Aleph J illustrated build guide

[Extreme_Boky]

I'm pleased to report that Extreme_Boky's suggestion led to resolution of the gain issue. I had in fact placed the wrong resistors in R1, R3 and R4. I guess I didn't pay sufficient attention to the designations "221K" vs "22K1". In any event, all is sorted now and the Aleph J is performing beautifully.

I'd like to express my gratitude to Extreme_Boky, Dennis Hui and Zen Mod for taking the time to respond to my post, and sharing your understanding of electronics and the Aleph J circuitry. While I'm at it, thanks also to 6L6 and flohmann for the excellent build guides. And of course to Nelson Pass for making these designs available to the DIY community.

Nice!

 

[aljordan]

My recently completed 300B monoblock project sure ate up lots of space on the rack.

Sorry for the OT, but what 300b monoblocks did you build?

 

[zoe]

2SJ74BL

I have some 2SJ4BL parts I bought 8 years ago I matched them yesterday I have 4 I am thinking of using they test at 7.97 7.98 9.34 9.37 will this be ok or will it be uneven ?

 

[6L6]

Put the 7's together and the 9's in the other channel, will work great.

Idss (what they are matched for) has essentially nothing to do with gain or volume. And anyway, the front end has a constant current source, the matching is required only so one side of the pair doesn't hog the current.

P.S.
<--- The white dog that's my avatar was named Zoe.

 

[zoe]

thanks thats what I thought just wanted to make sure. Im about to solder them in. Im also building ba-3 pre from your guide

thanks for all your help!

 

[mkane77g]

Aleph J has low volume on one side. R27 doesn't respond. Showing zero MV. Lights power up, heatsinks cold. What should I check?

 

[adason]

you have one side working, so compare them...

 

[mkane77g]

Compare as in measure voltages?

 

[adason]

yup

place ground of your multimeter probe to zero DC, then with live probe measure voltages on crucial spots

write these into the schematics, in blue color for working channel, in red color for non working channel

ZM will be with you shortly

 

[Zen Mod]

pics could help

 

[mkane77g]

I'm on it thanks. I'm measuring the outside pins @ Q 5-6-7-8 and the voltage vary wildly. In all honesty I don't have a clue what to measure. PS measures out good though. Stood the hair up on my head.

 

[mkane77g]

Non working LED's in backwards. I'll get the tripod out.

 

[avitkauskas]

mkane77g, is your V- supply connected to the board? From the picture it looks like the wires are connected to the different contact groups in the brick.

 

[mkane77g]

more

 

[Dennis Hui]

Yes, I also don't see anything on the other side of the green wire at the terminal block.

 

[mkane77g]

Another Senior moment. Anything I should check while I'm in there? Thanks

 

[adason]

perhaps that fixed it
fingers crossed

 

[adason]

i built Aleph J few weeks back
both channel worked, biased well, nice stable zero on output, except no led light on one channel
later I discovered that instead of 4k7 resistor for led voltage drop, I used 4M7
crazy thing is I took all those 4k7 resistors from the same bag, must have been some mixed up bag

 

[mkane77g]

Back to two channel stereo. I don't have a clue how that could have happened.

 

[Eric]

... I discovered that instead of 4k7 resistor for led voltage drop, I used 4M7 crazy thing is I took all those 4k7 resistors from the same bag, must have been some mixed up bag

On more than one occasion, I have received 220K resistors in a bag labelled 220R. Since I made this discovery, NOTHING goes into a PCB without being measured first.