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Old 6th March 2012, 04:43 PM   #11
generg is offline generg  Germany
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I had the same effect (Kristian boards) and did not find the reason ....... Also at that time I had no oscilloscope or sound card solution.....
At I did what Zen Mod said I simply kept the 10k in the signal path.......
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Old 6th March 2012, 04:48 PM   #12
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You will see clipping with the cheapest of oscilloscopes, even the $10 USB E-Bay specials.
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Old 6th March 2012, 05:49 PM   #13
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@AudioSan

can you give some details about the caps you used in your setup? I also want to use these boards, but I can`t find caps which will fit in pcb and are really good. to know where to buy will be good too ;-)

greetings Arno
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Old 6th March 2012, 06:07 PM   #14
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Old 6th March 2012, 06:19 PM   #15
generg is offline generg  Germany
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Quote:
Originally Posted by julius20 View Post
@AudioSan

can you give some details about the caps you used in your setup? I also want to use these boards, but I can`t find caps which will fit in pcb and are really good. to know where to buy will be good too ;-)

greetings Arno
Hi Arno,

I am not AudioSan...

my experience

Elna Silmic 50V/220uF bypassed by 100nF, that is the setup I returned to, after trying Obbligato, Blackgate, Erol, Cornel Dublier.... every cap had its own advantages, but overall I preferred the Silmics.....
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Old 6th March 2012, 07:25 PM   #16
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Quote:
Originally Posted by julius20 View Post
@AudioSan

can you give some details about the caps you used in your setup? I also want to use these boards, but I can`t find caps which will fit in pcb and are really good. to know where to buy will be good too ;-)

greetings Arno
what caps? the red ones? they are panasonic. i got them from mouser.
10uF 250V i think. its a long time ago
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Old 6th March 2012, 08:29 PM   #17
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at houser i couldn`t find it, but at digikey
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Old 12th March 2012, 12:03 PM   #18
Mfly is offline Mfly  Netherlands
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Well, thank you all for your input.

Unfortunately I was listening last night on the single ended inputs and after about 3 hours listening time the distortion appeared sometimes (even with the 10k resistors on the input).

It sounds like the sound is transformed into high frequency static. The 9610's also get quite hot (they are on small heatsinks). So this seems like oscillation from what I have read so far...

There are 680pF capacitors between the collector and emitter of the ZTX550's. Would adding 1nF capacitors between the base and collector as described here be a possible solution?:

preamplifier Pass X2.0/1

Or should I be buying a scope (which isn't a bad idea anyway) and do a more thorough analysis before I start adding components?
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Old 12th March 2012, 12:20 PM   #19
Zen Mod is offline Zen Mod  Serbia
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make this , connect it to output and crank it (volume ) all the way up (disconnect amp before )

and - buy a scope

if you have oscillation , LED will lit
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File Type: gif oscillation detector.GIF (2.5 KB, 211 views)
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Old 12th March 2012, 12:30 PM   #20
generg is offline generg  Germany
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I just remember.....

I put the same 680pF on the lower side in the same place to the ZTX450 and the osci was gone....
But I do not know if this had any disadvantages, can anybody comment?
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