Thanks for the link, you beat me to it. 
As for the board, I was envisioning the same basic layout as the F4, F5c, etc... The longer board with the outputs all on the lower edge.
Also, I would love to see R7 replaced with a trimmer pot, as that's where you will be able to dial out any DC offset on the outputs... Maybe put pads for a parallel resistor there as well...
J109's are basically impossible to get anymore, so most people will be using a matched pair of J74's... it would be handy if they were face to face so their cases can be zip-tied together for better thermal tracking.
Thanks a bazillion for the offer!
As for the board, I was envisioning the same basic layout as the F4, F5c, etc... The longer board with the outputs all on the lower edge.
Also, I would love to see R7 replaced with a trimmer pot, as that's where you will be able to dial out any DC offset on the outputs... Maybe put pads for a parallel resistor there as well...
J109's are basically impossible to get anymore, so most people will be using a matched pair of J74's... it would be handy if they were face to face so their cases can be zip-tied together for better thermal tracking.
Thanks a bazillion for the offer!
Ok i fell flat with the second channel
Offset is (-)23.6Vdc
R7 - 36V
Q3 Vce-36V
Q2 Vce - 0V
Q4 Vce ~ 4 V
Z1 - 9.9V
R8 - 9.1V
All source resistors are around ~.56xV
Q5 & Q6 gets pretty hot (case temp of 70C after 5 mins)
So before i unmount the setup, anything that comes to anybodys minds pls.
I have used 2Sj74 & BC550/560 (have been careful with the pinouts)
Offset is (-)23.6Vdc
R7 - 36V
Q3 Vce-36V
Q2 Vce - 0V
Q4 Vce ~ 4 V
Z1 - 9.9V
R8 - 9.1V
All source resistors are around ~.56xV
Q5 & Q6 gets pretty hot (case temp of 70C after 5 mins)
So before i unmount the setup, anything that comes to anybodys minds pls.
I have used 2Sj74 & BC550/560 (have been careful with the pinouts
)
Last edited:
Can I jump in and suggest right now, please fellers, that a new thread is opened for discussion of a new UMS Aleph J board design rather than doing it in here?
I'm interested in following if not contributing to the process and I think it would be a mistake to bury something that important in the 13?th page of an existing thread.
Much respect to craigtone for bravely volunteering ;P and all due respect to 6L6, and Mr dB.
I'm interested in following if not contributing to the process and I think it would be a mistake to bury something that important in the 13?th page of an existing thread.
Much respect to craigtone for bravely volunteering ;P and all due respect to 6L6, and Mr dB.
Ok i fell flat with the second channel
Offset is (-)23.6Vdc
R7 - 36V
Q3 Vce-36V
Q2 Vce - 0V
Q4 Vce ~ 4 V
Z1 - 9.9V
R8 - 9.1V
All source resistors are around ~.56xV
Q5 & Q6 gets pretty hot (case temp of 70C after 5 mins)
So before i unmount the setup, anything that comes to anybodys minds pls.
I have used 2Sj74 & BC550/560 (have been careful with the pinouts
I dug up a old post from Zen it says
'so - voltage across R7 is completely dependent on input LTP's CCS (Z1, Q2,R8)'
So as of now Q2 seems to be the culprit as R8 & Z1 reads more or less ok
whatever you have , between +/-18 and +/-28Vdc
be sure that steady dissipation of each IRFP150 is no more than 50W , with proper heatsinking
Pa sez that input Jfets (in that configuration) are pretty safe up to ....... +/-35Vdc PSU , if I remember correctly
whatever - I don't like regs in power amp supply , for my taste better solution will be to un-wind some turns of xformer secondary , if possible
be sure that steady dissipation of each IRFP150 is no more than 50W , with proper heatsinking
Pa sez that input Jfets (in that configuration) are pretty safe up to ....... +/-35Vdc PSU , if I remember correctly
whatever - I don't like regs in power amp supply , for my taste better solution will be to un-wind some turns of xformer secondary , if possible
pls help
Change q2,q3,q4 but things are not right
ZD1-9.36V
R8-8.75V
Q2 Vce-13.8V
Q2 Vbe- 0.6V
R7-8.7V ?????
R16,17,18,19- 0.59xV
Q5,Q6 Vgs - 4.2V
Q7,Q8 Vgs- 8.1V ???
Q4 Vce-4.68V
One other thing the good channel has 0v across 5pF, while the bad one has 2.8v
I am confused
Change q2,q3,q4 but things are not right
ZD1-9.36V
R8-8.75V
Q2 Vce-13.8V
Q2 Vbe- 0.6V
R7-8.7V ?????
R16,17,18,19- 0.59xV
Q5,Q6 Vgs - 4.2V
Q7,Q8 Vgs- 8.1V ???
Q4 Vce-4.68V
One other thing the good channel has 0v across 5pF, while the bad one has 2.8v
I am confused
Ok done..there. was a short on one of the JFEtS.
Both channels are working.
While these are early days with burn in and all,my idea was
J requires around 1.6v to drive it to 25W while F5 requires > 2V to drive it to 25W.
But all things being equal for the same setting F5 is louder? ??
My aleph is SE with -ve input grounded & all components as per published circuit
Both channels are working.
While these are early days with burn in and all,my idea was
J requires around 1.6v to drive it to 25W while F5 requires > 2V to drive it to 25W.
But all things being equal for the same setting F5 is louder? ??
My aleph is SE with -ve input grounded & all components as per published circuit
In my build, Aleph J has more gain and sounds louder at similar input signal level compared to a standard F5.
To get the level of the F5 closer to the AJ, change the feedback resistors (R5 R6 R7 R8) from 100R to 150-220R in the F5 to increase the gain. (At the expense of feedback, but I have built one with 100R and one with 150R and I hear no difference...)
Yes, I agree wholeheartedly. I'm sorry that I let it go a couple extra days here.
As suggested -- http://www.diyaudio.com/forums/pass-labs/224881-aleph-j-universal-mounting-spec.html#post3268486
