Hiraga "le monstre"

[Sigurd Ruschkow]

JLH = John Lindsey Hood and not Hiragas amp.

Output impedance for the le Monstre is a few Ohms.


Sigurd

Originally posted by lineup


Lumba.
You should really have a read on a Nelson Pass paper from 2005.
.. unless you have already studied this great paper
See his investigation on feedback factor, in 4 rather classical amplifiers.
JLH is one of them.
I have attached a little teaser image.

Go download at www.passdiy.com
The PLH Amplifier: The classic JLH - Pass style

Then you thank me, lineup, for telling.
But most of all give a nice thought to Our One and Only Nelson.
For doing a good audio work .. and sharing it with us

[Lumba Ogir]

HKC,
The bias currents:
Input 1mA
Output 500mA

Sigurd,
nice to have you around. Thanks again.
Would this work?

[Sigurd Ruschkow]

Lumba,

I have attached my le monstre file. To use it in MicroCap
just rename the file to *.cir
and you can play with it, and also add your own ideas
as you have another 25 components to add to my CIR before
the evaluation version says stop.

Enjoy!



Sigurd

Originally posted by Lumba Ogir
HKC,
The bias currents:
Input 1mA
Output 500mA

Sigurd,
nice to have you around. Thanks again.
Would this work?

[lineup]

Originally posted by Lumba Ogir
HKC,
The bias currents: Input 1mA Output 500mA

Hello there.
Looks like another guy did the job for me. So I wont have to simulate and find out feedback factor

Now.
Almost any classical amp, is around in several variants. Often with some exchanged, 'more modern' transistors. We see designers make Revised versions. This is not the first, original version. But often improved in some way.
I refer to such a new variant. And this is what I will do, further in this topic.
Because, if I built Le Monstre, there is no way I would be able to use the original devices, anyway.

It is this new version I mean. With 2SK246 / 2SJ103 as good new substitute JFET pair.
Hiraga Le Monstre - Suggested new transistor substitutes.
Even if the numbers, currents can/will be different for the original, my advices, as method, can be used for any Le Monstre version. I mean what factors will determine the idle currents in output stage.
As I mention in a previous post


Also, without knowing the original current,
I suggested an initial value of 1.0 Ampere for 8 Ohm speakers.
It seems a good value to start with .. and can be increased later, when we got everything working and want to try with more current.

Sigurd suggests 2.5 A, which seems a bit high to me. Of course for speaker Z dips (downto 4-5 Ohm) and for 4 Ohms speakers we can really need this high currents.
What me and Sigurd agree on, is that the original 0.5/0.6 Ampere is a bit low. At least for modern speakers and operating at the higher end of the power (say 5-7 Watts RMS/8Ohm), and that peformance probably would be better with a bit more current.

Originally posted by Lumba Ogir
Would this work?

Can you explain your idea more, Lumba.
I do not get it from your image.

lineup

[Lumba Ogir]

lineup,

I would think that this 2SK246 / 2SJ103 version is really by Hiraga. But I do not know.

You do not know.

Sigurd suggests 2.5 A, which seems a bit high to me.

It`s fine...for a while.

Can you explain your idea more, Lumba. I do not get it from your image.

I blame the software.
It is an attempt to linearize the driver by increasing its emitter resistance.

[lineup]

Originally posted by Lumba Ogir
lineup,
I blame the software.
It is an attempt to linearize the driver by increasing its emitter resistance.

I see.
Yeah, the optimal value can be different, at different output levels + different loads (normally I do not use pure resistors for load, when I listen to my amps)

Nelson Pass puts it like this:

There is a sweet spot
for a every transistor in a given circuit.
For a special job to do.

This means an optimal resistance to set the 'best' average current of operation.
Such a resistor is almost always a compromize.
For the best operation at low levels of output and a high.
For normal (1kHz)audio frequencies music and for higher frequencies.

When designing such a blameless, good compromize amplifier
that will work with good quality in many situations,
it may require a bit of tweaking up & down, until finding 'the optimal compromize'.

lineup solen lyser här i norra sverige nu, Lumba!

[Sigurd Ruschkow]

I actually have used 2.8 A at 20V rails for a long time and as long as one has proper cooling, there are no problems.
I do use a 350mm long heatsink with 3x 80mm mains powered fans for a stereo setup. See attached image.

I tried your idea with degenrating the drivers, Lumba, but distortion increased.



SIgurd

Originally posted by Lumba Ogir
lineup,

You do not know.

It`s fine...for a while.

I blame the software.
It is an attempt to linearize the driver by increasing its emitter resistance.

[Lumba Ogir]

lineup,
an emitter resistor is the simplest linearization technique, although very effective, proved by listening tests, the only test method I trust. It`s extremely reliable and relevant.

[Lumba Ogir]

Sigurd,

I tried your idea with degenrating the drivers, Lumba, but distortion increased.

That`s a very good sign, THD rises as it should.

lineup,
start planning for the implementation!

[HKC]

Originally posted by danieljw
hello people

I just built "Le Monstre" using origional transistors
tried it last night.... I have to say the amplifier sounds really really good
has any one else tried it ???

pictures to come.

-Dan

Hi Daniel

Would you please tell where did you get the original transistors for Le Monstre? I tried to order from MCM Electronics but they do not ship parts outside USA.

Best Regards