Aleph J illustrated build guide

Official Court Jester
Joined 2003
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do not worry - your English is better than my German

confirm (to us) that you;re woorking by schematic from post #1, and post well lit big pictures of your right channel

now I'm interested what's Iq ( measure voltage across any 3W source resistor) and what's current through LTP ( input JFet pair) ; for that I need to see arrangement of resistors in CCS on top of input LTP, so I can tell where to get reading

do you have spare pair of input JFets?
 
@Jezza56, 18V vs 20V is something hard to answer. I would suspect that you'll probably see around 21V rail with 18V/600VA/6A, which is fine, but a little lower side. Normally, AJ rail is around 22V with suggested parts here, I guess.

I think that given I am now planning to run 3 channels from one power supply I will opt for 600VA with 20V secondaries this should put me around the 24V supply. I am trying to source the Toroidy transformers from Poland but it is very difficult as they only seem to ship to EU via online shop. I have another question will 35V caps be adequate for this supply as I would like to use this cap LGU1V223MELC - NICHICON | X-ON in my Power supply?
Cheers Jezza
 
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I am trying to source the Toroidy transformers from Poland but it is very difficult as they only seem to ship to EU via online shop. I have another question will 35V caps be adequate for this supply as I would like to use this cap LGU1V223MELC - NICHICON | X-ON in my Power supply?
Cheers Jezza

You'll need to write to Toroidy re: shipment to Australia:
zamowienia@toroidy.pl
Hubert Gryczewski

Caps are fine

PS
my Aleph J is a standard build from the store, so is the power supply (dual, fast switching diodes X 8). Bias is quite high (4 amps total)
The Toroidy I have is 230V AC / 2 X 20V AC, 400VA. I get 25V DC rails loaded, with 240V AC mains
 
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Hello together,

I think I´m winning the idiot of the month award:

After building the Aleph J everything went fine. It only had 2 mV DC on its outputs and was dead quiet.
After listening to a few records, I connected my laptop. With this in line, I had an audible hum. After trying this and that I taped the laptops net-ground and connected it to 250V.
It immediately banged and now there’s a big hum on the right channel of the Aleph J.

It´s there if a source is connected and if not. The level of the hum can´t be regulated with a volume pot. If I connect it with music the hum is there, but music will be audible.

I can´t see damaged any parts.

What could have happened?

The laptop will work without the buzz, but on a battery supply only. If you want to use it as a source to play digital audio files AND have the laptop powered by its power supply, you’ll need an isolated DAC (USB isolation)

I’d assume there was a little arc-flash between the NIC metal shell and the cable you were using to ground the laptop???

Replace both input transistors on the affected board and then try again.

Taking into consideration that removing the PCB and then replacing the input transistors is a major pain, you should probably replace all transistors and a Zenner diode, and be done with it.

Good luck
 
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Up and running

After a very slow build prosess, my Aleph J is on the test bench.
Running 450mv bias at a little high supply voltage (24V)
The voltage will drop some once i get the 0,22mH coils hooked up later,

Temp at transistors is 58deg C and about 6-7deg C lower on the sinks.
I can prob thank the good thermal capability of the Keratherm® Red Insulators as well as 3,5mm screws instead of 3mm and 4mm thick copper washers covering the whole frontside of the transistors,
Screws and washers mounted with premnium thermal grease.

I tryed 500mv bias and the temperature on the transistors is still some degrees under 65C but i guess i will run it at 450mV for now.

The heatsinks are Birmingham Aleminium (300mm x 84mm x 100mm) runnig at 0.163 °C/W.

I guess they are the main obsticle for pushing more power thru the amp.

The transformers are 20V Ac 800Va, rectefied thru MURF860 diodes, first bank of capasitors are 6 X 10000Uf Elna (3 for + and 3 for - for each channel)
Next Capacitor bank is 16 x ROE EYH 3300uF (8 for + and 8 for - for each channel)

Voltage out is quite high (over 24V) but if i loose aprox 1-2 volt over the inductors i hope it will run cooler at the same or more bias.

Holton HPA-LSP-One Rev 5 - Loudspeaker Protection Board is doing security,
Still i have one thats faulty, need to look into that.

Will be testing at my main speakers next weekend.

Shared album - Per Glad - Google Photos

Thanx for all good advice and inspiration
 
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Hi there everyone. @alanhuth and I (who are assembling the noobs guide thread over here) finally put together our Mouser BOM cart with what we hope are all the non-DIYAudioStore parts for an Aleph J. If anyone spots any mistakes or poor parts choices, we'd be grateful for corrections!

Also, I already see that we didn't get the PSU filter caps I thought we were getting. I had meant to get these Nichicon 27,000 uf caps, but we seem to have ordered the 18,000 uf ones instead. Oops. I assume not worth the shipping to change 'em now?

PS Envious of the progress that @JMacII and @rhing are making!
 
Up and running part 2

After a very slow build prosess, my Aleph J is on the test bench.
Running 450mv bias at a little high supply voltage (24V)
The voltage will drop some once i get the 0,22mH coils hooked up later,

Temp at transistors is 58deg C and about 6-7deg C lower on the sinks.
I can prob thank the good thermal capability of the Keratherm® Red Insulators as well as 3,5mm screws instead of 3mm and 4mm thick copper washers covering the whole frontside of the transistors,
Screws and washers mounted with premnium thermal grease.

I tryed 500mv bias and the temperature on the transistors is still some degrees under 65C but i guess i will run it at 450mV for now.

The heatsinks are Birmingham Aleminium (300mm x 84mm x 100mm) runnig at 0.163 °C/W.

I guess they are the main obsticle for pushing more power thru the amp.

The transformers are 20V Ac 800Va, rectefied thru MURF860 diodes, first bank of capasitors are 6 X 10000Uf Elna (3 for + and 3 for - for each channel)
Next Capacitor bank is 16 x ROE EYH 3300uF (8 for + and 8 for - for each channel)

Voltage out is quite high (over 24V) but if i loose aprox 1-2 volt over the inductors i hope it will run cooler at the same or more bias.

Holton HPA-LSP-One Rev 5 - Loudspeaker Protection Board is doing security,
Still i have one thats faulty, need to look into that.

Will be testing at my main speakers next weekend.

Shared album - Per Glad - Google Photos

Thanx for all good advice and inspiration
 

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