Does this Mark IV mod exist

[straitouttahell]

I just did it.

Since I had to tear the amp apart to fix some stupid footswitching issue, I thought I may want to try swapping C332 and C344.

After briefly playing the modded amp, I feel it's been a substantial improvement. It's not turned my MkIVa into a Dual Rec (which would have sucked), it just changed some shades to the overall colour. It's still a MkIVa, but let's say with a little less salt and a tad more pepper :wink:

Rhy2 seems to have considerably less flubbiness. It's still somewhat flubby, but much better than before. I haven't suffered huge gain losses, with the gain maxed out there's still plenty of distortion for my open chord rhythm works 8)

Lead mode with Mid Gain engaged is now HUGE. I have never used Mid Gain before, but I may reconsider it after the mod.

I have only played the amp briefly and at little higher than bedroom levels, so I'll have to wait to road-test it to say my final word, but so far I must say I'm impressed.

Suggestion: if you're not sure you can count on at least good soldering skills, don't try it. You're going to de-solder the components from the top, the pads are very thin and you definitely don't want to remove them together with the caps. Identifying the right caps it's going to cause you some headache, as the component ID is printed UNDER the caps. I had to get through half preamp schematics to make sure I was about to desolder the right components. Also, remind they're electrolytics. You don't want to install them the wrong way in. Lead free solder wire sucks, I only use 60/40 Sn/Pb :lol:

My 0.02€

 

[Monsta-Tone]

Also, remind they're electrolytics. You don't want to install them the wrong way in.

:lol: I actually did that once with a cathode bypass cap. It actually blew up after a minute or 2! I'll never do that again! :lol:

 

[dwsabianguy]

What about Mad Science Works or Darren Riley ?

I trust Yontz at Mad Science works as well. He has done some good work for me in the past. Just didn't know if he knew about it. And didn't know if this is what you did for living. If it was I was going to give you first dibs since you brought it up.

Do you think he knows about these mods?

I've had Yontz work on my amps (I trust him with Mesas more than I do Darren Riley, since Yontz is Mesa certified) on a couple occasions - he's the one that did my special Pull Shift (well, non-pulled) mod. He made the non-pull a good bit less raucous and WAY more musical. It means that my IV doesn't get quite as loud as a stock IVa, but I gotta say, it sounds way better.

And the Extreme mode on the V is just the stock IV Lead channel, sans Pull Shift.

The R2 mod sounds very intriguing, but I have to say, I actually like my tone on R2, especially with my Strat and a little extra boost. But it might be worth trying when the caps finally die in my amp.

 

[primal]

Rookie Question

Are the Caps you swapped surface mount or through whole?

 

[Restless Rocks]

The tiny "lytic" caps are thru hole but are easily removed if you carefully use some de-soldering wick (copper braided wire) and be sure to use a soldering pencil of no more than 20watts heat. If you're asking if you have to lift the board the answer is no.