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= 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. |