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Geoff 6th July 2001 10:37 AM

Due to popular demand, I am in the process of adding the Hiraga Class-A designs to my website. I have been able to obtain a copy of the three articles relating to 'The Monster' and these are currently being translated. I would also like to include the full article for the 20W design, instead of just the schematics. Can anyone please help me out with a copy of this article (l'Audiophile No. 15)?

Thanks in anticipation,


Geoff 10th July 2001 12:37 AM

Thanks to jam I have received a copy of the most recent (April 1980) Hiraga 20W Class-A article. After translation,it will be posted on my website.

Jean Hiraga describes the circuit in this article as the definitive version. The schematic has some component values that are different from those on the schematics that I have seen posted elsewhere on the web. Prospective builders might wish to note this and to see the latest schematic which I will put on my website in the next day or so.

Thanks again jam for arranging for the supply of the article and thanks to Scott Nixon for sending it.


phil 10th July 2001 06:27 PM

Geoff, the new additions to the web site are very good. I look in often. Still progressing with my JLH.

drakonis 11th July 2001 09:13 PM

Hiraga's transistors....

I've been 'playing' with this little amp. and transistor substitution doesn't seems to be that critical while you select them appropiately for their function and ratings. Freq. response is very good since it appears to be a kind of current amplifier...

Anyway, you have started a nice site, please keep on going with it, it is a very interesting and refreshing one!!!...

....mmmmhhh!, I would like to suggest you to include the John Curl JC3 class A amplifier, I still have to build one, but from simulating it, it has an excellent response and easy adjustments with conventional transistors (even you can make that amp shorter by using FETs at the output stage)...


jam 11th July 2001 10:15 PM

More Class A Schematics!

It seem's that you have started something here.


[Edited by jam on 07-11-2001 at 07:20 PM]

tschrama 11th July 2001 10:28 PM

Geoff.... keep up the good work..
excelent webside!!!

what's that about a john curl class a amp ?? found nothing on the web except that the Mark Lev ML-2 was similar??



tvi 12th July 2001 04:42 PM

Very much looking forward to reading the original L'Audiophile articles.

You might be interested in this site recently,
<a href="">~stigerik/html/audiosys.htm</a>.

Check his Hiraga page, the schematic is a little different again, he implies he copied the schematic from an original unit purchased second hand.

He also thinks its single ended Class A?

His "Tangen MPA-30" looks interesting.

<font size = "+1" face = "fantasy">James</font>
<font size="-2" face = "cursive" >Recently retrograded to Opera 5.11 from 5.12</font></center>

Geoff 12th July 2001 06:00 PM


Thanks for the link, though I had seen this site before. As you say, the schematic posted for the Hiraga seems to be another variation. I think I will stick with the circuit that was published as the final (or definitive, it depends how you translate it) version in l'Audiophile.

If anyone reading this post speaks French, could they please help me out with a translation of the word
'appairage' as I have been unable to find this in any web-based dictionary. The context is 'Neanmoins, nous avons juge preferable d'effectuer un appairage' (please excuse the lack of accents).

There are also a number of technical terms that don't appear in the dictionaries I have access to. Some I can make an educated guess at, but others are a little more obscure. If anyone can help me out by translating a few of these terms, I would be glad to hear from them.


drakonis 12th July 2001 07:08 PM

JC-3 Amplifier....


This is the only link that I have for this amplifier:

As I said, I have to build one pair.... so far I just have it simulated and looks good, also, just for the fun of it, I simulated this same amplifier but using FETs just after the VAS transistors and, again, displayed results were promising besides of eliminating some silicon....

The reason I had about suggesting Geoff to include this little amp too is that so far his site could become one of the only occidental web sites to display class A non-NP amplifiers in just one place for DIY.

Of course, I believe, we should help by really building what we suggest if he decides to include a particular piece in such a way that his web site happens to have real value and it doesn't become just other compilation of the same non-built circuits that pollutes the internet... =)


Geoff 12th July 2001 08:04 PM


I do not intend to include information on my site that is available elsewhere on the web for the very reasons you mention.

My aim is to provide comprehensive information about a few well-respected designs and to include, where possible, the original articles when these are not been published elsewhere on the web. A schematic is all very well, but I like to read about the designer's intentions, his thought processes, what compromises he had to make, and how he arrived at the final design. I am sure that others find this of interest as well.

My personal preference is for simple, current feedback, Class-A amplifiers with BJT output stages, so it is unlikely that you will ever see a MOSFET design on my site (anyway, these are well covered elsewhere, in fact there is only one site that needs to be visited and I don't need to say which that one is, do I? :-).

It is therefore possible that my site will be limited to the JLH and Hiraga designs (JLH has published enough material to keep me occupied for several years particularly if I were to extend into RIAA and pre-amps), but I don't rule out the possibility of adding other circuits if they are interesting, simple, give a high standard of performance and are not covered in any detail elsewhere on the web. Any suggestions are welcome, and if there is sufficient demand I will see what I can do. But please let me get the Hiragas finished first!


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