Hiraga "Le Monstre"

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Joined 2005
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Hi all, I have a minor issue with my Le Monstre that I bought second hand from Netherlands some 10 years ago.
It has the original output stage with 2sd844 and 2sb754 but..... the power supply is defenitely not original, not even resembling the original power supply. Well, maybe the transformer is ok but the rest is a mix of caps from different eras and not even close to 300 000uF in total. I want to change this now cause I want to hear what the amp can do with proper feeding.

My idea is to use the medium stage power supply according to the shown picture (taken from the original article in le Audiophile) but I need help implementing the batteries.
View attachment 806013

When you build the big power supply it is clear that you implement car batteries which connect when the main is disconnected via a fourway switch but when you implement this smaller power stage (still going to have 2 x 12V 12Ah batteries and 2 x supercapas 0.47 F) there is no clear picture how to implement these batteries.there is no schematics for this stage.
Can I get some help scetching this implementation I would be very greatful cause I am not shure if the batteries should be switched into use or used parallell with the caps without any switch and if so.... will they serve as superbig caps or will they have to be charged separately and then connected via a switch.
I really want this to be close to the original while the output stage is still original cause it will come a day when I have to rebuild the whole amp and it will never be the same again.

Please, need the help since I am not able myself, I just know how to duplicate the schematics via physical work onto a pcb, not how to do the schematics themselves.

Sorry, forgot to say that I intend to use two separate feeds (mono) so in total 12 x 68000 uF plus the supercapas.

Can you show a few photos of the amplifier and maybe we can help
 
Hi all, I have a minor issue with my Le Monstre that I bought second hand from Netherlands some 10 years ago.
It has the original output stage with 2sd844 and 2sb754 but..... the power supply is defenitely not original, not even resembling the original power supply. Well, maybe the transformer is ok but the rest is a mix of caps from different eras and not even close to 300 000uF in total. I want to change this now cause I want to hear what the amp can do with proper feeding.

My idea is to use the medium stage power supply according to the shown picture (taken from the original article in le Audiophile) but I need help implementing the batteries.
View attachment 806013

When you build the big power supply it is clear that you implement car batteries which connect when the main is disconnected via a fourway switch but when you implement this smaller power stage (still going to have 2 x 12V 12Ah batteries and 2 x supercapas 0.47 F) there is no clear picture how to implement these batteries.there is no schematics for this stage.
Can I get some help scetching this implementation I would be very greatful cause I am not shure if the batteries should be switched into use or used parallell with the caps without any switch and if so.... will they serve as superbig caps or will they have to be charged separately and then connected via a switch.
I really want this to be close to the original while the output stage is still original cause it will come a day when I have to rebuild the whole amp and it will never be the same again.

Please, need the help since I am not able myself, I just know how to duplicate the schematics via physical work onto a pcb, not how to do the schematics themselves.

Sorry, forgot to say that I intend to use two separate feeds (mono) so in total 12 x 68000 uF plus the supercapas.

I built many amplifiers before from ClassA to ClassAB to Class D, personally I would not power a Class A amp using batteries, BTW I also own a Le Monstre amp(still own it and sitting near me)), it sucks(pulls) too much current even when it is running idle.
The battery PS is IDEAL for Class D amp, I built one too sounded good as well powered by batteries.
 
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Hi TIC (or whatever your name is)
Things to keep in mind is that NOT ONLY the capacitance is important but more important is their ESR. Capacitors with very low ESR must be it.
The amplifiers draw a current of about 0.6A each, which is not that much.
The schematic of my amp you can see in my post prior to yours. This resembles the original, but i used a small trick to switch on the batteries to reduce the currents when switching them on: the battery-voltage can be somewhere between 12.5 and 13.7V and you don't want to switch them to all this load of capacitors when they are empty. currents could exceed 100A easily, then.. I charge the capacitors till they are 13.2V and then i switch the batteries parallel to them with a big 30A relay.
Back to ESR: even the best batteries have an ESR that is at least ten-fold that of the used LOW-ESR-capacitors. SuperCaps have a relative high ESR too. So, to be honest, the batteries and SuperCaps are a niche, and i can't hear any difference between operation with or without batteries..
Important is to buy good capacitors. use Epcos, Vishay, Spraque or one of the better brands and select them on their ESR, rather than their capacitance. 68.000uf/25V is fine. These can be bought for around 18 euro's each. (Mouser, Farnell for instance)

Kees
 
Long time...

Sorry that it took tome but I have been occupied with other things but here it is, and yes, she is worth a better power supply and some (very much) tidying up among the cables. But it will not be done in a day or two cause the man who "helped" have been very able with plastic padding, hot glue and silicon so just dismanteling will take some delicacy and time.
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Setting bias

Hello,


I am building le Monstre 8W with parts and pcb's bought from Hifistor from Serbia.
This is actually my first diy amp project.
And I have great diffculties setting the bias and DC off-set.
One channel had a bias three times higher, while the second one has a bias 20 times lower then 0.55A.


Has anyone any experience with parts and pcb's from Hifistor?
Can anyone help?


With kind regards.
 
First thing: check the circuit, for device values; device orientation and for dodgy soldering. I always manage to get one of these wrong with every build (now that I'm not doing it everyday)

Second: check your DC settings further back in the amp. (refer to my first point).

Posting those on your schematic to this thread may allow the assembled eyes to spot the problem.

Finally, we move to yanking active devices out of the circuit and measuring curves.
 
Setting bias

Thank you for your reply.


I checked the circuit and did some research on this thread.


And noticed that others have put 5k pots parallel to R2 and R3, see attachment.


There is quite a difference in value between the settings of the pots. Is it due to the fact that the transistors are not matched?


Best regards to all.
 

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Does anyone have a schematic and component values for the Jims_audio kit using the Sanyo output transistors? I bought the kits years ago and have no documents with them. It’s mainly the resistor positions I need. Also I have two trim pots in each kit, I know where one goes but not if the other is a spare?

Thanks
 
As of today, I can boast that I also have a Le Monstre amplifier, currently in the JLH69 box and with its regulated, +/- 19V supply, current through the output transistors is 1A, transistors are 2SK170 / SJ74 + 2SC3324 / SA1312, 2SC3467 / SA1370 and output pair 2SC4467 / SA1694.
It works perfectly, I'm satisfied. The sound is great. It's not like my version of the JLH69, but I've been working on it for almost a year to perfection, I also need to give Le Monster a chance, I still have plenty of transistors to try, though it sounds great as well.
 

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