[Niteshade]

There are so many interesting configurations that are interesting!

What do you think about an amp that uses something like EL34's and has a transistor drive circuit?

It's an amp configuration that's rare these days and I don't understand why.  I never thought using a solid state power section and a tube drive sounded that good. (Note this is not related to using a tube pre on a solid state amp in any way.)

A solid state drive section should not add coloration to the amp. It is my theory, that if done properly, will increase the amp's performance!

[FullRangeMan]

The expensives Kron tube amps use a Transistor drive, Iam surprised this looks good(I was think it was a bad idea...)
http://www.kraudio.cz/

[JoshK]

KR Audio does that.  Electra-print has some circuit designs on their site for using an opamp to drive tube finals.

Personally, I am not convinced this is a good idea.  Linearity of a transistor isn't typically their strength.   The drive is a very critical part of an amp IMO.  I am willing to accept some H2 or H3 but shun anything that would yield higher harmonics.

Some jfets have triode like characteristics that yield simple harmonic profiles.  I am sure you could use a transistor to yield the waterfall distortion profile in the amp, but I doubt it'd be very simple.

Then also how to deal with the reverse transfer capacitance?  I would not put up with a difficult to drive front end, as it solves one problem to cause another.  Transistors typically have higher capacitances than most tubes.  Miller capacitance is a hard enough problem to ward off in a tube front end with requisite gain.

[JoshK]

I think that tubelab.com's power drive topology is a much more elegant solution to gaining a killer drive stage.  Aikido and its many variants is also a very elegant solution.

[earwig]

The Space Tech Labs(HP 150) 150 watt per channel Hybrid amp sounded unbelievable real.It was like Louie Armstrong was breathing and alive in front of me.Best i ever heard.Uses 2x6L6 and 2x6sn7

[Niteshade]

Small signal transistors can perform linearly if they are set up properly. Using FET's is not a bad idea either. The one thing I like: You loose filament EMI issues. Rectifying and filtering low voltage, high current DC is a PITA, not something I like to do. I have found some efficient ways around the issues, but still don't like the added cost and parts.  Note: Don't get me wrong! I like tube based driver stages, but I think this option is going to be better for those who are not into tube rolling and consider purchasing tubes a drag. Four El34's or 6L6's isn't too much of an investment every so many years. The transistors should last virtually forever if the circuit is gentle on them and there is no reason why it shouldn't be. I expect performance could meet or exceed that of the best small signal tubes available.

[Johnny2Bad]

You do see some stuff where there is like one 12AX7 and lots of SS doing the work. In some of these designs, the tube is just there as a hook ... they probably would be cleaner without it. I had always assumed you don't see much of the SS pre/VS power because of ouput/input impedance issues going from the SS stage to the vacuum stage. Maybe you can mitigate that with an integrated; some other members probably have a better handle on that than me. Z issues is the first thing I would normally look at, to make sure they were a good fit, if it were separates.

[starkiller]

I have 2 Anthem AMP 2 SE's in my home theater system and they sound very nice. Seems to me you get the sweetness of the tube and the balls of SS

[roymail]

Blair, you asked...
What do you think about an amp that uses something like EL34's and has a transistor drive circuit?

You're speaking of an integrated design, right?

You know I'm kind of simple minded... 

Thanks.

[gerald porzio]

These hybrids are neither fish nor fowl. They appeal to audiophile vegans wanting the best of both worlds. While attaining neither, it helps strengthen their decision making in a hobby where vacillation is encouraged by soliciting others opinions on too many forums.

[satfrat]

I had a RM200 to play with for a little while. It uses solid state input and tubes(KT88) as output. I thought it worked very well, and it sounded really great as well. It was rated at 100 watts, Modjeski claims that as the impedance load drops it makes more power. Not sure of that, but it did drive my Virgo 2's with no power issues at all. It was an amp that I would consider owning.

Of the other hybrids I used reverse of this configuration, they all seemed to be a compromise on the 2 platforms, not bad at all, but not completely one way or the other. My friends Counterpoint sa 220 , highly modded was pretty spectacular, it had all the drive and bass of a solid state amp, with great tone, and almost as much dimensionality as tubes, but not really.
I don't think I could ever own a solid state amp, but a hybrid would be a good compromise for me, and the RM 200, was even closer to the tube sound.
Are there any other hybrids that have tubes as output?

mike

Chris's Butler amps use a tube output stage, you've heard them numerous times Mike. 
 
Cheers,
Robin

[Scottdazzle]

These hybrids are neither fish nor fowl. They appeal to audiophile vegans wanting the best of both worlds. While attaining neither, it helps strengthen their decision making in a hobby where vacillation is encouraged by soliciting others opinions on too many forums.

Gerald,

Your comment is contradicted by the performance of the Music Reference RM-200.  It is superb, whether fish, fowl, or neither.

Scott