Simple Symetrical Amplifier

[Samuel Jayaraj]

Lazy Cat, it would certainly help if you could also post the biasing circuit and the full schematic of the BIGBT version. Building, comparing notes and observations, both actual listening and simulation would become easier and practical. Thanks.

Nico, great work as always.

[Nico Ras]

Thanks Sam.

[Lazy Cat]

Originally Posted by bogdan_borko

It`s a Hawksford LFD preamp concept, but nice circuit anyway.

http://www.essex.ac.uk/csee/research...D%20preamp.pdf

Originally Posted by Lazy Cat

I see So nothing new on the planet Earth, just fun continous

Thanks for the link, I see it for the first time, but who would believe me.

[Lazy Cat]

Originally Posted by Samuel Jayaraj

Lazy Cat, it would certainly help if you could also post the biasing circuit and the full schematic of the BIGBT version. Building, comparing notes and observations, both actual listening and simulation would become easier and practical. Thanks.

Nico, great work as always.

Yes I know it would help, but all circuit is so simple that by reading this thread, you can find all the parts posted and like LEGO you can easily connect them to mine version.

Will do that when come back to the cockpit from the vacations. Enough hand drawing for now.

More about BIGBT's in this thread:

Balanced IGBT for amplifier output

On the pic you can also see what is possible to get at the output of my simple symmetrical amp with BIGBT's incorporated.

[Lazy Cat]

This graph Nico got from sim is somehow related tu upper plot or am I wrong.

[Nico Ras]

Lazy Cat, it may be placebo effect, but I think that the Lateral MOSFET with transistor driver sound better subjectively, it is slightly better balance overall than your half IGBJT but hard to tell for sure, I have issues whith getting the bias quite right on the IGBJT,

My last test that shows a definitive difference by making a synchronized recording of both topologies on either channel of the storage scope and perform X - Y, Although they sounds in many ways, the difference on the scope jumps out at you as being radically different.

On my version all the harmonics are present but in much lower amplitude and causes a very smooth transition between notes. In your latest suggestion you have predominant but much higher even order products and sound warmer.

My humble conclusion is:
1st Circuit a little harsh, clean and highly defined.
2nd version with BJT driving Mosfet is totally neutral sounding a little laid back and relaxed
3rd version with MOSFET driving BJT sounded very warm and even too relaxed drum boom but not thud as with the previous two. Although sounding great, it is difficult to split a big bass drum from a low electric bass, on the other two this definition is more easily detected.

Make of my findings what you like, it is subjective. Same set-up, same music piece, slightly different experience,

The fire-walk will be is to set-up and blind test the three topologies and try to establish which has the broadest i9mpact on the listener. Because we are from different cultures our experience will differ thus may I suggest we do these tests on each side of our world and compare the outcome - subjectively of course when we reach a conclusion. We stick with the version that indicates to be most acceptable and offer this as the BETTER THAN GOLDMUND, I think that one of these three topologies will topple that throne.

[Nico Ras]

Originally Posted by Lazy Cat

This graph Nico got from sim is somehow related tu upper plot or am I wrong.

Yes it is. Here is BJT driving MOSFET

[Nico Ras]

Nico signing off, Thanks Lazy Cat and others for your contribution, this was an interesting experience and will lead to something radically different from what are normally seen here on DIY Audio.

[Lazy Cat]

Excellent job Nico, hats off.

I agree completely, cause it is much simpler to say: OK we have the best version, let's do it, bang boom PCB that's it.

But no, we will certainly perform listening test, like you said in different cultural environments and pick the winner. I like the idea very much Nico.

By reading your post one idea fallen on the top of my head, what if BJT+BJT would also be the one to include it in the test and rule out the first one which incorporates only mosfet (1st Circuit a little harsh, clean and highly defined). So the 1st is now BJT driving BJT, this one could have all the goodies from the 2nd 3rd. Agree?

All in all the basic circuit inside current feedback loop proven to be stable in all three versions and can be easily adopted as universal to many more complex circuitry including current sources/mirrors et cetera.

And finally, yes BETTER THAN GOLDMUND is going to be.

[Lazy Cat]

Originally Posted by Lazy Cat

This graph Nico got from sim is somehow related tu upper plot or am I wrong.

Originally Posted by Nico Ras

Yes it is. Here is BJT driving MOSFET

OMG speed and stability, that's the way we like it.

So quite obviously for now BJT driving mosfet is in the lead, considering listening tests and sim performance.