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-   -   Aleph P current sources? (http://www.diyaudio.com/forums/pass-labs/5229-aleph-p-current-sources.html)

stefan 14th August 2002 08:46 AM

Aleph P current sources?
 
Hi all,
Can I use in Aleph P current sources with
bipolar transistors (i have a lot of them)?
Will this change the sound performance?
:confused:

wuffwaff 14th August 2002 01:48 PM

Hi Stefan,

yes you can. Wouldn´t know why not. As for sound differences it´s not so difficult to try both isn´t it.

I assume you´ll have to buy more fets than you need anyway;)

william

Nelson Pass 15th August 2002 08:47 PM

For all I know they will sound better. :)

stefan 16th August 2002 08:46 AM

Thanks, mr. Pass!
I'll try and if all is OK I'll post schematics here.

stefan 16th August 2002 10:30 PM

Simplified schematic - how will work?
 
2 Attachment(s)
Here is simplified schematics for Aleph P
with bipolar current sources.
I still didn't made it and I need your opinions.
Do you think this will work well?

Nelson Pass 17th August 2002 09:50 PM

Your input source is going to see some DC, so you might
consider caps for that. Also, some nice caps across the
Zeners will take out some noise. Maybe a few hundred
ohms in series with the transistor bases to keep them
from loading down the reference when they saturate.

Peter Daniel 17th August 2002 10:04 PM

How would it affects the circuit if feedback resistors R11 and R14 would be removed? I mean, is there a way to get rid off the input coupling caps?;)

stefan 19th August 2002 06:50 AM

I think that it's too dificult to make in this circuit.
In all cases input capacitors are simplest and safest way.

jan.didden 19th August 2002 06:58 AM

Quote:

Originally posted by Peter Daniel
How would it affects the circuit if feedback resistors R11 and R14 would be removed? I mean, is there a way to get rid off the input coupling caps?;)
I would try connecting R11 *after* C2, and R14 *after* C3. That would give you AC feedback only, but I would expect the circuit to auto-equillibrate with the input gates drifting to ground. Mr. Pass?

Jan Didden

Nelson Pass 19th August 2002 08:03 PM

The Gates have to be held at a positive potential or
the gain Mosfets will shut down, so some kind of DC
bias for them is required, or use a negative supply
rail instead of ground for your negative current
sources.


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