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In the Forum: Melquiades Amplifier
In the Thread: Fun with transformers?
Post Subject: Ari Polisois’ Direct-Coupled SimplexPosted by Romy the Cat on: 3/30/2006

 Resorob wrote:
I realise that this is a very old post, but you might want to take a look over here=>>

The article can be downloaded as PDF, the writer Ari Polisois developped a new kind of transformer called SC OPT "Self Compensating Out Put Transformer". This could be a unique transformer and  maybe it can handle the full range at full power. In any case I have never seen a similar transformer.

The SC OPT has three windings, primary, secundary and tertiary the tertiary winding compensates for the dc current running through the transformer to the power tubes. Since this magnetism is compensated for, practically the whole core is available for the music signal, maybe Ari Polisois can better explain. Should you want it you can reach him at:
Rob, thanks. I have seen the Ari’s SET a few years back and I believe it should be somewhere in my links.

I did not see anything special about the out transformer, at lease in the papers that I read. Also, even if I did see it I’m not convinced that I would be qualified to assess the effectiveness if what Ari offers as it all should be heard.

Regarding Ari’s amp. I would do the input choke filters and beef up the power transformer in the output stage. I do not know how about the Ari’s driver stage. The tube he uses is fine tube but how 2 series halfs of this tube might sound? It should be tried and assessed. Unfortunately Ari does not writhe a lot about sound. It would be interesting if Ari try in there one Melquiades’ 5E5P. Also, Ari for whatever reasons chose to drive the 6C33c too hard. i do not know why but I presume he has his reasons…

Anyhow, the most important subject in the Simplex amplifier is the Direct-Coupling. This is quite competed question and it is not as simple as people usually fill. The logic that the best capacitors are not capacitors is not really applicable in this case, although it is true and the quality and type of the coupling capacitors are hugely important.

You see, there is something that I call: the “Tactical Sound”. The Tactical Sound is the separate inflictions of sounds the different caps inflict to Sound. Also, there is something that I call the “Strategic Sound”. The “Strategic Sound” is not depends from “the sounds” and more relates to the robustness and function of Sound in it’s entirety. The “Strategic Sound” very little depends from the coupling caps or from any other sounds polishing mechanisms but rather form the general topology of an amplifier. The coupling caps unquestionably affect sound negatively (and this why the Melquiades uses the Cubes 950) but the coupling caps (or any other DC blocking between the stages) does affect the “Strategic Sound” in very positive way.

I am not convinced in what I am proposing as I am sure that there are different direct-coupled implementations and I did nit heard all of them. A few years ago Vladimir Lamm published a quite interesting article in Russian magazine about his M1.1 amplifier where he mentioned about his research in the subject of direct coupling and his observations about the negative effect it had to Sound. That article made me to think about it further and to look very careful at my very certain reactions when I hear the two stages direct couple amps. Generally I would concur what Lamm proposed in his article but here is the problem: all my auditions were not “clean” experiments, methodologically speaking. I heard a few (perhaps 3-4 amps) but all of them were “built and closed” amps and there are a lot of other thing in those amps that might very much offset the auditable results. I never had an opportunity to have two stages and then, by building different PS supplies to compare the Tactical Sound and Strategic Sound of direct coupled, C- coupled and perhaps the transformer- coupled.

I know some people who do it and they shared their observations with me. I was not pleased with the level of those assessments as people told me the stories about the Sound but not about Sound. So, the main question in the Ari’s Simplex is: was the direct-coupling a good or bad thing. Unfortunately Ari did not provide any reference point in order to demonstrate the level of his assessments. All that he said was that the Simplex has an “Excellent sound” and it is defiantly too simple statement.

Romy the Cat

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