Aleph JoJo brothers by Sasha

Hi all... :)

With two Aleph J mono brothers coming to life, I was thinking to share my journey with you here. I have collected so much from DiyAudio and never showed anything. These two are my 10th or something-like-that DIY build of amps, preamps and loudspeakers ... but this time I decided to make the chassis first, because I wanted to avoid another neverending "plywood project".

Few months ago started with CAD design and made decision to make wooden enclosures with heatsinks on the back. Heat sinks are generous and will have a lot of free air outside and inside the box for propper cooling and installation of everything some more eventually, that's why monoblocks...

cad design.jpg

So, after few weekends in my workshop:

chassis finished.jpg

Test of VU meters with Variac:

lights on.jpg

For now boards are populated only with resistors and cleaned so I don't have problems with cleaning when I solder big caps and trimpots and other small stuff...

pcb resistors only.jpg

First installation on the heatsinks - all holes and screws OK, we can continue with assembly process...


Back side, cooling fins will have enough fresh air for good flow:

back side.jpg

Never forget Papa and The First Watt... :)

Aleph J logo.jpg
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Next is to build PSU blocks from 300 VA toroids and around 100 000 uF of capacitance. It will be CRC filtering. Voltage will stay around 24-25 V because I want to stay close to original schematic...

Input pair are Toshiba matched pairs from Diyaudio Store.

Then to test soft start with thermistor&relay and also speaker delay and DC protection...

To be continued... :)
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@ nicoch58

Yes, that would maybe be better, but it would destroy my conception at this moment. Heatsinks are 83 mm with thick base and long fins, coefficient for one channel is 0,15 cw so for 100 W of dissipation I will have only 15-20 degrees temp rise. Not critical...based on my previous experiences there will be no problems.

With original level of PapaBias I expect that amplifiers will be warm, but not hot.... :)
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Saturday in workshop...from big 2 mm thick plate of FR4 made PSU base for all energy is for precision. :)

CNC beer.jpg

Two pieces - mirrored, beacuse monoblock connectors are also mirrored for shorter cables...

PSU fr4.jpg

Panasonic ERX for R in filtering...feel sorry for them because they are now discontinued, but were soldered before so I will use them...

5xR.jpg will be OK...320VA, 2 x 20V toroids, small transformer for VU meter and speaker protector. 10 mF-10mF-0.1R-15 mF-15mF per rail. 100000 uF per chanel. Small heatsinks will carry block rectifiers 400V 50A...all wires down under...clean and safe and neat lookie...Epcos bottles glued in place with two drops of 300 C resistant silicone...tried this before and working perfectly...


Two times...


Tomorrow soldering of all connections and maybe first variac PSU turn on...
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