Hello i`v build an second Aleph J and have some hum trouble.
I think its a ground loop but i don`t know what to try first.
I have paint a quick ground schematic not very beautiful but unique
If you have some ideas where to start or what to change?
board are done by myself, maybe i`ve made a fatal layout error used ground plane on each pcb for Signal GND
thats the pcbs
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-150.html#post3294378
I think its a ground loop but i don`t know what to try first.
I have paint a quick ground schematic not very beautiful but unique
If you have some ideas where to start or what to change?
board are done by myself, maybe i`ve made a fatal layout error used ground plane on each pcb for Signal GND
thats the pcbs
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-150.html#post3294378
Attachments
Danger Mouse
Bring left channel grounds to the same spot on the PSU as the right (the star ground), separating noisy power and quiet signal grounds. Then connect to the bridge isolating the amp circuit from the chassis.
Hopefully your board design made some effort to isolate signal and power grounds. Return them to the star ground separately.
Do you have a resistor or thermistor bypassing the isolation bridge? This is a good idea for safety. A CL60 works well, having a fair amount of resistance until current flows.
Bring left channel grounds to the same spot on the PSU as the right (the star ground), separating noisy power and quiet signal grounds. Then connect to the bridge isolating the amp circuit from the chassis.
Hopefully your board design made some effort to isolate signal and power grounds. Return them to the star ground separately.
Do you have a resistor or thermistor bypassing the isolation bridge? This is a good idea for safety. A CL60 works well, having a fair amount of resistance until current flows.
ok i will give this a try.
the CL60 are not in at the moment will use them when test phase is over
and all is at its place.
its funny i have a perfectly running AlephJ at home.
Try in my second some board where i have changed the ground routing a little bit thought it would be better this way and nothing works as it should
many thanks for your help
the CL60 are not in at the moment will use them when test phase is over
and all is at its place.
its funny i have a perfectly running AlephJ at home.
Try in my second some board where i have changed the ground routing a little bit thought it would be better this way and nothing works as it should
many thanks for your help
Hello hello and glad to be back
since we are on the last 100m with the summer I am thinking at some winter projects I could initiate.
one of them is an amplifier with no negative feedback, now my questions are :
- are there big differences in terms of sound between amps with negative feedback and those without?
- how can I modify my aleph J to eliminate nfb ? does it worth it ?
since we are on the last 100m with the summer I am thinking at some winter projects I could initiate.
one of them is an amplifier with no negative feedback, now my questions are :
- are there big differences in terms of sound between amps with negative feedback and those without?
- how can I modify my aleph J to eliminate nfb ? does it worth it ?
-it depends who made these amps ; since we are in Papaland , I presume it's logical that everyone knows that amps made by him aren't so much different , quality wise
-it's possible , but not entirely ; that'll be big ACA ; go read article - buffer instead of input LTP , but there is still "too much" gain left in output mosfet (lower one)
-it's possible , but not entirely ; that'll be big ACA ; go read article - buffer instead of input LTP , but there is still "too much" gain left in output mosfet (lower one)
Hello i`v build an second Aleph J and have some hum trouble.
I think its a ground loop but i don`t know what to try first.
I have paint a quick ground schematic not very beautiful but unique
If you have some ideas where to start or what to change?
board are done by myself, maybe i`ve made a fatal layout error used ground plane on each pcb for Signal GND
thats the pcbs
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-150.html#post3294378
i hope this will help eliminates your hum (at lest reduce
)
i am doing this wiring to all my monster...
Last edited:
i hope this will help eliminates your hum (at lest reduce
View attachment 368804
i am doing this wiring to all my monster...
Thanks for your help
Problem is solved i moving back to the layouts from the aleph wiki.
And going with all groundwires to starground between the last PSU caps.
Now all is hum free.
But was a lot of work.
Changed to much at the same time, maybe the PCBs was the error or the
groundrouting. who knows
one channel of my Aleph J started to behave strange, turned both channels on in the morning for an hour or so of listening after which both were functional, after this they were turned off for 2-3 hours.
oh well now after those 2-3 hours when I start up one of my channels generates noise(0.4V) only if it has the input cable attached(it produces the noise(hum)even if at the other side of the input signal cable isn`t nothing connected).If I let the input with nothing attached the output is quiet
I have no idea from where to start...
oh well now after those 2-3 hours when I start up one of my channels generates noise(0.4V) only if it has the input cable attached(it produces the noise(hum)even if at the other side of the input signal cable isn`t nothing connected).If I let the input with nothing attached the output is quiet
I have no idea from where to start...
No go on jfets from AMB. I decided to try a lot of LSJ74s from the DIYAudio store because I have zero confidence in the supposed Toshiba J74 parts from any other vendor than Ti.
Unrelated question on the topic of the Aleph J. My Buffalo/Legato DAC doesn't put out sufficient voltage to make this amp sing and I've read others have used 1:2 input transformers. Any comments or recommendations on a specific Lundahl part number? [Preferably one transformer per balanced channel]
Cheers,
Frank
Unrelated question on the topic of the Aleph J. My Buffalo/Legato DAC doesn't put out sufficient voltage to make this amp sing and I've read others have used 1:2 input transformers. Any comments or recommendations on a specific Lundahl part number? [Preferably one transformer per balanced channel]
Cheers,
Frank