Hiraga "Le Monstre"

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Circuit and Photos

I've drawn the final circuit - by hand, I'm afraid, since computer rebuilding is slow... If anything is unclear let me know and I'll try again.

This also seems like a good moment to post a couple of photos, so these follow in the next few posts.
 

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First two photos are of the PSU. Separate case, intended to be hidden out of the way.. I also designed it so it could handle two monoblocks or even two stereo amps to biamp... although not with separate circuits for the channels.
 

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And now for the amp we've actually been talking about.... The case is made from a junked car audio power module. (Around here, maybe everywhere, there is a fashion for sound levels in cars that would deafen people on the street at intercontinental ranges. A corollary of this is that the power modules burn out regularly, which is a handy source of heatsink material for free....) The object here was to try and do the amp for as near to free as possible, and to invest more time on the eletronics and less on the case. Of course, Spousal Acceptance Factor is at near-record negative levels....
 

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good question

a good guess they are both very good
maybe the only sound you will really enjoy
is your hearing of that
good old rock and roll music

... unless you're into rap and other modern garbage collections

:D :D of course
lineup .. is only jokin' -- Rap & Techno & Britney Spears Likes are The Musical Things to enjoy


:eek:
 
I do own one F5 i am using for highs but i am considering to move her for mids and build a Monstre or a Zenotron from JM Plantefeve or may be a mixture composed of the front end and the symetrical feedback of the F5 and the output stage of Le Monstre ( an F5 with BJT outputs ). These minimalistics amplifiers are so attractive and so easy to build, even without any PCB. They are an invitation to experiments.
But just dreaming for now and waiting for an heatsinks bargain on Ebay.
...I like all kinds of music but techno, sorry.
 
havent tried the F5 but it is an interesting looking design.....

I have been researching about the resistors to use.... tantalum or metal film...

I can certainly get better than 1% in metal film... and lower temp co-efficient...

but i have never tried tantalums..... i might have to try both...

-Dan
 
Hello!
I need some advice for output transistors.
In front I have:
2SJ74BL/2SK170BL
2SA872/2SC1775
2SD756/2SB716
My question is:
Should I go with 2N3055/MJ2955(maybe TIP3055,TIP2955), 2SC5200/2SA1943 or 2SC3264/2SA1295.
My rail voltage will be 22V and,as I planed, 1,5A on output transistors.
Thanks in advance!
 
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Hi there. I have tried several output transistors in Monstres, including 2SC5200/2SA1943, TIP 2955/3055 and MJW3281/MJW1302, with varying results. If you take a look at the posts above in this thread you can read where Dan and Lumba helped me alter the circuit to help the sound. I am not completely satisfied with any of the versions I have built yet, but of the options you list I would probably choose 2SC5200/2SA1943, although perhaps you will have to adjsut other values to get the best sound, as I did, especially if (like in mine) the other transistors in the circuit aren't the original ones.

On the other hand, of course, messing around with the circuit is great fun, and fascinating. I am looking at the two Monstres as we speak and wondering whether I should do another rebuild and experiment further. (Dan: When you try the 2SC2837/2SA1186 pair don't forget to let us know how it goes...) There really doesn't appear to be a definitive "modern equivalent" circutit for the Monstre yet. (Has anyone tried the BF862 jfets, for instance?)

Let me add that (like Dan) I used the 2SC5200/2sA1943 in a version of the LeClasse 20W, where I thought they were a better fit than in (my version of) the Monstre. I'd be using it still if it had better heatsinks.... This is a serious option, in my opinion, since the other transistors in the Le Classe circuit are easier to find than for the Monstre.

On a different topic, let me respond to the earlier question about the F5 comparison. I have a diy F5 in my living room system (photos and info on a thread on the PassLabs forum, if you are interested). I have compared it to both of my Monstres, and the F5 is definitely better, by almost any (subjective) measure. YMMV, of course, but I think an important point is that the F5 can be built with exactly the parts the designer intended , but the Monstre needs modern equivalents, so to get the best out of it you have to fiddle around. My F5 worked beautifully first time, but after 4 builds I still don't think I've done the best Monstre that I could. I would be most interested to hear how an F5 compares to an all-original Monstre.

Cheers

Nigel