Here's what I've been able to measure at the FETs.
Q3 273 (G) | 284 (D) | 270 (S)
Q4 272 (G) | 284 (D) | 270 (S)
Q5 204 (G) | 270 (D) | 203 (S)
Q6 204 (G) | 272 (D) | 203 (S)
Q3 273 (G) | 284 (D) | 270 (S)
Q4 272 (G) | 284 (D) | 270 (S)
Q5 204 (G) | 270 (D) | 203 (S)
Q6 204 (G) | 272 (D) | 203 (S)
Been using this amp this 2017 and will implement the paczeltf mods. For C7, C8, C11 and C12 you've mentioned 'gives a bit more room'. Is that headroom? Sorry, confused.
Thanks Ferenc.
Thanks Ferenc.
They look ok to me except for the 2V difference between Q4(S) and Q6(D), which are connected together...
Thanks Ferenc. I swapped the preamp tubes (M8136) which are 12au7 equivalent to a pair of Sylvania 6189s. Much quieter now with 6L6GC.
The highs are harsher or maybe imagining it with the Altec 604E.
I'll swap a EL34 and see how that goes.
The highs are harsher or maybe imagining it with the Altec 604E.
I'll swap a EL34 and see how that goes.
After all that drama, it was dirty pins on the M8136 (RCA 12au7s). I'm looking forward to doing the 'Ferenc' mods. 😱
My speakers are Altec 604E with great resolution and dynamics. The mods should be a good change. 😀
My speakers are Altec 604E with great resolution and dynamics. The mods should be a good change. 😀
That's good to hear Sunil.
I assembled mine in 2016 April. so far so good. driving my Klipsch Heresy IIIs.
I too had strange hum and traced it to the connection to the TV through it's AV out to the amp / preamp. TV has a optical out so isolated it from the amp with a small Optical DAC and hum is gone. Even with DAC it was there earlier but had used the USB of TV to power the DAC. On using a separate source the hum vanished.
Also have a subwoofer KEF Kube 12b connected to the speaker output through an attenuator. That has no earth connection (two wire chord) and it was creating sort of microphonics due to the speakers on the input to the sub. Ran a ground to the sub and all is well now.
Sometimes that you don't suspect could be the cause 🙂
I assembled mine in 2016 April. so far so good. driving my Klipsch Heresy IIIs.
I too had strange hum and traced it to the connection to the TV through it's AV out to the amp / preamp. TV has a optical out so isolated it from the amp with a small Optical DAC and hum is gone. Even with DAC it was there earlier but had used the USB of TV to power the DAC. On using a separate source the hum vanished.
Also have a subwoofer KEF Kube 12b connected to the speaker output through an attenuator. That has no earth connection (two wire chord) and it was creating sort of microphonics due to the speakers on the input to the sub. Ran a ground to the sub and all is well now.
Sometimes that you don't suspect could be the cause 🙂
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