Hi,
i got some of this transformers which are normally used in preamp PP output stages:
Sowter Type 8650
I would like to use them in SE, with triode wired 1620/6J7. It looks like rp for this tubes is ~7,5k in my circuit, i'm not sure what to expect from such transformer in SE.
Cheers, Miha
i got some of this transformers which are normally used in preamp PP output stages:
Sowter Type 8650
I would like to use them in SE, with triode wired 1620/6J7. It looks like rp for this tubes is ~7,5k in my circuit, i'm not sure what to expect from such transformer in SE.
Cheers, Miha
well you can always parafeed the amp... either choke load it or resistor load it. For calculations there are several excel based sheets such as the one listed here:
http://www.diyaudio.com/forums/tubes-valves/111947-parafeed-plate-choke-calculation.html
The transformer can then be un-gapped however component value and choice is critical to a parafeed design.
http://www.diyaudio.com/forums/tubes-valves/111947-parafeed-plate-choke-calculation.html
The transformer can then be un-gapped however component value and choice is critical to a parafeed design.
Thanks for confirmations. I would like to keep it transformer coupled with DC into it, like originally built by RCA. I looked into options Alex mentioned, but i don't want redesign here, i need to get as close as possible with modern transformers.
I have several big 50%Ni ungapped output transformers, those could be tested for the start. I know my lows will get worse at a certain point when Al value gets lower, but i don't have much current after all. Some people seem to get away with up to 4mA with this cores, this is what i have more or less. Does anyone of you have experiences with this? If it won't work well i can still buy gapped transformer, although this would cost me and i already have a few ungapped...
I just want to properly build something that works similar to original and see how it behaves. If i recall correctly, original output transformers were attenuated by ~1-2dB at 18kHz, 600 into 10kohm. I will try to find graphs. Not too good when compared to modern transformers, i will probably have different response with new transformers.
Miha
I have several big 50%Ni ungapped output transformers, those could be tested for the start. I know my lows will get worse at a certain point when Al value gets lower, but i don't have much current after all. Some people seem to get away with up to 4mA with this cores, this is what i have more or less. Does anyone of you have experiences with this? If it won't work well i can still buy gapped transformer, although this would cost me and i already have a few ungapped...
I just want to properly build something that works similar to original and see how it behaves. If i recall correctly, original output transformers were attenuated by ~1-2dB at 18kHz, 600 into 10kohm. I will try to find graphs. Not too good when compared to modern transformers, i will probably have different response with new transformers.
Miha
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