avitkauskas,
Extreme_Boky is right.
That primary wiring needs to disappear below the PS PCB (I think he meant PS PCB, not Amp PCB).
Your current filtering caps may not address the amount of ripple in this Class A design.
Where do your ground wires from each amp PCB to the PS board go? Are they on the same side? You should choose one GND side.
Do I see (2) chassis grounds? The electrostatic shield (yellow) wire goes to one part of the baseplate while the PS PCB/Thermistor goes to another. Try to make it all the same. Use thick gauge ground wires if you can.
Keeping the input RCA’s next to each other and bonding the ground tabs together would help but I think that is impossible in your build.
You can use an L-Bracket on the toroid (mount it vertically) and see if that helps. Changing the orientation of the toroid (move clockwise or counterclockwise) can also help. Move any and all primary wirings as far away from the Aleph J main amp board. You may need to move your white 3 terminal board that holds your thermistor/cap as well (closer to the toroid).
See Andrew Russell’s/Hifisonix’s writeup on proper elimination of ground loops and the like.
Best,
Anand.
Extreme_Boky is right.
That primary wiring needs to disappear below the PS PCB (I think he meant PS PCB, not Amp PCB).
Your current filtering caps may not address the amount of ripple in this Class A design.
Where do your ground wires from each amp PCB to the PS board go? Are they on the same side? You should choose one GND side.
Do I see (2) chassis grounds? The electrostatic shield (yellow) wire goes to one part of the baseplate while the PS PCB/Thermistor goes to another. Try to make it all the same. Use thick gauge ground wires if you can.
Keeping the input RCA’s next to each other and bonding the ground tabs together would help but I think that is impossible in your build.
You can use an L-Bracket on the toroid (mount it vertically) and see if that helps. Changing the orientation of the toroid (move clockwise or counterclockwise) can also help. Move any and all primary wirings as far away from the Aleph J main amp board. You may need to move your white 3 terminal board that holds your thermistor/cap as well (closer to the toroid).
See Andrew Russell’s/Hifisonix’s writeup on proper elimination of ground loops and the like.
Best,
Anand.
Cable is Mogami 12AWG, Part No W3103
MOGAMI® - Superflexible Studio Speaker Cables
Pins are solid copper:
165045 TE Connectivity / AMP | Mouser Australia
I fed as much of that 12AWG wire inside the pin as I could, and the remainder was wrapped outside the pin, and then everything was soldered with a 60W soldering iron.
MOGAMI® - Superflexible Studio Speaker Cables
Pins are solid copper:
165045 TE Connectivity / AMP | Mouser Australia
I fed as much of that 12AWG wire inside the pin as I could, and the remainder was wrapped outside the pin, and then everything was soldered with a 60W soldering iron.
Attachments
Thanks for all your comments, @Extreme_Boky and @poseidonsvoice.
I am very much convinced already that my problem is due to the scorched MOSFETS, so I already making plans and calculations what is the best way for me to change them. I will also look at the power resistors when doing it. Anyway, the big reshuffling of my Aleph is going to happen, so thanks for all the other suggestions as well.
I've read about dealing with hum and buzz a lot before and was also "playing doctor" with my amps with the headphones on the outputs. Still find it being very much a witchcraft - trying all these small miniscule differences to get the result. On the other side seeing others having quiet amps with all these bad errors that are supposed to be eliminated. But please don't take it as any critique or something from me - I am quite a novice and therefore I am very thankful for all these suggestions that I will have in mind when rebuilding my Aleph. Special thanks for the reference for the HBR installation!
On the other hand, I got a PM from 6L6, who promissed me more info about the Zen version (and even the PCBs!), so I'll see what happens first: I fix Aleph J or make Babelfish J version
- both ways will add a lot to my learning
I am very much convinced already that my problem is due to the scorched MOSFETS, so I already making plans and calculations what is the best way for me to change them. I will also look at the power resistors when doing it. Anyway, the big reshuffling of my Aleph is going to happen, so thanks for all the other suggestions as well.
I've read about dealing with hum and buzz a lot before and was also "playing doctor" with my amps with the headphones on the outputs. Still find it being very much a witchcraft - trying all these small miniscule differences to get the result. On the other side seeing others having quiet amps with all these bad errors that are supposed to be eliminated. But please don't take it as any critique or something from me - I am quite a novice and therefore I am very thankful for all these suggestions that I will have in mind when rebuilding my Aleph. Special thanks for the reference for the HBR installation!
On the other hand, I got a PM from 6L6, who promissed me more info about the Zen version (and even the PCBs!), so I'll see what happens first: I fix Aleph J or make Babelfish J version
- both ways will add a lot to my learning 
Did you compare model code on a case with a datasheet of the trimmer?
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Henry,
Do you have some of the large electrolytic caps already soldered? If so, it may be difficult to double check the value your pot is set at since the DMM is charging up the capacitor.
See here: Building: Amp Boards
He only mentioned being able to double check the value the pot is set at *before* he soldered in the capacitors.
Did you set the pot prior to soldering it in? COM/black lead on pin 1 and Red lead on wiper (middle pin/pin2).
Best,
Anand.
Do you have some of the large electrolytic caps already soldered? If so, it may be difficult to double check the value your pot is set at since the DMM is charging up the capacitor.
See here: Building: Amp Boards
He only mentioned being able to double check the value the pot is set at *before* he soldered in the capacitors.
Did you set the pot prior to soldering it in? COM/black lead on pin 1 and Red lead on wiper (middle pin/pin2).
Best,
Anand.
Can't remember if I checked it. I build these PCBs up in 2013, and then our dear country's exchange rate tanked which meant that I could not afford the transformer and casing then. Well, in the meantime I was able to afford those, so this was just a last minute sanity check before I wire the DC supply to the PCBs and start with biasing.
I guess best approach would be to desolder the trimmer and set it to 68k before soldering it back in. I was sort of hoping there would be a way to check it in circuit, but with all the caps and other components already soldered in it makes sense that I cannot get the correct reading.
I guess best approach would be to desolder the trimmer and set it to 68k before soldering it back in. I was sort of hoping there would be a way to check it in circuit, but with all the caps and other components already soldered in it makes sense that I cannot get the correct reading.
Lord Zen,
I think Henry is not sure if he had preset the pot many years ago, so he wanted to double check. I ran into the same issue and decided that I probably set it properly in the 1st place and I shouldn’t worry. Just start slowly with a variac and go from there. Alternatively one can desolder the pot and be extra careful.
Best,
Anand.
I think Henry is not sure if he had preset the pot many years ago, so he wanted to double check. I ran into the same issue and decided that I probably set it properly in the 1st place and I shouldn’t worry. Just start slowly with a variac and go from there. Alternatively one can desolder the pot and be extra careful.
Best,
Anand.
Just preseting before power-up.
No problems yet. Just don't want to cook the FETs and MOSFETs.
try to rotate to any side where you hear click on end; even if you can't hear click, rotate until it bores you; then just counter rotate for half declared rotations ( 10 for full?)
that will put you in ballpark and that's it
usually I'm not trusting in my self, I'm trusting only in properly connected instruments ( DMMs)
that will put you in ballpark and that's it
usually I'm not trusting in my self, I'm trusting only in properly connected instruments ( DMMs)
Hi guys, slightly OT: has anyone build, designed, or simulated Aleph with Sony VFET(s) instead of the lower MOSFET(s)? It would require a negative bias voltage on the VFET gate (extra negative voltge supply most likely). I am wondering if someone already came up with some solution and is happy with it? The presence of the bias supply might require a higher current hence extra follower... it would be great to avoid it and control the VFET gain from the JFET.
BTW I think I would prefer to have a single VFET per channel, alternatively, I would need to have a separate bias per VFET as I have only one pair of the N-ch matched, the other N-ch VFETs were not so happy in finding the second half
Is it worth it?
BTW I think I would prefer to have a single VFET per channel, alternatively, I would need to have a separate bias per VFET as I have only one pair of the N-ch matched, the other N-ch VFETs were not so happy in finding the second half
Is it worth it?
Caught out in the wild! What is this rare beast-y beauty?
For me, it's like having an old friend over for dinner that I haven't seen in ages... I have missed this amp! AJ was my second amp build ever after F5. It was audio heaven—lot's of lush editorialization perhaps?—but I soon realized the amp wasn't quiet at all—After a lot of learning and experimenting—HBRs etc—Nothing would solve the buzzing...I moved on to M2X... and that's been incredible for learning and audio awesomeness.... but it's a different amp (it's a GREAT amp—we are afterall comparing Ferrari's—thanks to 6L6 for pointing that out to me one day).....
So here's my original AJ PSU and trasnfo and chassis, and with a couple of new holes tapped—and some ZM magicalness—and YES! YES! YES!
I'm seeing AJ ZEN monoblocks in my future. Might derail my BA-3 build. (also NEED to get SISSYSIT right channel working, boo.)
THANK YOU ZEN MOD!!!!!! (And Nelson
Vfet and AJ Zen cohabitate-ing — I must be VERY fortunate — Keith Jarrett on solo piano on vinyl never sounded so good (and Coltrane, and Miles, and Wes, and The Duke). So big and bloom-y and tube-y? I don't know. There's nothing not to LOVE about this amp. Maybe I just take my music with a healthy dose of MORE.
A birdie also told me that the boards are already in v.2—we LOVE a motivated ZM!
OO so when can we expect to be able to buy these new AJ boards, ZM? Greedy Boyz got to know
....
Is it worth it?
as challenge, yes
sonically ....... not so sure
same nature and probable performance achievable with less complicated circuits, some of them already known, some still not
is there LTSpice model handy around for these VFets?
I'm sorta sleepy, so better no searching through my black hole PC
have an idea ........ and - you know you'll need 3rd, aux rail, neg to neg one .....