Fairchild 602

Hi Guys, I recently picked up used a fFirchild 602 Hi Frequency Tube Compressor. Pics are soon to follow.
I have searched for info on it but tend to come up empty. in fact the only reason I know it is a Hi Frequency Tube Compressor was I found a studio that had one. The controls are a five position threshold switch and tweeker pots for left and right gain. I went over it with a tech frind of mine and best we can come up with is it was used in DISC, vinal mastering to control presence peeks or possible in broadcast to keep High freq within broadcast bandwidth of a radio station. Anybody have any info on said unit? As well as I was thinking I could mod it out to be a full stereo compressor as opposed to the current Hi frequency only. Any help or suggestions?
:?

I was thinking I could mod it out to be a full stereo compressor as opposed to the current Hi frequency only.

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I have heard of this being done, but don't think I know anyone who actually has. I'll try and see if anyone I know has some info, but no guarantees.

best we can come up with is it was used in DISC, vinal mastering to control presence peeks...

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I'm pretty sure these were used in disc cutting to keep excessive high frequencies from blowing up the cutter head.

Zach

Thanks For info Zach. I am seriously going to try and mod it to a normal stereo comp. It would make a good DIY project the Pcbs inside are very small could be totally breadboarded. and the rest is tubes and trafos. It has a good sound as is but i think would be cooler as a stereo comp. :guinness:

I don't have anything to add other tahn the other day I racked up a pair of Westrex HF limiters. They are very different than the Neumann HK66 in my cutting rack. The Westrex have optical elements as opossed to the HK which have FET's. So far I have found them useful in replacing a wideband peak limiter when used for sound and not purely level. Like taming a snare drum. I likey. I think they have a relatively slow attack time because of the optical element. Not good for it's intended use but quite nice for it's sound.

Viitalahde thanks for the reposting. And thanks to everyone for writing. You know I knew it when i was picking it up that it wasn't worth much. After all it's a model that is pretty unknown. I am still going to try and mod it out to be a stero comp. It shouldn't be too hard.

What's the transformer lineup like?
Is that a tube based box?

OT: The guy at Pendelum told me at the show that the input tranformer for the 670 is an A-26. This is an output, so if they did use it, they turned it around.
Have to check the pinout on the schematic.
cj

CJ, It's mainly tube and trafos. i wish I had a schematic for the thing. the tube layout is as follows 1 6X4, 1 12AX7 and 1 12BH7 which would be a rectifire and 2 triodes. there are 7 trafos in it. Well I think 7 5 for sure and 2 that look like they could be. The the 2 that are suspect are long square metal with about 8 pins 7 which are connected. As for the known trafos, One is for power has an old skool 2 prong power plug in it. Outside of that I am not sure how I would go about testing the transformers as to I am new to the EE side of audio. I am learning slowly so any suggestions are appricated. Plus trying to find a place that would host the pictures inside and outside of the unit for a few days.

Cool. You have the perfect chassis for a G-9 preamp, or add another 12Ax7 and a 6BQ5 and you have an LA2a compressor.
Or you could make it into a vari-mu.
Look for any part numbers/markings on the transformers.

Sounds interesting CJ. I'll have to check for markings on the trafos when I get back home. I was thinking I could keep the compression the same and just remove the Frequency/filter part of the box?

HI CJ,
I checked and here is what I could find. What I believe to be the power trafo has this number on it 17-6840. There are 2 UTc trafos y-6431. And lastly 2 standard electronics corp trafos cat # 80-1. the standard trafo has this raiting on it, Freq resp from 30 - 15,000(15K) and a PWV rating of 535.
any ideas?