mixing tube and solid state amps

I would not at all be concerned with the speed of the tube amp "keeping up" with the solid state amp. This is silly! A number of us seek a tube amp because it creates a 3-dimensionality, a harmonic richness and and natural decay of notes that even the best of the solid state amps can not produce. For the most part, such tube amps do very well in all but the bottom 1 to 1 1/2 octaves. If the crossover is used to biamp with a subwoofer, say at 60hz or even 80hz or so, the situation will have more to do with level matching, i.e, not be so eager to turn up the sub's level beyond a natural level. If the crossover is more like the upper bass / lower mids, then the slopes/crossover points are far more critical than the "speed" of the amps. The tonality differences of the amps will be more pronounced. So the thing to do here is focus on getting a tube amp that really puts a smile on your face and then find a solid state amp to match the tonality.....not find a tube amp to match your solid state amp!
John

Larryrosen,

I was talking to a friend to day about bi-amping using tubes for the mids highs. His first response was make sure that the speed of the tube amp matches the SS amp.

Michael

I passively bi-amp with VTL MB100 tubes on the top and Sunfire Symphonic Reference on the bottom.
These amps are way out of gain match but I controll the gain of the Sunfire with professional ClearBock balanced line converter that I use to decrease the gain of Sunfire to match VTL.
Also VTL is connected to the high-pass(80Hz -3db and after 12dB per octave) output of preamplifier. THe benefit is to limit the "visible" freequency bandwidth to the amplifier thus significantly decreasing distortions that are quite big in tube amps in the bottom end.

Fatparrot, yes, I had an ARC amp that had input trim pots which I never used but I have to imagine that the quality here is not very good. I would really only want this on my low-frequency amp ... and ultimately it might be the high-frequency amp that needs to be attentuated.

Yes, when you actively biamp, the idea is to remove the speaker's crossover. But this implies an active crossover between the line stage and amp. The advantage of this approach is that you eliminate the poor quality inductors and capacitors that are typical in a speaker's crossover.

In an active crossover, no inductors are needed at all. Another benefit here is that there is often an increase in the speaker's efficiency because of the loss of signal caused by the speaker's crossover. But a problem here is that any poorly implemented active circuit between the line stage and amp can so easily result in the loss of the incredible harmonic richness and 3-dimensionality that some tube-based systems exhibit so well. I am looking to do this in the next month or so with the Space-Tech-Lab tube crossover with tube regulated supply.

Check it out: http://space-tech-lab.com/

If the idea is strictly to have the line stage drive two amps, each amp then driving a stage of the speaker's crossover, you are still biamping but using a passive crossover (the one in the speaker). This latter method is very popular in the UK where just about every speaker has the two sets of terminals (for high and low freqs) and a shorting bar to use only one amp. This is what Quincy above has described.

Hope this helps.

John

Hey, don't you guys know that tube amps are just distortion mechanisms? Thanks for letting me vent.

Eric Idle

Yes, It works well. I have a C-J Premier 11 tube amp and a C-J MF2250 being fed with two sets of pre-amp cables from my C-J Premier 17LS. I have then two seperate sets of speaker cables, one from each amp to the speakers. The tube amp powers the mid/high frequency. The solid state amp powers the bass. Not all speakers have two seperate hook ups, so beware. I went to this set-up because I felt the bass from the 11 was 'lacking'. It lacks no longer, and I get to keep the sweet sounding tubes at the mid/high frequency, where they sound their best!
Regards,

That is what I thought I would do. What is the right way to do this? Isn't just as simple as using the binding post's on my speakers? What am I missing here. What are the advantages to adding an active cross-over, over using the speakers?

Jafox, there are amps that have a gain input trim pot for gain matching, for passive bi-amping. I thought that in active bi-amping, you would want to totally eliminate any part of the speaker's crossover network. Won't just inputting into the bass and tweeter terminals still leave part of the speaker's passive crossover in the signal path?

Are you proposing a passive bi-amp or an active biamp? With an active biamp, it is typical for the low freq side of the active crossover to have a level control to match the two amplifiers' differences. It is highly unlikely you will find a tube amp and solid state that you like AND that also work well with your speakers AND have the same gain/input sensitivity. If you will simply use the speakers' crossover and remove shorting bars to drive the top and bottom ends with separate amps, I think your best bet would be to use the same amps.
John

that's how most people do it when they bi-amp with tubes. just make sure the amplifier gain matches so the mid isn't louder than the bass or vice versa.

kevin t