PR&E Channel strip racking with pics!

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bitman

Well-known member
Joined
Jun 30, 2005
Messages
500
Location
Keystone, Colorado
Hello all,

First a little history:
This is my first racking job. Historically, I have built my stuff from the ground up. I also live in a rural area so finding stuff like this to even go through the work of racking is rare. To that end I would like to thank M.R. an enginner for a local radio station that was sold off. He was gracious enough to tell me when his Pacific Recording and Enginnering console was headed for the dumpster. Truely, one man's trash is another man's treasure. Thanks also to Keef (aka SSLTECH) for his power supply schematic. While the supply for these strips is unregulated, except for the regulators, the is Keef's design. Also thanks to all of you here at the Prodigy Pro forum for all the help and inspiration leading up to, and throughout this project. I must also thank my GOD for he has given me the skills to do this and has interveened where nessesary along the way.

I was armed with all the schematics and the huge and very comprehensive manual for this board - Thanks again MR!

Now on with the show:

Here is the PR&E console the strips came from. There were only 3 strips with microphone inputs (Jensen transformer coupled). the rest are all line input only. The picture show the mixer with the 3 mic strips and Voice proccesor compressors already extracted.

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I ordered a 3U chassis from Par-Metal (series 10) along with a front panel from Front Panel Express. Here we drill out the holes for the XLRs and 1/4" plugs. I used a 7/8" bi-metal hole saw and hand drill to bore the xlr holes.

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Ahh... Nice fit! - I got these XLRS for $1.00 each on eBay!

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Yahoo the strips fit! - Just like I knew what I was doing or something!

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I cut a piece of the backplane off with a hacksaw to fix just three modules.

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And here is the circuit porn:
Looking down of the circuit, the analog section is on the left while the middle to the right is all 12V logic circuits that control the relays for signal routing.


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Then I built the power supply on perfboard. Show here finished and tested ontop of Keef's schematic page - Thanks again SSLTech!

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And the flip side....

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Hey! One of the strips is powered up! - Voltages are good and holding steady. However the feeble LM7812 I used to power the 12V rail for the logic is heating up fast. Better sleep on this. The huge Transformer is a 20X20 4A Toroidal that I scored for $14.00 on eBay. I'm going to power more than these strips with that 4 Amps. More to come on that.

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Wiring inspection time...
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All wrapped up! 3 channels in. The Analog I/O is wired up and everything tests out a-ok. Each channel sports a XLR mic input, an insert, and two outputs on one 1/4" TRS jack. The tip will go to the DAW, the ring to the monitoring system in my studio. The open hole in the rear will hold a plug which will carry the +/- 30vdc to 4 other compressor/EQ voice processor modules that are to be racked up next. These will plug into each channel insert with one of the comps left free standing. I took one of the front panel switches out and rammed a 1/4" unbalanced input jack in the front of each strip for instruments. Works great, boy do I dig the sound of that transformer input. Never been fortunate enough to play into one before. I am a convert! - About that HOT 12v regulator. I took about 15 of the logic chips out of each channel and left two, which where enough to turn on the output relays and pass signal. The current consumption went way down and now that regulator just cruises along.

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Here is how I dealt with the infamous Par-Metal chassis lip or stiffener.

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AND FINALLY IN IT'S NEW HOME!!!

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Here is a preview of the next racking. 4 of these sweet PR&E voice proccessors. DBX based COM/EXP/EQ :)

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That's all folks!

:LSB
 

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