Thanks 6L6...
Mostly, I'm curious to know the second part of my original question. After initial setup, powered down and amplifier has cooled off, then powered on, have you ever had your DMM across outputs and observed the maximum offset?
I also understand that it does take 30 minutes or more to attain steady-state.
I have yet to build the board, but would like to get some experienced first hand numbers from those in the know. Thanks!
Put my A'J together today and found that C6 & C7 are not the correct size or part. The BOM in diyaudio store points to 505-MKP4.1/250/5P10 (Mouser) but looking at Jim's BOM on first page, C6 & C7 are 05-MKP20.1/100/5 (Mouser) - Is the latter the correct one?
Thx
Neville
edit: I see the store has rev c and Jim has rev d...ugh 🙁 do we know what else is different between the 2 revisions? I hope nothing else
since I have already soldered everything else.
Thx
Neville
edit: I see the store has rev c and Jim has rev d...ugh 🙁 do we know what else is different between the 2 revisions? I hope nothing else
since I have already soldered everything else.
Last edited:
Because those caps are nothing more than bypasses, just leave them out. Nelson does. (They are a 'because it's nice' part, not anything vital or even in the original...)
FWIW, the one with 5mm lead spacing is correct.
Check your PM
FWIW, the one with 5mm lead spacing is correct.
Check your PM
It's not typical to bypass a coupling cap in any case. It's good practice to bypass filter caps.
Amp Camp version and how to upgrade the circuit
Sorry, but I am such a debit to forums that I can't figure out here how to post a new topic. What I won't to know is:
What Zen version is the amp camp kit?
The reason I ask this is that want to experience all the upgrades to the last Zen 9 amp.
I need to know how to upgrade each amp version--do I breadboard this or just modify the PC boards?
Sorry, but I am such a debit to forums that I can't figure out here how to post a new topic. What I won't to know is:
What Zen version is the amp camp kit?
The reason I ask this is that want to experience all the upgrades to the last Zen 9 amp.
I need to know how to upgrade each amp version--do I breadboard this or just modify the PC boards?
Thanks Jim and Roger for info on the C6 & C7. I'll just leave them out. I will update my BOM to reflect it as optional. I also have soldered R6 which I believe is for oscillation etc, since its already soldered would it be ok to just leave it than replacing it with a jumper?
not sure on that being optional. R6 looks like it's a fixed minimum value of voltage drop in the circuit to ensure bias adjust doesn't get too far out. I think it's around 8 or 10mA, this would be around 5V drop. I' d ask the more seasoned pro's before jumpering it...
R6 is just a set of pads if you need it to help stop oscillation if you have any. So jumper is normal.
The CCS (R8,C4,D1,Q2) sets the current of the Jfet differential pair.
The CCS (R8,C4,D1,Q2) sets the current of the Jfet differential pair.
I have updated my Mouser BOM to reflect C6 and C7 as optional and R8 to be same as R7 which is a 2K pot trimmer. Apart from that everything else between Rev C & D looks the same.
Mouser BOM
Mouser BOM
I finally got one side behaving properly .4 bias and 0 offset. when I plug up my B1 to input the offset goes crazy and speaker buzz's loudly. I'am wondering if I ran the grounds properly. I did boards to p/s and p/s to chassis with earth to chassis??
Hello. regarding the connection of the thermistor I have only one primary winding of the transformer:
how should I connect the thermistors?
I tried to put them in series to the second power supply, one for each phase,
but warm up a bit is this normal?
thanks
how should I connect the thermistors?
I tried to put them in series to the second power supply, one for each phase,
but warm up a bit is this normal?
thanks
Finally got my wiring done, and bought some fuses. I put a pair of 3amp slow blow fuses in my stock DIY chassis/back panel kit.
My switch circuit seems to work fine (once I corrected the polarity on the final relay.
Once I got that right, I got power on, with all LEDs on, except the soft start board, and I am wondering if that LED is in backwards.
However, I get a short pretty much right off. The click happens, the LEDs light right up, then slowly go back off as the caps dissipate. Wiring looks right. I ordered some bigger fuses, as I am headed to the beach this weekend. I will try it once with some 5 amp fuses. If that does not work, I will need to work out from the power to the boards, and see if I can figue the problem.
I am pretty good at putting stuff together well, debugging this sort of thing is the hardest for me.
My PSU - Antek 500VA 2x18V secondaries - DIYAudio Store PSU boards, V3 - Caps - 22,000 mundorf - Discrete diodes on the PSU Boards.
Am I missing anything obvious? I am working on getting pictures in.
My switch circuit seems to work fine (once I corrected the polarity on the final relay.
Once I got that right, I got power on, with all LEDs on, except the soft start board, and I am wondering if that LED is in backwards.
However, I get a short pretty much right off. The click happens, the LEDs light right up, then slowly go back off as the caps dissipate. Wiring looks right. I ordered some bigger fuses, as I am headed to the beach this weekend. I will try it once with some 5 amp fuses. If that does not work, I will need to work out from the power to the boards, and see if I can figue the problem.
I am pretty good at putting stuff together well, debugging this sort of thing is the hardest for me.
My PSU - Antek 500VA 2x18V secondaries - DIYAudio Store PSU boards, V3 - Caps - 22,000 mundorf - Discrete diodes on the PSU Boards.
Am I missing anything obvious? I am working on getting pictures in.
Last edited:
Your transformer wants at least a 4 amp fuse, its rated draw at 120V is 4.17A. I use a 6.3A slow blow for 600 VA transformers. You probably want to go with 5A slow blow. Even with the soft start, you get a pretty big surge.
That's what I'm hoping, and thanks for the words. I ordered both 5 and 6.3 fuses before I wrote that post. No smoke or light show, just fuse blow during power up, all quiet like.
Are both the fuses active in the IEC inlet in the DIYStore deluxe back panel kit? Or just one side hot, one side spare?
Are both the fuses active in the IEC inlet in the DIYStore deluxe back panel kit? Or just one side hot, one side spare?