Classic Aleph Amplifier for Modern UMS Chassis Builder's Thread

[pinholer]

Measure the resistance between top plate and bottom plate.

 

[dantwomey]

Toroid mounting getting hot ...

 

[dantwomey]

Measure the resistance between top plate and bottom plate.

Currently, the resistance should be zero.

 

[pinholer]

If resistance is infinite, then there is no loop. If resistance is zero, it's inconclusive.

 

[poseidonsvoice]

Like I said, in my previous post:

The concern is, if you were to test with a DMM, you could have a direct connection (ie. Short, 0 ohms on DMM) between the top bolt of one toroid across to the bottom bolt of next toroid. That would confirm a shorted turn.

You don’t want to measure anything close to 0 ohms.

Best,
Anand.

 

[dantwomey]

Nylon Flat Washer,

 

[rhthatcher]

@Toadroller - You nailed it! The Phaeton & Continental both have the W12.

Should I make a board called the Flat6? Spring will soon be here, and that's when Flat6 season starts...

@dantwomey - Have you put the amp on test or real speakers yet?

 

[dantwomey]

Looks like a nylon washer and some other insulation may rectify this issue.

 

[dantwomey]

Randy,

It's looks like I'll have to deal with the shorted turn issue first.

Regards,
Dan

 

[poseidonsvoice]

Also see if you can make the hole a little bigger so that the thread on the center bolt itself is not touching the aluminum plate. I thought about replacing the center thread out of something like nylon but the problem is integrity/strength.

Please post your solution because you already have invested time on that aluminum plate.

Best,
Anand.

 

[pinholer]

With two bolts the resistance could be zero without a loop formed if only one bolt was shorting between the top and bottom plates. However, that is probably not the case, but it is possible.

tLike I said, in my previous post:



You don’t want to measure anything close to 0 ohms.

Best,
Anand.

 

[dantwomey]

Aluminum plate is super hot so I do have a shorted turn. Or, the metal bases of my bride rectifiers are transferring heat to the plate.

Regards,
Dan

 

[dantwomey]

I'm going to order some nylon stuff from amazon to see if it makes a difference. Thanks to all for pointing out this oversight on my part. I'm always willing to learn.

Regards,
Dan

 

[rhthatcher]

Randall, do you think a 5U400 case would handle your main board with all 4 output mosfet pairs filled and a higher single trafo DC PSU, like 30 to 40 Volts?

https://www.diyaudio.com/community/threads/store-heat-sinks-thermal-numbers.392902/
I looked at Nelson's post here. Looks like a 5U400 is good for 158W per heatsink. Call it ~300W dissipation per chassis.

Back to post #1 on this thread there's this:

5U/400 could take the heat of an Aleph 60 or Aleph 5 Stereo / Dual Mono.
Of course the Aleph 2 Mono works nicely in a 5U/400, too. That's been proven a few times. I built a pair, and a few others have, too.

 

[poseidonsvoice]

Aluminum plate is super hot so I do have a shorted turn. Or, the metal bases of my bride rectifiers are transferring heat to the plate.

Regards,
Dan

Well likely a little of both, but the shorted turn issue definitely should be addressed for the longevity of your transformers. A shorted turn will kill the transformers over time due to a breakdown in the insulation. If there were a safety thermal fuse embedded in the winding of the transformer itself, then that will fail. The transformer usually has to be replaced.

Your bridge rectifiers will get “warm”, but that’s a truth with regards to Class A amps in high bias as all Aleph designs are. We enjoy the healthy warmth…But not failing transformers since that compromises the whole design!

Let us know your solution when its ready 🙏

Best,
Anand.

 

[dantwomey]

Ordered some ABS sheet. Will start fabricating when it arrives.

1/8" ABS

 

[poseidonsvoice]

Interesting idea. Where will you place the rectifiers since they dissipate heat in a full Class A design (2.2A bias in each channel of Aleph 30 I believe)? Front panel? Steel mounting plate?

Best,
Anand.

 

[dantwomey]

To answer Randy's question. I have a pair of these sitting in my basement waiting for the 'right' amplifier.

EKTA 25s

I dabble in speaker building as well.

Regards,
Dan

 

[poseidonsvoice]

Beautiful looking speaker. Looks like fun!

Best,
Anand.

 

[dantwomey]

Interesting idea. Where will you place the rectifiers?

Best,
Anand.

I'm going to put some plastic under the aluminum plate. Insulate the bolt and make some washers from the same material.

That should break the circuit. I'm guessing that if I get infinite resistance between the two nuts after that I should be good.
Right now it should obvious that the resistance between the two nuts is zero.

Regards,
Dan