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Old 7th May 2013, 09:58 PM   #421
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Haha, yes it is nice, isn't it :-D Very elegant French made design. Unfortunatelly Audioanalyse went bankrupt many years ago, but there are still a few A9's around. It's bigger brother, the A90 has even been displayed in the NY museum of modern art. That one has twice the outputs and twice the amounth of cooling compaired to mine. I've totally restored this amp from scratch. The amp was a real mess when I got it, it had been maltreaded badly by its previous owner .

When I had got it, all the connectors were desintegrated, a power transformer was burned out because of a combination of a main capacitor that went fully short circuit + using the wrong fuses. So replaced both transformers by two nice Amplimo's that can deliver even more current at the same voltage, replaced all 20 mains capacitors, one channel was gone (outputs went short) so replaced them aswell (the A9 uses MJ15003/MJ15004 aswell) and almost every other electrolytic capacitor has been replaced also. So basicly I totally rebuild it, but with respect to its origin

Before (spot the differences ):
Click the image to open in full size.

All connectors desintegrated, capacitors gone:
Click the image to open in full size.

Without heatsinks:
Click the image to open in full size.

New caps (bought them via Diyaudio ):
Click the image to open in full size.

Resulting after restoration in:

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

It is like new again :-D. I love it's sound. Its sound stage is pretty much comparable to the Krell, although the Krell has more power. Also it's electrical design has some similarities with Krell. They are from the same era (my A9 is from 1989, just one year older than me )

(Sorry for going slightly offtopic )
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Old 8th May 2013, 01:25 AM   #422
spurlte is offline spurlte  United States
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Really a nice job there Kaplaars. I am free to play with the monster tomorrow. Time to start chopping wires and attach terminals. Finally
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Old 8th May 2013, 03:47 PM   #423
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Quote:
Originally Posted by Kaplaars View Post
...
New caps (bought them via Diyaudio ):
...


Quote:
Originally Posted by Kaplaars View Post
...
(Sorry for going slightly offtopic )
Thanks for going off-topic.
This is a nicely done restoration project!
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Old 8th May 2013, 04:12 PM   #424
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Thank you ! Hahaha, and offcourse thanks for the capacitors Dudaindc! They are perfect for this project, exactely the right size and capacitance, they fit like a glove.
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Last edited by Kaplaars; 8th May 2013 at 04:21 PM.
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Old 8th May 2013, 11:19 PM   #425
spurlte is offline spurlte  United States
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Default multiple capacitors

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Thank you ! Hahaha, and offcourse thanks for the capacitors Dudaindc! They are perfect for this project, exactely the right size and capacitance, they fit like a glove.
I always wondered about multiple capacitors versus Can Type capacitors.
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Old 9th May 2013, 09:59 AM   #426
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I always wondered about multiple capacitors versus Can Type capacitors.
Hi David,

There are a few advantages when using multiple capacitors in parallel. In contrast to resistors, the overall capacity doubles when putting two capacitors in parallel. A capacitor has of course a capacity, but also an internal resistance (ESR= equivalent series resistance), and behaves a little bit like a resistor (so they are not ideal). When putting a few capacitors in parallel the capacity increases, but the over all resistance decreases (just like a resistor, for example when putting lets say two resistors of 5 ohm in parallel, the over all resistance becomes 2.5 ohm). This is very favorable, because less resistance means less dissipation. Dissipation is something a capacitor does not like, because dissipation means heat, thus the internal fluids (dielectricum) will boil out faster because of higher internal temperatures. Therefore the dielectrical layer becomes thinner, and is more likely to go down. The capacitor will 'pop', because the electric layer becomes to thin. Therefore measuring capacitance at capacitors is not always a good indicator of it's condition. When the dielectric layer becomes thinner, the capacity will get higher. So one could think a capacitor is okay, while it is actually dying. A few posts back I've posted some info about measuring leakage current when I've started up my capacitors. This is a great test. If the leakage current is too large (and thus the ESR), you can throw the capacitors in the bin . This process of degrading capacitors happens in a lot of 'modern' equipment like LCD tv's were manufactures save on capacitors. These inferior capacitors can't cope with high temperatures, and go down very fast. I've repaired a few TV's by just changing the capacitors

Especially in switching PSU's (like the ones used in LCD's, or in modern HYPEX amps) you need capacitors with low ESR. Normal ones will go down pretty fast because they heat up to fast.

But it is not all sunshine, running multiple capacitors in parallel has also a disadvantage. Chances of failure will rise, because there are more capacitors and thus there is more chance of failure. Also the first capacitor in row gets the lionshare of current during power on. Typically this first capacitor goes down before the others (just like in my Audioanalyse). So you have to be sure you use the right fuses. In the previous pictures you can see what short circuit can do to a transformer. Yes, like Gordon Ramsay would say 'THAT ONE IS OVERCOOKED'.

So when wiring the KSA pay very much attention to fuse all the wires that carry a lot of current. I fused the primary side of both transformers, and all four secondary leads of the transformers. I've also fused the little transformer that powers my speaker protection circuit.
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Old 9th May 2013, 10:45 AM   #427
spurlte is offline spurlte  United States
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Default Fuses

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Hi David,

There are a few advantages when using multiple capacitors in parallel. In contrast to resistors, the overall capacity doubles when putting two capacitors in parallel. A capacitor has of course a capacity, but also an internal resistance (ESR= equivalent series resistance), and behaves a little bit like a resistor (so they are not ideal). When putting a few capacitors in parallel the capacity increases, but the over all resistance decreases (just like a resistor, for example when putting lets say two resistors of 5 ohm in parallel, the over all resistance becomes 2.5 ohm). This is very favorable, because less resistance means less dissipation. Dissipation is something a capacitor does not like, because dissipation means heat, thus the internal fluids (dielectricum) will boil out faster because of higher internal temperatures. Therefore the dielectrical layer becomes thinner, and is more likely to go down. The capacitor will 'pop', because the electric layer becomes to thin. Therefore measuring capacitance at capacitors is not always a good indicator of it's condition. When the dielectric layer becomes thinner, the capacity will get higher. So one could think a capacitor is okay, while it is actually dying. A few posts back I've posted some info about measuring leakage current when I've started up my capacitors. This is a great test. If the leakage current is too large (and thus the ESR), you can throw the capacitors in the bin . This process of degrading capacitors happens in a lot of 'modern' equipment like LCD tv's were manufactures save on capacitors. These inferior capacitors can't cope with high temperatures, and go down very fast. I've repaired a few TV's by just changing the capacitors

Especially in switching PSU's (like the ones used in LCD's, or in modern HYPEX amps) you need capacitors with low ESR. Normal ones will go down pretty fast because they heat up to fast.

But it is not all sunshine, running multiple capacitors in parallel has also a disadvantage. Chances of failure will rise, because there are more capacitors and thus there is more chance of failure. Also the first capacitor in row gets the lionshare of current during power on. Typically this first capacitor goes down before the others (just like in my Audioanalyse). So you have to be sure you use the right fuses. In the previous pictures you can see what short circuit can do to a transformer. Yes, like Gordon Ramsay would say 'THAT ONE IS OVERCOOKED'.

So when wiring the KSA pay very much attention to fuse all the wires that carry a lot of current. I fused the primary side of both transformers, and all four secondary leads of the transformers. I've also fused the little transformer that powers my speaker protection circuit.
Where there is the student, there is a teacher. Wonderful. Slow or fast fuses?
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Old 11th May 2013, 02:53 PM   #428
spurlte is offline spurlte  United States
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Default Getting There

Hang in there guys. It is slowing coming together and hopefully getting there. Hey! How about 20mins of Rare Earth"s "Get Ready?"
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Old 11th May 2013, 03:22 PM   #429
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Hi all , OK I have decided to order boards from JIMS Audi. Does anyone know of equivalents to the 2SK2013 and 2SJ313 FET's .
Thanks
Alan
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Old 11th May 2013, 03:47 PM   #430
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Hahaha Hmm what I would prefer are slow blow (SB) fuses at the primary side of the transformer (because of the large inrush current caused by the transformer) and fast blow (FB) at the secondairy side of the transformer.

By the way nice setup David! Finally the fun part can begin!

Alibear; the original FETS are still around. I've bought a couple via this forum. Via DIYaudio member Zhoufang. You could try to contact him if he has still a few around. See:

FS: Toshiba 2SK2013 / 2SJ313
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