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cayin a55 with EL34 ?
Posted:
Sat Dec 17, 2011 6:45 pmby Dragan12
Hi,
does anyone can specify the modifications to be done on a55 in order to use the el34 instead of kt88 ?
Many thanks
Re: cayin a55 with EL34 ?
Posted:
Sat Dec 17, 2011 7:40 pmby brady
I'd be very very careful...
KT88 operates at different voltages and current from EL34
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 7:10 amby tony
^ if circuit is a fixed bias, you will need to readjust, if self biased, you can stick the EL34 in........
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 8:20 amby JoeyGS
Audioamplified can do it for you.
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 3:29 pmby JackD201
JoeyGS wrote:Audioamplified can do it for you.
I'm pretty sure they can. After all there is the A55 T which is precisely an A55 that runs on el34s.
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 3:36 pmby hypertriode
... but there's the load impedance (Z) of the OPT's to be considered for optimum; around 3.5k for KT-88 & 5k for EL-34's, with 4.3k working well with both EL34 & KT-88
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 4:38 pmby tony
^yes but remember speaker impedance also vary all over the place.......so reflected impedance is never constant but varies with frequency.....transformer impedance, like 3.5k and 4.3k are just turns ratios......
an EL34 plugged into an amp with KT88 will have to work harder unless bias is lowered, the lower plate loads implies more power....
a KT88 plugged into an amp with EL34 will have easier life than the first case....power is not increased, still guided by impedance macthing and of course by the plate swings.....
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 4:49 pmby tony
JackD201 wrote:JoeyGS wrote:Audioamplified can do it for you.
I'm pretty sure they can. After all there is the A55 T which is precisely an A55 that runs on el34s.
or perhaps the thread starter meant he wanted to stick in a KT88 instead....he can just do it.......
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 5:08 pmby carbondated
I'm not quite sure about the rationale behind this conversion -- it seems a sideways move, and not necessarily for the better
Re: cayin a55 with EL34 ?
Posted:
Sun Dec 18, 2011 10:52 pmby Dragan12
thanks guys to all of you!
Let me clarify: in my country (Serbia) the importer of the Cayin has only the A55 (KT 88 standard) and not the A50 (EL34 stanadrd) model.
He convinces me that i can use the EL34 just changing (lowering) the bias! I have limited tube amps knowledge but it seems to me that some resistors inside should be change as well (i read somewhere similar on the forums). If some of you (hypertriode?) can specify exactly which res i should change, it would help a lot!
Thanks again
Re: cayin a55 with EL34 ?
Posted:
Sat Dec 31, 2011 5:21 pmby tony