[Don Pearce[_3_]]

On 14 Oct 2017 23:47:58 -0400, (Scott Dorsey) wrote:

Don Pearce wrote:
On 14 Oct 2017 17:11:10 -0400, (Scott Dorsey) wrote:

Don Pearce wrote:
On 14 Oct 2017 09:54:25 -0400, (Scott Dorsey) wrote:

But, if this is the issue, you can tell because the distortion character
will change with the load impedance. You can see it on a scope and you
can hear it change as you add shunt resistances to your load.

Yep. More current makes this better. But better yet is some gain in
front and an external feedback loop that comes from the emitter pin.
Op-amp anybody?

No need to go that far, the simple Ring of Three circuit family can be found
in all sorts of applications like that. Gain is cheap in the solid state
world, so it's frequently to your advantage to trade it for linearity.

Not go that far? One op-amp is far easier - and cheaper - than a ring
of three transistors.

The minimal op-amp is at least four transistors, maybe five if you want
decent output current drive. Two for the differential input, one for the
intermediate gain stage, then one (or two if you want to make it push-pull)
for the output stage. Add a couple constant current sources, a compensated
reference on the output pair, and the number of components climbs pretty fast.
--scott

Unless you use an integrated op amp. 5532 is probably my favourite
do-everything op amp. The count becomes one op amp and two resistors.

d

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