Here is a little project I got off the old  Ampage forum , I think it was Enzo who suggested it. My friend Maynard wanted to bridge two bass amps together, using the preamp of one to drive them both. When we tried it we found there was a volume disparity between the two amps, so I asked for ideas at Ampage and Enzo suggested this box. It worked great, it's easy to build, and Enzo is right in saying it's nice to have one or two around for general purposes. This is pretty much the same thing as what is selling on Ebay as a "Volume Box". It also is claimed to be an attenuator, a power soak, a tone and dynamics control, and penis enlarger. Well, maybe not the last, but there's as little validity in the latter as in the former three. Those Ebay "Volume Boxes" sell for twenty bucks, pretty good profit for a pot, a couple of jacks and a cheap enclosure.

How to build a Volume Box

If you want it to pad down the preamp out signal, it is easy. Get a metal box and mount a couple jacks in it for in and out. Then mount a high value pot in there - oh, 100k or higher, it doesn't matter much on the value. Wire the input jack to the top of the pot and the output jack to the wiper. Wire the commons together and to the bottom leg of the pot. There you go, a volume control in a box.
These circuits are high impedance, so the 100k or 250k or whatever will not load it down. You have made a simple voltage divider, so you can dial down the level to any percentage of full volume you like.
Now run a cord from the preamp out of the master amp to the input of our box, then another cord from the output of our box to the slave power amp in.
I have a couple of these boxes in my drawer of tricks for general use. You never know when you want to modify a signal level.


                               Home                                                       My Tech Page