[JohnFerrier]

I think what I'm looking for is a Constant Current Class A design. In an Emitter Follow circuit, the Re is replace with a current source. This idea struck me when thinking about how people like to bias op-amps to class A with a current source. If I use an integrated buffer amplifier (HA-5002/BUF634), I plan to bias it to class A too. This is for a home rig, not worried about current draw. Also have heatsinks, so not worried about heat. This is a headphone amplifiers, so 25% efficiency ought not to be the end of world.

Suppose I could take any discrete complimentry design and hang a current source on the end (possibly delete some of the now unused components).

So has anyone seen interesting contant current class A designs (transistor not MOSFET)?



JF

 

[kevin gilmore]

You mean a single ended pure class A output with an
active current sink??

Like this
http://www.borbelyaudio.com/index41a.htm

or many of the nelson pass designs...

or the output stage of my KGSS...(active current sink emitter source)

or the output stage of the Blue Hawaii (active current source,
tube sink)

Replace the fets with transistors.

Non bridged versions of these circuits can have dramatically
different rise and fall slew rates.

 

[JohnFerrier]

Hi Kevin,

I should be painting right now, but saw your post. Thanks! I'll review your suggestions. And, yes, I'm interested in a bridged circuit.


JF

 

[Jupiter]

You can get PCBs for the Borbely amp from Borbely Audio or audiokits.com for $35-40. The PCBs for the PSU is the same.