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Nelson Pass 11th September 2005 03:43 AM

There is a .pdf draft copy of the PLH amplifier article
in the folder


audio3000 11th September 2005 05:23 AM

"My own approach is to make the signal path as simple as possible, work to lower the distortion
of that basic circuit before feedback is applied, and then apply minimal (or no) feedback, largely
in agreement with the comments in Linsley-Hood’s original article. The result is not always the
best objective measurements, but the sound is often interesting."

That's my diy principle too. I was inspired by your Zen amp and designed an MOSFET based amp along that line. It sounds very relax. Simple circuit suffers less from the noise/distortion generated by the extra circuits. Thus more music details can be heard. And I don't need lot of power to be satisfied..:)

Nice to have such a amplifer guru and mentor like you around and more importantly willing to contribute to the diyer community.

Many thanks, Kam

Magura 11th September 2005 07:58 AM

Very interesting.

I was missing a SOX or a ZV7 in the performance chart though, it could have been interesting.

Magura :)

Zen Mod 11th September 2005 11:25 AM

1.8M on

380KB on

hehe-important for us 56K users :D

Zen Mod 11th September 2005 11:34 AM


570KB F1 srvman is still at

paulb 11th September 2005 02:34 PM

I've been in the process of building a Class-A amp for many years now. I have a separate prototype (ugly) power supply built. I have a chassis, and heatsink arrangement. So which should I build? Nelson, you haven't made it any easier by adding the PLH into the mix.


One thing about this hobby is I'll never run out of things to build. Maybe I'll build prototype versions of all of them. And a Mini-A. Of course, I'll need better speakers to evaluate them properly.

plovati 11th September 2005 06:02 PM

...for honored myself dedicating this new amp to my name ;-).
But..where are the lights?

Circlomanen 11th September 2005 06:12 PM

In figure 5, the jlh with diff input I see a SUSY version. Just add a phase splitter and an output stage to the other side of the diff!:D

tschrama 11th September 2005 09:00 PM

A Pass-JLH article... you cannot image my excitement... read it at once.. Another great article by the one-and-only .. :) Thanks Nelson! I'm gonna read it many times, just like JLH's origial. Very , very interesting, especially the outtro ... allways like your way you look at these things, great inspiration..

Well done ;)


And a tip to the hat for Geoff of the class-A website and Rod. Cheers m8.

Blues 12th September 2005 12:10 AM

I enjoyed the read with a hot cup of coffee early today. The comparisons with the other amps was very interesting. You can see the Zenv4's excellent design by being steady across the board normalized or otherwise. Its voltage regulator and the Aleph CCS probably playing a big part. The PLH showing less distortion at lower power while the JLH is the opposite. Could this be because the PLH has 2 pairs of output stage? As per my read it looks like Fig.11 was the one tested. Did the JLH tested just had one pair of output stage? The Zen while having more distortion obviously is of the pleasant to the ears kind as noted by all the hundreds of DIYers who built it.

This recent article of NP brings into my consciousness the classic designs like the JLH and its designer. It's a nice feeling to know audio history and learn from it. Thanks Nelson! More please...

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