Where does LA2A distortion come from?

Which area(s) of the circuit generate the distortion inherent to the LA2A? I know it has considerable negative feedback. Aside from the transformers, where does it all come from?

Most of it comes from the output stage.

Cheers

Ian

The White cathode follower?

pull out the T4  module and check distortion

Man! Those T4Bs can mess you up. Been testing some equipment with and old Drip that made a harmonic mess during compression. Swapped it out for a new Kenetek and all is well.

It comes from compression just like in all compressors. When the rate of attack / release is fast enough to track the signal it will distort lower frequencies. If you look at bursts of tone on an oscilloscope you can really see how the waveform is shaped by rapid changes in level.

..... and the LA2A switched for the meter displaying output level VU adds quite a bit of distortion in the mids.

I have a couple of Drip opto modules and I didn't notice any unusual distortions ...  I may just check that again against a nos urei to that I have but never used.

In my measurements, I find the output amp to be very clean unless you open it right up.  And then it's usually the subsequent piece in the chain that distorts, not the la2a.

In my own builds, I find the distortion is more about how high of a signal I send to it, and the step-up ratio of the input transformer.

That and how hard you want to smash it down!

In my case,

One unit  has a Sowter input traffo which is smallish in size - it isn't all that great with hot, bassy signals. I have to take care not to push it too hard with say a tube preamp feeding it.

Other unit has some much larger Jensens and it is much more forgiving of input level with respect to overall THD.