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Aleph J illustrated build guide
Aleph J illustrated build guide
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Old 1st November 2014, 09:22 PM   #1021
whaleman is offline whaleman  United States
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Quote:
Originally Posted by 51frankie View Post
Whaleaman,
How are you connected with Cathedral Speakers? They have a great web site. I am very interested in replacing my pre-amp and they have two options that I am interested in.
Have fun with your Aleph J. I built one this past Spring and am in the process of another. 6L6 is the MAN!
Thanks for your interest, I am responsible for it. Those preamps have been superseded by a current-feedback preamp that some very smart people here helped me design, look towards the end of the National Op Amp inflation thread, pics and all there. The Aleph J is intended to mate with it. Those Cathedral speakers are my brew, they do very well. PM if you got further questions.

Here is the progress so far on the J, added a pilot light in the front. Wow, that 10MM thick faceplate gave me a workout to drill.
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Last edited by whaleman; 1st November 2014 at 09:26 PM.
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Old 2nd November 2014, 01:52 AM   #1022
whaleman is offline whaleman  United States
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Sides on then the front. Then slid the bottom shelf on from the back to the front. Not a chance of it sliding down from the top once components were on. Then bottom cover with rubber feet. BTW, for those with Home Depot, the screws that hold down the transistors are M3 10MM in length. They are in the slide-out drawers with metric nuts and bolts. The washers are #8 1 inch diameter. This is a precisely cut chassis and well worth the money.
Had to stop here tonight...pics.
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Old 2nd November 2014, 03:22 AM   #1023
6L6 is offline 6L6  United States
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Aleph J illustrated build guide
I like the big caps with clamps -- where did you get them?
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Old 2nd November 2014, 09:00 PM   #1024
whaleman is offline whaleman  United States
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Originally Posted by 6L6 View Post
I like the big caps with clamps -- where did you get them?
Those are from Mouser, I will get you the part numbers is a bit.

Thought I'd be enjoying the amp by now. Here is where I left off. Finished the amp, got it all wired right. Good voltages.

Went to set BIAS, got one side done, went to the other. Then went to adjust offset, left channel 12 volts! Right channel OK, got it down to zero. Went back to left channel, it dialed down way passed zero and back up to -18 volts! This went on for a bit and now it is at full rail voltage, matter of fact just about anything there is reading positive rail voltage. Also went back to measure BIAS and there is nothing there, 0 Volts. This is only the left channel. Other channel is working great.

The lights on the amp are pretty though.
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Old 3rd November 2014, 02:25 AM   #1025
whaleman is offline whaleman  United States
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I found the start of my problems, I cut R4 when attaching wiring and did not notice it. Fixed now and I replaced Q2, Q3, Q4. But still getting pos rail voltage at the gate of Q1B and obviously at the outputs. BIAS is 0. Output transistors are cold. Warm on the other channel as they should. So I am thinking Q5 and Q6 are blown since they run off of the positive rail? Q1B runs off of the negative rail no? I have a couple spares.`
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Old 3rd November 2014, 05:19 AM   #1026
Zen Mod is online now Zen Mod  Serbia
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Aleph J illustrated build guide
recheck all solder joints

cut R4 couldn't result in blown outputs , as long you didn't connect load
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Old 4th November 2014, 03:27 AM   #1027
whaleman is offline whaleman  United States
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Originally Posted by Zen Mod View Post
recheck all solder joints

cut R4 couldn't result in blown outputs , as long you didn't connect load
Thanks, no load connected. So maybe safe. I could use a pair of Linear Systems LSJ74 if anyone has a pair to sell in the US.
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Old 5th November 2014, 12:55 AM   #1028
whaleman is offline whaleman  United States
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Originally Posted by 6L6 View Post
I like the big caps with clamps -- where did you get them?
These are from Mouser, yes they are nice. Click on the link for the part #:

Caps link

Clamp link

This picture tells it all. Everything works fine now, the offset pot was all the way in down to zero. Once backed out, voltage came down.

BIAS at .400 of a volt. Nice! Hook up later...
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Old 5th November 2014, 01:14 AM   #1029
6L6 is offline 6L6  United States
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Aleph J illustrated build guide
I was expecting the caps to be bigger than 35mm... Those would fit on the diyAudio PSU board...

Still, I like the clamps.
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Old 5th November 2014, 01:46 AM   #1030
whaleman is offline whaleman  United States
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Originally Posted by 6L6 View Post
I was expecting the caps to be bigger than 35mm... Those would fit on the diyAudio PSU board...

Still, I like the clamps.
Yes, they kind of make it look business like.

OK, this thing sounds as good as you'll said or better! Toll!

I do have very very faint hum in the right channel, power type hum, not the signal ground hum type. So I cleaned up the wiring up, but still.

You know, the annoying kind only hear it between songs.

Tell me where to look--not the obvious stuff, done that.
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