Recent content by bjosephs

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Hi All, I’m trying to lighten my amp collection a bit and have posted this one in a few places. The amp is like new with tags still on it, I have all the original packaging and paperwork. I’m in the Taunton MA area and looking to do an in person cash transaction for it. Asking price is...

Could be pot tapers. They are marked as linear in most of these schematics but I know they switched Mark series mids from L to audio taper so that the 5 setting was actually lower than it appears. They could be using something custom. It can also be something outside of the tone stack. If...

The 1M resistor is there to keep the DC voltage stable on those tone stack caps. The signal is imposed on a DC of a hundreds volts and without a pull up/down resistor the unselected tones stack will start to drain down through the cap leakage. The switching pop could be big and a bit...

I would think so since all these sister models seem to use the same PCB and transformers. If you get stuck I’d be happy to help.

The front end is a typical Fender TMB tone stack. This calculator can show you the effect it has on response. Bear in mind that this graph is the tone stack effect, not the finished response because guitar signal is not flat and there are other tone shaping parts in the preamp. Tone Stack...

The answer is that achieving those tones requires a very specific balance of low, mid, and high frequency energy before the distortion stages. That balance is very much affected by the guitar and play style and very few amps give you any tone shaping tools pre-distortion. The Mark series is...

The single rectifier series 2 schematic I have show that this as the stock potentiometer values. 1 Meg for clean, 250k for dirty. I haven’t looked at the gain pots on mine but this seems right to me. I don’t think those caps are the ones that get modded. If you are trying to tighten the...

In case anyone finds this thread in the future. Mesa provided some better pictures and it really is as simple as moving one wire - specifically the white wire on the board under the header from a 100v to 117v pad. The header holds the two taps for the transformer primary.

It's a parallel loop. The phasey sound is the direct sound being mixed with signal that went though the trip out to your pedals and back. This is the same complaint with lots of Rectos from that time period I'll be modding the loop in mine when the amp arrives. I can't find a Tremoverb mod...

Hi All, I have one of these in transit that was built for use in Japan, I am in the US. Mesa confirmed that it is wired for 100v and that it will have a transformer that can be wired for 117v operation but they want me to take it to an authorized repair site for the work. I have a solid tech...