Gotta love Nelson Pass


SA/4e is nice!!!!

128x128jpainter236

One of Nelson's favourites it seems that he thinks highly of, was the Aleph L preamps, really different because it takes the best of both worlds and joins them together. 
It's a quality passive pre, but as the volume goes higher once it gets to 3 o'clock or higher it slowly turns into active pre for more gain if you need it for low gain poweramps or inefficient speakers. I've had searches out for a used one, but none of the owner ever sell them.

Nelson Pass
" I don't know why this invention didn't bring me fame
and fortune, but who can explain it.....
 At the 3 o’clock volume control position, the Aleph L offers a direct path from input to output.
The only component in the signal path is wire and switch contacts.
At positions below 3 o’clock, the volume control functions as a precision passive attenuator using discrete resistor ladders.
Above 3 o’clock, active gain is added to the output signal in 2 decibel increments, for amaximum of 10 dB.
As a result, you suffer the effects of active circuitry only when additional gain is necessary."

Cheers George

@georgehifi 

There was 2 versions of Aleph L preamps and only one of them works as you have described above. 

Versions distinguishable by how many wires go up tothe volume control – 6 wires = early version, more than 6 = later version.

   
Yeah the MkI was straight passive all the way, the MkII was passive all the way till 3 o’clock, after which it slowly became active.
Nelson introduced this MkII for very low gain amps like some of his, and very inefficient speakers <84db, that need more gain from the preamp.
But as he said you paid the penalty if used passed 3 o’clock because it’s now becomes an active preamp with added distortions/colouration’s.

Cheers George
@georgehifi 

I ended up with original First Watt B1 buffer preamp instead of the old and more expensive Aleph L preamp for a double price. Hope it was the right move, my speakers are 101db. Gonna get it tomorrow from the postman. Can't wait to check it out with my First Watt F2J power amp. 
I ended up with original First Watt B1 buffer preamp

No problem the B1 buffer is unity gain, which Nelson 1st designed to be a (no name), buffer for my passive "Lightspeed Attenuator" preamp so it could drive one or two very low input impedance amps of his which some of my Lightspeed owners had, this worked a treat for them.

Latter Nelson released it and called it the "B1 Buffer", and designed a diy around it on DiyAudio forums, and also I think a ready made retail unit First Watt B1 preamp.

Still to me if all is good between passive pre and the amp, no buffer is the best buffer whether it’s got gain or not.
And that’s why Nelson says "you suffer the effects of active circuitry only when additional gain is necessary" on the Aleph L, meaning passive sounds better on it up to 3 o’clock on the volume control after which the active buffer with gain comes in, then it’s not quite as good.

Cheers George