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Old 15th March 2004, 01:41 AM   #11
diyAudio Member
 
Join Date: May 2003
Location: Morton, Illinois
Default Correct

Dear Frank,
I think you are correct. Sorry about the mistake.
Is C18 68000pf? Looks like it to me. If so, it should be ok.

R15 should be increased, will help the bass response and add "flesh" to the voices. Might first try a large value, say 220k and see if it is ok or is too full. If to full, then back off the value till it satisfies your tastes.

Thanks for catching my mistake Frank.
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Old 15th March 2004, 01:52 AM   #12
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Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
Is C18 68000pf? Looks like it to me. If so, it should be ok.
68nanoF/630V it is.

Quote:
R15 should be increased, will help the bass response.
Agreed, it's at least worth a try to put a 100K load there.
5K6 is really pulling the lot down heavily.

Quote:
Thanks for catching my mistake Frank.
No problem, most everyone else overlooked it too.

The thing with these kits is that you can only change so much with these flaming PCBs.All along risking to overheat the traces as well...hate them things.
Long live P2P.

Cheers,
__________________
Frank
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Old 15th March 2004, 03:54 AM   #13
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Location: Wayne, West Virginia
Default C18

Hello!

You could even decrease C18 to 47nF or even lower and still get good bass response because at that junction (C18 and R10) you're getting a little positive feedback. I think like a bootstrap. So actually R10 (1 meg) appears larger than it is.

So as Frank said 68n (0.068uF) is plenty big.
And the top of R16 and R10 are not connected.

Wayne
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Old 15th March 2004, 05:01 PM   #14
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Join Date: Nov 2003
Location: Bristol
Wow!

Thanks for all the replies Guys! Sorry about the mis-type in the heading and the poor scan..

Some thoughts… The consensus seems to be that the coupling caps are ok into the impedances presented to them, thanks I did not factor this, I was looking at the caps in isolation.
That output load resistor does look small, think I will increase it significantly
I think I will also play with the PSU, some soft recovery diodes and replacing resistors with chokes ect.
I take the point about the cheap kit, you are right! I was attracted to it because it has some features that I like, relay input switching under micro processor control ect.

Is it possible the micro controller oscillator is affecting the sound? Should I try and shield it?

I thing scrapping the input coupling capacitor is a good idea, none of my sources seem to have a significant DC offset anyway.

The PCB is a pain, as is the limited space inside the case. This is really a last ditch attempt to salvage the unit before trying something else! P to P wiring of course!

Thanks again for the help!

Jim
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Old 15th March 2004, 05:20 PM   #15
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Location: Morton, Illinois
Default R15

R15 is the real problem, much too low. Creates a high pass filter and thus limits bass and extends sonically to the midrange sounding thin.
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Old 11th December 2004, 06:59 AM   #16
JohanH is offline JohanH  Netherlands
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Join Date: Dec 2003
Location: Noord Brabant
Default What's the status

Hello Jim,

Just picked up one of these as well and was wondering what you decided to do with it.

Thanks,
Johan
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