Aleph J illustrated build guide

[brianco]

...............not extinct, just dozy

 

[punkzter]

Is there a way to add a mono/stereo switch to this amp? I'm looking into building this amp or something like it, but want to maintain that capability that my current receiver has. It really helps out when listening to mono records.

Thanks!

~Brad

 

[Zen Mod]

best to implement mono switching in low level box - where selector and attenuator are situated

 

[roger57]

Parts Trickling In...

Just getting things together for the Aleph J build. Received heat sinks today from "heatsinksusa". It's been a while since I've received this level of service and quality. Precision extruding and cutting to length. Now off to the anodizer...will keep posting with progress...

 

[topofthedial]

It works!

I finally finished up my amp this weekend, adjusted bias and offset, and plugged it in over lunchtime to check it out. It produces sound, and that sound is good!

That said, I am getting some minor hum from the amp. I couldn't really notice it while music was playing, but it's audible when I get close to the speaker and music isn't playing. I've attached a picture of the inside of the amp. Any ideas?

Many, many thanks to Jim for his help, hooking me up with the final few parts I needed, and the awesome cup of coffee!

 

[BobEllis]

Is the hum the same from both channels? Try moving the terminal strip with the CL60s on it further from the amp board.

 

[Zen Mod]

according to pic , I think you messed something with doubling those PSU boards

 

[6L6]

Maybe. Perhaps a few more jumpers can be placed on the PSU board ground links.

But I think it's just to-long wires... As he lives just a few miles from my house, I'm thinking I can take a look at it soon.

 

[bnorrish]

Tough to tell in the picture. Is the PSU ground touching the perfboard where it joins the CL60 with the mains ground that is bolted to the perf board?

 

[Bones13]

There is a green wire from the grounding bolt to the ground pad on the cap board. I could trace it after blowing up the pic some. (Easily done on the ipad)

I'm in the "wires too long" camp, and the AC strip too close.

 

[topofthedial]

Thanks everyone. I'll try shortening some wires and moving the terminal strip away from the amp board later today. I will report back!

 

[Audio Zen]

Put my order into to Mouser for the BOM. For those interested in a quick purchase, here it is:

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=f98bd1dcde

Stock BOM but with 25 turn trim pots (used the 2nd option).

Thanks Jim, looking forward to another great build

 

[mk57]

Thanks Neville what a great time saver!!

 

[mk57]

What is the best way to set up the bias pot for the Jfets

 

[6L6]

For the input jfets? Don't use a pot, just a 1K resistor.

 

[mk57]

I put the 1k there and fired it up everything stable but that 1k resistor sent a smoke signal and the input jfets were red hot. What next?

 

[6L6]

???

Well-lit, in-focus photos please. Something is very wrong.

 

[mk57]

[/IMG]

An externally hosted image should be here but it was not working when we last tested it.

 

[Zen Mod]

you can put even smaller pics

they will be useful in same amount as these

 

[BobEllis]

I bet its a iPhone shot. I keep downloading thumbnails from Icloud instead of the real picture.