to me!).

Mike

Mike- Thanks, I am now beginning to understand the basics of the ML arrangement and it seems like it might be a good (and less expensive!) alternative to a "true" bi-amp with the advantage of eliminating a separate XO. A couple of questions, though- Do you find that you need the same watts to the LF as the HF in order to balance the volume between HF and LF? If not, how is balance achieved? Assuming that HF and LF amps are identical, do you find a sonic difference and/or volume difference in going this route vs simply finding a similar amp with twice the power and bi-wiring it to the speakers? (In other words, could one accomplish the same thing by bi-wiring an amp of twice the power?)

Thanks
Jim