Good detail work Variac,
The cat missed one swish on the feet of the second symbol.
My infinitely limited knowledge of Kanji tells me that could be huge.
The first symbol means "city" or "city of". I'll leave it to everyone's imagination as to what the second symbol means.
The cat missed one swish on the feet of the second symbol.
My infinitely limited knowledge of Kanji tells me that could be huge.
The first symbol means "city" or "city of". I'll leave it to everyone's imagination as to what the second symbol means.
LED's are notioriously unreliable when run in series or parallel from the same supply without individual surrent limiters- just a warning.
Won't a 133k anode resistor on the first ECC81 triode be pushing way into non-linear operation?
You might want to add a build-out resistor to the cathode of the cathodyne for balanced output.
Won't a 133k anode resistor on the first ECC81 triode be pushing way into non-linear operation?
You might want to add a build-out resistor to the cathode of the cathodyne for balanced output.
Merlinb said:
Won't a 133k anode resistor on the first ECC81 triode be pushing way into non-linear operation?
Quite the contrary, that's a particularly linear spot to operate it. At the full 11V peak output needed to drive the output stage, THD of the voltage amp is less than 0.03%.
Regarding LED reliability, you might check out what Bob Pease had to say in his book "Troubleshooting Analog Circuits."
Evangelos, my comments on the sound will be in the article that Bas is publishing. I'll say briefly that you will not believe that this is a 15W amp. There are several tricks (the LED array is one of them) which optimize the overload recovery characteristics so that clipping is almost un-noticeable.
You want something which is 8k plate-to-plate with a 15W or better rating. I used Dynaco iron and also tested UTC LS series. Both worked great. The next few will use James.
By adjusting the RC network on the plate of the first stage, you should be able to get any decent OPT of the right impedance to work.
By adjusting the RC network on the plate of the first stage, you should be able to get any decent OPT of the right impedance to work.
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