The Alesis 3630 is a very popular, full-featured compressor. It offers up RMS and peak compression, variable knee, adjustable attack and release times, and great metering for under a hundred bucks. But although it uses the same THAT 2150A chip found in dbx compressors, it never sounded as nice as dbx units to most engineers. A few years ago, an enterprising fellow on a message board announced that he had discovered a modification for the 3630 to open up the sound. Apparently, the gate detection circuit adversely affects the sound of the compressor. By clipping two wires, he was able to remove the gate detection circuit from the 3630 and make the unit sound more like a dbx compressor. Unfortunately, I didn't save the name of the author, so he will have to remain anonymous for this article. This is one of the easiest equipment mods you can do. All you have to do is open up the unit, clip two wires, close it back up, and you're done. I modified mine using a Swiss Army Knife.
There are three things you have to be aware of before attempting this mod. First, this will void your warranty, so you might want to wait until it expires before doing this. Second, the gate won't work anymore after you do this. If you still want to use the gate, you might want to skip this mod. But if you use the 3630 for recording into a DAW, you might not use the gate anyway. Finally, neither Tape Op nor myself is liable for any damage you do to the unit during modification. Attempt at your own risk.
Still curious? Well, grab a screwdriver, needle-nose pliers and diagonal cutters and let's get started.
Remove the six screws on the top and bottom of the unit. The side panels will come off.
Unscrew the six plastic nuts around the jacks on the rear panel. You might need to use the pliers or a socket wrench if they're on too tight.
Remove the U-shaped rear panel. There will be six metal washers on the other side of the jacks. Carefully remove them (or pick them up off the floor) and set them aside.
Pull the knobs off the 14 potentiometers on the front panel. You might need pliers or a screwdriver for this as well — they're stuck on pretty tight — but they'll pull right off with enough force.
Unscrew the nut around each potentiometer. Needle-nose pliers work fine for this, but be careful not to scratch the front panel.
Remove all the nuts and washers and slide off the metal front panel.
Disconnect the ribbon cable on the main board (marked J5). Slide the plastic piece over the front- panel pots, leaving only the main board visible.
You are going to cut two jumper wires. One is near the Channel A Output jack. Note that the board is upside down, so this is just left of the middle of the board, to the left of the blue Stereo Link switch. If the jacks are facing you, it's to the bottom-left of C20, parallel with the output jack (see diagram).
The second jumper to cut is to the right of the blue Stereo Link switch. You'll see six horizontal jumpers in a row. With the jacks still facing you, look to the right just below the closest horizontal jumper for a vertical jumper. There's a big blank space to the right of this jumper. That's the second one you cut (see diagram).
(Optional) At this point, you might want to see if the compressor is still working before you put it all...
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