Transformer in the output

[djk]

I'm pretty sure the Parker amp is P-P, a single-ended output transformer is a different animal entirely.

Build a circlotron, it's a very simple type of bridge amp.

 

[woody]

You might on the Passdiy webpage for the 1977 article Build a Class-A Amplifier. It does use rather low voltage and is single
ended. A + and - power supply is used so no output cap is needed.

 

[Conta]

Thanks, i found this as the most useful:
http://sound.westhost.com/jll_hood.htm

However I do not understand why go to lengths to avoid the output transformer.

My idea is like this (please excuse the poor quality of the sketch):

akis has attached this image:
Click the thumbnail to see the original image.

http://silver.ring.lt/kart.gif

 

[djk]

Which requires a transformer with an air-gap.

 

[latala]

The Quad 50E is a design that uses an output transformer and claims under 0.1% distortion You can use that as a start
regards Trev

 

[john_ellis]

Hi Akis

You've had some good advice here. Your speaker shouldn't see the DC. your transformer circuit won't work as it is.

A good transformer design is not easy to build. You could build a class A with a single transformer output, but large transformers (taking 3A or so static current) have high leakage inductance (stray inductance) that can ruin the high frequency response. Sowters have a range of transformers for valves and I'm sure they'd make a good job of building one suitable for transistors, with as low a leakage inductance as practicable. (They make one I think for Susan Parker's amp).

If you match the impedances (and design for 8 ohm pri/sec) then life might be easier - you could use the same wire gauge for pri/sec, and each layer of turns could be alternated pri/sec, and the difficulty of wires not fitting over different gauges is eliminated. But interwinding capacitance may still wreck the high frequency response....


cheers
John