Hiraga "Le Monstre"

I did build Hiraga 20 W and Monstre versions for several occasions. As well do I have one original manufactured 20 Watter for almost 15 years now.

The 20/30 Watter to my ears sounds more friendly and tubelike, almost warm. It has a beautiful midrange and a full bottom end and a silky smooth top end. The Monstre has more detail and depth into the music but can sound thin or harsh on occasions (but in its best moments outperforms the 20 W). I also build the Monstre using heavy batteries and 1,5 Farad of buffer: better still but maintaining forementioned peculiarties. I do not agree that the Monstre sounds like a triode single-ended tube amplifier, only in the transparancy of the sound I can see some similarities.

Interesting to know that I have build some cheap versions of the 20 Watter, using a moderate power supply (around 16 Volts DC plus and minus) and using standard 3055/2955, BD139/140 etcetera. Such an amplifier also has a remarkably good sound to it, bettering almost anything commercially available be a good margin. So for a few hunderd Euro's you can build yourself a pretty power amplifier.
 
And I forgot:

I did not build any Pass amplifiers but did have a diy-built version of the later DC single-ended mosfet design (with the big power resistors) that gave around 5 Watts of RMS power.

The sound was not up to my expectations (of course not bad, but way behind the Hiraga) and had a horrible hum in it as well. I do not know about the quality of building and/or used components though and my preamplifier was not up to the task (insensitive and lowish impedance this Pass amplifier). So, not a fair comparison this one.

Rudy
 
SE Monster?

Hello!
I have a strange, a bit stupid question!
Is it possible to create a SE version from the original PP Hiraga Class A (or may be from The Monster) as for example the JE Labs made from the Williamson PP tube amp? ( it could be not the best comparison.....)
I would like to hear the diffrence between the 2 operations and because I am an enthusiast of the SE amps.
Thanks!

P.S.: I built the Monster and it is a realy good amp.......
 
monstre

hello,

after building several class ab an a amplifiers, i have no doubt:

class a is the more natural an sweet sound.

now i want to build "le monstre" but since the transistors of the original schematic doesn't exists anymore, i like to know if some of you have the replacements.

thanks for your answer.:D
 
I have had a second hand commercial 30w Hiraga, for a large part because it is so beautifull.
Also i built a number of L'audiophile designs; the Preamp of Akihito Kaneda, Le Monstre, L'Ampli Fou.
I even made an effort on the Nemesis, a reason for reading Susan Parker's work with interest.
pcb's and most of the parts i got from the L'audiophile store in Paris, in those days in the Rue de Belfort.

The comparison between Jean Hiraga and Nelson Pass designs is not just i think.
I had the commercial Jean Hiraga JH50 PushPull tube amplifier on ESL's for a couple of days, my ears thought it to perform much better on Quads. Should be, cost a heap more than the 30 watter Hiraga.

I own an Aleph Null, bought it when only ocassionally a second hand commercial Hiraga was offered on sale in an audio store.
I built Aleph 4's, currently adding a number more.
So, i need not mention my preference.

Le Monstre i heard in the L'Audiophile store on typically French very high efficiency speakers, its a brilliant amplifier as the Hiraga is.
To me, putting Le Monstre in a car is the same as the difference between class A and class AB Mosfet amplifiers.
Try stuffing a high efficiency speaker system in a car, supposing you can then savor the beauty of the amplifier over the sound of the motor running and bad vehicle acoustics.

For enjoyment i drive a Chevy van with raised roof. I am 6'2" and able to stand in the 15' x 6.5' livingroom of the car.
The V8 only runs 1500 rpm when doing 60 mph, i can not hear the airco humming.
It has double 4 channel modified amplifiers, for a large part biased in class A with multiple decade MHz Sanken ringemitter output devices that tap from an added battery and two 1 Farad caps.
Sounds quite nice, but i bet a Le Monstre in a regular home on +100 db/watt quality units sounds a lot better.
 
Hum Pick up in Le Monstre

I have a strange problem in my Le Monstre. The amp is now where I measure 0.0 mv hum. But this is only without input cabling connected. Once the cable are connected it goes up to 0.2 - 0.3 mv with unterminated shielded short cables. With unshielded it is 0.6 - 0.8 mv ac.
This is with a double shielded power cord. Using an unshielded power cord the measured hum can reach 8 mv depending on cable orientation.
Connecting the preamp to the cables does not help, the measured hum is the same. The preamp has an output transformer with a 38 ohm DCR.
This is the only amp I own that has a problem with hum pickup. The input impedance is around 23K. All my other amps do not have a problem with input cable hum pickup.
On my 100 db efficient speakers the amp is almost dead quiet without cables. I can play with cable dressing and get it lower, but never as quiet as it is without cables.
Laying the cables close to the rear of the amp gives big hum, pickup from power transformer. This is a nice Victoria Magnetics toriod.
Also another goofy question. I have read about the bypassing of the cascode transistors to improve the sound. I tried it in another version, using the PCD Design recommended replacement transistors. It degraded the sound quality.
In this one, original transistors, it has not been tried. Did I do it incorrectly, or is it not needed if the power supply is well built.
One thing learned, this amp can sound great on the right speakers. But it is a devil in exposing power supply issues. Just moving a ground wire connection a couple inches can make the hum go from 0.0 mv to 2 - 3 mv on the outputs.
Anyone thinking of building this amp should be aware. The thing will require some tweaking to get the best out of it. I doubt if anyone has ever built one and had great sonics to begin with.

George
 
Dieter's PCB

Hallo Dieter,

you have lots of free space on that board, you could shift the components much closer together and make a tighter layout on the board. that means you need less board area and get a shorter signal path and less parasitics.
try to avoid sharp corners (smaller than 90 deg), make smooth areas (use polygones in your layout software).

you can probably cut the board are in half..
or more, if you use SMD resistors. 1206 or MELF is really easy to solder, no problem for any DIY.

also, the bypass caps are very close to the input stage and there are none close to the output.

Regards
Timo
 
output resistance

Hi everybody,

I am also interested in building le Monstre. Before doing that I wanted to look for "European" transistor substitutions and also to do some spice simulations. Although I am electrical engineer I am not, at least in audio, looking for a perfect amplifier.

But what bugs me the most is the simulation of the output impedance. I used the schematics similar to one posted here with Tip3055 tip2955 or replaced them with smaller MJE15030 or D44H11. I always got the output impedance of 2-4 Ohm. That seems a lot to me for the amplifier with the feedback. Do you have any comment on that?

Since we speak of replacements is there any for jfets SJ SK with some 2nxxxxx or similar that is more likely to be found? The same question is for every other?

Pred

PS
I was using LTSpice if it is of any significance.
 
Regarding to quite high output impedance 2 ohm seems ok, because the monstre exit on collector and was designed to be a 300B solid state equivalent, so with tipical tube damping factor.

Me too prefer to build on ewith current european transistor, but not easy to find replacement for these old toshibe product. High gm input fet that are critical for results seems impossible to find.
Here my list of equivalent (first item of each group is the original one). Any suggestion on equivalent?


POWER NPN 50V 7A 60W 15MHz 2SD844 TOSHIBA
POWER NPN 50V 7A 60W 15MHz 2SD1063 TOSHIBA
POWER NPN 50V 7A 60W 15MHz TIP35A ST

MEDIUM PNP 2SB716 TOSHIBA
MEDIUM PNP ~MJE350 ON SEMI

SIGNAL NPN 2SC1775E TOSHIBA
SIGNAL NPN ??

JFET NCH 2SK170Y TOSHIBA
JFET NCH 2SK364 TOSHIBA

SIGNAL PNP 2SA872E TOSHIBA
SIGNAL PNP ??

JFET PCH 2SJ74Y TOSHIBA
JFET PCH ??

MEDIUM NPN 2SD756
MEDIUM NPN ~MJE3440 ON SEMI
MEDIUM NPN 2SC2632 TOSHIBA

POWER PNP 2SB754
POWER PNP TIP36A ST


__________________
Piergiorgio
 
Source for parts

www.mcminone.com can supply all the original transistors. I built one using the recommended substitutions listed on the PCB-Design website. Later found the original transistors and built another.
The one built with the original transistors sounded much better. It also was more stable.
One tip I missed. Keep your ground length paths equal from rail to rail and channel to channel. Small differences in the ground paths will increase hum and effect dc offset.
Poor layout and build can cause big problems with stability. It will zing your eardrums.

George