Tube/Solid State Bi-Amplification


I've read about people bi-amping using solid state for lows and tube amps for mids and highs. How is this practically done? I have bi-amp capable speakers but I only have one input on my preamp. What additional equipment would I need to buy and is it readily available? Not to mention, are the results worth all this effort? Has anyone done this??
128x128gfields
It depends on your speaker and amps which will determine whether or not it is worth the expense. Your preamp I gather has only one preamp active output rather than the input you mention. You will first need a Y cable to split the signal to each amp. You then run a pair of cables to each amp. This is if each amp has the same gain. If they do not then you would get an unbalanced sound of top and low end. To balance these levels you will need an active crossover that lets you increase or decrease both or one of the two - like the Bryston 10. You could also use 2 peavey Cozmos units (250) each - this will allow volume adjustments of each amp. After you determine this a pair of speaker cables needs to be run from each amp to the proper terminals on the back of the speaker. You need to remove the jumpers that usually connect the two sets of terminals on each speaker . If the you did not use another device such as the crossover than you are set and are relying on the crossovers built into the speakers. This is also true if you used the Cozmos. If you used the Bryston Crossover you may have to disconnect the built in crossover to get a better situation. Some speakers have a switch on the back for biamping instead of removing jumpers. I like the results I get with my Mcintosh 352 (SS) and 2102 (tubes) amps and the VMPS RM 40's. I use the two Cozmos devices with great success. My preamp - the Mcintosh C42 has mutiple outputs so no Y adapter is needed. If it sounds complicated it can be but breaking it into steps helps - it does tend to get costly.
I also bi-amp, but my speakers come with an active outboard crossover splitting the bass and treble signal at about 200hz (it's a 4-piece system). The only things I'd like to add to Ljgj's fine post are that (1) the input sensitivity of the different amps will also play a role in how loud they are vis-a-vis each other--you'll really need a way to adjust the volume of the two amps, whether through an active crossover or perhaps some passive attenuators like EVS makes; and (2) depending on the crossover frequency, the sonic character of the amps you are using can make a difference (I have switched bass amps recently because the new ones are a little faster and leaner in the 200hz region, making for a better transition to my tubed amps on the top; I might not be so concerned were the crossover at, say, 50-60hz); you'd like to get amps that make the crossover sound as seamless as possible. It can be difficult and may wind up costly to do the biamping; I don't think I'd have done it were my speakers not set up for it.
Gfields,

Ljgi has summed up the situation well. I'd like to clarify one point, though. If you use an active crossover (like the Bryston 10B), you'll only need a single preamp output. You'll connect your preamp to the active crossover and then connect the crossover to your power amps. This is called active bi-amping.

You can also connect your pre to multiple power amps and then connect the amps to the speakers. This is called passive bi-amping. In this case you'll need multiple preamp outputs or Y-cables.
Biamp capable speakers usually means there is a high pass filter behind the mid/tweeter speaker input and a low pass filter behind the mid/woofer speaker input. Adding an electronic crossover will mean that you have both active and passive crossover components operating together. -- I use a theme and variation of the tube/solid state approach with a tube amp running two-way floorstanders (bi-wired) and a solid state running a sub. The floorstanders are run full spectrum while the sub amp has an active low pass filter as well as volume and phase control.