PCB Layout for Hiraga Le Classe A?

[GKU]

Jacco,

Certain time ago they moved to:

11/17 Rue de la Chine
F-75020 Paris
Metro: Gambetta

but Mr. Walther is still running the shop.

Rgds

GKU

[GKU]

Stabbist,

The PSU actually used in my Hiraga Le Monstre is a regulated version, originally developed for the Kaneda 50W due to very good experiences made in the Hiraga Class A 20W mono version.

This version subjectively provide smoother and more detailed heights in my active LS-system driving the Technics 10TH800 tweeter.

Attached please find the schematics.

Rgds

GKU

[GKU]

Stabist,

Sorry I forgot to add the pdf version in case you can't open the other file.

Please see the pdf-attachment

GKU

[jazz]

Hi there,

Regarding transistor substitutes for the 'le classe A', 2sd718 and 2sb688 may be used for the power transistors. The small signal transistors should pose no problem. Alternatively the 2n3055/mj2955 may be used for the power transistors along with bd139/140 instead of the sa872/sc1775. this last one is a lesser option though.

One further remark concerning some of the caps. The original schematic has some frequency compensation caps. If you can do without them, do so. if you need them, try experimenting with the 2200pf cap in the feedback path. styroflex is not recommendable in my experience but that's just mho.

Hope this helps.

Regards
Joris

[GKU]

Hy,

one additional statement to the remarks of Jazz.

I agree, the power transistors are 2SD718 and 2SB 688.
The small signal transistors as 2SA872 A and 2SC1775 A should not be replaced based on my experience at least not with BD139/140. But very important, all transistors should be carefully matched pairs. La Maison de L'Audiophile sells matched pairs.
For the drivers I don't have a designation, does any body know the types? The last orders I have placed at La Maison de L'Audiophile but would be interested to purchase directly from Japan as I do with the other types.

Rgds

GKU

[jazz]

hi there, again

As GKU rightly pointes out, I made a mistake. The sa872 and sc1775 should not be replaced. Use the bd139/140 for the driver transistors if using the 2n3055/mj2955 only.

The origingal driver transistors where the 2sa634 and2sc1096 which are obsolete. If using the sd718 and sb688 the driver transistors to use are the 2sa968 and 2sc2238.

sorry for the mistake

regards
Joris

[GKU]

Hi Joris,

Thank you so much for your correction and for the info about the driver transistors.

GKU

[Panelhead]

Originally posted by Stabist


Can you please tell me what kind of PSU did you use for Le Monstre?

Thanks

I used a passive filtered supply in mine. It is a C-L-C-L-C. It really helps when used with 100 dB efficient speakers.
One item, I had continual problems with noise. Finally tracked it down to grounding issues. The design is extremely sensitive to ground paths for the +/- supply rails.
Ended up getting it down to 0.3 - 0.4 mv by moving grounds in the power supply around. I learned a lot about grounding while chasing all this out.

George

[ralf]

Hi George,

since you have big experiences in grounding:
what are the most important things in doing good grounding?

tanks,

Ralf