I don't understand people using ECC83 with directly heated triodes . I have built a few such as the Shishido 2A3 and was never happy with the sound . Better off with an ECC81 , ECC85 or 5965 for high mu drivers . These have much lower Ra and should be able to drive the 6B4G grid nearer to 0V so more output power available . Expect around 2 watts with an ECC83 and 6B4G and nearly double that with a <10k Ra driver . Then there is also the ECC83's ability to drive the miller capacitance , which will limit the HF and may lose a few dB at 20kHz (which is audiable) , hence the reason why SRPP has been chosen in the design
316a
316a
Probably, yes. But why?
I want to be a retro style amplifier, I like how it look 75. Other variant it is with 76 ant 6SN7 driver. Any comment?
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I don't understand people using ECC83 with directly heated triodes . I have built a few such as the Shishido 2A3 and was never happy with the sound . Better off with an ECC81 , ECC85 or 5965 for high mu drivers . These have much lower Ra and should be able to drive the 6B4G grid nearer to 0V so more output power available . Expect around 2 watts with an ECC83 and 6B4G and nearly double that with a <10k Ra driver . Then there is also the ECC83's ability to drive the miller capacitance , which will limit the HF and may lose a few dB at 20kHz (which is audiable) , hence the reason why SRPP has been chosen in the design
316a
Fully agree. Most "loftin-white" amplifiers are actually not "loftin-white". But there are ways to make ECC83 work FAR better. I am getting well over 2 watts and am using 6SL7 - Directly coupled with no coupling capacitor or cathode bypass. I will post my schematic in the next post...
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Nobody can say anything to me about this schema?
It never sounded that special to me when I tried it.... and I tried many kinds of designs like it. If you take a look at the plate curves and do some maths then you will probably figure out why.
I directly coupled 6SL7 to 2a3 and it sounds truly superb. No cathode bypass either!
But I did it in a special way. see below and google Darius Loftin-White to learn more on how it can be done. Even ecc83 can drive 300b if you do it like Darius did. It won't have that old radio tube glow though...
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btw - you could also use AC on the 6B4G and use a heater hum cancelling circuit like Darius did:
http://rl12t15.blogspot.fr/2008/03/ecc83-300b-darius-loftin-white.html
I haven't tried it yet, but will if I have some time. I have some 6B4's here and a hum cancellation circuit is cheaper than a good AC circuit.
http://rl12t15.blogspot.fr/2008/03/ecc83-300b-darius-loftin-white.html
I haven't tried it yet, but will if I have some time. I have some 6B4's here and a hum cancellation circuit is cheaper than a good AC circuit.
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