Le Monstre /8 W class A

[Hoerninger]

More than once there was the question for a small class A amp, which is sufficient for an actively driven compression driver - at least at home :yes: .
This amp seems to suffice:

JEAN HIRAGA'S LE MONSTRE / MONSTER (http://diyaudioprojects.com/Solid/Jean-Hiraga-Le-Monstre/)(link)
(http://diyaudioprojects.com/Solid/Jean-Hiraga-Le-Monstre/)http://diyaudioprojects.com/Solid/Jean-Hiraga-Le-Monstre/Hiraga-Monstre-Monster-Class-A-amplifier-schematic.png
____________ (http://diyaudioprojects.com/Solid/Jean-Hiraga-Le-Monstre/Hiraga-Monstre-Monster-Class-A-amplifier-schematic.png)
Peter

[Robh3606]

Hello Peter

Have you built it??

Rob:)

[Hoerninger]

Rob,
this circuit I have not built, I just found it during the free days. :)

But as I have some insight into amp circuitry, it looks very reasonable for me.
The first four transistors form a buffer, which is mentioned here:
Cheap Chinese Electronics: Fet Buffers (http://www.slugsite.com/archives/926) (Link)

Then follows a symmetrical stage with complemetary darlingtons.
For the Hiraga's monster there are many links (Google).
Circuit board:
http://www.kk-pcb.com/hiraga.html
(additional: transistor substitutes)

I thought it would be passable to post.
____________
Peter

[Robh3606]

I thought it would be passable to post.

Certainly just wondering if you have heard one??

Rob:)

[Allanvh5150]

If you look a little harder you will find a more up to date version. Same circuit but with more modern components. :)

[Bruno GINARD]

HI all,

I have eard this amplifier in Paris, on a Onken : Western electric Horn system.

Jean HIraga decides to create this circuit after viewing a prototype of a HUGE class A amplifier, but with only one transistor and a very low power output, designed by STAX ( in the past they made class A amplifier).

THe monster is a "3OO B" equivalent in the conception , perfect for use in the mid in high of a "horn system.. If i remenber, price of the component is cheap, but you have to realise a very HUGE power supply, with a large value of caps........some audiophiles réalised it with battery supply....

Tell me (us) more if you try this scheme, i am interested for my 2441 and 2405 in a multi-amp solution..

regards

Bruno

[Hoerninger]

I thought it would be passable to post.
I used the world "passable" as it is of solid design and broadly discussed in the internet - but not in this forum. Online you can find some listening impressions too.

Yes there are other versions.
____________
Peter

[Ian Mackenzie]

But you still need a capacitor for protection of the driver.

In such a two way design for compression driver the limiting factor is the sensitivity of the overall system. The more sensitive the system the less bebefit there is for biamping particularly if you already have a large enough class A amplifier ie 25-50 watts.

I mention this because people debate the benefit of biamping the 4435.

I also would not underestimate the benefit of using class A for the woofer, the improvements are quite noticable over conventional amplifers.

Larger class A amplifers have higher DC bias and this directly proportional to sound quality.

Therefore in practise a larger class A amplifier has more virtues for non biamped applications.

[carolus]

Hi Peter & Bruno,
....my best greatings for/in this new year ...

FYI,
I built 15 years ago my 4xmonsters with Kaneda pré-amp and his 4 way actif filter.
This (big) system drive my 4 way horn (home made) system.
Oversized Klipsch, WE66A, Iwata 2 inch, and Iwata 1inch ....
A very good audio experience (and symbiose monster/horn).
Caps 1 (one) farad, with power off I had music for appr. 45 sec ...
First a run it with flaoting-battery (very expensif in electricity), after that with a 600VA transfo.....
With only 5Weff (for the low) I had appr. 110dBA (in my living/listeningroom).
The monster Dc output is very stable in the "low". (....near 0,001Vdc).
The concept is very good for high efficient (multi) systems.
At this moment the monstersystem is in "parking" and i use a (home made) OTL T12 .
If yo can built "the" monster ....do it....with plenty caps ...Its great music.
Allez salukes.
Karel
(I can sent pict's)

[Bruno GINARD]

i agree with Ian... the difference on a HIgh efficiency lspkrs sytem between a class A amp and another is impressive... the best bass i have had on my E 145 in Hartsfield's was with a Plinius 102 class A amp... the "problem" ( with the plinius) was in the high, where a 300 B Se, or a "mid cost"Vincent SP 331 are better....
I have eard the new Everest in Paris with a couple of mono/class A huge PASS amps...It waz impressive...from the bas to the ultra high...

I agree too about the relation between high efficiency an multi amp configuration.. I am trying to optimize my hartsfields for 4 years.... (on a 100 based scale, i think i am near....85 !) Last week i have tried a bi amped configuration, with 300 B in the high, SP 331, or a 6550 PP old Williamson scheme amp, for bass . FIlters are Marchand passive models, 24 db at 500 Hz...

I have puted back the original passive configuration this (early) morning, thinking that i have time to spend to work around the loudspeakers ( ie 2441 and his diaphragm) and the filter , better to try multi amp configurations...
the only very positive difference was the transparency in the mid with the direct coupled amp in bi amp configuration........... it's crazy what a passsive filter scheme can "eat' the details and little informations..

[Ducatista47]

I have eard the new Everest in Paris with a couple of mono/class A huge PASS amps...It waz impressive...from the bas to the ultra high...

I agree too about the relation between high efficiency an multi amp configuration.. I am trying to optimize my hartsfields for 4 years.... (on a 100 based scale, i think i am near....85 !) Last week i have tried a bi amped configuration, with 300 B in the high, SP 331, or a 6550 PP old Williamson scheme amp, for bass . FIlters are Marchand passive models, 24 db at 500 Hz...

... it's crazy what a passsive filter scheme can "eat' the details and little informations..

This all makes me feel better. The past few years my personal experience kept demonstrating that for critical listening and enjoyment

1) Class A sounds much better than the alternatives
2) High efficiency speakers are a must to get the highest level of reproduction sound quality, and not only because of the amplifier situation. The only exception I can think of is electrostatics
3) Passive crossovers are something else in the circuit to degrade the signal; better off without them
4) Since only the very best active crossovers are good enough, no crossover is the ideal

My full range Hammer Dynamics Super 12's are my go to speakers for private listening. The 4345's, wonderful as they sound, are being relegated to party duties and the odd music or situation where it has to be quite loud. Five or ten watts through the top of a biamped 4345 could break glass.

There is a reputedly excellent active designed by Ian and Nelson Pass; you build it yourself. I do not know if anyone besides Ian has built one. http://www.passdiy.com/gallery-misc-framed-total.htm Click on the top entry,"Hi-LO Xover." As you can see, it is no simple matter.

Clark