Hiraga "le monstre"

[colin.hepburn2]

Originally Posted by colin.hepburn2

Boy you guys like to confuse a beginner
Are you saying none of the transistors I have listed will work with the schematic I posted could you pleas just post the part numbers I require for
Q1
Q2
Q3
Q4
Q5
And suggest a good transistor for Q6/7 in place of the 2N types
And if you can do the same for the updated version that uses the BC550C/560C transistor
This will give me Better choices on which one to build I think this will be much easier than talking about comp pairs that are not used but I have taken note of all your posts which will help in understanding the different transistors Valves are must easer
Thanks

No this is the Schematic I have which is the HK version

[lineup]

THe tricky thing is to find the JFET pair.
Once you have 2SK170 and 2SJ74,
then there are a number of different you do well with for the other.

First, Q1, Q5, cascoding, is not at all any trouble. Most any TO92 will do.

Power transistors, Q6, Q8, could be MJL3281/1302 or 2SC5200/SA1943.
The reason is that I think those have good gain + low sat (saturation voltage).
Saturation is how much at least voltage a transistor needs to run a specific current.
If we use power transistors that needs high sat voltage, in this amplifier,
we 'steal' away from the only 12V we have to swing with.

Q4, Q2 I see as the critical choice.
They do a very important job, driving the big power transistor.
They should be small transistors that can do well at, say, 10-20 mA.
I would feel better to use BD139/BD140, than to use BC550C/BC560C.
Better also than BC550C/560C is also 2SC2240/2SA970,
if I am correct in that above 5-6mA BC550/560 are not at their best.
At least not as good as 2SC2240/2SA970 when it comes to currents above 10 mA.
My simulations shows an idle current like 9-10 mA for Q2, Q4.
This should be okay for 2SC2240/2SA970, which have low power/heat limit.

There are also TO92 variant of BD139/140 called BC639/640. Specified 1.0 Watt
One weakness with 2SC2240/SA970 is power limit only 300mW.
Otherwise they are fine.

Hope I did not confuse you even more.
This was my thinking.
I am sure there are other fellows that can tell you better.
That know more about and have built.

[colin.hepburn2]

Originally Posted by colin.hepburn2

No this is the Schematic I have which is the HK version

NO read the post

[colin.hepburn2]

Originally Posted by colin.hepburn2

No this is the Schematic I have which is the HK version

Right I will try again Can you just verify if the following is correct and advice on best ones for Q6/8 thank you pleas don't give number that don't apply to this schematic that just is confusing thank you
Q1 2SC1775
Q2 2SD7567
Q3 2SK170BL
Q4 2SB716
Q5 2SA872
Q6
Q8

[gaborbela]

Hello
Every schematic use the same transistors and JFets. Do not be confused!
I answered to your question in my last post , please read it .
There is no reason to write about Q1 you wrote they don't have (out of spec mean fake)
If you don't get Q1 , U can't use Q5!
For Q3 2SK170 OK only if you get for Q7 2SJ74 and bot have to have the same grade (BL,GR,Y type)
Q2 is a mistake!
Greetings

[gaborbela]

Hello

I would like to ask for help. I have a need for 2PC 2SC1775 hfE between 400-450.
I have at least 35PC 2SA872 but all has hfE between 400-450.
Also I have some 2SC1775 much higher hfE 500-650.
I would like to buy 2PC 2SC1775 with right hfE or I'm willing to trade with 2SA872.
Guaranteed orig Hitachi part I have and also I would like to get.
Greetings

[gaborbela]

Hello
Here is a schematic for the mosfet Hiraga le Monstre amplifier.
I have a question , to mi it look like the 1R 5W resistor value to high.
Usually with lower value resistor all amplifier tend to sound better . Of course it have to be readjust the current.
My question if I use R47 that would made the amp unstable??
Did someone ever tried to use lower value ?
Thanks
Greetings gabor

[neazoi]

hello, At last finished the construction so I need to set the bias now.
First of all how to set the 100ohm potentiometer? at the middle point??

I power the le monstre from patteries only, do you know a good bias point so then the batteries go from 13v down to 12v the amplifier will still operate in class-A?

Thanks

[njepitt]

Originally Posted by neazoi

hello, At last finished the construction so I need to set the bias now.
First of all how to set the 100ohm potentiometer? at the middle point??

I power the le monstre from patteries only, do you know a good bias point so then the batteries go from 13v down to 12v the amplifier will still operate in class-A?

Thanks

Hi,

People more knowledgeable will correct me, I hope, if I am wrong, but the 100R pot is to adjust DC offset, not to set bias. When I built this amp I put it in the middle to start and then adjusted it to get DC offset as close to zero as possible.

You could probably adjust the bias by changing the 1R resistors on the output transistors, I guess, but I'm pretty sure the amp will operate in class A at 13v or 12v as it is. (Or did I misunderstand your question?)

Cheers

Nigel

[gaborbela]

Hello
My first question to you the power supply voltage .. If around 12V and you use GR or BL type JFet better to use 2x1K trim pot instead the 1K resistor .
The 2 piece 1K resistor set up the bias.
To me when I used 12V and BL type JFet 470R was OK to set up the bias around 1A.
That is the reason at first U use 2pc 1K trim pot (variable resistor) And adjust to the half both.
If you need higher bias increase the resistance . If you need lower bias decrease..
The 100R trim pot is for the offset.
After you set up the right bias you can replace the two trim pot..
Greetings