A Concise Guide to the Published Amplifier Circuits of Nelson Pass

phase reversal

As I age I need to ask for help from younger minds: is there a Nelson Pass design that leaves the final phase inversion to the user (reversing black and red speaker terminals)? I found no mention in this guide but I have this notion that there is one...BOZ maybe?
The one and only
Joined 2001
Paid Member
If I do that, I label the output terminals so that the user will connect the
positive of the speaker to the "red" and negative to the "black" and then
I tell them about it in the manual in case they are connecting something
else to the loudspeaker and need to know who is Ground.

Looks like it hasn't been updated for a while. Perhaps we are at the point where a Wiki guide to all the circuits with links to forum posts containing circuits of interest would be beneficial to all? I know I am curious about more than one circuit which has a thread running to hundreds of pages...
Joined 2002
Paid Member
Here is an interesting patient of Nelson's was it ever made into
a working amp?


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Newbie question.

Does this mean that you can take some `nice' semiconductor and cascode it with a monster hockey puck: some super delicate jfet/SIT/vfet and hang a great big high gain switching lump on the side and get all the nice character of the `audiophile' device with much bigger output?
Pass Aleph 1.2 circuit boards

It has been a couple of years since I have been on here due to operations and Hospital stuff, I was wondering if the following website is still reliable
for ordering circuit boards for Aleph amps and power supplies, I haven't decided what to build. I might do a set of powered speaker like the ones Nelson did a while back with multiple Aleph amps inside. I prefer active crossovers and sealed cabinets with DSP for bass extension. I can't find any current comments on the reliability and quality of the circuit boards and stuffing lists that come with them on this site. Anyone know anything?
Brian Burke
Sorry if this is a lame question; which of the FW power amps are easiest to build in terms of procuring components ? Assume that I have the cabinet and heat sinks all covered by buying a super chassis that could support all FW builds , my goal is to build a keeper i.e. to choose a topology and design that I can keep running without worrying about procuring exotic JFET/MOSFETs . Background to this question is I tried to embark upon the F6 build but I am finding it hard to procure output transistors so dropped the plan , I have no affinity for F6 and I am open to other FW designs that can output similar power.
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Joined 2009
Paid Member
Easiest to build, Amp Camp, JFET's and kits can be bought at the store (link at the top of the page).

The BA1, BA2, BA3 are very flexible, BA1 (with single ended output stage) is closest to Aleph J/J2 sound, while the BA3 (with complementary output stage - ideal for low impedance speakers) will take you more in the direction of the F5 sound.

You can add 'flavour' with the BA3 P3 preset, Iron Pre, H2 Harmonic Generator, B1 Preamp with Korg triode, or what ever takes you fancy.
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