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Aleph J illustrated build guide
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Old 8th December 2019, 05:21 PM   #4351
Zen Mod is offline Zen Mod  Serbia
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Aleph J illustrated build guide
in case you purchase some other ones , you can always apply your own custom stickers , written Audio Grade or whatever on them

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Old 8th December 2019, 05:40 PM   #4352
elwood625 is offline elwood625  United States
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Thought so, I hate marketing, unless of course I'm doing it to sell someone something...
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Old 8th December 2019, 05:46 PM   #4353
TungstenAudio is offline TungstenAudio  United States
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The Nichicon FW series capacitors are great for power supplies. Not too expensive, either. I also use the KG and KS series for snap-in connections.
When I'm using a large number of caps for bulk storage, I tend to use Cornell Dublier SLPX series with 50V rating. They are designed specifically for PSU use and can handle a larger amount of ripple current.

Last edited by TungstenAudio; 8th December 2019 at 05:49 PM.
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Old 8th December 2019, 06:04 PM   #4354
elwood625 is offline elwood625  United States
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TungstenAudio -
Thank you for the info, I have a set of 8 22,000 25v 35mm diameter caps for the Aelph, I'll save the FW's for a phono preamp power supply.
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Old Yesterday, 05:22 AM   #4355
Pavo is offline Pavo
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Well I'm still fighting this hum and offset instability in the right channel. I'm too much of a newby to know if they are related. I've had the board off the heatsinks multiple times to look for any grounding problem and cannot find one. I've checked every connector multiple times for a short to the chassis and even replaced the Keratherm. Bias remains relatively stable. The offset starts at 150mv + when I first power up the amp and then comes down. It jumps around a lot even when it comes down closer to 0. When I short the RCA the hum decreases drastically and the offset jumps up to 250mv. Any suggestions on what to look for next? Is this likely a ground loop I'm missing or is this a component issue or oscillation?
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Old Yesterday, 01:35 PM   #4356
ItsAllInMyHead is offline ItsAllInMyHead  United States
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Quote:
Originally Posted by Pavo View Post
When I short the RCA the hum decreases drastically and the offset jumps up to 250mv. Any suggestions on what to look for next?
I'd focus on eliminating potential for cold joints or other easier to solve issues prior to looking for bad components as a result of firing up the amp with one rail. I don't have the expertise to help diagnose that. Others may chime in and know instantly if that could have caused an issue that ties to what you're seeing in your symptoms and measurements. The fact that you had no hum for quite some time after the issue leads me to believe that's not the root cause, but odd things happen. Generally, symptoms that appear over time with no other root cause - tend to be related to cold/bad joints or things changing due to heating / cooling / loosening / wiggling etc.

When you're experiencing the hum before you short the input, do you have anything hooked to the inputs (pre-amp or interconnects)? If no, move on. If yes, disconnect everything, and see if the hum stays the same. In your first post you said, "If i ground the input it quiets but does not go away." Did you mean short the input? If you meant ground, how did you ground it?

Grounding schemes are heavily discussed. I can only tell you what has worked well for me - that is also supported by some people I trust. I am not an expert on this subject. Consistent and intermittent hum seems to be a PITA to diagnose, so I try to take all preventative measures. 3 things below that I'd do if I were in front of your amp. I'd look at the right channel first, but double check the left too.

1) Simple visual check - Take a look at the inputs and see if they are isolated from the chassis. The first picture you attached just barely shows the input wiring, and I can't fully see how the jacks are attached to the chassis. Either way, if there were isolation washers or sleeves included, make sure they're in properly. Based on your discretion and what you find, you can do a check for continuity from the jack to the chassis later.

2) Wiggle check - The GND wires to the input jacks look like they have insulation melted around the joint or heatshrink covering them. I can't tell. Try wiggling the gnd wire and the jack. See if that changes the hum. If it does, you know where to begin. Does the hum change when you touch the metal on the jack with a bare finger? With and without shorting plugs?

3) Quick solder touch up / continuity check / tidy - If the GND wiring doesn't look great to your eyes, perhaps clean up those joints just for insurance. Start with the right channel. While the gnd wire is separated from the jack, you can do a definitive check for continuity to the chassis. If it the jack shows continuity to the chassis - look at isolation. Again, it's not strictly necessary, but I do mine that way. You could also put a little tighter twist on the input wiring. It looks like you have the length. The tighter twist likely won't solve the hum, but it may make you feel a bit better.

If you are so inclined, you could de-solder the In+ from the jack also and twist the gnd and In+ together. This shorts the input and removes the input jack/chassis isolation as a potential root cause. If that solves the issue, then ... see step 1. You can also see if you can get your DC offset to stabilize under this condition.

That's the easy stuff that should take under an hour (without the DC offset check and waiting for thermal stability). It may even work.
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Old Yesterday, 03:10 PM   #4357
Ben Mah is online now Ben Mah  Canada
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Aleph J illustrated build guide
Quote:
Originally Posted by Pavo View Post
What I'm getting now is a very loud hum out of the right channel only. I'll call this one "hum 2." The amp works still, just much louder than it ever was and seemingly NOTHING was changed to make it start.
Did you try ItsAllInMyHead's suggestion:


Quote:
Originally Posted by ItsAllInMyHead View Post
5) You can try running your AC mains wiring between the internal chassis plate and the bottom plate and running all the primary wiring closer to the front
Your AC line is right next to your right channel - not a good thing for low noise. If you haven't done it yet, move your AC line to the middle of the chassis. There is room between your transformer and power supply pcb to place your connection block and thermistors.
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Old Yesterday, 07:05 PM   #4358
theRog is offline theRog  Switzerland
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Pavo,

have you tried moving the dc power cabling and the signal cabling around?
If that changes the amount of hum try this:

tie the dc power cables and the signal cables together by using zipties.
this way there is no 'ground' loop for the transformers stray field anymore... I have had this problem and this was the solution ;-)

Cheers,
Roger
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Old Yesterday, 08:56 PM   #4359
Mazeppa is offline Mazeppa  United States
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Aleph J illustrated build guide
Quote:
Originally Posted by Ben Mah View Post
Did you try ItsAllInMyHead's suggestion:

Your AC line is right next to your right channel - not a good thing for low noise. If you haven't done it yet, move your AC line to the middle of the chassis. There is room between your transformer and power supply pcb to place your connection block and thermistors.
ItsNotAllInHisHead, those are very good suggestions.

Highly recommended to physically rearrange as stated by Ben Mah.
Always distance/shield supply AC wiring and equipment from DC power, signal input and output.
Remember to route AC supply wiring to transformer between bottom cover plate and preforated mounting plate as mentioned earlier.
Check out some of the pics in this thread: diyAudio Power Supply Circuit Board v3 illustrated build guide

Hang in there, once you get it sorted, you'll have one of the best amplifiers around.
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