Thank You again Sadik your answers are very helpfull. Yess you are right about image , but on pcb I do not have problem with shorted circuit on pad of 0.33R . I checked dc ofset and it were good but when I played with trimm potentiometer I burned my speaker (not big damage because it was experimental speaker) however your advice about bias and that how to setup it, is very helpfull and I hope that it will solve my problems. Now I need to find another speaker and than I will try to setup bias.
Hi file1,
pl dont mind my frank comments.
1. the layout is not upto the mark, in class A with o/p transitors side by side, unless you keep the amp in at 0 deg C with forced cooling, i see no reason why they shouldnt overheat and burn!.
2. a very good observation by sadik. I see that the C and E of o/p transistor shorted or very near to short, as clearance appears to be less than 1-2 mils. the general manufacturers specify atleast 6-10mil clearances min.
3. high current traces are quite thin.
4. it appears that you have not used DRC feature of eagle, to check for min clearances and dimension to pad/trace clearance.
5. many traces are unnecessarily long.
It would need a whole revamp to make it acceptable.
sorry if that is negative comment, but just wanted to point out few things.
reg
Prasi
Hmm I appreciate all review's . Sadik please could you send me your pcb's on e-mail?
The idea for o/p transistors is to be connected by wire , not directly from PCB board.
C and E are not shorted , but I will check this again. Clearance is bigger in reality , but not more than 3mm , I will reconsider to repair that.
The idea for o/p transistors is to be connected by wire , not directly from PCB board.
C and E are not shorted , but I will check this again. Clearance is bigger in reality , but not more than 3mm , I will reconsider to repair that.
Le Monstre - Powered with Thermal
Just powered up an 8w Le Monstre and quite surprised at the low heat output from it.
Pair of 9v Transformers from Troidy, PCB's from Jim's Audio and Chassis from Modushop.
One thing I did was to mount the mosfets on either side of the PCB as it would have been a squeeze to put them where the PCB wants them to be, so now I have 1.5mm round copper leg extensions and one extra joint per leg! Didn't want to do it like this but.... Might make new PCB's with Mosfet in the "right" place!
DC Offset is zero on both sides but the bias is 850 to 950ma. Would it be a recommendation to bring this down into the 5-600 region or just leave alone!
There is very little heat inside this amp, even after 3 hours the mosfet is below 40c and the fins are only very slightly warm.
The sound is very very impressive even after 4 or 5 hours. It is open, airy, very wide and deep soundstage, highs are pure and clean. Can say one of the most impressive amps I've heard yet and its less than 6 hours old! I listen to an F5 most of the time and, to me, this Hiraga sounds slightly better right now, but I know others will think differently!
A big thank you to everyone here for all the discussions, advice and images of their work because without that I wouldn't have completed mine!
Just powered up an 8w Le Monstre and quite surprised at the low heat output from it.
Pair of 9v Transformers from Troidy, PCB's from Jim's Audio and Chassis from Modushop.
One thing I did was to mount the mosfets on either side of the PCB as it would have been a squeeze to put them where the PCB wants them to be, so now I have 1.5mm round copper leg extensions and one extra joint per leg! Didn't want to do it like this but.... Might make new PCB's with Mosfet in the "right" place!
DC Offset is zero on both sides but the bias is 850 to 950ma. Would it be a recommendation to bring this down into the 5-600 region or just leave alone!
There is very little heat inside this amp, even after 3 hours the mosfet is below 40c and the fins are only very slightly warm.
The sound is very very impressive even after 4 or 5 hours. It is open, airy, very wide and deep soundstage, highs are pure and clean. Can say one of the most impressive amps I've heard yet and its less than 6 hours old! I listen to an F5 most of the time and, to me, this Hiraga sounds slightly better right now, but I know others will think differently!
A big thank you to everyone here for all the discussions, advice and images of their work because without that I wouldn't have completed mine!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Motivated recently in building a "Le Monstre" amplifier and having read thoroughly all 143 pages of this thread, started some 15 years ago, but still being alive and kicking, I have one main question.
Given the almost impossible availability of the original output transistors, I have seen a couple of suggested replacements. To name some of them, here is what I have gathered out of this thread:
- MJL3281A/MJL1302A
- MJL21193/MJL21194
- MJ15024G+MJ15025G
- MJ15022/MJ15023
- MJL21194G+MJL21193G
- MJL21196+MJL21195
- NJW0281G /NJW0302G
Someone suggested to stay clear of MJL3281A/MJL1302A and NJW0281G /NJW0302G, because they are 30 MHz transistors and could result in an unstable amp. Also, although they are suggested and have been used in some "Le Monstre" implementations, I would exclude the 2955/3055 pair.
So, my question is, which pair of the currently produced/available BJTs would be the best replacement of the original for this amp? Also, how many pairs should I get in order to find two satisfactory matched pairs?
Thank you,
Evangelos
Given the almost impossible availability of the original output transistors, I have seen a couple of suggested replacements. To name some of them, here is what I have gathered out of this thread:
- MJL3281A/MJL1302A
- MJL21193/MJL21194
- MJ15024G+MJ15025G
- MJ15022/MJ15023
- MJL21194G+MJL21193G
- MJL21196+MJL21195
- NJW0281G /NJW0302G
Someone suggested to stay clear of MJL3281A/MJL1302A and NJW0281G /NJW0302G, because they are 30 MHz transistors and could result in an unstable amp. Also, although they are suggested and have been used in some "Le Monstre" implementations, I would exclude the 2955/3055 pair.
So, my question is, which pair of the currently produced/available BJTs would be the best replacement of the original for this amp? Also, how many pairs should I get in order to find two satisfactory matched pairs?
Thank you,
Evangelos
Hello.
I am planning to build a 8W Le Monstre and I wonder if anybody have any thoughts about this PCB and components. The seller says that the semiconductors are not matched, but states that the difference between matched and non matched are inaudible... Symmetrical amps need matched semiconductors to be... symmetrical, right?
Hiraga "Le Monstre" 8W A class Amplifier D.I.Y. | eBay
I am planning to build a 8W Le Monstre and I wonder if anybody have any thoughts about this PCB and components. The seller says that the semiconductors are not matched, but states that the difference between matched and non matched are inaudible... Symmetrical amps need matched semiconductors to be... symmetrical, right?
Hiraga "Le Monstre" 8W A class Amplifier D.I.Y. | eBay
le monstre test
I have made le monstre - one channel for test purposes, sound is nice, a bit too harsh in comparision with jlh69. I'll experiment a little with various transistors to see if I can make it sound a little warmer
. Maybe I need to add some small capacitors on C-B?
I have made le monstre - one channel for test purposes, sound is nice, a bit too harsh in comparision with jlh69. I'll experiment a little with various transistors to see if I can make it sound a little warmer
. Maybe I need to add some small capacitors on C-B?Attachments
Hello,
Time to remind the original French article I guess... Everything else is... something else !
Amplificateur 8W Le Monstre
And the PSU...
L'alimentation
Time to remind the original French article I guess... Everything else is... something else !
Amplificateur 8W Le Monstre
And the PSU...
L'alimentation
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I have made le monstre - one channel for test purposes, sound is nice, a bit too harsh in comparision with jlh69. I'll experiment a little with various transistors to see if I can make it sound a little warmer
would be good to look at the output with a 'scope before throttling with c-b caps, check the square wave response for issues. I find my JLH too relaxed (I have too many output transistors, too much capacitance). I believe Le Monstre should sound superb so worth persevering.
Hi,
You will not get correct operation - or sound for that matter - with different components. You have to use the original components or you will get a very different amplifier!
A lot of Chinese crooks sell fake parts and call it Hiraga but believe me it's most definitely not.
The real thing is unconditionally stable and sounds wonderfully sweet, a bit like a SE valve amplifier.
You will not get correct operation - or sound for that matter - with different components. You have to use the original components or you will get a very different amplifier!
A lot of Chinese crooks sell fake parts and call it Hiraga but believe me it's most definitely not.
The real thing is unconditionally stable and sounds wonderfully sweet, a bit like a SE valve amplifier.
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