Aleph L Question

Mark A. Gulbrandsen · 6th February 2004, 03:04 AM

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?

Mark

stappvargen · 6th February 2004, 09:22 AM

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.

/Niclas

Nickolas K. · 6th February 2004, 11:30 AM

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.

Nick

Mark A. Gulbrandsen · 6th February 2004, 01:19 PM

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.

Mark

6th February 2004, 03:04 AM	#1
Mark A. Gulbrandsen diyAudio Member Join Date: Sep 2001 Location: Salt Lake City	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? Mark

6th February 2004, 11:30 AM	#3
Nickolas K. diyAudio Member Join Date: Apr 2002 Location: Athens	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. Nick __________________ Is this phase one of Lumpy Gravy?

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6th February 2004, 09:22 AM	#2
stappvargen diyAudio Member 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. /Niclas

6th February 2004, 01:19 PM	#4
Mark A. Gulbrandsen diyAudio Member 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. Mark