Jean Hiraga - Le Monstre 8W Class A Power Amp

[kanwar]

Schematics

Hi Bijin,

Nice build, especially the VU meters.......

In the schematic above there are missing base to emitter resistors in the output pairs, i don't know if they are "intentionally" missed by designer or not, but technically speaking they should be there otherwise there is risk of cross-conduction between output devices[Q6,Q8].

Kanwar

 

[bijinmb]

Hi Bijin,

Nice build, especially the VU meters.......

In the schematic above there are missing base to emitter resistors in the output pairs, i don't know if they are "intentionally" missed by designer or not, but technically speaking they should be there otherwise there is risk of cross-conduction between output devices.

Kanwar

You mean R12 and R13?

 

[kanwar]

You mean R12 and R13?

No, i am talking about placing resistors from base to emitter of output transistors.
There is another way to do it also, placing a single base to base resistor[560R to 1K] from Q6, to Q8. This will help alot in stabilizing the amplifier at high temperature operation.

 

[bijinmb]

No, i am talking about placing resistors from base to emitter of output trannies.

I think its intentionally missed.

Please have a look at here as well Kanwar.

Jean Hiraga's Le Monstre / Monster - DIY Class-A 8W Amplifier

 

[kanwar]

I think its intentionally missed.

Please have a look at here as well Kanwar.

Jean Hiraga's Le Monstre / Monster - DIY Class-A 8W Amplifier

Ya, its not there in the original design also, but very strange for me.
Have a look at the updated sch.

Kanwar

 

[Nikhil]

One of the best DIY projects I have seen so far. Clean and mean looking amp.
Outstanding build quality. Superb effort!!

 

[deba]

fantastic finishing.............well done..........

 

[grubyhalo]

Bravo! Love the VU meters, where did you source them?

 

[bijinmb]

Bravo! Love the VU meters, where did you source them?

Really tough to get good VU Meters now a days and very high lead time.

I have literally contacted used dealers who deals vintage cassete deck etc from top of Kerala to bottom, to get this and finally after 3 months i collected 6 of them. This is the best way to get VU meters at affordable cost now a days.

I think element14 have some old stock but price is on the higher side.


I believe this analog meters will hit the market in the future and become a part of modern amplifier trend.

Like boys coming to college with Vespa, Yesdi, Rajdoodh, RX-100 etc...LOL...

 

[kanwar]

Bibin/Bijin,

Have a look at post 880

Hiraga "le monstre" - Page 18 - diyAudio

 

[apk]

Bibin/Bijin,

Wonderful amplifier build! You guys are really taking DIY quality to the next level. Hats off to you both.

Really love the blend between vintage looks (VU meters) and modern finish. BTW, I too own a power amplifier with VU meters!

How much did the entire build cost you? What speakers are you driving with these amplifiers?

Best,
APK

 

[bijinmb]

Bibin/Bijin,

Have a look at post 880

Hiraga "le monstre" - Page 18 - diyAudio

Thanks Kanwar for shooting that link.

Actually i had a discussion with one of my colleague regarding the point you have mentioned and this was his comments on that.

"hmm
its actually recommended
for lots of reasons
but old sch didnt consider it
its just to put the outputstage safe.

its not just about temp its about amplifier volume
if you are driving low the existing one is best

but one need to calculate it first or things will not work accordingly"

and i too think, this is a needed mod which is pretty easy to do as well.

 

[sbg]

WoW!

one question though.
the orientation of the heat sinks is like =
normally I would see ||||||| in most of the cases.


could be marginal and may not be of concern but will this not effect the cooling ?

 

[bijinmb]

Bibin/Bijin,

Wonderful amplifier build! You guys are really taking DIY quality to the next level. Hats off to you both.

Really love the blend between vintage looks (VU meters) and modern finish. BTW, I too own a power amplifier with VU meters!

How much did the entire build cost you? What speakers are you driving with these amplifiers?

Best,
APK

Thanks APK.

Some people are really found of Analog VU Meter's for some reason.

Posting a close up view of the VU meters i have collected.







The entire build cost's roughly around 24-26K since this was a complete DIY from the scratch (cabinet, getting right heat sink, transformer, lot of planning regarding the design layout in CAD, acrylic work etc..). It took lot of time and effort.

But the engine is set now. And i think it won't cost that much for the next build on wards.

The AMP is presently paired with the Active 3-Way floorstander in Passive Mode.

 

[bijinmb]

WoW!

one question though.
the orientation of the heat sinks is like =
normally I would see ||||||| in most of the cases.


could be marginal and may not be of concern but will this not effect the cooling ?

Simple answer is YES to some extend.

And the bottom line is Hiraga - Le Monstre won't need that BIG heat sink for its cooling. What I've put is almost double the size in reality so the heat sink orientation won't have much importance here due to the larger size.

And for my curiosity I ran the AMP for 2+ hrs and checked the heat sink temp. with a thermometer and it was just 42 Degree Celsius. I would say just warm.

But as a matter of cutting down the cost, it can be build with lower sized heat sink with fins in vertical orientation.

 

[manniraj]

Why don't you sell these DIY effort as a fully assembled item on your site? I think there will be lots of customers to grab them :licklips:

Thanks

 

[bijinmb]

Why don't you sell these DIY effort as a fully assembled item on your site? I think there will be lots of customers to grab them :licklips:

Thanks

I can't sell through the site because I don't have ready stock.

Customers won't be that patient after paying for their product.

But if somebody wants a complete build, they can just PM or call me or contact though the site. We are happy to offer them a good deal.

Or if many are interested I can initiate a Group Buy.

 

[manniraj]

Oh ok I understand and thanks for the offer. I just PMed you but not related to this build. Please check..

Thanks

 

[bijinmb]

Here is the suggested new design of Jean Hiraga - Le Monstre with locally available parts.

Schematics:



Parts List:

 

[kanwar]

Thanks Kanwar for shooting that link.

Actually i had a discussion with one of my colleague regarding the point you have mentioned and this was his comments on that.

"hmm
its actually recommended
for lots of reasons
but old sch didnt consider it
its just to put the outputstage safe.

its not just about temp its about amplifier volume
if you are driving low the existing one is best

but one need to calculate it first or things will not work accordingly"

and i too think, this is a needed mod which is pretty easy to do as well.

Yes, its needed in order to keep the output stage safe by keeping the bias voltage stable and assisting in better turn-off phenomena after crossing crossover transition. The value depends on the bleeder current one needs to set in the drivers.