unusual single ended triode amps

http://www.diyhifisupply.com/diyhs_joplin.htm

 

This one's unusual



All the rest are the same really.

Nice to see Antonio is thinking of buying a proper SET

 

LOL i was wondering when you post a picture of one. Good call.

 

A wonderful excerpt from the review by the late great Gizmo

 

I've no doubt whatsoever it will sound stupendous!! - looking forward to hearing it a lot!

..it does look like however ..can I say 'utilitarian'?

 

Are they 811's Mike?

 

I am always open to innovation, but not that, it is not a proper SET...

 

That one is Murray- the one I'm hoping to get is one of the few that were built with 300b's.

It should sound very much like my ZH270 on low feedback but with a much lower noise floor. All I need then is a micro Zotl for the ET-703....

 

Is it fair to call an amp where there is a transformer between the tube and the output 'output transformer less'?

Paul

 

Theres nothing wrong with the 811 if set up nicely. It's a good sounding valve and a deal cheaper than a 300B!

Do you mean the centre tapped filament transformer or some other transformer Paul?

 

That will depend on what you consider the job of an output transformer to be I guess Paul.

 

out of curiousity and not only addressing well protected berning amps - OTL amps directly into horns, does that smell of trouble (and burn)?

 

Ive seen a number of valve amps go pop, blow, and catch fire. I have yet to experience that with a Berning.

With OTL poeple think lots of output devices running a 100% all the time multiplying the chances of unreliability massively. Think Flutterman - most people do.

All these things are not an issue for the Berning design - tube lives of between 10 and 20 years are to be expected and there are a number of protection circuits. I managed to short one channel on mine repeatedly for about four hours on and off. Not a jot of damage to amp or speakers. Try that with some Chinese box of tricks.

 

I think it is disingenuous.

In the Berning designs the circuit that includes the speakers also includes transformers and mosfets. The circuit the other side of the transformers includes the tubes. It's not what Murray would recognise as SET. It's not 'OTL', the 'Zero Hysteresis' designations make more sense.

I'm sure it's a fine amp, although it does have audible distortion and enormous complication. When I've tidied my Quad IIs perhaps we should try them out, proper Class A low distortion valve technology...

Paul

 

You can call it whatever you like Paul. The main thing is how it sounds - not what it's called in my opinion.

This is how DB apparently described its operation at one point:

The Mosfets and transformer operate at 250khz. As I would take the accepted meaning an output transformer to be an audio output transformer, I would have to say that the Berning circuit clearly does not have one - so is output tranformerless. But if you would prefer to call it something completely different then that's fine with me.

I look forward to hearing the Quads - hopefully driving the electrostatics.

 

Mike, where does the current come from to drive the speakers?

 

From the primary of the impedance converter bridge transformer - but that is operating at a fixed ultrasonic frequency (250khz)- not at variable audio frequencies as required by valve amplifier output transformers.

And before we get to the next question about Mosfets in the converter bridge- it's the valves transform characteristics that are perfectly mirrored at the output, not any modulations caused by the switching Mosfets or distortions brought on by a normal output transformer.

Let's ask another question. Markus, are audio output transformers fixed frequency?

 

Do transformers have a frequency?

 

Are they designed with frequency in mind?

 

My 2 Chinese box of tricks never went pop, like your great western valve amps...

Also, myself and a number of others, would never buy valves if it wasnt for those Chinese boxes of tricks...

If the Berning was that good, wouldnt it sell more than, you know...