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Old 6th February 2004, 03:04 AM   #1
diyAudio Member
Join Date: Sep 2001
Location: Salt Lake City
Default Aleph L Question

On the original Aleph L schematic (not Ver 1.2) there is a capacitor in each channel across the constant current source driver Q102, Q103... The caps are C102 and C103. The schematic calls for 680uf in this location but this cannot be correct.The space alloted on the PCB is way too small for a 680uf cap. Does anyone know what the actual value might be. Needless to say without the cap the circuit suffers from bad parasitic oscillation but adding a .01 cleans it right up and its all very stable. Anything much larger than this value causes massive high end roll off. Whats up here?

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Old 6th February 2004, 09:22 AM   #2
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Join Date: Sep 2002
Location: Göteborg
If I would risk a guess it is probably 680pF (at least it has the same size as c104 and c204 on the PCB). My guess would be that any film cap that fits on the pcb will do the job. When constructing a professional application it is often finacially beneficial to use the same value on as many components as possible.

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Old 6th February 2004, 11:30 AM   #3
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Join Date: Apr 2002
Location: Athens
Default 680pf cap

It is 680pf.
I had the same question when i was building my L and when i called Karen on the phone she confirmed it.

Is this phase one of Lumpy Gravy?
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Old 6th February 2004, 01:19 PM   #4
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Join Date: Sep 2001
Location: Salt Lake City
Thanks guys for your answers. I was thinking the same thing muself but wanted to see if anyone else had been stumped by that one. I'll pick up some more caps today.

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