Hiraga "Le Monstre"

masag1,
I would try to avoid that capacitor, would rather reduce the resistor value from 220 to 100 Ohms (or more).

LuYit, you are totaly wrong...
Reducing the FB resistor will increase overshoot.
Either increase it, but then THD rise, or compensate by paralleling
it with a cap as little as possible connected in serial with a resistor...
 
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wahab,
this is an unusually pure, fast and stable design even with heavy loads without polluting capacitors in any location, I would not worry much about overshoots.

Overshoot ( ringing ) is very much a stability problem, being only 8 watts it is not a big deal , like a small fire cracker going off when the smoke come out :p


Wahab:

Does the actual measured response look the same as your sims ?
 
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Here's a small ringing at 160KHz (sorry about picture quality ). It was measured in test version where output transistors connected to PCB with wires.

DSC06923.jpg



According to some books this output type may have a slight degree of instability.
I will try to repeat measurement in final version.
 
masag1,
what´s wrong with polystyrene? Have you actually used the 2SA1407/2SC3601? What have you learned from building 10 amps?

What I have learned?

The 8Watt is very easy to build, and a stabile, reliable amp. My first one is 18 years old and still working in my equipment.
I never had to readjust offset. The only thing was to resolder the joints, yeah, 18 years of work do some changes in the crystal structure of the solder.

All the other 8 Watt amps are still working, giving fun to my friends.

Using the 2SA1407/2SC3601 as drivers allowed me to reduce the compenstion cap frm 2nF to 1nF, but sound was not sufficient, maybe we have to adjust the currents.

We are in work with a vesion, that has an CCS at the input. So we don`t have to look for the GR Idss J-fets, and we can play with the current.

Regards

Sam
 
Here's a small ringing at 160KHz (sorry about picture quality ). It was measured in test version where output transistors connected to PCB with wires.

DSC06923.jpg



According to some books this output type may have a slight degree of instability.
I will try to repeat measurement in final version.

Oscar can you show @ 20 ,1K,20K, 50K, 100K it would be interesting to see square wave response in the audio band.
 
Hi Osscar, can you try this ? Thanks.

After a two-night listening, I can tell you something, compared with F5:

Thanks for your comparison with the F5.
I was curious. Have you compared it against the LM1875 ? levels have to be matched . You can even use low voltage mains hum as a signal source and measure the levels on both amps with a DMM. Quick and dirty way of doing this. You have to make sure you don't clip the 1875.

Can you please try this and let us know ?
Thanks.
By the way your LM1875 implementation looks great !:up:
 
Hi and tnx;

Unfortunately, the LM1875, I practically do not use - it's more like a interior design element. This LM 1875 sounds almost like LM 3875 ( which I listen to quite often ) they both are very similar: sounds a little harshing and not so detailed like my class A amps, but it is a matter of taste and of course chipamp cost.

regards

Oskar
 
unfortunately I can not put a normal 20Hz square signal, because my generator cant generate clean 20Hz wave :( sorry.
but instead I measured the output voltage at normal listening volume- its below 1V . When playing a very loud - output around 2.5V. ;) with 8 ohm 93db speakers.
 
@neazoi

Was looking to your homepage.
Very impressive, your batteries:D

Do you still feed your 8Watt directly from a minidisc- player?

Try a buffer between minidisc and 8Watt.

I have used a CD-player first then a buffer and now the FF2010 linestage from Joachim Gerhard (serach for Mpp Thread)


There is still potential to tease out of the 8Watt

Regards

Sam
 
continue to compare the two A-class amplifiers ( F5 and Monster) :

DSC07152.jpg


multimeters for dc offset and bias control.

My women prefer a monster, but for me its have too many basses, F5 is more sharp and transparent like a Knife . Scientists say that old men of the age remain insensitive to high F :D


I like both of them :) F5 v& monstre

P.s.
Wine is also DIY from red grape, very strong ,decibels to be multiplied by 2 :D