Aleph J for Universal Mounting Spec

[WalterW]

Don't know... I now have 4 Pass Amps to listen to...
A pre-amp and a very good DAC are the next things to build
I've ordered a DDDAC PCM1794 kit today.... that's my project which helps me through the long Dutch winters...

But.... a F6 or something with the BAF2013 Sony 2SK82 and 2SJ28 Amp are tempting....

Walter

 

[henryve]

Walter

Uitmuntende vakmanskap (Excellent workmanship).

As usuall your work is an example to aspire to. Keep up the good work

 

[WalterW]

Hahaha, henryve, nowadays we say "Uitmuntende vakmanschap"..with sch...

Walter

 

[rif]

WalterW - any issues/concerns with the MOSFETs so close to the caps? I'm working on my own aleph j layout.

 

[henryve]

Hahaha, henryve, nowadays we say "Uitmuntende vakmanschap"..with sch...

Walter

LOL. Yes, us ex-Dutchies have been left in the sticks down here for far too long!

 

[WalterW]

do you mean the PSU caps?
Then no issues at all...

 

[WalterW]

LOL. Yes, us ex-Dutchies have been left in the sticks down here for far too long!

hahahahaa

 

[ticktock]

Very very beautiful build, Walter !!



BTW, what's the lead spacing of C1?

 

[dodog]

Finished my Aleph J...

Walter-

That's a beautiful build!

What is that hookup wire running from the RCA jacks? Do you mind sharing where you got that?

 

[WalterW]

Thanks, it's a silver wire PTFE (Teflon) coaxial cable used at very high RF frequencies, I bought it 20 years ago in a Army Dump I believe...

 

[WalterW]

My Aleph J plays very nice, I listen to it a lot, but I have a few questions...
The turn off thump is so nasty... there is a lot of DC at the output, my woofers almost explode... Is there a solution for this? It sounds terrible for a few seconds...
Second, Is there a way to make the Aleph J more appropriate for 4 ohm speakers, like mine? I understood that at 4 Ohm the Aleph does half the power than at 8 Ohms?

Walter

 

[Zen Mod]

give us pictures and exact schmtc (values ) , to see where's culprit for kaboom

 

[WalterW]

Hi ZM, pictures are in post 598, I followed the original schematics except having a pot for R7 and R27.
When I turn the amp off, with the 230v switch, the negative rail discharges much faster than the positive rail. I see the LED's at the PSU boards dimming much faster at the negative rail...
I can measure the values of the potentiometers tomorrow.... if you wish

 

[Zen Mod]

it seams pcbs are stuffed Dodo as per FW , with pot here and there ( not relevant for your kaboom)
do you have bleeders at cap banks ?

if yes , what values up and down ?

 

[Bones13]

Very very beautiful build, Walter !!



BTW, what's the lead spacing of C1?

22 mm

also shown are the 4 caps that I have picked up waiting to build this amp. The older axial Wima caps are off ebay, so I don't have a clue as to quality or even veracity. Anyone with suggestions, please have at it.

 

[ticktock]

22 mm
Anyone with suggestions, please have at it.

THX, mate !!
If you see any chance to fit a lead spacing of 27.5, give this one a try:

FKP4 1.0 µF FKP4G041006J00 RM27.5

FKP4G041006J00KYSD WIMA | Mouser

 

[WalterW]

Hi ZM, I have on both rails a 2,2K / 3 Watt resistor.

Walter

 

[WalterW]

BTW: you shouls listen to this song (Grover Washington Jr - The Best is Yet to Come) on your Aleph J, highs are spectacular, so detailed, it's a nice amp....

 

[Zen Mod]

try without bleeders on neg rail

do you have any additional load on PSU , besides amp circuit itself ?

relays , logic ..... ?

 

[WalterW]

No additional load just the LEDs at the PSU boards and at the AMP boards. No logic, no relays.....
Used this chassis with PSU for my F5, no thump, just changed the F5 Amp boards to Aleph J boards...

Should the Aleph J be thump less ( is this English? Sorry ) ? Or is it known to have a big switch off thump?
Because my ACA also give a big thump...
Will cut the resistor leads tomorrow :-(