Amp mods

[edmiller9999]

It seems like there's a lot of discussion here on amp modifications. I, personally, have a Mk IV and would never, ever consider modifying it. However, I'm interested to see how many of you have done so.

 

[screamingdaisy]

For me, the trick has always been to figure out how Mesa actually intended the amp to be used as I find that once you have that figured out it opens up a lot of possibilities.

 

[crguti]

I did simple mods to my DC-5. Now it's the perfect amp.

 

[SonicProvocateur]

Mark III -> R2 volume mod, must have for total balance.

Anything else seems very to taste. I could live without the +mod, presence mod, bias mod, or the odd and end resistor mod for changing voicings.

I would never however switch out my lovely tranny for a Mercury. Seems like blasphemy.

 

[mreeve25]

"my lovely tranny"

:lol:

 

[SonicProvocateur]

:lol:

We came in lulz for all mankind!

 

[zodiac272]

if moding a IIC to a IIC+ counts, then yes count me in

scott

 

[chipaudette]

I've got a IIC that was upgraded to a IIC+ by MikeB at Mesa. It's got a 60/100 watt combo with GEQ and reverb. I use both the combo speaker and a Thiele cab that I have.

After playing with it for a while I found that it didn't have quite enough sizzle for my taste. Therefore, I made a (easily reversible) modification to the amp that added a switch in the back (I used the hole for the slave out jack). The switch cuts on the 1000pF capacitor that jumps across the plate resistor of the last lead channel gain stage. The cap here is one of the main circuit differences between the IIC+, the III, and the IV. Using a 3-position switch, I've got all three values, which is 1000pF, none, and 500pF, respectively. I find that I use the 1000pF most of the time, the "none" setting rarely, and the 500pF a decent amount of time. To anyone but me, it's a fairly subtle mod. To my ears, though, it makes a decent difference and it's a fun mod to have. The extra bite and sizzle really helps put me in a metal mood.

The other (easily reversible) mod that I did to my amp was to swap out the mid pot for a mod pot from a Mark III...in other words, one that is pull switchable. When I pull the pot, I can have another function. I've chosen to do a mod that alludes to the IIC++ mod, which is to add a cathode cap onto the tube stage at the mix point between the clean channel signal path and the lead channel signal path. When engaged, it can add some serious compression and fizz to the sound, if that's what you're feeling like. After the novelty of it wore off, though, I hardly ever use it...it is just too mushy. If I used the pull-switch to activate some relays or LDRs, maybe I could bring in and out more elements into the circuit, but as it stands, I wouldn't do this mod again. I'll probably undo it the next time I'm in the amp (which is rare these days).

Those are the mods that I've done. Anyone else got some good ones?

Chip

 

[gonzo]

i changed out the caps on BASS control, took out .047 cap, put in .022.
tightened up the bass control nicely, still never take it over 2, but before that, it sat on zero.



next mod: tweak values on the phase invertor section.

 

[chipaudette]

i changed out the caps on BASS control, took out .047 cap, put in .022.
tightened up the bass control nicely, still never take it over 2, but before that, it sat on zero.

Is this on your Mark 2B? Does the 2B have the "Pull Shift" on the bass? If not, I can totally understand swapping the bass cap. If you do have the pull shift, then I'm a little surprised that you feel that you have too much bass. With my bass pot pushed in, I often find it a touch too thin...especially on the clean channel. Every guitar and amp is different, so you (of course) know what sounds best to you...I'm just surprised.

Cool. I like it when people are bold enough to mod their amps to suit their own taste. More people should take control of their hardware that way...as long as they don't electrocute themselves in the process.



Chip

 

[tonejam]

I've replaced the reverb tank in my Studio 22+ with a full size one. I use a 12AY7 tube in V1, which helps balance volume when switching to overdrive. I've had a mod (kit from Londonpower) which provides a master volume control, reducing the voltage on the output tubes(among other things). This is a GREAT mod when used subtly, makes the amp better for coffee shop volume levels. Lastly, I've replaced the speaker with a Weber alnico Blue Dog.
The amp now does everything I want. Would NEVER sell it!

 

[Monsta-Tone]

:lol: Guess everybody knows my stance, but I'll take a shot anyway! :lol:

Not all of us can afford a IIC+.
I found a way to take the average Mesa entry level amp, like the DC or the Studio or Caliber, etc. and turn them into the fire breathing monsters that their big brothers are. Simple as that.

If you have an amp that you love the clean tone on and wish the lead tone was better (or vice-versa), and if you are tired of changing amps constantly looking for what ever tone you are after, then it makes more sense to mod the amp you have. I don't like making extra holes and de-valuing the amp's future resale though. Although, my Heartbreaker has a couple of extra holes up front! :mrgreen:


As for transformers, well, it's a matter of personal taste. I have found personally, that Mesa tends to under size their output transformers because of the amount of coil saturation that occurs when the amp is used. I personally do not like this form of distortion. If you have an amp that you are satisfied with, it does not make sense to change the OT. Changing the OT on my Maverick is about the only mod that I have done to the lead channel and it basically made the amp come to life. I felt that the lead tone was incredibly lacking before. Now it really sings.

 

[dangit]

yes

i had a tech install ftswitchability for effects loop on bot my studio .22+ combos so i can switch the loop in/out
i used to love that-haven't used it in a long time

i put alnico blue dog in one of the .22's
nice
although the stock mesa spkr was fine

also had a tech put the ftswitch drive mod in my lss
cool

 

[scottcrud]

Both my .50 Caliber +'s have had one or both transformers replaced. One with a true 50 watt Mercury Magnetic output transformer.
I took the other one to Kendrick Amps back in 98 and had Gerald install 100 watt output and power transformer, as well as 2 6550's instead of 2 6L6's.

 

[littlephil]

I'd never mod my IV. It sounds perfect as it is anyway

 

[edmiller9999]

Nope. :lol:

I really blew the wording/scope of this question. Too many guys have an amp or two deserving of worthwhile mods. I probably should have asked who modded his Mark IV. Duh. :?

 

[dangit]

Nope. :lol:

I really blew the wording/scope of this question. Too many guys have an amp or two deserving of worthwhile mods. I probably should have asked who modded his Mark IV. Duh. :?

no harm done...

 

[gonzald1]

Added a bias mod on my roadster. i can now use other tubes with proper bias setting.

 

[mxr2000]

I would like to do a effect loop mod to my .50 caliber amp to make it more usable and musical,anybody here done this on this amp, also a extra gain pot to balance the clean and gain channel is a most to get the most out of this amp, any body here know about some other mod that can be done to this amp to make it even better?.. thanks

 

[Monsta-Tone]

Search the DC forum. The DC and the .50 Cal are fairly similar.
The DC Loop mod and Master Volume mod will work very well on your amp!