Aleph-L preamp

"I don't know why this invention didn't bring me fame

and fortune, but who can explain it....." [Nelson Pass]

So let's change this a bit ;-)

The Aleph-L preamp is in contrast to the Aleph-P an unbalanced design, which may be favored when one only uses unbalanced sources, since an unbalanced design usually needs less parts.

The Aleph-L was available in at least 3 Versions, Aleph-L 1.0, 1.1 and 1.2, however the information presented on this page focuses in present on the last version (1.2) since it features a fascinating design consisting of an hybrid approach, where - depending on the position of the attenuator - the preamp works passively or actively with a direct connection of the input signal to output in between.

Schematics can be found in this [thread].

The original design used a 23 stepped attenuator which is quite expensive to build and is therefore often replaced by a digital one:

A pcb for the Aleph-L with the digital Aleph-P 1.0 volume control (64 stepped) is right [here].

Panos29 did also a nice [Aleph-L pcb] with the 64 stepped digital attenuator from the Aleph-P 1.0 using the ADC0804 A/D converter.

---