DoSuSy - LTspiced project. Comments?

[anli]

Will be glad to see your comments:

http://freedns.ru/andrew/dosusy/DoSuSy-0.11.4.pdf

Andrew

[anli]

Well, there is short page in russian for the project. But there is
the only table with measured harmonics, and this table is
international :-) It's here:

http://freedns.ru/andrew/dosusy/index_en.html

Edit: This page is now translated in English.
/Hugo - Credits to Janneman

Andrew

[anli]

Hi, All!

Probably some additional comments are needed (many "Views", too few "Replies").

Background:
I have not DIY-ed during rather long period, about 8-10 years. A week ago
I didn't know anything about spice modelling at all.

The aim:
Cheap but musical amplifier. Well, anybody wants it, I see :-)

Will be appriciated:
I'll be very happy to see your comments concerning

- possible schematics drawbacks,
- possible realisation caveats and traps.

There are rarher simple difficulties, like a selection of bjt model for
current sources in preamp-driver stage (well, do you remember? - only
a week ago I have discovered spice modelling. There are too many
parts around... Own spice models library is so small...). And there
are more serious problems, for example, frequency correction.

Schematics:
It is very simple. I'll be glad to answer your questions. Probably,
I must say about schematics part which is right hand of output stage.
The aims of this part is:

- make both current source currents equal (there is feedback from output
stage to differential stage, you see?),
- set (this is class A) these current sources current value.

With hope to get your feedback,
Andrew

[Netlist]

Hi Andrew

I really think that your effort deserves more feedback.
It looks like a very interesting but complicated (to me ) approach.
It’s a bit annoying that we can’t understand the Russian text at your site.
Perhaps you could do a little effort and translate the important parts in an English page.
What about moving this thread to the Passlabs forum?
After all it’s about Nelson’s SuSy if I’m correct.

There you go, a few ideas to get the ball rolling.

/Hugo

[Real_Macgyver]

The distortions values looks really great, if it also sounds good than its a hit!

[anli]

Hugo,

OK, I'll try to translate to english my little page. The problem is I'm
not familiar well with schematics terms, so, please, do not be angry
with my translation :-)

Is it right way to move to Passlabs forum via mentioning this thread
and giving a link to this new page (and mentionig here about new
created thread)?

Andrew

[Nelson Pass]

I think it's a very clever design.

[anli]

Nelson, it's very pleasure to see your (even brief) positive feedback, thanks!

Andrew

[john curl]

Congratulations, Anli. You have made a power amp that is interesting to even experienced designers.
I might point out a few things: First, I understand the common mode latchup problem. I made an amp with the same input stage (with transistors only) back in 1969. The first thing that it did was latch up! I, too, had to put in a common mode servo to fix the problem.
A year later, I tried to feedback to the emitters(sources) rather than the gates, and the common mode latching went away. Most of my designs, since then, have been with emitter or source feedback.
If you think that adding source resistors (10ohms or so) to your input devices might limit you, perhaps you should find a higher Gm fet, such as the Fairchild IRF 9510, rather than the 9610 to make up the difference.

[anli]

John,

Saying "latchup" - do you mean a process just after turning supplier on?
(I warned about my poor knowledge of terms :-) If it's so - OK, I'll
try to analyze first second behaviour.

And I'll try 9510/510 instead of 9610/610.

As for sources resistors... Well, preamp own gain is about 35 times only
(it works with rather high current and low load resitors - to recharged
output transitors gates quickly). So, at any point, I see a problem in
introducing such resitors. I need some time to recognize and answer
more defintely :-)

Andrew