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.
Archive for August, 2015
Tags: amp, amps, art tube, Boogie, Cab, classic rock, demo, dual, Dual Rectifier, Mesa, mic test, mxl, peavey xxx, recording
Tags: Boogie, Circuit Board, Dual Rectifier, engineering, Gut Shots, Guts, Inside, Loop, Mesa, Mod, modification, Output Transformer, Pictures, pot, Soldering, Test
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.
Tags: 2x12, 4x12, amp, amps, Cab, Cabinet, guitar, Mono, Parallel, Peavey, Series, Stereo, wiring, XXX
I 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.