I have a question concerning the schematic. While reading the Aleph J page on the Firstwatt site, I found this:
"[FONT=Arial, sans-serif]8)No electrolytic capacitor in the signal path"
But, on the schematic on page 1, C3 is on the signal path, no? Why this change?
[/FONT]
"[FONT=Arial, sans-serif]8)No electrolytic capacitor in the signal path"
But, on the schematic on page 1, C3 is on the signal path, no? Why this change?
[/FONT]
Papa's habit - pulling our legs all the time
that's just audio , and just proper decent engineering
no more , no less
that's just audio , and just proper decent engineering
no more , no less
C3 is necessary , and in signal loop
C1 too , as foolproof part , so it can be shorted , if there is no short circ between operator's headphones
😉
C1 too , as foolproof part , so it can be shorted , if there is no short circ between operator's headphones
😉
I thought someone was going to help me put mine together, but too many things got in the way and then I moved about 5 hours away. By chance, are there any plans to post some youtube videos on the build?
bias good, DC offset bad!
Hello friends,
I recently had to open up my Aleph J and in revisiting it after a couple years I found the DC offset had risen...a lot! I tried to re-bias and realign the DC offset but cannot get it back down to what I consider reasonable. Right now the left channel is at 47mVDC and the right is at 95mVDC.
Any suggestions? 😕
Hello friends,
I recently had to open up my Aleph J and in revisiting it after a couple years I found the DC offset had risen...a lot! I tried to re-bias and realign the DC offset but cannot get it back down to what I consider reasonable. Right now the left channel is at 47mVDC and the right is at 95mVDC.
Any suggestions? 😕
adjusting R7 seemed to have no effect no matter how many turns...until the Bias started to drop badly...
Perhaps I should consider a cap at the output instead of the input?
Perhaps I should consider a cap at the output instead of the input?
Ive biased all my amps without shorting plugs or load across speaker terminals. I usually get DC offset around 9mA, never 90!
Would this DC offset be an indication that the 2SJ74s are now no longer matched?
Is there an adjustment I can make to the R7 as in making it a 5K instead of 2K?
Is there an adjustment I can make to the R7 as in making it a 5K instead of 2K?
The Jfet are not going to change.
Assuming that you are at the max. resistance portion of the pot, yes, changing it to a 5K would be fine.
Or just place a 470R-1K resistor in series with the pot. (whatever you happen to have on hand)
Assuming that you are at the max. resistance portion of the pot, yes, changing it to a 5K would be fine.
Or just place a 470R-1K resistor in series with the pot. (whatever you happen to have on hand)
Hi everyone
I'm a long time member and haven't been on diyaudio for years. I decided to replace my Aleph 30 that I built 7 years ago with an Aleph J.
I built a power supply, populated the boards, and tested one channel. After some adjustment, it seems to work fine.
Now, I power on the other channel. I measure R18 and I get 0.35V. I measure R19 and I get 0.9V. After a few seconds Q8 was smoking.
Why do you think this happened?
I made sure Q7 and Q8 were matched, Q5 and Q6 were matched too.
R27 was set to 68K, R8 was set to 1K.
I'm a long time member and haven't been on diyaudio for years. I decided to replace my Aleph 30 that I built 7 years ago with an Aleph J.
I built a power supply, populated the boards, and tested one channel. After some adjustment, it seems to work fine.
Now, I power on the other channel. I measure R18 and I get 0.35V. I measure R19 and I get 0.9V. After a few seconds Q8 was smoking.
Why do you think this happened?
I made sure Q7 and Q8 were matched, Q5 and Q6 were matched too.
R27 was set to 68K, R8 was set to 1K.