Mesa MarkV / Saturation 'mod'

Fantastic thread guys!

I had not changed any of the valves in my Mark V since I bought it new around a year ago. I have now changed V4 and V6 to Jan Phillips AT7's and am really pleased with the results.

I am a classic rock guy (low channel volumes , high master , 45W, variac ,tube rect. etc)and am now able to increase the treble and presence in each channel (Fat,Crunch and Mk iv)and get loads of bite and chime without the ice pick in the ear. Any honkiness has also reduced so I've been able to push the 750 Hz slider up slightly from the classic V shape to just below the centreline to round the sound out.

I've got a gig on Saturday so I'm just hoping it will sit well in the mix!

Regards
Rob

Funny I have not gotten too it yet...... been busy with the drums and finally have them where I want, nice woody tone. Was considering getting a pro drum kit but thwarted that with different drum heads... now focus shifted to guitar....Yeah, I had loaded V4, V5, and V6 with 12AT7 before. Not bad but not great either. SPAX7 in V1 typically cures the ice tone but when playing loud that is difficult to tame. With stock tube in V1, I have to drop the treble down completely and kill the presence. Have to visit this perhaps today and see what happens. May just use a long plate 12AX7 in V6 (helps with the FX return as well as the master volume for CH3). Mullard Reissue or the JJ ECC803s seem to have a bit more roll of on upper frequencies. Will have to try the Jan/Phillips 5751 but may have to remove the tarnish off the pins (same with the other NOS tubes). Not sure if they are nickel plated or silver....my guess is for nickel.

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It is all trial an error. I have been reading up on the differences of the 12a?7 tubes. Differences of opinion seem to be floating around about tonal characteristics. I would be more concerned about the plate voltages on the preamp tubes more so than the gain effects or roll off. Still would have to play around with what tube I have in my stash. I became fond of the Mullard RI long plates on V4, V5, and V6 (assuming you can get a few that do not have the mechanical noise issues, I have 4 out of 6 that were good, the other two pinged when channel switching and one could easily be triggered to go micro-phonic.) I have had similar issues with the Chinese ones with the clips on the plates as they are not as good as the earlier versions with the square getter that Mesa used to offer. The Mark V is an interesting amp to tube roll and responds to tube changes. I found quite the opposite in the JP-2C but I have not fully explored tube rolling in that amp but I did have a noisy preamp tube I had to track down and replace so I tried substitutes just to hear the difference. Note that the Mullard CV4004 work great in V4, V5, and V6 as well. I had installed all old stock Mesa Chinese tubes into the Mark V, had the best noise floor ever with no hum on the clean channel or CH3. CH2 is always quiet, the down side is that the CH3 becomes more compressed than with the stock tubes.

There may be a good complement of preamp tubes that work well with the Mesa STR440 6L6 power tubes. When going to something else like a =C= or TAD it makes sense to change tubes as the power tubes also have their own character.

Here is the thread on the 5751. It has been a while since I visited the tube section.... Do not recall if I was using SED =C= or Gold Lion KT77 at that time, probably the =C=. V1 seemed to be the better place for the 5751 but found the SPAX7 to reduce the ice as the 5751 had its own character to it.

http://forum.grailtone.com/viewtopic.php?f=16&t=63630

I will dive into the Mark V once again and try just changing V4. There are other means to alter character just by changing the PI tube. Sovtek LPS will brighten up a Roadster but has a different effect in the Mark V. Sometimes it is hard to quantify into words what the actual effect is.

Hi guys,

Got another couple hours spare on sunday so put the old stock 6L6's back in and wow.

Just to quantify, i loved the amp from the first day that i got it but always struggled a bit with loud volume levels. Got rid of a Boss GT-8 i had in 4cm, that helped. Then tried some settings i found on the board here. They helped a lot. Got hold of some EL34's and they helped even more to tame the harshness of the amp. I figured that i just prefer'd them to 6L6's.

Now i can love both. With the following setup;

V1 - Tungsol
V2 - Stock Mesa 12AX7
V3 - Sylvania 12AX7
V4 - Jan GE 12AT7
V5 - Sylvania 12AX7
V6 - Jan GE 12AT7
V7 - Sovtek LPS

With the EL34's;

Ch1 is pure and sweet, not quite as sweet as with 6L6's but by no means bad at all. Tweed loves these power tubes. Ch2 absolutely roars. i mean it really roars. Real throaty sounding, which i love. Ch3 is incredible, no ice at all. So much more usable range on all the controls. iiC+ especially great now.

With the 6L6's;

Ch1 is heaven, a little reverb and Fat mode is the best clean I've ever heard. Tweed is not quite as nice as before but Clean and Fat modes definitely favor the 6L6's. Ch 2 is still great, not quite as gnarly as before but by no means shy at all. Ch3 is very similar to how it was with the EL34's, just with more bass. A bit ballsier maybe.

I cant decide now which power tubes i prefer on Ch3. Still think the EL34's have the edge for Ch2 and Tweed in Ch1 and the 6L6's have the edge for Ch 1 Clean and Fat but its pretty close now for all modes with both sets of power tubes as the range of control is much more usable across the board now the the highs are under control. The things that used to favor one power tube over another don't seem to have as pronounced an effect now. Think I'm going to stick with the 6L6's for a while as haven't used them in over 2 years to see if they grow even more on me. Maybe then if i can afford it I'll see about getting some of those TAD 6L6 GC...

Thanks,

Wayno.

Wayno,
The TAD 6L6GC-STR were the one's I had used. Sounded great, not as awesome as a quad of =C='s but similar. They have other tubes too (short bottle 6L6WGC-STR that seem to have higher ratings by customers) but not sure which are the better versions. The Preferred series has a similar tube to the 6L6GC-STR but they sounded bright to me, not as full bodied and bold like the TAD versions. I finally started liking the Mesa tubes in the Mark V.

There is one tube position that was left out.... V3, it sits after the cascade gain stages of CH3 (V5 to V4) and is in front of V6. Not sure what a 12AT7 would do there. Something else to consider if you like the 12AX7 in V5 and V4.

Loving this thread!

Following my previous post, I installed a JP12at7 in v5 & v6 and all ice-pick highs were gone. On the other hand, the gain structure was demolished to the point where I had to dime the gain in ch2 & 3 which created other problems with the overall sound which I could not compensate for. So I then replaced the JP12at7 in v5 with the Ruby 12ax7 and things got a bit better but still lacked the saturation level and depth that I'm looking for. After playing with this setup for a few days, I swapped the JP12at7 from v6 to v5 and, so far, I'm very, very pleased with the results. Still does not have the saturation and depth that I'm looking for but the amp sounds so much better overall. If you play classic rock or blues, this is definitely the mod for you!

I'll be playing this setup tomorrow in full band scenario and will report back the results from the frontline shortly thereafter.

Thanks everyone for the info and tips...this has been the most helpful thread for my tone search with the mv since purchasing the amp and playing it live over ten years ago!!! Kudos to everyone who has taken the time to add their 2 cents on this topic...really.

Hey Bandit,

Would love to get hold of some =C='s but doubt i could justify the cost of them to the wife now. Shame as they seem like they had a good thing going there. Out of all the new production tubes they seem to be the only one's which are widely regarded as great. Wish i could afford them. Next best option seems to be the TAD 6L6 GC's, can get a matched quad for around £80 here in England, =C='s are more then twice that! Why did they get so expensive? Supply and demand? Even so, £80 is going to be hard to find at the moment, young family and all that, so will have to wait I'm afraid. Full bodied and bold sounds like i'd love them with the Mark V the way i have it now. Maybe I'll get to treat myself in a few months time if i keep my overtime up. In the meantime, I'm more than happy with the stock 6L6's and the EL34ii's as you might have guessed haha.

Ok, forget using a 12AT7 in V3, just did it and well, blah. CH1 was noise free though, CH2 about the same CH3 was about the same.

Moved onto V4 and bingo that so far is the hit for sweetness on CH3. Ran all voices at good level and loved the difference. Brings the tone closer to the JP-2C. I left the settings I had enjoyed for a few minutes as is and returned the tube the stock tube. Very muddy tone. Even with the base dialed out. Had the gain and presence set to 2PM, bass at 10am, midrange at 1pm. Actually prefer the 12AT7 in V4 with the rest stock except V1 (using an SPAX7). I should try the Mesa 12AT7 as I have a few of those on hand (RA100 uses them, also reason for the JAN/phillips and RTF 12AT7). This time I used the JAN/Philips. Last time I used the RFT. Note that the cost of the NOS JAN or the RFT is less than the Mesa 12AT7. Definitely going back to the 12AT7 for V4. Did not kill the bright switch as I can still hear a difference, not much of one but there is a difference.

Back again.... Mesa 12AT7 is okay and removed it in favor of the Jan/phillips 12AT7. I then realized I had the bass dialed out so not a fair comparison (needed to do this with the stock 12AX7 as it got flubby and muddy). Played with the Mark V combo a bit with the JAN tube in V4, have the MC90 in it now so my sig is out of date. Since the JP-2C is in the same room, fired it up and wow sounds very close. To be sure, changed the Mark V over to the vertical 2x12 and let it rip. Sweet deal, if you want your Mark V to sound like the JP-2C do the mod. I found it very difficult to actually tell the difference.
Mark IV mode is much closer to CH2 on the JP-2C. The bright switch seems to cut the bass just a little when it is on, turn it of and almost mirrors the JP-2C CH2 (without the shred switch turned on). The Extreme Mode is similar to the JP-2C CH3 but not quite as liquid.

I also noticed that the 5BEQ had more tonal effect. Also for the first time I was able to use the preset setting while using Extreme mode.

V4 = Jan/Phillips Make the Mark V a keeper for me now. I was considering getting rid of it when the TC-50 arrives. Dang it, running out of room for my amps and gear. Drum set stays so that is not optional to move.

One last word (yeah right....) if the 12AT7 can hold up in V4, this would make it the lower cost option to make your Mark V sound as close as you can get to a JP-2C. Before, I suggested the grid slammer or flux drive. Wonder what they will do now? Too bad this does not fix the edge voice in CH2 to me that has to be the pits, perhaps I am running the gain too high. Awesome advice APEMAN for starters....Thanks for steering me in this direction. Best mod so far and beats the long plate 12AX7 (those help on the V6 position but not sure it is needed.)

Awesome thing is, you do not loose any feel from the amp, actually it just gets better. Controllable feedback, and the full power chord is amazing.

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APEMAN, I leave the responsibility to you. It was your suggestion to give it a go. Once I decided to try out the 12AT7 in just V4 I noticed something that sounded familiar and it was sitting right next to me in the room, the JP-2C. I have been using the Vert. 212 with this amp as it will not kill my hearing though the 212 and the 412 was too much (in a good way). For some time I could not stand the Mark V though the V30. I could tolerate it for a short while. Something about CH3 was missing but CH2 had the mojo. After the "mod" I was pleased with the overall tone of the Mark V on CH3. Also the MC90 no longer sounded honkey with CH3, it sounded fuller. Compared the V to the JP and my jaw dropped to the floor. They sound the same (comparing Mark IV mode to CH2 of the JP). :shock: :shock: Extreme also meets the CH2 (JP) and seems to get into the CH3(JP) territory. The down side.... you have to flick the 3 position toggle to change the voice so you cannot easily change on the fly with the footswitch. You get the flavors of the JP in some respects but that is limited to one channel. Heck even the IIC voice was better not that it was bad.

The cool thing, I can actually set the gain much higher than I normally would as it will not get muddy (so distorted that definition is completely lost) also you can add more bass with a moderate gain such that it sounds like the JP-2C. I was able to set CH3 of the Mark V to the same settings on CH2 of the JP and I could not tell the two amps apart. Will have to try it out using the horizontal cab with the V and Vert with the JP so my reference does not need to be unplugged. Odd enough that the Mark V replacement is due to arrive today. (bought the TC-50, but not intended to replace anything with it, but it will consume me for a while).

I will not go overboard on this (too late... already did). This adds yet another level of manipulation that does not require a solder iron and can easily be done with two hands and no specific tools (unless you have a head and cannot fit your hands between the chassis and reverb tank to swap out one or two tubs, V1 is a PITA to change and may require unnatural bending of the limbs to replace it. One reason why I converted my head to a combo.)

I'm glad you worked with the amp too apeman! I've never been happier with it than I am now. Kudos for opening and or re-opening our eyes to this simple yet super effective mod. I hope I haven't hijacked your thread with my wordy posts.

Thanks to you too Bandit, I've enjoyed reading your thoughts over the last year or two with your love/hate relationship with the V. I'm happy I think you're going to keep hold of yours as it is a truly outstanding price of machinery.

Now if only I could get my band to pull it's finger out so I can really crank this baby up!

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That my friend is to be discovered. EL84s will always sound like EL84s which is not a bad thing.... All depends on the tuning and bias point on each of the 12AX7 in the chain. One note: I did experiment with some different tubes in the JP and it was not rewarding, either no change in tone or character or it sounded off the mark.

APEMAN & Bandit... thanks so much for this. I got my V combo in 2010 and fought with over the years. Tweaking, leaving, coming back... (rinse / repeat)... and never felt like I could get the goods out of Ch3. Until now!!! 12AT7 in v6 ... subtle, but perfect. I have been enjoying this so much that I haven't tried in v4 - will do so soon, but really enjoying things now. I felt like somewhere in there was my "lifelong" amp but would always end up frustrated trying to pull it out. Now, it seems to have finally showed up!!! Cheers!

That is great soundbee. I know your frustration. I have been able to cure some of the brittle tones with different preamp tubes but was not as effective in providing that lower mid range boost that seemed to be missing from CH3. The difference in impedance of the 12AT7 brings out some of the tones that are getting lost from the 12AX7 tube which is the secondary gain stage following the gain control. My amp was very brittle with any level of presence other than at its lowest setting, Treble was also kept below 10am. Now I have the amp fully loaded with Mesa tubes except for V4 and I love CH3 as much as the JP-2C. I can hardly tell the two amps apart from each other.... Only difference is you have to move a toggle switch between Mark IV mode (equivalent to the CH2 of the JP) to the Extreme (equivalent to the CH3 of the JP). Mark IIC is also great too but I could never dial in the Mark V IIC+ mode to sound like the JP-2C. To me that is the bench mark tone of Mesa Boogie. Also was present in the Mark III and Mark IV but you really had to figure out how to get there.

bandit2013... I've read a couple of different posts / threads on this mod... what position have you landed on for your 12AT7? You mention below V4... is that still your favored position? Why...?

Thanks again!
-kevin