It is vice verse.
I assume you did not experience a jaw dropping sensation when you look in the room, but don't see that guy who touches contrabas strings by his fingernails.
I designed many of them. No hum, no noise, sounds like real performers in the room.
Back in the 60ies the concertina phase splitter was often used in RF amplifiers! Any tube phase splitter will be unbalanced if the load is unbalanced.
Inserting a driver stage and moving the splitter at the input has removed the issue. But the conclusion is that now the splitter has much easier life! It's not because there is an OP amp. A tube concertina or a tube LTP splitter at the input of the amplifier presented in this thread will behave just as good as any OP amp, if done right. Reading about some SS suggestions adding a tube might be cheaper.....
Inserting a driver stage and moving the splitter at the input has removed the issue. But the conclusion is that now the splitter has much easier life! It's not because there is an OP amp. A tube concertina or a tube LTP splitter at the input of the amplifier presented in this thread will behave just as good as any OP amp, if done right. Reading about some SS suggestions adding a tube might be cheaper.....
OPA452 in current production -- +/-40V=80V single ended @45mA
LME49830 can swing +/- 100V @45mA -- will go out of production in September 2016 but you can still buy for less than $7 ea.
You don't want to hear clipping of the opamp; soft tube clipping is an additional good feature to absence of solid state distortions; if your opamp clips earlier than the tube you loose this feature as well.
Also, you need very fast opamp, otherwise you loose one more feature of tube amps, wide open loop bandwidth.
Also, you need very fast opamp, otherwise you loose one more feature of tube amps, wide open loop bandwidth.
There's a completely fleshed-out design example with 'discrete op-amp' high voltage drivers and direct coupling given in post #2 of this thread. It should be pretty easy to adapt this design for use with other power tubes. I have released this design into the public domain -- you can ignore the copyright notice.
Nope. The big investment of a tubeamp is transformers (output and mains), tubes, where powertubes take the lions share.
Driver tubes and components is a tiny part. Using op-amps will involve additional powersupplies, most likely symmetrical
that is not needed in a tube design.
The need for op amp(s) in a tube power amp is similar to the need for mosquitoes in a summer house.
Driver tubes and components is a tiny part. Using op-amps will involve additional powersupplies, most likely symmetrical
that is not needed in a tube design.
The need for op amp(s) in a tube power amp is similar to the need for mosquitoes in a summer house.
Not necessarily, if you want something special.
I wanted to take use of full potential of great 6N6P twin triode. In typical AB1 circuit this can produce some 3 W. With AB2 some 7...8 W is available with very good linearity.
If this were built with tubes only, the circuit would become quite complicated and a lot of glass is needed.
Attachments
This could be easily done, in fact I have done it with ADA4700s. I got a pair of decent quality but inexpensive 48V switching supplies to make +-48V rails. I used a configuration like the input stage of an instrumentation amp to drive the tubes.
Distortion of the ADA4700 was very low and only 2nd and third harmonic were detectible almost up to clipping. Many here will consider the idea heresy, but it works extremely well in practice.
That point was already passed. If an opamp can drive a KT88, it can certainly drive the much easier load of an EL34.
Nope. Don't agree with most of petertub's post, but have to say that driver tubes are typically an already very small portion of a tube amp's cost.
Hi artosalo, in case that you have missed, Mos57 described a delay related issue of a similar op amp splitter on post #15 newbee-phase-splitter-question which RJM1 offered solution on post #25.
I repost the picture here, bottom schema.
I repost the picture here, bottom schema.
That's a fun looking project, any chance you made extra boards?
Would you be willing to share the power supply schematic as well?
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