Archive for August, 2015

This is the result of testing equipment during a time when I was trying for vintage guitar tones.  I used an MXL condenser pencil mic.  It was about 6 inches back, straight on, pointed 3 inches left and one inch down from the cone.  I wanted to capture a balanced, smooth sound.

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FX loop alternative

To the left is the previously posted alternative loop modification schematic to change a Mesa Dual Rectifier from a parallel loop to a serial loop.  It’s easy.  Most of the time required for the mod is spent taking the amp apart.  (Here’s a link to a 2 Channel Recto with the same mod.)

The following pictures are provided to show the inside of the amp, the job, and a crappy job someone did of soldering the output transformer to the daughter board.  I used a 22 gauge wire with the insulation removed for a clean, short jumper.  I’ve seen people use insulation for the job, but the space is tiny.  Note that my solder joints look a little matte.  This is from the lead-free, silver solder I used.  Almost every joint looks that way when I use it, no matter what, but it hasn’t been a problem.

Update July 2016: Verified.

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Peavey XXX RewiredI rewired my cab to have top and bottom pairs, instead of left and right.  I run it 2×12 once in awhile and wanted to try it this way.  The top pair is a little tighter and the bottom is about like normal.  I thought this would be a good opportunity to explain the wiring and source impedances needed for this cabinet.  It is a 16 ohm mono and 8 ohms for each side in stereo.  The diagrams shown are actually the same as stock, since the pairs are only moved to different locations.

Ex:1 A single amp in stereo needs to use 4 ohm output jacks to have a safe match.  The amp adds the outputs together to make 8 ohms.

Ex 2: A single amp in mono needs to use a 16 ohm output jack, but an 8 ohm output would still be safe, if your tube amp can handle it..

Ex 3: Two amps into one stereo cabinet use one 8 ohm output jack from each.  Because the loads are being seen by separate amps, they don’t reduce to 4 ohms, like would happen with a single amp running parallel loads.  The cabinet is basically two 2x12s in one box when used this way.  If one source amp is removed from the third example, an 8 ohm connection into one pair of speakers is using the cab as an over sized 2×12.