Despite the tremendous popularity of the single-ended amplifiers have a certain group of audio people, let to be honest: the SETs do not sound REAL in audio people’s listening rooms. I was in many of those listening rooms and have heard many best SETs out there. Yes, SETs are wonderful “washy-washy modifiers” but they NEWER self-inclusive. SETs frequently have no real dynamic, no serious bottom octave, severely deficient lower harmonics content in midbass, frequently they have rolled of high frequency, very frequently sound too slow and transiently challenged.

Depend of the tubes they use, the topologies, feedbacks and many other “tweaks” the SETs sometime resolve  (deceive or mask out) one or another limitation but they never “have it all”. In addition, the SETs most of the times are low power and used with high sensitivity loudspeakers (mostly very poorly and mistakably done). Some people also mistakably attribute some benefits of high sensitivity and even the benefits of compression drivers to the “SET Sound”. However, the reality for the SETs is ways less attractive, and particularly if to be honest with what we are hearing and listening.

I know people who told me long stories about the ingeniousness of thier SET that go flat at full power down to fractions of cycles and that their SETs are capable all-together DYNAMICALLY PROPERLY reproduce a full audio range. The realty always was very far from thier words. During the actual listening thier installations were not able to reproduce dynamically properly anything below 60Hz-70Hz and if thier systems even tried, then the 2-3 bottom octaves were juts (as far as I concern) the distorted LF noise. I love to hear all this stories about the exotic transformer cores, exclusive “never could be found” power triodes, unique biasing techniques, the smart sectioning and kinky winding techniques of the output transformers. I am a gullible person and I believe in anything… but you demonstrate to me a credible result first! It never had happened and if the attempts were made then the results were good enough only to impresses some kind of idiot-reviewer along with his/her childish audio publication. Even the best SETs I have heard (ironically, but it was the commercially available pre-2001 production of Lamm ML2, slightly tweaked and with over-dumped output stage) were quite far from what I would expects from “better” SET.

I am not advocating any topology, power tube or anything else specific. Instead I am bitching about the entire family of amplifiers – the SETs – the amplifiers so severally restricted by the non-resolvable compromises in output transformers that those compromises make the SETs kind of  “give or take” amplifiers….

Well, the answer the the SET dilemma is laying right in surface and only Got in Her ultimate Feline wisdom know why what I’ll be proposing do not used extensively in audio. The REAL, problem-free single-ended amplifier might be ONLY dual channel single-ended amplifier when one channel care lowers frequency and another channel cares higher frequency.

For instance:

Take a pair of any of the SETs that you like (if you do) and drive with one monoblock your HF channel. Take another monoblock (use the very IDENTICAL MONOBLOCK – this is VERY essential) and drive the output stage with non-regulated high-current capable source with LCRC filter, having the last capacitor of enormous value. Then get for this monoblock a slightly overdamped single section transformer with quadruple inductance of primary and dual-triple spare in current. Drive with this monoblock your lower frequency section (also it would be very simple to run a low pass right here if you wish). Now you will be hearing the full range Single Ended Sound in the way how it meant to be! This you will have the REAL dynamic and the real harmonic content of SET topology that will not be screwed by the typical single ended hypocrisy…. 

If you try it then you would probably will be laughing like I do when people talk respectfully about sound of Single Ended amplifiers coming from a single channel. A one channel “full-range” SET is a victory of desires over senses, nothing more or less. Do you remember a story how a Korean police officer was convinced under hypnoses that he should not eat his K9 because he is not Korean anymore but a Jew? Do you remember how that guy was looking at his dog and telling himself that it was not a dog anymore but a Gefilte Fish? This is what the audio people do when they feel that a single-channel SET sounds acceptable….

Nothing further could be said,
Romy the Cat