The Ultimate Suplifier

[Marc Vi.]

Today I launched my new website www.suplifier.nl. In this website I publish an article called “the Suplifier” which I wrote more than 15 years ago in a Dutch electronics magazine. Based on the principles of the Suplifier and on new insights, I moreover release now "The Ultimate Suplifier": a balanced input, DC coupled, symmetrical, bridge tied load, class A amplifier with no global feedback using transistors.

I open hereby the discussions on the theoretical starting points and the circuit of “The Ultimate Suplifier”, which you find on my website. I saw recently some threads and many posts on the issue of the output configuration. In “The Ultimate Suplifier” I propose, beside other new improvements, a brand new output configuration.

May I invite you all to give your comments on the principles and the circuit of “The Ultimate Suplifier”.

Marc.

http://www.suplifier.nl

[mfc]

Hi,

Good work! Looks like we are thinking similiarly.

The output stage I see on your website is
what I'd call darlington-sziklai, whereas the one I've
been interested in of late (shown in the thread 3 Different
Outputstage Driver Arrangements, Your Opinions!) is
what I'd call sziklai-darlington. Both are similiar but slightly
different depending on which part of the circuit has the sziklai.

The second (sziklai-darlington) is similiar to the Blomley amp.

I wonder if there are others out there who have investigated
these combinations. Seems to be more linear than triple
darlington. How do you like the sound?

[djk]

I like your output stage, it looks almost like a straight rip of the Threshold S300.

http://www.diyaudio.com/forums/attac...amp=1024679649

[georgehifi]

This this a better look at the original S300 mkII optical bias circuit.

Cheers George

[Jan Dupont]

Hi Marc,
Congratulations with the website

I'm very courious to see what this thread will bring into the open about this interesting amp.....
I will hold my horses for a short period before making comments

Marc, you know where to reach me when time comes

[mfc]

Hi,

Don't you find that there is a limit to the number of
devices you can place in a local feedback loop? After
3 devices, the return (in linearity) levels off.

Mike

[Marc Vi.]

MFC,

I see a great difference between the output stage of the Blomley amp and what I propose. First the Blomley amp is no real Sziklai-darlington configuration. But moreover I think that an output stage must be only a current amplifier and for that reason it should be driven by the emitter of a transistor. As I see it well, the output stage of the Blomley amp, which starts with Tr7 and Tr8, is both a voltage and current amplifier.

I don’t understand your question about the limit to the number of devices you can place in a local feedback loop.

DJK an Georgehifi,

Yes, there is likeness to the output stage of the S300 MKII. I think that the emitter resistors R30-R41 will make the CFP work less well. Better is to place those resistor(s) in the collector as I did. But I understand why they did it this way. It is the only opportunity to place more than one output transistor parallel and to correct for the mutual differences between the output transistors. To my opinion it is not good to drive 6 !! output transistors by only one driver transistor. This must give much more distortion.

Marc.

http://www.suplifier.nl

[mfc]

Originally posted by Marc Vi.

...First the Blomley amp is no real Sziklai-darlington configuration.
http://www.suplifier.nl

Hi,

The Blomley has a sziklaii like the output stage (attached below)
not yours. Look at Tr8/10, Tr7/9 and mine Q2/Q3, Q6/Q5.

The similiarity between your output circuit and the attached is
that they have 3 transistors consisting of a sziklai and a
darlington in one case and a darlington and a sziklai in the other
case. The arrangement is different but a single stage is formed
from a compound of these two building blocks in both cases.

I see these "different" output stages being similiar. You can
call it different. I wasn't trying to start an argument about whose was better.

What I think these types of circuits do is provide more local
feedback then other configurations and can thus produce a more
linear stage. If you see something that I'm skipping over, please
elaborate more.

Especially useful for running in Class A with little to no global
AC feedback

Mike

[Marc Vi.]

Mike,

I do agree that a three transistor output consisting of a Sziklai and a darlington is more linear and is especially useful for running in Class A with little to no global AC feedback. In this way your last attachment and my configuration are similar. And they are similar in the way that the output stage behaves like an emittor follower. But the Blomley amp output stage is not behaving like an emittor follower because the output stage is also voltage amplifying, if I see it correctly. And that makes a great difference. And, as I see it, the Blomley output stage is not a real Sziklai/darlington configuration but maybe that is of minor interest. But I am quite sure that without global NFB the Blomley amplifier and it’s output stage has a high distortion.

Marc.

http://www.suplifier.nl

[Steven]

The Blomley output stage is in no way behaving as an emitterfollower. The output is actually a current mirror with gain. Without overall feedback the ouput impedance would be quite high (as is the case with current mirrors).
It is maybe not directly clear to everyone, but the diodes D1 and D2 are the 'input transistors' of the current mirror. Tr7-11 and Tr8-12 are the 'output transistors' of the current mirror. The gain of the current mirror is 1000, which is the ratio R20/R17 or R21/R18. Tr 4 and 5 are the phase splitter of the amplifier.
The open loop voltage gain of this amplifier depends a lot on the load it sees and changes with changing load impedance (like a loudspeaker).

The ouput of Marc's suplifier is behaving as an emitterfollower, and a quite linear one.

Steven