Aleph J illustrated build guide

[peppennino]

Very good idea to build two monoblocs with two different amp PCBs and alternately sharing one PSU and connectors

 

[peppennino]

Very excited: my NOS Toshiba arrived today in Italy!
Time to complete my BOM and begin the adventure

 

[davidjt]

6L6's recommendation for the AJ to follow up my ACA project worked out so well, now he's on my shoulder whispering "M2X, M2X......".

So, does anybody have a line on mono block chassis with adequate heat sinks?

Maybe I'll go with 2 diyAudio store 4U's, each containing an M2X and SissySIT board. Have to do some measuring and see if they would fit into my IKEA towel shelves/stereo rack.

2515 Aluminum Single radiator Enclosure Amplifier Chassis/ Preamp Case/ PSU Box | eBay ?

 

[RafaPolit]

That is actually a neat case! How did you perforate the back panel?

 

[aljordan]

I did what you are thinking about a while back but with an Aleph J and an M2. See this thread for details.

6L6's recommendation for the AJ to follow up my ACA project worked out so well, now he's on my shoulder whispering "M2X, M2X......".

So, does anybody have a line on mono block chassis with adequate heat sinks?

Maybe I'll go with 2 diyAudio store 4U's, each containing an M2X and SissySIT board. Have to do some measuring and see if they would fit into my IKEA towel shelves/stereo rack.

 

[Mazeppa]

That is a nice looking chassis.

Thanks for the lead, davidjt.

 

[peppennino]

Thanks for link. Isn't 23x15cm a bit small for AJ dissipation?

 

[peppennino]

If I build monoblocks with two 200VA transformers, is it a possible (and good) solution to build a PSU like that for each channel?



With those resistors (or smaller R value):



And those caps:



Thanks for help

 

[qwertyl]

If I build monoblocks with two 200VA transformers, is it a possible (and good) solution to build a PSU like that for each channel?

Yes, but better get 35V caps. Are those resistors wirewound? I normally use here Panasonic 3W metal film/oxide resistors. You can connect a few in parallel for higher power rating.

 

[darrr]

The original power supply has 4x0.47R/3W, which is about 0.12R / 12W. If you want only one resistor I would use it

 

[peppennino]

Thanks to both. I wrote "or smaller one" since 100mΩ 10W are hard to find...

 

[TungstenAudio]

The Kemet ALS40 series are excellent capacitors. You will need the 40V rating for an Aleph J power supply.

 

[darrr]

Thanks to both. I wrote "or smaller one" since 100mΩ 10W are hard to find...

So the best choice is 4x0.47R/3W like in oryginal

 

[Zen Mod]

40?

 

[peppennino]

I calculated around 23Vdc on rails. Am I wrong?
What is the problem with wirewound resistors?
I just found this:

The alternative is thick film with heatsink...

 

[Eric]

I have a modular external power supply I use with my Aleph-J, M2, and M4 amps. The power supply is arranged in CRC fashion, using 3 x 0R22 3w mills wire wound resistors on each rail. This works fine and they only get mildly warm. Just mount them in free air so they can cool a little. I would aim for no more than 0R1 total resistance between caps and go for about 10w total power rating - mine are 9w.

 

[Mazeppa]

Thanks for link. Isn't 23x15cm a bit small for AJ dissipation?

Yes, may be a bit small for AJ.
I confused the issue by going off topic, talking about M2X and SissySIT amps, and asking about mono block chassis for them.

 

[peppennino]

I have a modular external power supply I use with my Aleph-J, M2, and M4 amps. The power supply is arranged in CRC fashion, using 3 x 0R22 3w mills wire wound resistors on each rail. This works fine and they only get mildly warm. Just mount them in free air so they can cool a little. I would aim for no more than 0R1 total resistance between caps and go for about 10w total power rating - mine are 9w.

Many thanks, Eric

 

[Mazeppa]

I have a modular external power supply I use with my Aleph-J, M2, and M4 amps. The power supply is arranged in CRC fashion, using 3 x 0R22 3w mills wire wound resistors on each rail. This works fine and they only get mildly warm. Just mount them in free air so they can cool a little. I would aim for no more than 0R1 total resistance between caps and go for about 10w total power rating - mine are 9w.

An excellent approach, and in hindsight I wish I'd have gone that way.

B-u-u-t, I went with a 5U chassis intending to swap amp boards as time went on. Also seemed like a good idea, but now I don't want to muck with the AJ, lest I mess up its mojo with my sometimes clumsy electronics work.

Remember, I'm an electrician that can solder and if I run into trouble that requires an electronics man, I've put myself in deep merde.

Yes, I did have a spot of trouble getting the AJ going, and yes, the forum brothers got me through it.
However, that was dicey enough that I'm wanting to get a back up amp going before I go messing about in the 5U/AJ with anything like a 2nd set of boards, or raising the bias a tad, or bypassing C1, etc.

Nothing to it, but to do it.
I just need to get some chassis and PS components ordered and go to work instead of talking about it.
Then I fire up my system, get lost in well reproduced music and wonder why I want to change anything.

Great problem to have.

 

[qwertyl]

I calculated around 23Vdc on rails. Am I wrong?
What is the problem with wirewound resistors?
The alternative is thick film with heatsink...

25V caps should be Ok, but still I would use 35V caps to be on the safe side

Not sure if it matters here, but most wirewound resistors are inductive.
I see that Panasonic 3W resistors are NRND. What about Vishay/Dale 3W CPF resistors?