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If you can get one the Eminence MOD 12 is a great speaker for the small combo cab. If you want something lighter weight, Jensen Neo Tornado, the 100 watt version. Cheers Stephan

Many thanks Jon for sharing all this. cheers Stephan

The diodes appear to be OK. Next things to check would be the filter caps in the power supply for shorts as already mentioned. In order to check the power transformer you have to disconnect any secondary wires from the circuit, tape them so that they cannot short against anything, put in a...

From what I have read the IICs can be upgraded to a IIC+, which is what MB have offered as a factory upgrade. I also know that the first Mark IIIs (no stripe/dot/black stripe) had the same power transformers so they would be the next best candidates. Everything else is too different to be modded...

Thanks for this forum and thanks for having me here. Cheers Stephan

I will review the pedal in the context of the manufacturer's description and the way I tested it (standalone before clean amp, push a driven amp and clean boost after overdrive). This is how Mesa Engineering describes the pedal: The FLUX-DRIVE™ is the overdrive pedal for those who want more of...

I guess you meant by "can't be done" "can't be done exactly", and if so, I agree. Different circuit boards have different stray capacitances. I also agree that power transformers have an influence on the tone, and it is well known that the transformers on the Mark IIC+ were different. But the...

The smaller electrolytics are mostly in parallel to the cathode resistors on the preamp stages. They increase gain. Unless they are faulty you will probably not notice much of a difference between one electrolytic and another. Cheers Stephan

Here is what I did to my purple stripe: 1. Change C30 from 0.002uf to 0.001uf. 2. Change C516 from 0.01uf to 0.0047uf (this cap is in the feedback circuit in the output section) Check whether the output of the lead circuit has the 220k II 250pf to 100k II 500pf voltage divider. My amp had it...

That purple headshell rocks.

Hi Jon, Thanks for your great work. Can you please upload one schematic as standard pdf-file? I have difficulties downloading it. Thanks, Stephan

The main differences are (1) the resistor in parallel to C27 which is 2M2 in the Blue/Green and 3M3 in the IIC+ and up to Red. This affects mainly the gain in the clean and crunch (R1 and R2) modes, as it forms a voltage divider together with the 470k resistor to ground. In theory it should...

Given that the Mark amps are Fender based they are an excellent pedal platform. One of my favorite drives with them or any other clean amp is the Barber Direct Drive (any variant of it). Cheers Stephan

I used those when I retubed my Mk III a few weeks ago. Too early to comment on the reliability but no problems so far. Cheers Stephan

Jon, Many thanks for sharing! The lead circuit is quite similar to my purple stripe 60 Watt, except that - the resistor in parallel with the lead drive pot is 470k instead of 150k, which would provide for a bit more bass at higher settings. I think the 150k is actually beneficial as it tames...

Thanks for clarifying this - have not seen the schematic of that particular amp.

Fully agree - that's why I always speak of "modes" instead of "channels". Cheers Stephan

I hear you - it is the same feeling I had years ago with my Acoustic G 100 T that broke down after a gig triggering a 200$ repair bill - mucho dinero for a student, and I could not work on amps myself at that time. The only thing to regain confidence in the amp is to play the amp. If it works...

Does the howling stop when you turn down the guitar volume? If it continues to howl with the guitar volume down the problem is the amp, most likely a microphonic preamp tube. V1 is the most critical tube. If it does not howl with the guitar turned down at the settings you want to use, it is...

Bias in tube amps is necessary for safe operation of the output tubes. Generally this means that the grid must be at a lower voltage than the cathode. In amps with grid bias (often referred to as "fixed bias"), the cathodes are at ground (= 0V) and a negative voltage is applied to the grids of...