So...

I did some more testing and measuring.

Here's my compression curve. (Sowter 6062 & 9185, 2x 6BA6)

As a reference I took the curve from the original manual.

I applied a 1000Hz Sinus.

Setting the compressor to SINGLE & FAST.

Taking U

_{out} after Output-TX.

My first try was to measure U

_{in} after the input pot at test points #F and #B (#3, #7).

But somehow the result curve looked like as if it was compressed

along X-axis, after the knee point.

I don't know why this doesn't work...

If anyone can explain that to me, that would be GREAT!!

Next try...

I cranked up the input pot fully cw and controlled U

_{in} via ProTools, measuring at XLR

_{in}.

U

_{0} = 1.228V

I shifted my curve to fit the knee point of the original diagram.

I think the curve looks pretty good even if it's at the upper tolerance limit according to the manual.

Maximum gain reduction is ~

[email protected]_{in}.

(Leaving the input pad out would of course give more...

... if it's linear... don't know)

*Update:*I did another run - changed the mode to SINGLE and SLOW.

Changing to SLOW Recovery increases compression.

Now my compression curves fits the original even better

Next comes a new meter scale... next problem...

(the compression behavior is never linear, should the meter scale be linear..??)

ROCK-ON!