# Mesa Boogie Rectifier Modification



## chrisboles226 (Nov 24, 2009)

Update: I originally offered to mod the amps for free of the first 2 people who were local. I'm now extending that offer to the first 2 people who get their amp modded as long as it's within the U.S.




Hey Guys,

I have owned so many of the rectifiers over the years and came up with what i believe amazing series of modifcations that work on all of the rectifier series. I have owned the Triple Rec 2 channel, Triple Rec 3 channel, Dual Rackmount Rec, Dual Rec 3 channel, Single Rec (V1). I have performned these mods on The last 3 Rectifiers I owned as well as 4 other peoples amps. I have refined the modifcations over the years to not only what works but what is worth the time to perform the mod as well as the cost of the parts.

TUBES: 
A big part of the sound of these amps is Pre and Power tube choice. I have a desire to harness the raw agression of the amp while tightening it up and making it more upfront, focused and open. ( times out of ten I find that JJ Electronics have the right tubes for the job. I base tube selection on what best compliments the amplifier design as well as peoples taste. I prefer The JJ E34L and JJ ecc83 tubes in these amps. The E34L's (thats right E34L not EL34) have worked for me in tightening up the bottom end and inproving the cut and midrange chunk/djent of the amp as well as providing hgihgs that are present but not piercing(very hard to do). The JJ ecc83's bring out the gain structure of this amp very nicely allowing a very nice saturation to overdrive ratio that I as well as many people prefer over the stock tubes hands down. They also help obtain a more linear EQ range which makes the controls a little more effective. Tubes are a very subjective thing as is tone but depending on what you are after we could also go with any other tube choice out there. 

THE MODS:
well I have designed these for somebody who would want to really make this thing more of a shred amp but anything is possible. In additon to the mods I have there is usually the ability to add a nob in the back( or front if you prefer) allowing control over 1 or more of these mods. After i did all these mods to a 3 channel dual rec of mine I installed a mercury magnetics ouput tranny . which set me back $300 and I absolutely hated it. I felt it overdid everything I had to done to the amp for 6x less then the tranny. So I wanted to hear it in a rectifier that wasn't modded and have a friend from a local band who's guitarist let me do the experiment. It sounded great and drastically improved tone but I A/B it and I truly feel i like the amp I had moddified with a stock tranny sounded raw/ more defined. I thought if you throw a great tranny in a great amp it would sound hot but that is wear art meets science to be able to balance and porportion things with out overdoing it

#1 I make the amp adjustable bias since mesa has their fixed bias which is so cold that it causes crossover distortion which is unmusical at best. The bias mod allows a more organic sound on the overdrive channel with improved harmonic content and gain saturation and overdrive.The clean channels also benefits greatly from this by really warming up and becoming more 3D. This mod is simple but very effective in combatting mesas poor design of cold tube bias. 

#2 I make channel 2(3 channel models) have the gain and presence circuit of channel 3 the only difference now is that chnnel two sounds like channel three with the mids focused slightly more on the lower mids then channel 3. I found myself playing on this channel exclusively for rythms with that chunk/djent and then switching to channel 3 for leads which is something channel 2's design did not allow me to do before.

#3 I modify the tone stack of channel one to mimic a fender deluxe reverb. This means now there is enough muscial character and 3D sound to play beautiful sounding clean passages with an emg81 bridge pickup. This mod can be easily custom tailored for any guitar and playing style /clean channel requirements.

#4(optional) I add 2 global eq controls one for channel 2 and one for channel 3 allowing you to shift the focus of the eq section up and down the frequency range. This allows me to set up channel 3 for a fluid tone that sounds like a neck pickup with more even more fluid gain while still having it on the bridge pickup. It could also be made to shift the focus of channel more into the upper midrange of marshalls from the plexi-jcm800 range or to an engl type grind.

#5 Retolexing. Pretty simple idea pic any tolex color or material you want and I can professionally install it. I have does this many times on many different amps.

All of thes mods can easily be custom tailored for anyones needs. I will offer the mods listed above free to the first 2 local people who are willing to bring their amp to me(PM me first come first served). I can mod it while you wait. The only cost to you is the tubes. I really only want to perform this service for forum members as I'm not trying to make too much money here just offer some cool mods too people who need them and hopefully build a rapport here. I know this service is very particular in that is for mesa rectifiers only but I don't have time now to to the reaearch and trial and error on most other amps. after I do the local mods I believe I'm thinking of a price of $125 I'll have to see how much time is involved in each but I have a rough idea.

alright let me know what you guys think. Does this sound like a service that would be worth offfering? 

Thanks chris


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## fretninjadave (Nov 24, 2009)

You can also change 1, ecc83 to a 12bh7 in your preamp to clean up your overall tone.


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## chrisboles226 (Nov 24, 2009)

Glad to hear others chime in with mods and tweaks. This thread is an open discussion and while i won't give away all of my secrets I would be glad to help anyone with their questions and ideas. We never stop learning and i still find new stuff out all the time so I appreciate and value others opinions and appreciate any correction if my info is a little off. Id'e rather have working mods out their then satisfy my ego.



fretninjadave said:


> You can also change 1, ecc83 to a 12bh7 in your preamp to clean up your overall tone.




while changing out a 12ax7 to a lower gain triode is safe and does work. To properly give the tube a shot you must realize that even preamp tubes are biased so since your changing the gain factor you need to compensate with the cathode resistor based off the new gain and existing plate voltage.

Doing so is simple but doing it right is a bit more tricky!


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## Leuchty (Nov 24, 2009)

Thats awesome mate.

What is a good bias range for the 3ch. Dual Rec, just out of curiosity>


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## chrisboles226 (Nov 24, 2009)

The math for that is P= I x v so since 6l6's can safely dissapate 30 watts lets go for %70 of 30 watts which = 21 watts of dissaption

21= I (Bias) x v The volts can be measured on the plate with a meter but on average its 450-475 or you can be safe and go high and say its 500 volts.

I(Bias)= 21/475 Which = 44.21 ma for the bias!



This is the bias I like. If you bias hotter(more ma) than 70% you will wear down tube life signifigantly and it starts to compress the low end and flub the top and bottom. on the other end if you bias colder(lower ma) than %70 it will start to tighten the bottom slightly as the highs start to become more harsh and the clean will start to lose its depth rather quickly and too low will cause crossover distortion. I'de say an acceptable range is 55% to 80% but again its subjective the most ideal thing is to do the math and figure out the min and max value of bias you wanna go for from say 40% to 85% turn the bias up slowly and not the differences and find what you believe to be the sweet spot.

​


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## kazE (Nov 24, 2009)

Sounds great, surely a cheaper alternative to FJA or Voodoo.

When I get a Rectifier next year I hope you're still around. In the meantime, someone please get theirs modded and post clips before and after.


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## budda (Nov 24, 2009)

FJA Offers warranties, I think. Not to knock buddy, but you have to be able to back up your work.

I think if you don't like what a mesa has to offer in the first place... don't get one. Modding is to enhance what you already love about your amp, not make it into something else.

Can't you clone channels on the 3ch recto's? I know you can on the 2ch ones.


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## chrisboles226 (Nov 24, 2009)

Point taken. As far as warranties I warranty all work free from defects for a year. It is so standard and almost implied that I forgot to even write it down. To be able to back up my work is the reason I wanted to do some local mods first for free to allow people to have honest reviews of it and post clips. Its also the reason my price would be what it is because I am an unkown and need to build a rapport. I have many years as an electronics tech in through hole and surface mount technology. I spent years tweaking amps so I'm no novice. I am well versed in use of all equiptment and own a nice scope, signal generator etc...

Mesa does not have channel cloning on the 3 channel models and the tone stack is completely different between channel 2 and 3. I have a love hate relationship with the amp stock which is why I mod it . To be honest I eventually just built my own amplifier to satisfy my needs but a modded mesa is my favorite commercial amp in conjunction with some engl's. Modification like you said is _ideally_ to enhance things but sometimes there are things that can be done to completely restructure an amp easily and these new sounds can only be achieved by the mod not by any other amp.


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## budda (Nov 25, 2009)

I think power to you, and I look forward to the feedback .

I'm content with my roadster stock, thank gord lol.


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## chrisboles226 (Feb 14, 2010)

I would like some opinions if possible I know some people must have some?


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## MaxOfMetal (Feb 14, 2010)

I'd love to hear some clips A/B'ing the modded Rectos to the stock ones, whenever you can.


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## Arsis (Feb 14, 2010)

This sort of makes me want to buy a Dual and get'r Modded.


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## chrisboles226 (Feb 15, 2010)

I would definitely get an A/B recording for uphere. I don't own one as I built my own amplifier, and I will launch my amplifier website before summer, but for now I like the work and I think it's a great way to get my name out there. Alright im gonna extend this to not just people who are local. Anyone who would want their mesa rectifier modded just contact me with what particular amp you have and what you want. The first 2 people who want their amps modded I would do it for free, but Shipping and tubes aren't included. It's a big thing to send your amp out to an unknown that's why all my mods are reversible and can be put back to stock for no fee if you wish.


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