CFB and Ultralinear are both great way to deal with the output stage distortion, Ultralinear OPTs are easier to get these days, but CFB not as much. Crowhurst's twin couple topology never took off (in fact, I seem to recall some poor reviews...), you certainly will not see many implementing such topology these days with the iron cost being as high as they are now unlike the old days.
Patrick Turner has done a lot of work with the CFB topology and has quite a few articles on his site, great read - highly recommended.
Patrick Turner has done a lot of work with the CFB topology and has quite a few articles on his site, great read - highly recommended.
Hi - yes I've found the Turner website. I suspect I will find it as helpful as the Morgan Jones book, which is high praise. Everything he does looks extremely well-executed and he explains it well.
I think I've found what I want, strictly perhaps not what I need. I have just ordered some 13E1's. Love at first sight. With Lundahl Ll1620 6k plate to plate in triode mode. Not monster power - perhaps 50W and I am looking at the Turner Audio schematic.
Yes I am impulsive. If I also go insane I might do parallel outputs! It's going to be a big one.
Yes I am impulsive. If I also go insane I might do parallel outputs! It's going to be a big one.
I see you read Turner's articles on the 13E1s, how much are these monsters going for these days?
a pair of QE08-200 can do 300 watts, class AB2 at B+ of only 750 volts.....http://www.rell.com/filebase/en/src/Datasheets/7378_QE08_200.pdf
Attachments
That's mean RJT... I have paid for the 13E1's and they are so very pretty. I do like the idea of a 'semi-civilised' transmitter tube though... I might buy a pair of these as well. I must not let my wife know! I have a half-thought through driver good for 100 plus volts RMS so it will drive either.
A few questions ..
Has anybody out there actually built a QE08-200 amp? I have not actually found a finished project with this tube in it.
I am currently designing a high voltage push pull test driver stage with two Apex PA94s. This will be a long-term piece of test gear to allow me to test final stages without having to lash up tube drivers. I've had a good read of the application notes and as I see it at a gain of 100 the PA94 is (or can be made with the right design) unconditionally stable. Run off +/- 300V rails this can swing +/- 260V 😀. Has anybody tried anything like this - I appreciate the heresy of using this as an actual amplifier but as a piece of test gear it seems like a good plan?
Has anybody out there actually built a QE08-200 amp? I have not actually found a finished project with this tube in it.
I am currently designing a high voltage push pull test driver stage with two Apex PA94s. This will be a long-term piece of test gear to allow me to test final stages without having to lash up tube drivers. I've had a good read of the application notes and as I see it at a gain of 100 the PA94 is (or can be made with the right design) unconditionally stable. Run off +/- 300V rails this can swing +/- 260V 😀. Has anybody tried anything like this - I appreciate the heresy of using this as an actual amplifier but as a piece of test gear it seems like a good plan?
hi, i have a quad of these tubes, still looking for another quad before i start on this project..
enjoy 🙂
YouTube
YouTube
https://www.youtube.com/watch?v=h12BfEXb0dk
...and his whole channel!
here is his thread:
SRS461 | QE08/200 Monoblock Amps