Hiraga 30W vs. Le Monstre

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Today I listened to my Hiraga 30 W class A against my Le Monstre.
I am using them on hybrid electrostatics from 350 Hz upwards. The electrostatics have a sensitivity of around 90 dB so power is sufficient on both. I use a parallel notch filter in series with the ELS for impedance correction around 20 kHz as the Monstre didn’t liked the impedance at high frequencies; resulting in no highs without the filter.

Good points are:

Hiraga: better imaging and greater depth of sound
Monstre: sounds more ‘natural’, less sharp edges on female vocals and some solo instruments

Both are very good but I’d like to know what I have to do to get the best of both worlds.

So are there modifications I can do on either to improve the shortcomings or do I have to build something like the JLH for ESL?

Thanks in advance for your input.
 
Thanks a lot!!!

It looks even more simple than the original circuit (except of course for the capacitor on the input)

Did you have a chance to compare it to the original?
How would it behave on an ESL?

Johan

Dang it, I knew posting this question here would make things more complicated.
 
Johan,

I've build both but in the end stayed with the monster. I like it's sound slightly better but that's highly subjective. A change to the monster that really helps imho is bypassing the 'bias' cicuit of the input cascodes with some good quality caps. Also both circuits sound best without any bandwith limiting in my experience but given you're load that might not work for you. I played around with resistors somewhat and settled on tantalums for the input resistors and kiwame for the others. With these changes i think i reached a nice midpoint between the le classe and the monster, in my situation at least.

hope this helps

Joris
 
Joris,

Thanks for your answer. My feeling also is that modding the Monstre would be more awarding than modding the class A..

Where did you put the bypassing caps and what values did you use?

The filter I use fortunately does not limit the amps bandwidth but adds a couple of ohms to the ESLs impedance around 20 kHz. Especially the Monstre did not like the low impedance in the highs and responded by not giving any power to the highs at all. The class A does not suffer from this; if it means I can keep my Monstre I can live with the filter.

Do you know of a local source for the resistors you mention?

Thanks again,
Johan
 
Johan,

I bought the resistors from www.triodes.nl, located in Breda but they only sell via internet.
The input cascodes have two resistors (2k value) tied to the base of the upper transistor. One resistor from the power supply line to the base of the upper transistor and one resistor from the base of the upper transistor to ground. These resistors form a voltage divider. It is the last one you'd want to bypass with a cap. Have a look at www.bonavolta.ch/hobby/fr/audio/monster.htm for the schematic. the upper transistors are the 2sa872 and 2sc1775 ones.

As for the sort of cap I suggest you first buy four cheap (phillips electrolytics or something like that) electro's of about 100 uf 35 v. Make sure the leads on these caps are long enough so you can solder them directly over the resistors. First try these and see if you like the effect. Then if you like the effect you can try something esotheric like a solen 1uf mkp or something like that. My experiments didn't indicate that value or quality where really important though so i simply settled for roederstein eke 100 uf 63 v bypassed with an additional 10nf multilayer ceramic. This has done it for me but i don't exclude that a better type such as the solen will be better (probably a matter of taste as well).

sorry i don't have a schematic editor right now or i'd give a pic.

groeten
Joris
 
Jazz,

do you remember what the difference were between the kiwame and the tantalum resistors?

I have decided to build another Monstre or two and have finalised my choices on resistors between the two mentioned.

I'm assuming you've built the Monstre with both type of resistors and would like to know how you ended up with tantalum as input resistors and kiwames for the rest.

PS any other suggestions are welcome as well
 
transistors for Hiraga le Monstre

JohanH,

I read in your reply that you are going to built another 2 Le Monstres.

I want to build a Le Monstre for a long time, but i can't find some of the transistors, (the one's of the original schematic).

Can you please tell me were to find them? Or are you using substitutes?

I should be greatfull if you can help me with an adress to buy them.
 
Wim,

maybe I should have said "rebuild". I was lucky enough to find some Monstres with spare transistors on marktplaats.nl. Having said that, it is still possible to find some of the transistors. Stuut en Bruin had a couple of the original Toshiba 2SD844; of course not anymore :D . There's a guy in Germany that sells complete kits through ebay (although he's using the SMT version of some of the transistors; he probably sell parts as well.)
I found some of the transistors simply by googling them and mailing the companies that listed them as available.
Be sure to ask if the ones they're selling are the original Toshiba, Hitachi etc. ones

Good luck

PS A friend of mine who has some experience with the Monstre is toying with the idea of building one with current (european) transistors.
I'm sure any input is appreciated.
 
Transistors

Hi Wim & Johan,

I'm not shure, but I think that I have a few in stock.
Not enough for 4 mono's but I think enough for 2 mono's

I'll check for you next week and get back to you with the results.

I've built the Le Monstre two times and then took all the parts out and never built one again. I was in love with the low level details, It sounded like a tube amp with great control over the speakers. After that I built Electrostats and that was the end of my journey with Le Monstre amps.

The PLINIUS SA-102 is comparable with the Monstre 8 Watt Class A! But with more power and control. I've built a Le Monstre with different parts and the sound was allmost the same,and really good. But don't use high speed BJT's like the 2SC2922.
The sound of a Le Monstre is unique, but Plinius is somehow better!

You'll hear from me.

Regards,


Audiofanatic ;)
 
"But don't use high speed BJT's like the 2SC2922."

What is the highest speed that should be used. I have ordered some boards and need to pick the otput BJt's. I have some MJL 1302, 4302, MJ15003, 2n3886 and matching pairs, 2sa1386, and 2sc5200 and matching pairs. Thanks.:confused:
 
hello Mike,

The original output transistors have a Ft of 10 and 15 MHz respectively. To aovoid nasty resonances, and damage to amps and tweeters it is recommended to either check the finished amp with an oscilloscope or avoid HF nasties by using original type transistors.
Rumor has it that even after taking said precautions the nasties may occur.

Please let us know how your amp with 'modern' transistors works.
Many of us are very interested to get the result of the original with modern day components.

Hope this helps.

Johan
 
Johan,

Ouch this is dangerous ground i'm going to step on but what the heck, here goes..

I think I remember Hiraga went in to component selection in the original articles somewhat and chose tantalum resistors, but that could also be in the article on the le classe i'm not sure. Hence i simply put in tantalums for all the low wattage resistors. I didn't like the result very much. The sound was quite 'thin' and edgy.
I remembered from building allen wright's fvp5 that i didn't like the tants in the cathode or anode circuits very much because they had exactly the same effect. As grid/base/gate resistors they where perfect however with very good dynamics, resolution etc. When i swapped the anode resistors in the tube pre for kiwame the sound became much more fluent but with the same good resolution and dynamics, a more 'friendly' sound. Hence i tried the kiwames for the 'load' resistors of the cascodes and for the feedback resistors. The result in combination with the tants was very neutral and fluent with very good detail and dynamics.

To summarize: Both the kiwame and the tantalums are said to be low noise types and better then metal film and i sort of agree. I use the tants for 'signal resistors' with low current swing and the kiwames for 'load resistors' where higher current swings take place. One can also use riken ohm resistors in stead of the kiwames which i expect to give a warmer sound but i like the neutrality and fluent charachter of the kiwames better.

This is all highly subjective though and just mho. Oh I used the tants for the 2k resistors as well where they are very good.

groeten
Joris
 
Joris,

Thanks for the input.

Yes I know this is dangerous and highly subjective. The reason I chose tantalums as one of the options is indeed that Hiraga had them in their catalogue for Monstre parts. Your Post (and the cost-difference (I am dutch too)) makes me want to try the Kiwames first.

Do you know if triodes.nl sells other values thans they list as well?

Johan
 
Johan,

On the site it is said that other values can be ordered but i don't know if there's i minimum quantity or something like that. From what i know the guy behind the website runs it because he's a diy'er himself so i don't know if he's willing to stock values that are rarely used. It might take him a while to gather enough orderes to send out for a shipment. Patience is a virtue, they say....

groeten
joris
 
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