[Steve]

Do you have some photos Steve?

Here is a photo of one test chassis sitting in storage. The toroid is a custom wound, dual winding filament transformer.


cheers
steve

[FullRangeMan]

Thanks Steve, these top cap tubes looks great

[jeffreybehr]

Atma-Sphere makes excellent-sounding, RELIABLE OTL amps.. I've had several pairs and currently am enjoying a pair of MA-1-(3.1)s to drive my Serenity Super-7s.
http://www.atma-sphere.com/Products/#MA-1



These amps run VERY well with fewer-than-original number of output tubes.. While I'm heating the house I use four pairs (rather than the original seven pairs) per amp, and while I'm cooling the house, three or even two pairs.. Of couse, maximum power is lower and output impedance is higher with fewer tubes, so using fewer tubes goes only so far.. These amps have FAR more power than my 96dB-sensitive Super-7s...
https://www.audiocircle.com/index.php?topic=141060.0
...require, but having 140 Watts (max. into 8-Ohms) available increases flexibility in choosing speakers--in case I ever go (more) insane and buy a pair of Revel Ultima2 Salon2s.         

[kentajalli]

I just stumbled on this .
I do have a pair of monoblock OTL power amps (circlotron) , it can use 4x6C33C output tubes per side - but I use only two - OK it gives less power, but somehow I prefer the sound.
To cut the crap here is my take on them:
- They are problematic - at times they are noisy and I can not find the cause - they can be unstable but not too much - need to keep a constant eye on them.
- compared to standard tube amps (with trannys) - they are not polite! - they don't sound soft and restricted. Bass goes so deep, it annoys the neighbours and treble is very life like, provided you have the right speakers.
- Unforgiving! - play shit through them and they play shit right back at you.
The best I can describe them is akin a top flight £20k+ solid state amp from some exotic brands such as Krell.
They do not sound like a tube amplifier, only the midrange does - fat and sweet.