Hiraga "le monstre"

[jeepy]

Originally Posted by Williams Audio

hi all,
yes it is expensive thing to be an audiophile, specially with class a pwr amps
but i do have the power supply from an older project so after assembly the monster i will send a report,
best regards,
williams

Yes please. Also I should mention that due the low damping factor of Hiraga's amps it may not work as well as some other topologies with MOSFETS ore more powerfull class AB, with electrostatic speakers. These amps reach the top of the best with big boxes (360 liters) like the 'pseudo' bass reflex Onken equiped with Altec 416, 415 or even 414 in smaller cabinets. Again, my thoughts!

[brixvold]

Originally Posted by lineup

=========================================

- Transistors in my May 2008 final version ( was doing this one day 1 month ago, 2008-05-31 )
input:
2SK170GR + 2SJ74GR .. IDSS is ~ 4-5 mA
... no problem using them without cascode, as 2SJ74 takes 25 Volt.
- But I added cascode at 6Volt level (half supply) with:
BC560C + BC550C
I do not remember, but probably this gives a bit lower distortion.
I usally avoid cascoding JFETs, unless I see there is some benefit from it.
- Second stage, drivers.
BD139 + BD140
Nothing mysterical. They are the best bang for buck drivers ever made and used in audio.
In this amplifier, Le Monstre, they will fit in very well regarding quality.

- Output transistors.
TIP41 + TIP42
I started out testing with MJ15024 + MJ15025 = TO-3 high power.
But these TIP41/TIP42 OnSemi devices performs better.
Probably because they have higher gain.
Rated 65 Watt and as they will only dissipate like 0.8 x12-15 VDC = 10-12 Watt for Class A,
there is no problem using these easy to find & budget price devices.
Lineup

And now I'm wondering what are you using in the 2013 version?
And could you recommend which PSU to build for this amp, is it preferable to use the original?

/Cheers from the other side of Kattegat

[Stee]

My idea is using Jfet bootstrapped
as Diamond input buffer
like first design

[Stee]

But these TIP41/TIP42 OnSemi devices performs better...
try 2SA1693 & C. (6A Ic)

[triode_al]

Originally Posted by Stee

My idea is using Jfet bootstrapped
as Diamond input buffer
like first design

Fun circuit.
You dont need the transistors above the input that act as a stable voltage source - they will amplify the current on the 1 k and hence destabilise the source itself on the 22k/22k divider.

[Stee]

OK but Jfet can't works with 24V

[Telstar]

Hiya,

I decided to build an headphone amp based on the Monstre circuit.

My starting point was the one published by kk-pcb.
Since I wanted much less gain (and lower distortion) I had to touch the feedback resistors. Therefore I chose slow and low-gain driver transistors (the fairchild pair with only 4Mhz Ft) and also added a little compensation on them. I hope this wont make the amp oscillate.

The input jfets are not matched which I have in my scrap bin, likewise for the BC. One heatsink per channel will be used, good up to about 10W.
The two resistors R14 and R15 are just to reduce the power dissipation of the output transistors within the dissipation alu available.

My goal was to keep a nice harmonic spectrum (mostly 2nd and third) and plenty of power/current to drive eventually even orthos, and without using exotic transistors.
I wont start building it before a couple of months, since I have other stuff on schedule, but the simulation looks promising.

PSU will be the regulated sigma22 which I use on most of my headphone amps, with 80-120VA transformer.

[masag1]

Good luck to your projects.

Which way you want to set the quiescent current?

Didn't you read some articles about this circuit?

Regards

Sam

[Telstar]

Originally Posted by masag1

Which way you want to set the quiescent current?

What do you mean by "which way"? If you mean how much, it's about 200mA per output transistor.

Didn't you read some articles about this circuit?

Yes, I read the original articles online and all this thread. I cannot use 12x gain to drive phones, therefore I had to do what I did.

If you think there are some mistakes in the schematic, please correct me

[masag1]

"Yes, I read the original articles online and all this thread. I cannot use 12x gain to drive phones, therefore I had to do what I did."

Why you have to use these large, slow output transistors? You only have to drive phones?

My opinion is, there are better solutions for a headphone amp in the DIY.

There is a pix of the last generation "Hiraga 8 Watt" from Klaus Scherm, Germany.
He changed drivers and output trans, and made a tricky setup with current sources for the input Jfets.

sounds great, and was successful at the poweramp shootout at the german "Frickelfest"

Endspiel/es02

Frickelfest 2012/hb/ff12_079

Frickelfest 2012/wl/1 (20 von 60)

Regards

Sam