I just picked up a Multimax 3-band mono compressor from a local giant conglomerate media outlet's dumpster. It needed a few components in the power supply section. It seems to work fine now, but I have no idea how to adjust it, and the paint on the adjustment pots has all been broken except for the VU meter calibration pots.
It has a tag that says it's been converted for AM use, which is where I intend to use it for a new Part 15 station. I've done a few searches of this and other sites, and Googled, with no results. Does anyone out there have the adjustment procedure, schematic, or manual for a Multimax? I have Sound Solution, but I would like to put this on the air with a "real" processor. So far, I've got less than $5 into it, which is a good deal if I can figure out how to use it. There are GAIN pots on each of the three per-band cards, and three pots that change the way the lights on the front illuminate on what I call the "main" card.
Thanks
I just say, have fun with it. play with all the dials and knobs till ya get something you like 🙂
Howdy,
"I just say, have fun with it. play with all the dials and knobs till ya get something you like :)"
Heh ... yep ... FWIW I agree. I don't think you can hurt anything within the unit itself by twisting knobs. It's mainly what you hear that counts, but check out the meters for limiting. What do the connection jacks look like? Can you post pictures?
Trust me, you will not remember the original settings so before you change things write down or mark the original settings. This applies especially to any internal pot settings since the settings may interact and you can get into a situation where it won't work right and you won't be able to find the correct combinations by trial an error. You always want to be able to follow your marks to get back if you need to.
Neil
Thanks to all who contributed advice. After making some pencil marks, I've started adjusting the Multimax and I think I've got an idea of how things work.
Inside: 
Front Panel / Inside: 
Lights on: 
Front: 
All four cards: 
Connections on the back: 
Main board, right: 
Main board, left: 
Front closeup: 
Front closeup: 
I've got some other cool stuff I saved from the dumpster like a CRL SPP-800 that I have yet to get working. Many thanks to the person who posted the manual for that.
Additional information, not for the faint of heart:
I missed out on getting a couple of Texars that didn't work, Giant Worldwide Conglomerate(tm) just throws out hardware like that when it's deemed obsolete and it stops working. What a waste! I'd love to hear an Audio Prism on a Part 15 station, and there are still many commercial stations that use them to this day.
I had one of these on a mono FM about 20 years ago.
I do not have a manual, but here is what I can pass along from memory.
The chassis and compressor cards are the same as PR&E used in their companion unit, the MULTILIMITER. The capacitors around the VCA chip on the compressor cards were changed for faster attack and release times and the output card included an asymmetrical peak limiter for AM use. It's been so long since I saw a Multilimiter though.
The MULTIMAX was basically just a slower version and I don't recall it having a limiter on the output card at all. The two pots on the compressor cards were for meter zeroing and compression threshold levels, IIRC.
The three lower pots on the output card are the mixer for the output of the compressor cards. I believe the upper pot was the gating threshold.
With no audio present, all three compression meters should read 0vu. As signal is applied, they should deflect left according to the input level and the "normal" LED's should light. You will have to do this with the audio source set to around 100Hz for low band, 1000Hz for mid band and 8000Hz for high band. There will be some interaction between bands as the bandpass filters had a good degree of overlap.
A 20 dB increase on the generator should show 20dB of gain reduction. If the output of the source is at -25dB and suddenly is increased to, say, -5dB, you should see the LED's above the GR meter switch from "normal" to "slow" indicating the gating it operative.
A lot easier to tweak than a DAP 310 by a long shot, but not nearly as complicated a piece of gear, either. These do tend to "swim" between bands under heavy compression. I used to let a little more midrange through before the midband compression kicked in to overcome that.
Hope that helps.
I have a manual for the PR&E Multimax somewhere in my archives...although I haven't seen it in a while, I'll look for it.
Good news! I've got the Multimax sounding great (No station yet, but I'm working on that. DDS carrier current transmitter is in the design stage.) Even better... I now have a genuine Texar Audio Prism and a Burk EAS that needed some work.
One of the M-100 cards has a problem, but I've got some excellent guidance from someone who has worked with them before. Should be up and running in no time.