> I have an A-133 Dual polarizer and find the outputs to be very noisy. It is audible at any gain level which is problematic for audio rate usage. Are there any mods to reduce the noise floor of the outputs.
>

There have been a couple of threads at MuffWiggler over the past year or so about swapping-out op amp chips to try and improve bandwidth and/or noise:

http://www.muffwiggler.com/forum/viewtopic.php t=16535

http://www.muffwiggler.com/forum/viewtopic.php t=5163

but the few reports about the 133 suggest doing so didn't improve the situation a great deal:

http://www.muffwiggler.com/forum/viewtopic.php p=224422#224422

It thus seems that at least part (if not most ) of the noise problem stems from the fact that the LM13700 is in the audio path. However it might be worth your while investigating or even trying, as 'your mileage may vary' as they say...

Tim