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Old 19th December 2012, 11:40 PM   #4891
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George,

Seems to me then if it was not a fluctuating heat issue, that can happen if instaled inside pre or poweramps.
No, mine is a separated / stand alone unit. I posted it on this thread but couldn't find it.

That maybe you could have had some very strong dc offset or test bench type audio signal come into the input or output that has given your ldr's a bit of a hammering, this can change their resistance character and unmatch them.
Don't understand either, It has been playing for me after finished. I didn't touch it until couple days ago.

Am I right from your pictures that you have separtate left and right led volume controls?
A single Alps dual 100k pot.

And did you say they were 1Kohm?
There was only one 1k trimmer on the louder side, but I put another one on to test after I found the problem.

Time to get another matched set.
Oh, is there anyway I could try / test it before I talk to Uriah for a new set.
Thanks

Albert
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Old 20th December 2012, 12:05 AM   #4892
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It is possible that a dual 100k pot can have problems, but this would show in both channels equally, as a jump or lowering of both channels equally. But seeing you have a single dual pot and have wired it as I've shown in the Lightspeed Attenuator circuit, controlling both channels it takes the pot out of the equation because it's only happening on one of the channels.
Before installing another quad set of led/ldr's you could question your 1k trimmers they are far less costly to replace than the matched ldr's.
And btw you only need one trimmer, and it goes on the louder of the two channels.

Cheers George
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Last edited by georgehifi; 20th December 2012 at 12:09 AM.
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Old 20th December 2012, 12:09 AM   #4893
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Quote:
Originally Posted by georgehifi View Post
It is possible that the 100k pot can have problems, but this would show in both channels equally, as a jump or lowering of both channels euqally. But seeing you have a single dual pot and have wired it as I've shown in the Lightspeed Attenuator circuit, controlling both channels it takes the pot out of the equation because it's only happening on one of the channels.
Before installing another quad set of led/ldr's you could question your 1k trimmers they are far less costly to replace than the matched ldr's.
And btw you only need one trimmer, and it goes on the louder of the two channels.

Cheers George
thanks n I will change that trimmer asap. let U know.
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Old 20th December 2012, 03:27 PM   #4894
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George,

After replacing the 1k trimmer on the louder side, the case remains. I then move to question the Alp volume pot. I couldn't find the dual 100k, but there are 2 single turn Bourne 100k pot, blue in color, sitting on the bench. I make the conversion in no time and it works perfect on test, and I put it to the system and it sings flawlessly well. The only drawback is the pots are not log pots and it's too sensitive to make adjustment. I just have to turn 2 mm to the volume I need. Is there anyway I could make improvement with these pots, or I have to buy new ones ????
Thanks

Albert
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Old 20th December 2012, 07:26 PM   #4895
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RV24BF-10-15R1-A100K Alpha (Taiwan) | Mouser

And they probably have the singles as well.

Cheers George
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Old 20th December 2012, 07:27 PM   #4896
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Originally Posted by georgehifi View Post
RV24BF-10-15R1-A100K Alpha (Taiwan) | Mouser

And they probably have the singles as well.

Cheers George
big thanks
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Old 20th December 2012, 07:47 PM   #4897
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Originally Posted by georgehifi View Post
RV24BF-10-15R1-A100K Alpha (Taiwan) | Mouser

And they probably have the singles as well.

Cheers George
big thanks
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Old 21st December 2012, 04:01 PM   #4898
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George,

I brought 2 single A100k pots in local store to replace the Bourne and now I have more room to tune. Everything back to normal as before. I can recall I read somewhere that you mentioned I should put the volume half way when not in use, say 12 o'clock. I'd love to know more since my intention is to keep it on 24/7.
Thanks

Albert
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Last edited by albertli; 21st December 2012 at 04:11 PM. Reason: more information
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Old 21st December 2012, 08:34 PM   #4899
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Good to see you have got it going again, but you know you still have a damaged/unmatched set of ldr's, but by using separate l & R volume controls you have, band-aid fixed your problem.
Yes volume left at the half way posistion will turn on the led's at only half brightness when your not using it, and hence make them last twice as long.

Cheers George
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Old 21st December 2012, 08:54 PM   #4900
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Funny I just got an diyaudio pm/email from "shaker" I don't know if that's his forum name or not but he has not activated his return pm via this forum.
He asks
"Hello,
I wanted to ask you (being the designer), is there any way I can use unmatched resistors? How can I do it and get away with it. I can solve this issue in case I understood what to do, I can use controllers, may be this helps?
thanks"

Shaker by unmatched resistors I asume you mean unmated ldr's, to answer your question, you can get around it depending how unmatched they are by doing what Albertli did above by using separate l & r volume controls.

PS Just found out his forum name is "metal"
Cheers George
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Last edited by georgehifi; 21st December 2012 at 08:58 PM.
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