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Old 10th October 2013, 03:58 PM   #1
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Default Aleph 3: replacing aging capacitors or what else?

I have been using an Aleph 3 for more than 16 years (forget the exact number of years). Last year, I moved to a new home and replaced my damaged Thiel 1.5 speakers (bought together with Aleph 3). But I started to notice that there is dee-dee sound coming out from the tweeters and very low level of hum coming out from the mid-ranges of Tempo 25, even without connecting the DAC.

At first, I thought it is due to the polluted AC in my new home. Yes, I can hear low level hum coming from my neighbour even I do not switch on the amplifier. I connected a schaffner filter to the Aleph 3 and found no improvement. And then I suspected that there maybe DC current making the xformer hum. I incorporated a DC filter into the schaffner box. Yet, no change. Eventually, I suspect that the Aleph 3 capacitors maybe too old. So, I am going to replace them. If it solves the noise problem, fine. If not, I may need to build a F5 Turbo, mono maybe.

Here is my actions:

1. de-solder the caps from Aleph 3;
2. measure the caps with a dmm to see if the caps are really dry-out;
3. replace the caps.

I studied the schematic (I have never thought that Aleph is a direct-coupled amplifier). There are 8 x 22,000/25V panasonic caps. 6 x 220uF/16V panasonic caps and 1 x 0.001 compensation cap. The possible replacement (found in RS HongKong) are:

1. panasonic TS-HA 22,000/25 or 35V rated 105C;
2. epcos B41231 or B41303 22,000/40V;
3. Mundorf 22,000/25V or 40V ($$$)

4. 220uF can be replaced by panasonic FM 50V ( I have lot of them at home)
But, it seems that C101 is in the signal path (right?), is it a good idea to replace it with higher grade cap such as a bipolar one?

is it worth replacing R102 ~ R104 too?
Or, do you have any other suggestion?
Comments are welcomed
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Old 10th October 2013, 04:40 PM   #2
PKI is offline PKI  United States
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Panasonic are good. Use Elna RFS (silmik II) for 220uf.
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Old 10th October 2013, 04:54 PM   #3
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by B&W_arthur View Post
....

1. de-solder the caps from Aleph 3;
2. measure the caps with a dmm to see if the caps are really dry-out;
3. replace the caps.

I studied the schematic (I have never thought that Aleph is a direct-coupled amplifier). There are 8 x 22,000/25V panasonic caps. 6 x 220uF/16V panasonic caps and 1 x 0.001 compensation cap. The possible replacement (found in RS HongKong) are:

1. panasonic TS-HA 22,000/25 or 35V rated 105C;
2. epcos B41231 or B41303 22,000/40V;
3. Mundorf 22,000/25V or 40V ($$$)

4. 220uF can be replaced by panasonic FM 50V ( I have lot of them at home)
But, it seems that C101 is in the signal path (right?), is it a good idea to replace it with higher grade cap such as a bipolar one?

is it worth replacing R102 ~ R104 too?
Or, do you have any other suggestion?
Comments are welcomed
example of well put question-post , with proper info attached


so :

#1 - yup
#2 - ESR meter is what you need ; dried caps are usually good on DMM , but still dried ; so , just proceed to replacing them , without measuring
#3 - so , yup

regarding big caps - in my book epcos is Godzila amongst industrial caps , Mundorf decent , but no thanks , for usual money (so no better than Epcos)

small compensation caps - leave them in , as is

small 220uF caps - whatever* you have of decent industrial quality ( really *anything up to 470uF)

- put decent bypass cap ( my fave is polycarbonat , MKC) of 330n-1uF in parallel to C101,C102,C103
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Old 11th October 2013, 02:01 PM   #4
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Quote:
Originally Posted by PKI View Post
Panasonic are good. Use Elna RFS (silmik II) for 220uf.
Thank you PKI.

I went to a electronics parts shop this evening.
I found that Silmic II is too long to be used (see picture).
However, Silmic II can be used for the C101 because there is more space (another picture).

To make things simple, I will opt for Panasonic FM 220/50V.
It has exactly the same size as the one on the PCB.
Also, it has higher temperature rating: 105C.
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File Type: jpg 20131011_212444.jpg (361.9 KB, 246 views)
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Old 11th October 2013, 02:07 PM   #5
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If the Aleph 3 is similar to the Aleph 4 - I expect it is, then the 'lytic in the signal path makes a huge difference. I've used Silmic II in mine and it made a HUGE difference.
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Old 11th October 2013, 02:36 PM   #6
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Quote:
Originally Posted by Zen Mod View Post
example of well put question-post , with proper info attached


so :

#1 - yup
#2 - ESR meter is what you need ; dried caps are usually good on DMM , but still dried ; so , just proceed to replacing them , without measuring
#3 - so , yup

regarding big caps - in my book epcos is Godzila amongst industrial caps , Mundorf decent , but no thanks , for usual money (so no better than Epcos)

small compensation caps - leave them in , as is

small 220uF caps - whatever* you have of decent industrial quality ( really *anything up to 470uF)

- put decent bypass cap ( my fave is polycarbonat , MKC) of 330n-1uF in parallel to C101,C102,C103
Mod, thank you for the compliment.

I have not yet decide on the power caps because I have no idea about the dimension of the caps in the original Aleph. There is limited space.

I find some BC MKC 1u/100V sitting in my parts box.
However, I have never try them.
Mod, can you explain why you prefer MKC?
Because of its stable temperature coefficient?

I use Wima mkp most of the time and use MKS if large capacitance is need.
So, I have no idea about how MKC sounds. If possible, you may compare
MKC's performance to those caps in the picture.

Picture:
Top : all mkp - wima 0.1/100, Vishay ERO 1837 0.1/100, Rifa PHE426 0.1/250V, Wima 0.22/250V

Bottom: epcos 1u/63 MKT, wima 1u mks, BC MKC 1u/100V

Another question: C101 is on the signal feedback path, it needs bypass too?
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File Type: jpg 20131011_211751.jpg (459.1 KB, 235 views)

Last edited by B&W_arthur; 11th October 2013 at 02:44 PM. Reason: missing picture
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Old 11th October 2013, 02:41 PM   #7
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Quote:
Originally Posted by KatieandDad View Post
If the Aleph 3 is similar to the Aleph 4 - I expect it is, then the 'lytic in the signal path makes a huge difference. I've used Silmic II in mine and it made a HUGE difference.
Dad, thank you for sharing your experience.
It sounds encouraging.
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Old 11th October 2013, 02:48 PM   #8
AMV8 is offline AMV8  United Kingdom
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Hi
If you want to measure the ESR of your present capacitors before deciding to change them for new ones you can buy an ESR meter on ebay for $20. Just type in "ESR meter"
If you pay $25 the meter will also test mosfets and transistors and measure inductance and resistence.
I bought one a few months ago and it works very well and is accurate when checked against my old Fluke meter.
If the original capacitors were from a good manufacturer you may well find they are still good. I still use capacitors from BHC, ALS, Seimans, Phillips and Kendeil that are 20 -30 years old but the ESR and capacitance measures well and they sound ok.
Don
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Old 23rd October 2013, 02:32 PM   #9
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Thumbs up A quick update

Quote:
Originally Posted by KatieandDad View Post
If the Aleph 3 is similar to the Aleph 4 - I expect it is, then the 'lytic in the signal path makes a huge difference. I've used Silmic II in mine and it made a HUGE difference.



KatieandDad, I replaced the 2 caps with Elna Silmic II last night. Everything seem fine.
My first impression is GREAT!

Zen_mod, here are the changes made:

PSU 22,000 caps replaced by panasonic UP 22,000/35V
PSU bypass with BC MKC 1U
C101 replaced by Elna Silmic II 220/25V
C102 & C103 replaced by Panasonic FM 220/50V
C103 bypass with 0.33 mkp panasonic

Good news:
Now, the Aleph 3 no longer produces deezzzz sound from the speaker when turned on.
Before the present operation, the amp gives deezzz sound from the speaker even no source equipment or interconnect ties to it.

Bad news:

But, when an interconnect is plug into the amp, the deeezzz sound comes back even with switching on the DAC connected to it.

There is a ground loop. Right?

Another question: How to use the ESR meter?
I tested the old caps. The 220 caps only give me 190u or less.
The 22,000 caps give only less than 20,000.
However, they give very low ESR reading.

Last edited by B&W_arthur; 23rd October 2013 at 02:34 PM. Reason: add information
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Old 23rd October 2013, 02:41 PM   #10
Zen Mod is offline Zen Mod  Serbia
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ESR meter is having two probes - each of them goes to one cap terminal

be sure that both Aleph and preceding components are having NTC from audio gnd to safety gnd-ed case

that way you'll not have ground loops
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