Aleph J illustrated build guide

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#4,161
There is a small bopp sound when powering up and louder when powering off. When connected to preamp "Bopp" becomes "swoap"in one channel when powering off. The "swoap" sound is really annoying and independent of preamp. Tested with B1K and B1.
 
#4,165
sov said:
There is a small bopp sound when powering up and louder when powering off. When connected to preamp "Bopp" becomes "swoap"in one channel when powering off. The "swoap" sound is really annoying and independent of preamp. Tested with B1K and B1.
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Not sure. I’m also running a B1 and only have the very slight shutoff bump. I’m a novice, and can’t really offer you much help, though your idea of solder reflow is where I’d start.
 
#4,166
After listening to my M2-x with Ishikawa inputs for almost a year I decided it was time to give my Aleph J some listening time again. I can’t say enough how much I love this amp! My M2 is amazing in it’s own right and has its merits, but I’ve fallen in love again with my J. There’s something about the way it handles the details in the upper frequency band that makes me stop and rewind a song to listen to a particular passage again. It works really well with my Korg B1 and system in general. I took it out of storage, let it warm up for 2 hours, the offset and bias were exactly as I’d left it. I’ve had a huge grin on my face all afternoon listening to this gem of an amp. So glad I brought it out of storage. As Zen Mod has put it, the cockroach has turned around and is smiling.
 
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#4,167
vlv81 said:
@pggriff

Speakers Worthy of Pass Amps?

Some examples of what people are using in here. Most are high ish efficiency examples but a couple of pages back someone mentioned some 86dB that they loved. Depending on your listening level that may be fine. I think 6l6 might have mentioned one or two of the Troels designs, possibly the DTQWT?
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Thanks vlv81 , I'll have a look at the DTQWT. My two ways are a Troels design , bookshelves that are moving to my computer desk after my next build.
 
#4,169
Ook. You made me realise I bought all the parts for a TQWT 2 years ago and haven't done anything since. I even got a really nice sheet of block bamboo for the cabinet and some black Richlite for the centre piece.

(I did use some of the Richlite for my HPA-1 clone, so all's not lost.)
 
#4,170
Don't seem to be able to adjust bias any longer

Listening to my Aleph J, seemed time for a tune-up and check over. Not doing anything wrong, just seemed to have lost some magic.

I was amazed to see offset at 4 mv one channel, 6 on the other. Bias from output to output .39 - .40. After checking tightness on outputs, I set offset on first channel close to 0, and checked bias. Just a tad lower. Turning bias pot, I'm unable to change bias.

Skipping over to other channel, same thing! Although on second channel, It is now setting on .26.

Time out, thinking I'm making stupid measurement mistake....not seeing it.

What did I fry or measure wrong?

Russellc
 
#4,171
You’ve got a bad solder joint somewhere. Where? No idea. It’s a DC couples amp so might be anywhere. Start poking and prodding at the PCB with a DMM in bias and offset and see if things change when you touch components or flex the PCB.
 
#4,174
Russellc said:
Ok. Once Again I get to show my own stupidity on inter web....it helps if you don't use offset pot to try to adjust bias, and bias pot to adjust offset.

You may return to your regular programing.

Russellc😀
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I can't imagine how ANYONE could ever do that... or hook up two sets of probes (one on bias and one on offset) with one DMM and turn and turn only to realize the probes were not connected to the meter... *cough* 😀
 
#4,175
ItsAllInMyHead said:
I can't imagine how ANYONE could ever do that... or hook up two sets of probes (one on bias and one on offset) with one DMM and turn and turn only to realize the probes were not connected to the meter... *cough* 😀
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Easy, turn offset pot thinking it's the bias pot. When I measured, bias down to .227......it was when I went to offset measurement and it was up to 52 mv it hit me...

I've reset it many times, but setting it, M2, (3) BA3, F5 and other odds and ends, I finally mixed up two pots.

Despite reading entire thread, and using two multimeters.

Amp works beautifully.

Russellc
 
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#4,177
Russellc said:
Easy, turn offset pot thinking it's the bias pot. When I measured, bias down to .227......it was when I went to offset measurement and it was up to 52 mv it hit me...

I've reset it many times, but setting it, M2, (3) BA3, F5 and other odds and ends, I finally mixed up two pots.

Despite reading entire thread, and using two multimeters.

Amp works beautifully.

Russellc
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Sorry... I was joking that I had done precisely the same thing and in addition was silly enough to also try to measure bias without having a set of leads hooked up to the DMM on another occasion. To everything turn, turn, turn.... with no result. That joke fell flat. 😀

Anyway - so glad you've got it sorted. Enjoy!
 
#4,180
6L6 said:
Ha! Didn’t see the “both channels” when I answered. Silly me.

You figured it out, awesome!
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Well, sort of yes, sort of no. Original "problem" was loss of "magic" I'm used to. Remember, when I first measured everything bias and offset was fine, as it is now. Amp is playing, but left side feels cool, other channel nice and warm. For a short few mins, that side was .50v and was warm. Is it possible I cooked the outputs BUT it still bias and offset normal, and music comes out?

Cold side 33 C and hot side mid low 40s C


Bias is .43 v, offset 1-2 mv right now, but sink is cool. This is on the device, btw.

Russellc
 
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