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Old 10th November 2011, 08:12 PM   #1
Dukja is offline Dukja  United States
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Default Aleph3 recap

I just got a Aleph 3 to push a very inefficient headphone (HE-6), so not much room effect in my sonic impression. Up to now I am very happy with the large soundstage and accurate focusing from the 3. However, I wish the mid/upper bass may be tighten up and has some more impact. Also, I wouldn't mind if the midrange get more body.

From what I read here, it seems replacing those 8x 22k caps may help (also consider these original caps really approach its age limit). I have some questions as a newbie here (although I have EE training and did some vintage amp recapping) and appreciate your help.

I opened up the case and found some MOSFET boards attached to the heatsinks have L shape solid wire connected to the PCB with 8 caps. I'd like to know the good procedure to separate them and replace the caps without damaging boards.

Also, I read people use caps with larger capacitance (>22k uF) as upgrade. What is the good value to use if I want to improve in the above mentioned aspect.

Thanks!
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Old 10th November 2011, 11:09 PM   #2
Dukja is offline Dukja  United States
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No one worked on their Pass Lab Aleph 3 (not the DIY ones)? or is it ?

I read a post from Nelson in 2009 claiming none of the 3 need recap yet. Will two more years change it?
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Old 10th November 2011, 11:17 PM   #3
Zen Mod is offline Zen Mod  Serbia
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hard to say without checking them with ESR meter

regarding other question(s) , well - I didn't worked on original Aleph
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Old 11th November 2011, 01:46 PM   #4
Dukja is offline Dukja  United States
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Default Hotter is worse?

Last night I have another listen with Aleph 3. I found out that when the amp was not fully warm up (may be first 1 hr), the sound actually was nicer. After the amp is totally heat up to about 120~130F. I found the high became thinner, midrange recessed, and bass became softer and weaker. So I wonder if this is the sign of any component showing their age? On the other hand, this could be my preamp. So, I'll need to start them at different time to test. Thanks for your insight!
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Old 14th November 2011, 06:09 AM   #5
Dukja is offline Dukja  United States
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OK, I had more listen with Aleph 3 at hot (~120 F) and moderate temperature (~100F) and could not get firm conclusion that hotter was worse again. So maybe that was just me being picky and play volume was not the same. I also take a good look at the internal of Aleph 3. It seems that I just have to desolder all the while L shape connections (16x) from the MOSFET boards in order to free the PSU board. Anyone could offer a better idea? Also, I couldn't find any internal photos of Pass Lab Aleph3 with Google. Is it OK to post some here for people to give suggestions? Or I am at the wrong place to ask such question? Thanks for any help!
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Old 14th November 2011, 06:58 AM   #6
Zen Mod is offline Zen Mod  Serbia
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post pics ;

or wait that Papa answer on your question
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Old 14th November 2011, 04:11 PM   #7
Dukja is offline Dukja  United States
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Thanks a lot for the reply. I'll post some photo when I get home and wait for Papa's help if such trivial thing ever catch his eye.
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Old 15th November 2011, 03:20 AM   #8
Dukja is offline Dukja  United States
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Here is the internal shot:
Click the image to open in full size.

Those L-shaped connecting wire (actually 14 of them) are the ones that I plan to desolder in order to get to the back side of those 22k caps. One thing strike me about Aleph 3 was how compact it has been designed. This "3D" construction make short signal path and use all surface and volume effectively. However, it seems to make fiddling inside a little bit hard (at least for a newbie like me).

Any good idea to replace those caps?

BTW, are those small electrolytic caps on the MOSFET boards the so-called coupling caps? I guess that it is also a good idea to replace those, right?

Thanks!

Last edited by Dukja; 15th November 2011 at 03:29 AM. Reason: Add more comments
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Old 15th November 2011, 03:34 AM   #9
imix500 is offline imix500  United States
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Is it just me or do a few of those caps look bulged?
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Old 15th November 2011, 03:41 AM   #10
Dukja is offline Dukja  United States
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I think it may be due to optical distortion since I took the shot at rather close distance.

Here is another one with slightly different angle and with more pixels to inspect.
Click the image to open in full size.

I try to feel the top of the cap and them seems to be rather flat to me. But on a second look the middle one at the bottom row does seem to be bulged if we use the plastic wrap around the top of the cap as a guide.

Any more trained eyes would help?

Thanks!
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