Thursday, September 15, 2011

Old School PPI Pro Mos Amps - Precision Power!

Most of you old school car audio fans know the early 1990's was a time when aftermarket car audio was getting extremely popular. At this time, it was rare to find a factory CD player and the factory speakers were weak at best in most cases. Manufacturers such as Rockford Fosgate, Linear Power, Precision Power (PPI), Autotek, Orion and Soundstream (to name a few) were some of the very popular aftermarket car audio brands at the time.

The competition between the manufacturers was intense and each one was trying to best the other. Orion's HCCA series amps, released in the late 1980's were extremely popular and had an edge power wise on most other amps with their rating and ability to handle extremely low ohm loads. These low-wattage rated / low ohm handling amps came to be known as "cheater amps". The cheater amps could put out as much as 8x their rated 4 ohm power rating at lower loads. PPI hit the "cheater" market in 1990 with the Pro Mos 2050. Pro Mos was short for Professional Mosfet. This first gen Pro Mos amp was rated to handle loads down to 1ohm and would provide 4x it's rated 4ohm power at 1ohm. Cough up around $800 for a 50x2 amp, and get a 400x1 monster when loaded down. Interestingly enough, Orion's 25x2 "cheater", the 225 HCCA was stable down to 1/2 (some even say 1/4) ohm loads and would put out in excess of 400 watts and cost less than $600.

I've shown a comparison of the Orion 225 HCCA and the PPI Pro Mos 25 in a previous posting and video. You can see my preliminary power output results HERE.

PPI Pro Mos 2050 (top), Pro Mos 12 & Pro Mos 25 - Image (C) OldSchoolStereo.com


These Pro Mos amps were available up until around 1995, adding additional models including the Pro Mos 12, 24 and 50 (replacing the 2050) beginning in 1991. They also released 4 channel models; the Pro Mos 425 and 450. These Pro Mos amps were no frills, offering no internal crossovers or bass/treble controls. They offered a DIN connection for powering a PPI pre-amp or crossover in addition to the standard RCA input jacks. The Power and Ground connections were made via 8 or 10 awg leads and the speaker/remote connection was made by an infamous molex connector. I say infamous because this connector has been a huge failure throughout the years. The wires don't stay inside the connector and the molex connector itself breaks very easily. Many people created terminal strips or soldered the leads to the circuit board.

The Pro Mos amps you see in the photo above are the "art series", finished in white including a unique design by an artist. These amps were also available in black with red lettering.

See the video demo below:

Also, visit YouTube and subscribe to my channel for more exciting OLD SCHOOL car audio gear!

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5 comments:

twinsmommy said...

I personally have always loved this series of PPI amplifiers; built for what they're supposed to be, utilitarian and sexy in that simple, plain way. I've always had a liking for the ones decked out in black though. I've always found it hard to integrate the whole Don Johnson/Miami Vice pastel watercolors into almost any car. Except an aquamarine or lavender Geo Metro convertible. LOL

Sorry about the name...I'm actually TwinBassDaddy

Greg Sweet said...

Do you remember Competition brand amps? I bought one in 1990 from a friend that owned a car stereo shop. He told that they were essentially these PPI amps re-branded with slightly larger heat sinks in your choice of enameled white, red or blue. The parent company was one of the surf wear companies, I think it was O'neill out of Santa Cruz, Ca.

Muhammad Amir said...

They offered a DIN connection for powering a PPI pre-amp or crossover in addition to the standard RCA input jacks. PPI help

mark ulibarri said...

I have a precision power ProMos 50 in great shape and was wondering how much it is and it's in great shape? Let me know thank you!

dwillis said...

Hey Mark, those usually go for between 150-200 on eBay. Is your amp black or white with art graphics?

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