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Old 13th September 2013, 10:42 AM   #511
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Rotterdam ....that explains why you're a good guy Rudi !

Please have some kroketjes with Mama this weekend. Tip: don't talk about Ajax or Amsterdam in general.
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Old 13th September 2013, 06:56 PM   #512
nertia is offline nertia  Scotland
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I have finally got to a point where I could play music through the preamp.
I have it connected to a Hifimediy T2 amplifier and it sounds absolutely amazing. I was not expecting such an improvement in sound quality over the Alps pot I was using before.

I have a slight issue that when the volume is turned all the way down, I can still hear music playing very quietly through both speakers. The maximum resistance I measured was 5.7k at minimum volume.

When I was measuring the LDRs I attempted to correct the channel balance by soldering a 33k resistor in parallel with the adjustable LDR's output, and this allowed me approximately match the resistances over the first third of the volume pot's travel. Could this be the reason for the problem? It seems funny that it affects both speakers and not just the right channel.

Having said that, I will quite happily live with this if it cannot be fixed, the music sounds so much better.

Thanks again to Rudi and Uriah.

Mat
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Old 14th September 2013, 03:03 AM   #513
wineds is offline wineds  Australia
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nertia that is normal, LDR shunt cannot go to zero resistance like a real pot can
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Old 16th September 2013, 06:35 PM   #514
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Default issue

Ok gents. I put vcpre into thick cardboard box until I get real enclosure sorted.
Hooked it to cd and old arcam power amp to test. Music plays well for about 30 sec and after that.., click record to listen.
Cannot plug to myref amp yet cause doing some works on it so impossible to say if it is an amp issue.
Any ideas ?
Link to wav:
https://www.dropbox.com/s/nmsg4eqnb9w6xqr/amp%20rec.wav
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Old 17th September 2013, 10:54 AM   #515
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Now I can confirm same issue with another amplifier. Same weird gated sound appearing after approx 30 sec of power on.
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Old 17th September 2013, 11:11 AM   #516
atupi is online now atupi  Romania
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Check the voltage provided by micrel reg to the silonex optocouplers.
They are in the signal path. Maybe the micrel reg becomes hot or unstable and swings the voltage on output.
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Old 17th September 2013, 11:50 AM   #517
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Originally Posted by billyk View Post
Thanks Uriah!
It should never be a chore!! I for one am very grateful for your dedication to the hobby and to all of us around here. I really think that without you there would not be the many, many of us that now enjoy these !!!
You are running yours into a fetzilla if I'm right? How do you find it?
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Old 17th September 2013, 12:03 PM   #518
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I have lme49710 can I swap it with mcp6021 to check things ?
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Old 17th September 2013, 12:26 PM   #519
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If not please advise which legs to test
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Old 17th September 2013, 12:44 PM   #520
billyk is offline billyk  United States
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Originally Posted by ajst2duk View Post
You are running yours into a fetzilla if I'm right? How do you find it?
I wish I could tell you! It is still in the boxes awaiting construction. Oh! The frustration I feel! All those beautiful parts calling me. Anyway, life is very busy for me right now with work and family. I just have about enough time to visit with you folks here.
I hope to take some time off and have some just for me time, then I will get to building!!
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