Bi-amp questions

**Alien_Shore** · October 13th, 2012, 02:22 PM

Let's say I want to bi-amp an Altec 2-way setup or even a duplex.

Using either a passive or active XO, I'll need two discrete amplification paths per channel.

I've read that generally speaking, old (circa 1960's) HF compression drivers will do better with tube amps (high output impedance), while the LF drivers will be fine with solid state amps. Do I have this right?

If these distinctions don't really have much of an audible difference, it'd be easier if I had a single amplifier with four discrete channels, so I could basically just use one amp. Plug the source into the XO, the four outputs from the XO into the amp, and amp to drivers.

Is there such a thing? Most bi-amp set ups I see are independent stereo amps for LF and HF.

**fpitas** · October 13th, 2012, 04:11 PM

I used to use a regular SS amp (SLA-1) for the horns in my system (511s with Radian 475 drivers), but now use a First Watt J2, which sounds worlds better. The J2 is class A, so perhaps that is part of the magic. Certainly a regular class AB SS amp, even a very good one, is not designed to work its best at the 50mW sort of level a horn requires, but the class A amp distortion just gets better at low levels:

http://www.firstwatt.com/pdf/prod_j2_man.pdf

**Panomaniac** · October 14th, 2012, 12:00 AM

Yes, you will be much happier with a tube amp on the horns, or a good Class-A transistor amp. I've used Class-D on the woofers with very good results.

**Old Guy** · October 14th, 2012, 07:45 AM

I think I would reverse that...a tube amp will work better at the higher impedance than a lower one....not necessarily that high impedance works better with tube amps. In fact, many speakers can benefit from series resistance, as the solid state amps are often more linear at 8 or 16 rather than 4. I'm a fan of one driver per amp channel. That minimizes the interaction. I have heard some very good very linear small solid state amps. Many think tubes are warmer. I have both, some days I listen to one over the other. I'm not sure I am in the camp of one is superior. I CAN say since solid state tends to be cheaper there is a glut of cheap solid state amps. But the best against the best is pretty darn close. Many high end items are no better than the best mid level, or even the best cheap stuff. These days much of the high end is designed for looks and profit.