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

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 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

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

>"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 Tue, 27 Nov 2018 10:21:13 +0200, Tauno Voipio
<tauno.voipio@notused.fi.invalid> wrote:

>On 26.11.18 22:36, John Larkin wrote:
>> On Mon, 26 Nov 2018 12:24:23 -0800 (PST), jurb6006@gmail.com wrote:
>> 
>>> Thanks folks. It'll take some time to sift through all that. At this point I think I would be alright feeding it 24 volts but not 36.
>>>
>>> It seems a couple do not realize that I am not using the primary.I am using the secondary as a split primary, which is why I need the 4 and 16 ohm taps. It must be balanced.
>>>
>>> On that Spice print, that IS the secondary. I am also going to incorporate Shottky diodes at the collectors of the outputs to emulate tube sound best as I can.
>>>
>> 
>> Does that circuit actually work? I guess it should, barring any DC
>> imbalance issues.
>
>
>I just wonder why on earth the transformer. In tube designs, it
>was a mandatory part, to get a ballpark match to the low impedance
>of the speaker(s), but a complementary transistor amplifier can
>be made to work directly to the speaker.
>
>I've made a bunch of tube amplifiers (about 5 decades ago), and the
>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.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics

On 26.11.18 22:36, John Larkin wrote:
> On Mon, 26 Nov 2018 12:24:23 -0800 (PST), jurb6006@gmail.com wrote:
> 
>> Thanks folks. It'll take some time to sift through all that. At this point I think I would be alright feeding it 24 volts but not 36.
>>
>> It seems a couple do not realize that I am not using the primary.I am using the secondary as a split primary, which is why I need the 4 and 16 ohm taps. It must be balanced.
>>
>> On that Spice print, that IS the secondary. I am also going to incorporate Shottky diodes at the collectors of the outputs to emulate tube sound best as I can.
>>
> 
> Does that circuit actually work? I guess it should, barring any DC
> imbalance issues.

I just wonder why on earth the transformer. In tube designs, it
was a mandatory part, to get a ballpark match to the low impedance
of the speaker(s), but a complementary transistor amplifier can
be made to work directly to the speaker.

I've made a bunch of tube amplifiers (about 5 decades ago), and the
output transformer was a PITA, honestly.

-- 

-TV

On Mon, 26 Nov 2018 12:24:23 -0800 (PST), jurb6006@gmail.com wrote:

>Thanks folks. It'll take some time to sift through all that. At this point I think I would be alright feeding it 24 volts but not 36. 
>
>It seems a couple do not realize that I am not using the primary.I am using the secondary as a split primary, which is why I need the 4 and 16 ohm taps. It must be balanced. 
>
>On that Spice print, that IS the secondary. I am also going to incorporate Shottky diodes at the collectors of the outputs to emulate tube sound best as I can. 
>

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


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Thanks folks. It'll take some time to sift through all that. At this point I think I would be alright feeding it 24 volts but not 36. 

It seems a couple do not realize that I am not using the primary.I am using the secondary as a split primary, which is why I need the 4 and 16 ohm taps. It must be balanced. 

On that Spice print, that IS the secondary. I am also going to incorporate Shottky diodes at the collectors of the outputs to emulate tube sound best as I can. 

I am really thinking about a tracking regulator now, that way I can cut back the peak power when the temperature rises. I also will incorporate a sabotage proof protection system, like another one, if you hook the speaker wires to say, the AC line it just burns the wires off and still works after being turned off for a few seconds and turned back on. Any amp I build that costs more than a couple of cases of beer will have that. Simply indestructible, in fact I jst might make a challenge. You can connect anything to anything but you can't go inside the case. Reward money in escrow. 

I just might not...