Plh

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#2
"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
 
#6
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.

Thanks!

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.
 
#9
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 😉


regards,
Thijs



PS
And a tip to the hat for Geoff of the class-A website and Rod. Cheers m8.
 
#10
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...
 
#13
Hi Nelson,

Even if I fully understand you saying I grew tired of telling the readers how wonderful it sounds. . . ., I do not want to see you saying so.

Nobody listening to you . . .?

Sadly, among other things, I know there are few people who praise that mine has wonderful or better than the other, just by nothing but writing ill of the other’s name. Your projects are sometimes things offered in such sacrifice. It means that yours are elegant and wonderful to their jealous minds.

You are different from them. I have never seen that you are comparing yours with others to the public. Nevertheless, I have seen that many audio diyers love your projects and build lot.

Regards
jH
 
#17
Hi Nelson,

On page 7 I read “ P1, R6 and C4 form a filter to take out power supply noise..." On the schematic (Fig. 8) it is C5?

Thank you very much for publishing the article. I was not expecting that for at least a couple of weeks. In fact, I expected that you'll publish only the simplified schematic, and a User manual. I also thought this was going to be another Firstwatt product...But you surprised all of us.

Shall we dare to think what's gonna be next? I wouldn't, not before I try this one🙂

Thank you!

Vix
 
#18
#19
I was just about to download the datasheet for the IRF244 and found it is now obsolete. I guess it may be still available for now.

http://ec.irf.com/v6/en/US/adirect/...ueryName=irf244

You think they would give a suggested replacement for idiot's like me who don't have a clue.
Click to expand...
You could probably use IRFP150, IRFP140, IRFP240, IRFP250, IRFP3710, IRFP054 too name a few. I dont think its very important, but you will get better specs with lower voltage rating and higher transconductance. Read the early papers on the Zen. Mr Pass writes a lot about the devices there.
If I could get some of them the IRFP044 or 054 would be my choice.
 
#20
Hi Lumanauw,

He is a bad teacher, and I am a bad student too. 😀
I'm too busy in enjoying F1/J-Low. No time to do THE homework.
You know? I used to threat my class mates do my homework.
This time you are, Lumanauweeeeeeeeeeee!
I will give you choco candies after you finish my homework.

Regards
jH
 
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