The AM Forum

I am thinking about building a clone of this compressor. I have all the parts together. Anyone ever used one?

Pat
N4LTA

Yes, it was in a radio station production room.  Easy to set up, but not very adept at not pumping when going from silence to plosive speech if set too agressively.

Keep your head and it will do the job just fine.

73DG

Nice unit ! Great on bass guitar. Never used one on vocals. A bit slow as is.
Do a Google on it and you will come up with several mods for more useful performance and other tips like input and output attenuators, changes in the attack /release, etc. It also makes a nice mic pre with the 6AL5 pulled. Lots of gain. Can be a bit noisy. Have to select the first tube, 6BC8, for low microphonics and matched sections.
  Have overhauled a couple of them.
 I have a fairly nice clone that was reasonably well built using UTC transformers but had a crummy meter. Have to finish the mods on it and mount a proper scaled and better looking meter.

Yes,

I am building it with the mods published by "New York Dan". I will be using Hammond BC quality 800 series transformers and a modified power supply. Not crazy about the voltage doubler supply. I will use a full wave with a choke input using a Hammond 270X PT. The Mods I am using have a 250 ohm balance pot to balance the two sections of the 6BC8.

Have all the parts but the output transformer (Hammond 841)and should get it today. Will use good quality Cornell Dublier film caps throughout and good Clarostat pots. Look forward to testing it.


Pat
N4LTA

I had a similer model for a short time. Perfect to reproduce the compression artifacts heard on the sax intro to The Pink Panther theme.

Got $600.00 for it on ebay.

 Overloading the Mic pre on that track didn't help either, but then it wouldn't have had that "in your face" snarl if it had been done cleanly.

 Good choice on the iron Pat. Hammond has a long and consistent history for Broadcast and Recording quality transformers. You might try using P&O caps for coupling in a comparison when you are done. Film caps tend to be a bit "dry" sounding. Not a bad thing. Just a different flavour. More "vintage".
 A good stiff power supply is needed to maintain low frequency accuracy and reduce any control voltage modulation in that area. I'm considering going with a choke input for that reason.
  Yea, "NY Dave" does good work with mods. Have chatted with him several times on the old Prodigy recording forum.

 I have been wanting to clone the popular Federal Limiter for some time due to the completely balanced topology. The better to maintain asymmetry. The shame of it is that I had a pair and sold them for big $$ to a Studio years ago before I had a Ham Radio use for them.

Good luck,
Bill

P&O caps - not sure what they are  - polypropolene  in oli?
Pat
N4LTA

Paper-in-oil.

Vintage Russkies are the cheapest and easiest to obtain today.

73DG

I ordered five Mojotone Vitamin Ts to give them a try. They are supposed to be good quality and I can get a good deal on them. Wish the old Spragues were still available.

Wish I had lived here in North Adams when they cleaned the Sprague factory out in the mid 80's. Have heard of barrels full of Vitamin Q caps going to the dump or somewhere. Now all we have left is the PCB contamination downstream from their
dump site behind the factory. They had to demolish the building where the oil filled caps were made and and decontaminate the soil around it as well. The rest of the Sprague complex is a State Art Museum, MASSMOCA now. About 3 blocks from where I live.

Bill