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mchapman 5th June 2006 07:29 AM

Aleph CS and interaction with PS
Hi all,

I have only just recently discovered the Pass labs forum and have been doing quite a bit of reading.

I am interested in building a low-power Aleph-X to drive 4 ohm, 94dB 1W/1m speakers, and for the most-part understand the circuit, but there are a few things I don't fully understand.

Firstly, regarding the CS:
I fully understand the non-aleph CCS of Zen 2 and I understand the output sensing and the feedback to the CS in the Aleph design.
Here are my questions:
- Does the Aleph CS disipate any more power (than the static CCS equivalent) or does the extra current (from current gain) end up entirely disipated in the load?
- I assume that under dynamic conditions, the Aleph CS draws non-constant current from the PS? If this is the case, the prevalence of CRC PS filtering makes me wonder if the PS dips significantly under load and if it might not be better to use a regulated supply. Does anyone have any experience to validate one way or another?


Mark Chapman.

Nelson Pass 5th June 2006 07:10 PM

The Aleph CS has a constant DC draw value, and varies on
an AC basis, so it has an average constant draw, but at any
instant it could typically be from 0 to twice the average value.

Assuming that the capacitance is adequate, we don't see the
supply dip under load.

mchapman 5th June 2006 08:46 PM

Thank you Mr. Pass!

Your response is much appreciated and enlightens the subject for me considerably. Like any good answer, it raises more questions, but I will study the circuit more before bothering anyonce here further.

Kind regards,


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