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):
All connectors desintegrated, capacitors gone:
Without heatsinks:
New caps (bought them via Diyaudio):
Resulting after restoration in:
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)
.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
):An externally hosted image should be here but it was not working when we last tested it.
All connectors desintegrated, capacitors gone:
An externally hosted image should be here but it was not working when we last tested it.
Without heatsinks:
An externally hosted image should be here but it was not working when we last tested it.
New caps (bought them via Diyaudio
):An externally hosted image should be here but it was not working when we last tested it.
Resulting after restoration in:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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
)
...
New caps (bought them via Diyaudio
...
...
(Sorry for going slightly offtopic
Thanks for going off-topic.
This is a nicely done restoration project!
multiple capacitors
I always wondered about multiple capacitors versus Can Type capacitors.Thank you
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.
Fuses
Where there is the student, there is a teacher. Wonderful. Slow or fast fuses?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
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.
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:
http://www.diyaudio.com/forums/vendors-bazaar/169819-fs-toshiba-2sk2013-2sj313.html
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:
http://www.diyaudio.com/forums/vendors-bazaar/169819-fs-toshiba-2sk2013-2sj313.html
Heat Sinks
Just wanted you to know that your parts are hard a work. I received them a little banged up, but I truly appreciate your effort in helping succeed in building this beast. Thanks Stu
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Yes Kaplaars, Zhoufang has been on the run and missing for awhile--seems there are some complaint. But what do you think of this ebay offer from ebay from Israel? I got them albeit the shipping took forever, but them seem legit.Hahaha
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:
http://www.diyaudio.com/forums/vendors-bazaar/169819-fs-toshiba-2sk2013-2sj313.html
4X 2SJ313 2SK2013 Original Toshiba MOSFET 2 2 | eBay
JFETS
4X 2SJ313 2SK2013 Original Toshiba MOSFET 2 2 | eBay
I got mine from here and I hope they are good.
4X 2SJ313 2SK2013 Original Toshiba MOSFET 2 2 | eBay
Looking good Spurtle!
I picked my up fets here, if you don't want to go the ebay route:
http://www.diyaudio.com/forums/vendors-bazaar/232093-fs-tos-2sk2013-2sj313.html
Been on the transistor search, been able the find 2SA970 but not 2SC2240. Could MPSA42/92 or BC549/BC560 be used for Q1-Q4?
Btw..Jim's latest boards have the corrections that were discussed earlier in this thread.
I picked my up fets here, if you don't want to go the ebay route:
http://www.diyaudio.com/forums/vendors-bazaar/232093-fs-tos-2sk2013-2sj313.html
Been on the transistor search, been able the find 2SA970 but not 2SC2240. Could MPSA42/92 or BC549/BC560 be used for Q1-Q4?
Btw..Jim's latest boards have the corrections that were discussed earlier in this thread.
Aha Alweit! Yes, I've bought a pair of SJ74's from him in the past. These were 100% geniune. I think Alweit is a relieable source.
Hi all,I am awaiting arrival of boards from Jim's audio but I am confused over which circuit they actually use. There seems to be quite a few versions of the Mk 2. Can anyone post the circuit that Jim uses, so I can get myself sorted out with parts etc. so I can start building as soon as possible.
Thanks
Alan
Thanks
Alan
New PCBs.
I barked at Jim's Audio (Stanton), about Kaplaar's findings and it just makes me feel really good that he at least responsed to our inquiry. But to actually fix the problem, well I have to say, there were a bunch of people who at to say a lot about how Chineese products are ****. At least we have Jim's Audio who does have worth while products for us do-it-yourselfers. But he said he was thinking of putting together at a kit form of the ksa-100 MKII. I wonder if he ending up having as much problems of finding the all the right parts and backed off. But stil, three cheers for Jim's Audio. I am also building his Marantz 7c phono preamp with PSU PCBs. All I need now are the appropriate transformers. I think that we, as diyaudio'ers, should continue to bark at Jim's Audio, as this would demand quality merchandise for OUR efforts.
No
Hey, where you been? There is no anything on Jim's boards otherwise we would all have one. What you see is what you get. Sorry. I had to learn this too. Now. Why would you want more than what is available from the threads available here from here--diyaudio?
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