My friends, this is the first time I post a comment, rode my aleph j. I measured the voltage at the output (speaker) and I 24vdc. I do not know what happens, measure the voltage between gnd and also (gate, drain and source), all voltages are 24vdc, can someone help me? I reviewed the circuit many times. I will be very grateful.
Greetings
Greetings
some more info will be nice. is the problem in 1 or 2 ch? is it a single supply or dual supply?
and is this a new build? or has it worked fine for some time? original or DIY amp?
and is this a new build? or has it worked fine for some time? original or DIY amp?
Dear AudioSan, thanks for the interest. The problem is with the two channels, the source is + - 24V symmetrical. I bought the fets in Germany (mached quad) per channel. I tested the ZTX before soldering them. The 2sj109 I have not tested. The voltage at the output of the speakers is 24vdc. The mosfets do not heat, no power consumption. There 24vdc in source and gate drain ....
Greetings
Greetings
okei. i bet your sj109's is fake. then this will happend. 90% of all on the marked to day are fake.
buy 2 matched pairs of sj74 insted. f.ex from spencer.
another reason for this can be the PSU. f.ex that there is no -24V
measure the PSU first. see if you get +/-24V.
but i think it is the sj109's.
buy 2 matched pairs of sj74 insted. f.ex from spencer.
another reason for this can be the PSU. f.ex that there is no -24V
measure the PSU first. see if you get +/-24V.
but i think it is the sj109's.
Thanks AudioSan Thanks also Zen Mod. In source actually possess -24 +24. Actually the problem should be the 2sj109. You know a good supplier on ebay, or another vendor?
Greetings
Greetings
don't use 2sj109. allmost all of them are fake.
real ones cost 30£ pr pc.
use a matched pair of 2sj74 pr ch insted(2sj109 is 2pc 2sj74 in same die). send a PM to spencer🙂
real ones cost 30£ pr pc.
use a matched pair of 2sj74 pr ch insted(2sj109 is 2pc 2sj74 in same die). send a PM to spencer🙂
Very grateful AudioSan. Get me out just a doubt, the jfet is 2sj74BL? For I have several pieces at home. Should I change something in the original scheme for employ them?
Greetings
Greetings
What boards are you using?
You won't require any other component changes... and if you're lucky the boards you have will have the layout printed on them already for discrete J74's.
You won't require any other component changes... and if you're lucky the boards you have will have the layout printed on them already for discrete J74's.
It is trivial to put 2SJ74's in the 2SJ109 pin pattern, and any kind of matching
will work.
A question: On your amplifier which has +24V out, what is the voltage
prop across the potentiometer?
😎
will work.
A question: On your amplifier which has +24V out, what is the voltage
prop across the potentiometer?
😎
Dear Mr. Pass, thanks for your interest. Sorry I do not understand the question. My English is a little poor ....
Greetings
Greetings
If I understand right, the input voltage is 0v in the pot.
* Mr. Pass, there is the possibility of some other problem?
Greetings ...
Rogério
* Mr. Pass, there is the possibility of some other problem?
Greetings ...
Rogério
I had also Problems with my 2sj109bl
I think they are genuine (bought my a thime ago from Little Diode seems they have origin Parts).
But in the Aleph J they produced a slightly Hum.
First thougt it was the PSU but after changing the 109er hum was gone.
Later testet the 109er Idss was ok around ~8mA.
Hmm... what can be wrong with these little critters?
When i know the parts are the problem i would use them no more.
but if the problem is elsewere then i can take the 109er
Because "could be illusion" but I thought they sound a little bit better to me as a pair of 2sj74er
-but a humming amp drives my crazy😀
May be someone of you knows whats happend in my amp😀😀😀
greets Alex
I think they are genuine (bought my a thime ago from Little Diode seems they have origin Parts).
But in the Aleph J they produced a slightly Hum.
First thougt it was the PSU but after changing the 109er hum was gone.
Later testet the 109er Idss was ok around ~8mA.
Hmm... what can be wrong with these little critters?
When i know the parts are the problem i would use them no more.
but if the problem is elsewere then i can take the 109er
Because "could be illusion" but I thought they sound a little bit better to me as a pair of 2sj74er
-but a humming amp drives my crazy😀
May be someone of you knows whats happend in my amp😀😀😀
greets Alex
Alex,
About your issue with the 2SJ109.
Did you try them with pin 4 connected as allowed on PDs board. Or did you have pin 4 open as suggested in the data sheet.
I wonder how NP do with that pin..
About your issue with the 2SJ109.
Did you try them with pin 4 connected as allowed on PDs board. Or did you have pin 4 open as suggested in the data sheet.
I wonder how NP do with that pin..
I had pin 4 not connected. I have the board layout from there:
AlephWiki : Aleph J
Had anybody compared the sound of a 109er with a pair of 2sj74?
(All settings the same except from the input Jfets)
And what was your experience? Do they sound similar for you or is there a difference in your ears?
no diff to my ears
frankly - I never cared enough to make comparative test - just judging by amount of enjoyment - there is no diff
frankly - I never cared enough to make comparative test - just judging by amount of enjoyment - there is no diff
Rear panel + some questions
First power amp build ever. It is taking time, but I am getting there.
The PCB's are done (expect for MOSFETs) and I am working on the PSU (hardwiring).
Not ever having done any metalwork, and not having the equipment or physical strength, I decided to out-source the rear panel. UPS delivered my beautiful rear panel on Friday from Schaeffer. I just had to put the parts in to see what it would look like. 🙂
Enclosed a (lousy) photo taken with my mobile phone.
Question:
I need to tap holes into the heatsinks and will probably out-source to a local metal shop. What size thread (M3, M4, etc) do I need for MOSFET's? And what depth? Metric answers, please 🙂
Another question:
I am using this type of connector (ring, fork and others)
SVES1-3.7 - MULTICOMP - CRIMP TERMINAL, FORK, 3.7MM, RED | Farnell Nederland
and have bought an expensive ratchet crimping plier
430021 - CK TOOLS - CRIMPING PLIER, RATCHET | Farnell Nederland
but am unable to apply enough force to crimp the connectors.
Are similar connectors (in fork, ring, etc varieties) available in a solder type? If so, what are they called and where can I buy them?
First power amp build ever. It is taking time, but I am getting there.
The PCB's are done (expect for MOSFETs) and I am working on the PSU (hardwiring).
Not ever having done any metalwork, and not having the equipment or physical strength, I decided to out-source the rear panel. UPS delivered my beautiful rear panel on Friday from Schaeffer. I just had to put the parts in to see what it would look like. 🙂
Enclosed a (lousy) photo taken with my mobile phone.
Question:
I need to tap holes into the heatsinks and will probably out-source to a local metal shop. What size thread (M3, M4, etc) do I need for MOSFET's? And what depth? Metric answers, please 🙂
Another question:
I am using this type of connector (ring, fork and others)
SVES1-3.7 - MULTICOMP - CRIMP TERMINAL, FORK, 3.7MM, RED | Farnell Nederland
and have bought an expensive ratchet crimping plier
430021 - CK TOOLS - CRIMPING PLIER, RATCHET | Farnell Nederland
but am unable to apply enough force to crimp the connectors.
Are similar connectors (in fork, ring, etc varieties) available in a solder type? If so, what are they called and where can I buy them?
