Hiraga "le monstre"

[hifidaddy]

Originally posted by NU_NRG
Someone here know where we could find pictures of this amplifier?

Hi,

the "Le Monstre" was a pure DIY project in that "L'Audiophile" magazin, whereas its big brother, the "Hiraga Le Classe A" was also a commercial realisation.

I try to load a pic of a commercial "Classe A", which was the first realisation of that amp, with 20W power each channel. The later revised "Le Classe A" had up to 30W per channel, and bigger lytics in the filter stage 330 000 uF (4 times).

BTW, later years of production are much prettier.

regards,
Hartmut

[hifidaddy]

regards,
Hartmut

[dice45]

Hartmut and all,
agreed, the Hiraga amp had better PRaT, and "Le Monstre 8W" was more smooth and open in the mid to treble region. I had this amp running for years, making me tube nuts completely happy with it. Control in the low end was remarkable, provided listening volume was moderate.

I once heard a battery operated version, fed form 170Ah battery capacity and several Farads of PS cap capacity.
This was better than my unit, considerably, this was really something.

One warning: the input FET determining the quiescent current (by its transconductance is ultra-sensitve to electrostatic hazard; i killed my monster, performing an innocent mod (other resistor brand) and then finding the sucker sucks 4 times as much current, frying itself.

[NU_NRG]

thank you hifidaddy

I'm surprised to see how simple this amp looks. It was said somewhere that it wasn't marketable because of it's huge size. If someone would decide to build one of these, how would it compare to the Zen or Aleph from Pass?


-Simon

[jazz]

Hi there,

Hartmut and Bernhard, did you build a complete diy version of the le classe and if so which version? I built it three times as well but never managed to get rid of some low level (but audible hum) in that design and i tried everything but nothing worked so i finally settled on the le monstre. I agree with the difference in sound, to me the le classe sounds more friendly and warm. The le monstre has an incredible detail and bass though.

Stefano, one other tip due to the large differences in behaviour of the fets the load resistor of the input cascode will probably have to be tinkered with in order to get the right standing current. more resistance is more current and the other way round. Sorry by the way for not posting the url in my first reply.

Greetings Joris

[Dozuki]

I have not read what articles of this amp are in English (yet), but I was curious if you guys are Beta matching your transistors. If so, are you matching the NPN to the PNP compliments?

-D.

[hifidaddy]

Originally posted by jazz
Hi there,

Hartmut and Bernhard, did you build a complete diy version of the le classe and if so which version? I built it three times as well but never managed to get rid of some low level (but audible hum) in that design and i tried everything but nothing worked so i finally settled on the le monstre. I agree with the difference in sound, to me the le classe sounds more friendly and warm. The le monstre has an incredible detail and bass though.

Greetings Joris

Hi Joris,

I had commercial 20W and 30W Hiraga Classe A at home, and there was absolutely no hum. You should check your ground routing. There are quite a lot of DIY Monsters in Munich, and all of them worked very good. Most folks I know use a regulated power supply for the Monster, which they say sound better than half a Farad of caps. The regulation is that published in L'Audiophile magazin, consisting of a zener, a small signal bipolar, and a power mosfet. I could search for the schematic and scan it, if anybody is interested.

regards,
Hartmut

[jazz]

Hi,

Harmut, thanks for you're reply I'd be very interested in the regulated psu and am sure to try it. I am currently designing a project in which i plan to build several amps in a certain style and both hiraga's are apart of this so any tips or hints are welcome. Due to the cost and complexity the project will span a couple of years though. As for that hum, I'm by now suspecting it has something to do with the casing i'm using but changing that will mean a complete redesing and has to wait for the definite plans of my amp project.

regards, Joris

[hifidaddy]

Hi,

this power supply for power amps has been designed for Kaneda style class A power amps, but the voltages can easily be changed to your needs, just by changing the voltage reference, which is just a zener diode. For Hiraga, 20..25Volts each rail are good, for "Le Monstre", about 12..14 volts. As the Hiraga and the monster only idle currents in the one amp region, at least for the monster the second Mosfet can be omitted.

regards,
Hartmut

[ralf]

Hi,

has anyone expereiences with both, and can tell something about the differences?


Ralf