What Solid State Amps with Output Transformer do you know of?

[forr]

This may interest you because it uses an auto-transformer with a standard solid state amp.
Currently on french forum Audax, there are some discussions about an old patent for a circuit called SEREA which is said to improve the sound of speakers (no reinjection of back EMF ?):
http://www.audax.fr/forum/read_mess.php3?id=22708#ID60652
See the following post :
Reponse de Ruchat
Posté le : 19-09-06 à 05:22 (US)

An approximate translation :
Have an SS amp of more than 30 W and an output transformer for a push pull of EL34 (a mains toroid sould work too). Connect the amp output to the 4 Ohms and ground connections of the transformer secondary side. Connect an 8 Ohm speaker to the 8 Ohm and ground connections of the transfomer secondary side. On the primary side, leave it open circuit, or use a 10 Kohm or an RC circuit to get the best square wave.

 

[Onvinyl]

hi all,

thanks a lot for the input so far! Seems there are not many *modern* designs out there!

hi forr,
unfortunately, my school-trained french is more or less completely gone. Do you happen to have a schematic of the provided idea(s)?
Merci!
Rüdiger

 

[Tube_Dude]

Currently on french forum Audax, there are some discussions about an old patent for a circuit called SEREA which is said to improve the sound of speakers (no reinjection of back EMF ?):

Hi Forr

Interesting audio forum , I really appreciate the thread :

http://www.audax.fr/forum/read_mess.php3?id=49046#ID60771

About feedback (contrareaction en Français... ) and the EMF interaction in a feedback amplifier.

I also remember the 800 Ohms Philips speakers that can be used with tube amps , without the output transformer.

Also in the 80 I use to read the articles in the HI-FI Stereo Magazine from R. Brault, that was a fanatic against the use of any feedback in an audio amplifier.

Last time I hear from him, was in a article about a Fabro Elactronique amp designed by him, but I don't know if it had any success in France...

Cheers. (Salut... )

 

[forr]

Hi,

I will try to draw the SEREA schematics. We haven't found the original article yet. It was published in Le Revue du Son around 1973.

Brault :
before having some audiophile inclinations (no feedback, high impedance output amplifiers) Brault wrote a book about amplifiers which was very good and which makes me understand the fundamentals about solid state electronics and amplification.
Fabro remained a confidential compagny, I do not know if it exists anymore. I met Brault about fifteen years ago, he was a quite old man.

Philips 800 Ohm loudspeaker :
the very thin wire of the moving coil was fragile.

 

[Zen Mod]

I really dunno why threads are sometimes dangerously near blablabla?

as I already wrote-go to turneraudio


http://www.turneraudio.com.au/solidstateamps4-50w-mono-mosfet.html


if nothing else-it's worth reading

 

[Tubelab_com]

I have seen car stereo amps, mostly cheap ones sold by Radio Shack that use a push pull SS amp driving the 8 ohm speaker through a step UP output autotransformer. The whole amp ran directly off the 12 volt car battery. I guess that this is cheaper than building a boost converter to generate a higher voltage.

 

[anatech]

Most PA amplifiers use a transformer to match 25 and 70V lines. They may also couple directly from the transformer primary also. This means the transformer is across the 4 / 8 ohm output all the time.

Any DC offset and the fuse blows. Load protection idea! Heavy though.

Look to Bogen or Dukane to name two. These are proper transformers and not an autoformer.

-Chris

 

[tiefbassuebertr]

I found the following:
Nemesis: 2SK135 SE Amp
Nemesis PP 2SK135 PP Amps
Zeus: Zeus SE Audio Power Amplifier

Are there more?

I'm looking for diy, of course, and maybe schematics of commercial amps.

Rüdiger

check out this thread:
http://www.diyaudio.com/forums/soli...osh-ma-6800-ma6800-power-stage-schematic.html