Guesstimate A Transformer

>"Does that circuit actually work? I guess it should, barring any DC
imbalance issues. "

I built about a half dozen amps with similar topology. They worked. In fact people would bring them back and say they went bad but in all cases they had blown the speakers. 

Those were common collector outputs, Darlington in fact and were driven by a 1:9 transformer from a normal speaker output of an amp. I am changing that because I do not want the input transformer and I want a normal feedback loop that I can control. I also want line level inputs. Tone controls. Things like that.

On 27.11.18 17:09, John Larkin wrote:
>> output transformer was a PITA, honestly.
> 
> That transformer allows the outputs to be emitter followers, and to
> get more voltage into the speaker. True, there are simpler ways to
> drive speakers... like buy a class D full-bridge chip.

So is a classic complementary-symmetric audio output stage.
What's the difference here?

The transformer adds a degree of difficulty to get the overall
feedback from the output to stay stable.

-- 

-TV

On Tuesday, 27 November 2018 15:28:33 UTC, Tauno Voipio  wrote:
> On 27.11.18 17:09, John Larkin wrote:

> >> output transformer was a PITA, honestly.
> > 
> > That transformer allows the outputs to be emitter followers, and to
> > get more voltage into the speaker. True, there are simpler ways to
> > drive speakers... like buy a class D full-bridge chip.
> 
> So is a classic complementary-symmetric audio output stage.
> What's the difference here?
> 
> The transformer adds a degree of difficulty to get the overall
> feedback from the output to stay stable.

and a nest of other issues. Output transformers were always the curse of valve amps. So try some PD500s & electrostatic speakers. 25kV 1.6mA 30W.


NT

tabb...@gmail.com wrote:

> 
> > The transformer adds a degree of difficulty to get the overall
> > feedback from the output to stay stable.
> 
> and a nest of other issues.
>
  
** All of which any transformer designer worth his salt knows how to deal with.



> Output transformers were always the curse of valve amps.


** You do love to exaggerate.


> So try some PD500s & electrostatic speakers. 25kV 1.6mA 30W.
> 


** Now doing that IS going " out of the frying pan and into the fire ". 


 

...  Phil 

On Wednesday, 28 November 2018 07:29:13 UTC, Phil Allison  wrote:
> tabby wrote:
> 
> > 
> > > The transformer adds a degree of difficulty to get the overall
> > > feedback from the output to stay stable.
> > 
> > and a nest of other issues.
> >
>   
> ** All of which any transformer designer worth his salt knows how to deal with.
> 
> 
> 
> > Output transformers were always the curse of valve amps.
> 
> 
> ** You do love to exaggerate.
> 
> 
> > So try some PD500s & electrostatic speakers. 25kV 1.6mA 30W.
> > 
> 
> 
> ** Now doing that IS going " out of the frying pan and into the fire ". 
> 
> 
>  
> 
> ...  Phil

You could have a free x-ray at the same time


NT