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RE: CCS in a circlotron???

Posted by Banat on January 3, 2015 at 11:21:00

In Reply to: RE: CCS in a circlotron??? posted by Lew on January 3, 2015 at 09:47:58:

Lew

Your conclusion is correct , there is no advantage by putting two CCS in circlotron circuit , it is same effect as we put there two fixed high values resistors inside of circlotron circuit .
I not claim that bootstrapping of DC coupled driver stage is superior solution but before anything else I`m must say next :
By repairing and by serious upgrading for one of my customer his one very old but very good sounding SS amp finally I try to replace simple passive bootstrap circuit around voltage gain stage with active one(CCS) which was consist from one BJT , diode and few resistor , result was significant improvement by measuring THD level , but that original smooth and well defined final sound presentation have gone , special on bass spectrum ,after that I was put back original passive bootstrap circuit and everything was fine again.
Guided with this experience I want try to bootstrap DC coupled drivers stage in the same manner , only with passive components .
Main idea is to keep voltage across R1 & R4 Constant ,since if voltage across those two cathode res.is constant than the current is constant to, drivers tubes will work with constant current to across the whole audio spectrum and drivers stages linearity will be improved .
Original Rk with value of 47K want to divide in two power resistor connected in series , R1&R4 will be now 39K and R2&3 around 4K7 ,optimal value of bootstrap capacitors(Cb & Cb`)I need to found by experiment and with listening test to, I will try with many different values for Cb ,anything between 2u2/450VDC and 100uF/450VDC .
Finally I think that by this type of bootstrapping of driver stages some influence exist on the output impedance of circlotron power stage to , I expect some lower output impedance to .
And yes I have no doubt that both CCS and SLCF work just fine by your OTL amps .

Edits: 01/03/15

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