Travel back in time...
what it actually is...
how it works
What it does...
tube opto compressor
James F. Lawrence founds the Teletronix Engineering Company in Pasadena California
Introduction of the Teletronix LA-1 of which only about a 100 units were made
Introduction of the Teletronix LA-2
improvements on the original design lead to the release of the LA-2A (grey faceplate) The first time a turret board was used instead of plain point-to-point wiring . Better wiring layout led to lower noise floor
Lawrence sold Teletronix to Babcock Electronics in California
Studio Electronics (owned by Bill Putnam) which was later renamed to United Recording Industries (UREI) took over Babcock Electronics’ broadcast division including the Teletronix brand
UREI continued to manufacture the LA2A but with a silver faceplate instead of the grey one
The LA2A was discontinued due to slow sales after the development and introduction of solid state technology drove out space consuming tube gear (resulting in products like the LA-3A & LA-4)
Bill Putnam Jr. refounded Universal Audio reissuing the LA-2A – this time with a grey faceplate again.
The rise of analogvibes begins…
Limit/Compress Switch: switches the unit between both modes, but the difference is rather homeopathic – only with extreme Peak Reduction settings you’ll notice a difference
VU meter: either reflects the amount of gain reduction applied or the actual output level of the unit
Gain control the amount of gain applied to the signal AFTER the actual compression circuit – kind of the make up gain. In fully CCW position the signal is completely attenuated – in fully CW position it will most like not only blow your speakers but even your entire room – the LA2A is a gain monster!
Meter switch: controls the VU meter to either show gain reduction, output +4 dbu (todays studio standard) or +10 dbu
Peak reduction controls the amount of gain reduction applied – even though the front panel layout suggests it comes behind the gain pot, this actually is the first pot the signal hits after entering the circuit
R3 Stereo Adjust control to adjust the gain reduction control voltage when connecting two units for stereo use
UTC A-24 output transformer
The T4B opto cell – this is where the magic happens! Learn more about how this component works and what it does inside of the LA2A in my „The 3 knobs“ e-paper
12AX7 & 6AQ5A tubes of the gain reduction control circuit
R37 frequency response control of the gain reduction control circuit learn more about it in my „The 3 knobs“ e-paper
12AX7 & 12BH7 tubes of the amp circuit
UTC-HA100x (or UTC A-10) input transformer
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how it works...
Part I - Overview Teletronix LA2A
Part II - Main components & gain reduction of the LA2A
Part III - What the heck is a T4 cell?
Part IV - The amp curcuit
Featured: The Teletronix LA-2A in action.
...time to wire it up a notch
Part V - The Tube Opto Compressor blue print
One more thing...
years of epic history covered
minutes of epic videos on how to do it
pages of ultimate guide mojo
...time to Build Your Legend
Get The Ultimate Tube Opto Compressor Chassis Kit
Now you are good to go, but also please have a look at this video - it's only a matter of life and death!
How to electricute yourself (NOT)
In this short video I give you some quick advice about to be save and sound whilst building your legends. Also have a look at the how-2-build-it epaper. There you’ll find the six essentiell rules which should make building your own tube gear a safe ride.