Will this work for an EL84 push pull?

[zobsky]

The EL84/6Bq5 has low drive requirements. Would something like this work well (theoretically) since I have all the tubes and transformers lying around:

[CD player]-->[low mu triode (eg. 12B4A with myu of 6)] -->[coupling cap]-->[cinemag CMLI-15/15B] --> [EL84 push-pull]-->[OPT]

cinemag transformer link: http://www.cinemag.biz/line_input/CMLI-15-15B.pdf

I'm not sure what the allowable signal voltage swing and current capabilities are with this transformer, despite looking at the spec sheets (or maybe I don't understand how to translate insertion loss and input level in dB to volts ).


Thanks

[Wavebourn]

Mo then plenty!

It will give you about 10V swing on 20 Hz with 1% distortions. Use CCS and source follower for triode load if you don't want "sweet" distortions from "voltage controlled variable resistor" triode.

[zobsky]

Thanks, .. I also have pairs of #27 and #37 tubes which I can use as input/driver tubes (somewhat higher mu of about 9 but less current driver of ~ 5mA ). Would these be better, from a design and sonic aspect, .. from someone who has worked with them.

[Wavebourn]

Actually you need a very low gain of a voltage amplification, so only feedback deepth will depend on tubes. Use the cheapest you have.

[rdf]

If that were my pile of parts I'ld be inclined to investigate putting the Cinemag at the very front, doubling out the 12B4As and maybe running them fixed bias. BTW, I don't see a secondary centre tap on that model, how would use it as a phase splitter?

[zobsky]

Originally posted by rdf
If that were my pile of parts I'ld be inclined to investigate putting the Cinemag at the very front, doubling out the 12B4As and maybe running them fixed bias. BTW, I don't see a secondary centre tap on that model, how would use it as a phase splitter?

Your suggestion is similar to a suggestion SY had for me a long time ago
( http://www.diyaudio.com/forums/showt...504#post315504 ) . Now that I'm planning an easier to drive push pull project, I was wondering whether using the transformer after the input tube will work.

Re. phase splitting, ... I think a resistive divider was reccomended (see post linked )


P.S. don't know if this is obvious, .. but essentially, the big goal is to see if I can build an optimal 2 stage push pull amp, ..hence the choice of the (relatively easy to drive) EL84 as the power tube and the 12B4A (or other suitable tube) as a high current input / driver.