Hiraga 30W vs. Le Monstre

[Upupa Epops]

To Ipanema : My mail to you comes back - have you some other address ?

[Ipanema]

Hi Upupa,

Here is my new layout arrangement. all outputs had been pushed up and input down. VDD and VEE have less spreading but need a jumper to connect the feedback resistor ground and input ground cos' can't find a way to make a short path between them What do you think of this new layout? Will it still hum?

What do you think if I fill all unrouted area with copper and connect it to PSU ground?

Regards,
Ipanema

[Upupa Epops]

Hi Ipanema, you can jump with " 0 R resistors " at every positions, where you have crossing of two lines. And I say again, use for every outlets from PCB screwing terminals, NOT soldering points .

[rmgvs]

Atot,

you state in post #68 that you tried the Monstre with bipolar inputs (instead of sj74/sk170) after some redesigning. Can you show us the circuit of that redesign? In what way did it sound different than with the fets?

[atot]

Hi!

Here is the schematic of the BJT input version.

Due to the smaller output impedance (1.3Ohm) of this version, the bass is less with my speakers, that is the main reason I preferred the FET version. I have to admit that I did not make extensive listening tests to compare the FET and BJT input version, so there can be more difference in sound.

[edl]

That's like Canopus amplifier.

[plovati]

Me too have lot of difficult to find some replacement for original Hiraga amplifier. In particular th hig gm input fet that are critical for results seems impossible to find.
Here my list of equivalent (first item of each group is the original one). Any suggestion on equivalent?


POWER NPN 50V 7A 60W 15MHz 2SD844 TOSHIBA
POWER NPN 50V 7A 60W 15MHz 2SD1063 TOSHIBA
POWER NPN 50V 7A 60W 15MHz TIP35A ST

MEDIUM PNP 2SB716 TOSHIBA
MEDIUM PNP ~MJE350 ON SEMI

SIGNAL NPN 2SC1775E TOSHIBA
SIGNAL NPN ??

JFET NCH 2SK170Y TOSHIBA
JFET NCH 2SK364 TOSHIBA

SIGNAL PNP 2SA872E TOSHIBA
SIGNAL PNP ??

JFET PCH 2SJ74Y TOSHIBA
JFET PCH ??

MEDIUM NPN 2SD756
MEDIUM NPN ~MJE3440 ON SEMI
MEDIUM NPN 2SC2632 TOSHIBA

POWER PNP 2SB754
POWER PNP TIP36A ST

[plovati]

Sorry, I realized that there is a 3D more pertinent, devoted only to the Monster. I moved the post here:

http://www.diyaudio.com/forums/showt...698#post714698

[tlf9999]

Originally posted by atot
Hi!

Here is the schematic of the BJT input version.

here is my implementation of the BJT version, with MOSFET at the output.

What I found is that you can bias this thing into class B. However cross over distortion starts to creep up when bias goes below 350ma (you can go lower with a bjt at the output).

I would say 750ma and up is better.

R5/R8 are trimmers for biasing and output DC adjustment. R10/R7 and R9/R6 for gain, R14/15 can be omitted or dialed up to 10k if you use BJTs at output.

[tlf9999]

BTW, if you don't need as much power, you can use mosfets with lower gate capacitance (irf510/9510, or even bjts) and this will run a lot smoother and faster.