
We've all heard of the Fairchild 670, (atleast we know the $30,000 price tag on it), but what if I said the word Protech? Most audio junkies have heard of the former, but the latter is one of the best kept secrets in audio. It's basicly a Fairchild on it's own, an engineering marvel for a very vintage sound, a spawn of Fairchild. One of the mainstays of boradcasting and recording. It offered an expansion feature beyond the unity gain point. As I recall, it went for about $1500 in its day(thats $8,000 in todays money), and now one can be had for around $4-7,000. I've always wanted one but never got my hands on one, until now! For a whopping $6,000.
The insides:
Point to point handwired, made in the early 1970s. The caps are extreemly clean, and the VU is professional quality. Cheap VU's may have entirely different sensitivities and use a different current limit resistor, this one is anything but cheap. 0VU for a +4dBu input if fed via a 3K6 resistor. Just an amazing VU circuit.

Next, lets look at the output transformer. Mine was a bit dirty, so I got some non-residue contact cleaner and gave each CTS pot a small squirt and then rotate it a few times.
Simple, and back to a new state. The power supply is extreemly well built quality, with balanced I/O, the filter cards are seperate, not one large pcb. It's made to lower noise as when you boost input, you are not boosting the accumulated noise of the previous stages.

The sound:
There is a reason why people still pay thousands for this. The 66303 warms things up with or without doing any compression. In other words, simply having it in the signal path creates an impairment, a cool, big fat round sound. With short release times and a lot GR, you get a nice crunch - think UA 1176 in all four mode.
If you engage side chain, and pull it back from 440HZ down, it has the further effect of more GR (like another threshold working on lower frequencies). There is also a tight switch-which is great for parrallel smashing.
On drums the 66303 retains the lower end -with kick/snare. On snare you get that nice 1176's twack with thick body-which I just could not get with neve/buzz. Hello sunshine-this was what was missing in my studio. As noted-the gain is very grity and full of character, and it has oodles-is the FET operation and the incredibly tactile and linear attack/release/sidechain/tight settings. I did some serious a/b with an 1176-and the 66303 was more thick/tight lower down. You can do serious sculpting, on drum sub I thought initially 66303 killed the higher frequencies compared to 1176, then realised I have release at 3 oclock, pulled release shorter-and pressto her are the cymbals/high hats again!
Needless to say, it sounds great on everything but especially the nitty gritty vocals. Think old school rock, in a very empty mix, this compressor WILL fill in the empty space.
If you happen to find one of these rare compressors anywhere, let me know, I will glady buy another.