Mesa MarkV / Saturation 'mod'

[bandit2013]

I still have not moved the JP-2c out yet. Mark V is presently next to the TC-50.... I sort of got annoyed with it when the Celestion Crème 90W changed on me and went into tunnel mode. I though it was done for before but was sounding great for a while after I over heated it with the JP-2C. MC90 back in the V. That is okay.... but may shove the EV back into it. On the fence at the moment. Sometimes I wish I had not converted to a combo as the Vetical 212 cab sounds awesome. I do have the horizontal but limited space in the family room at the moment which is where I usually noodle around with the guitar the most.

Still using the same 12AT7 and no issues to report. Sounds great....

 

[Bankim]

Has anyone opened up their amp and run voltages on V4? While the max current on a 12at7 is greater than a 12ax7 the plate voltage max is about 10% less if I recall. The reason I ask is that on my amp after running the at7 in v4 for several hours channel 3 develops a faint noise similar to an ac current 60hz hum. Perhaps this is due to a really unusual coincidence or my amp just has an issue but it has happened on one new jan/phillips, one new jj, and one used groove tubes 12at7. Channel 3 is fine when I put any 12ax7 back in. I don't mean to throw a red flag because I see no reason this substitution would not work within specs.

Have you tried the at7 in V6 ?

I usually have the AT7 in V6 but just for change I have it in V4 for the last couple of days. I am really intrigued by your finding because I faintly remember this hum as well. It doesn't have the hum when the amp is just started up but after an hour or so, there seems to be a slight hum. I have to also note that the Mark V now loves to have some volume with the tube swap, so maybe its the volume, or something else.. Will need further testing. I ll keep the 12At7 in V4 for a few more days just to be sure.

Thanks and let us know how it goes for you. To answer your question, my preference is running at7s in v4 and v6 at the same time.

In my case the hum will start in a new at7 in v4 after a couple of hours (in channel 3 only). After that if I continue to leave that at7 in v4 the onset of the hum will occur sooner with every use and eventually will happen just as soon as the amp warms up. The hum is present only in channel 3.

What I am really concerned about is after this happens the tube is no good. I can put it into my original Super Reverb or Twin Reverb in the phase inverter slot and it is too noisy.

Finally had some time to myself past weekend. Played the amp for a couple of hours with the 12AT7 in V6. It sounds punishing. So brutal and smooth at the same time. Playing in dropped D never sounded better. Had to look up some Tool riffs just for the heck of it. 8) Anyway, there is definitely no hum with the 12AT7 tube in V6. The FX loop sounds like it compresses the sound a bit more when engaged. I usually prefer not to use much effects when playing alone, so thats ok, for now..

With the 12AT7 in V4, it still sounds great but missing some gnarl. Didn't get the 60 Hz hum that crept in previously. Either V4 or V6, the amp is just a joy to play with. Just a note that the amp was at gig levels yday.. It was loud ..

Wish I had a recording set-up at home just to put this across.. maybe in a month or two..

 

[Dreamtheaterrules]

I finally got home last night and got another solid 45 minutes with the V25. At this point, I'm confident that both the Crunch channel, and all voices on C2 have been improved. Significantly. The simplest explanation is, the crunch is just sweeter. Warmer, less cold... I really think this is not subtle. This is the Mesa tones I've been looking for.

Crunch was already my favorite channel on the amp. Again, might be part AT7 and part old Mullard, but the Crunch mode is just sweeter. The clipping is less "hard" sounding. Oh, it can definitely be just as mean and aggressive as before, just sounds BETTER!

C2 is transformed. I spend probably 30 minutes on IIC+ mode last night, which has always been my least favorite mode on C2. It was just KILLING it no matter where I put the dials. I had the gain from 9:00 to 3:00 and it just sounded better than it ever has. At 3:00 it got real mean and nasty. Old Metallica tone! But without the bees. I actually turned the 750 slider up just a bit and it just filled in, not quite as scooped, just as mean. Quick flips thorugh IV and Xtreme, also just better, and clearly so!

The timing of this is funny. I just got a new amp and it's the best amp I've ever played, and I couldn't stop playing it. Now I haven't turned it on in a while. Not that it's any less great, just that the revelation that is the new V25 must be thoroughly explored. I could say a lot more even after just two test sessions, but don't want to just ramble. Will say this: IF it changes the big Mark V as much as it changed this one, I will finally fall in love with that amp the way I expected too when I bought it. And this: 3 Weeks ago I decided I didn't need two version of Mark V. If it improves the big one this much, I won't consider selling either.

 

[Markageddon]

Yes its fantastic isn't it...

Glad you're enjoying it mate. You're right about the sweetness. Smooth, screaming leads, with so much more clarity and definition to the string/note.
Rich brutal chords and oh so playable and organic feeling.
Extreme mode is unbelievable when dialled in too.
The V4 mod in the big one replicates the same type of gain feel. And the dials operate similarly.
You have much to look forward to. Whether 25, 35, or the 90w: Definitely a keeper.

Great that you're also getting the time to play/appreciate. Thats what this is all in aid of, after all.
Diving of that springboard into an azure blue ocean of tone...!

 

[bandit2013]

I decided to go back to 12AX7 tubes. Not that the 12AT7 was bad or anything, just wanted a change and I knew exactly what was going in the amp as I had a small surplus that I have not been using... my old collection of mildly used Mesa 12AX7A from the late 1980's. What I am referring to is the triple mica Beijing Chinese tubes with the dimpled square foil getter. I have used them before in the Mark V and the characteristic is amazing. For starters the hum goes away in the clean channel (dead silence with no signal), CH2 rips and CH3 does not have an ice pick tone since the tubes become compressed when overdriven too hard. It is similar to the saturation mod but huge in tone. I did not fully load the preamp section, just V1 though V6. I only had that many to use so I stuffed a Sovtek LPS in V7. Now that is a Mark Tone on all accounts. Heck even the edge mode sounds half decent. I thought this was ideal such that I ordered 10 of them from Doug's tubes. At least there are some available. I will let you know how the newer ones sound compared to the Branded Mesa tubes. Now I will have to get the JP-2C out and compare the two. I ran the Mark V though the Vertical 212 and I was impressed that there was no ice. Even ran it in Extreme mode with the preset on the EQ. Also since I changed speakers in the Mark V combo to the Celestion Red Back (once that thing is broken in it is much better than an EV). Go figure, I was thinking of selling the Mark V again as it just was not all there for some reason. Now it is all there with spades. I can save the 12AT7 for use in the RA100 or the TC-50 as both amps use the 12AT7 for the FX loop.

If you are interested, the reference for the square getter tubes.... Unfortunately just one tube probably will not cut the mustard. At least I had a surplus of some lightly used one's. 10 of them set me back a bit. Also if the newer one's seem to rich for V1, I have 6 old ones to use up.

http://www.dougstubes.com/nos-chinese-12ax7-80-s-90-s.html

 

[Markageddon]

Have you tried the 12x7a AND the AT7 yet?

Got a friend coming over with his 35 most likely on Saturday.
Hes up for trying the mod, will post the results.

 

[bandit2013]

No I have not. For some reason the dynamics of the 12AT7 was loosing its luster and the Old Mesa tubes make up for it as the compound gain stage does not generate the high order harmonics as much as the re-branded JJ tubes. I have been here before with these tubes (but prior to adjusting the negative bias voltage a small amount with a resistor change as the original bias was causing premature red plating on the center pair of Mesa 6L6GC STR440 tubes. I could not use them at all, SED =C= 6L6GC had not issue and were the only tubes that lasted longer than 8 months (they are still good to date but not in use at the moment). Also at the time I was running KT77 power tubes which really added to the sinister tone for CH2 crunch as that is all I was using. However with the Mesa 6L6GC STR440 on board, I am getting some awesome results and now the Mark V is performing better than I expected, even better than the JP-2C but will have to confirm if and when I get that amp in the other room (my attention has been on the TC-50). Actually I am getting similar tone and gain characteristics with the old Mesa (square getter tubes) if not better than I did with the stock Mesa tubes and the 12AT7. Win-Win for me. Awesome though the Mesa Vertical 212, and surprisingly amazing with the Celestion Red Back in the Combo.

 

[Markageddon]

Blimey. Tone worth an 8 month 20 dollar tax..!

The cabs and speakers will definitely have an effect, yeah.
Ive not tried those.

Thanks for sharing. \m/

 

[Dreamtheaterrules]

While I do intend to make one swap back to 12AX7 then swap back to AT7 just to get a true A/B test in one night...

I'm in and I'm staying! The only thing that I could think of that would make me change my mind on the AT7 in V2 of the V25, is if the 5751 is even better. Otherwise, I'm getting ready to order some NOS AT7 and 5751 tubes for the Marks.

I was just getting ready to do Dougs Tubes Kit. Now it looks like I"ll order some Tung Sol's for V1 (haven't tried that yet) some LPS for PI and maybe some Chinese tubes for the other PRE slots. I do want to try a nice tube in V2 of the Mark V to see if I can sweeten up C2 on the big one. If i get it sounding like the V25 crunch,but bigger and ballsier... then the amp will be the holy grail amp I thought it would be for me.

The Mark V25 Crunch channel is sweeter than ever now, and the C2 Voices are all just varying versions of the great Mesa tones I was really after. I have one bad pre-tube to track down in the big one, then I'll drop the 5751 in V4 to see what happens.

 

[Newysurfer]

This is about my MarkV - I see people struggeling to get a heavy saturated musical tone from it the same I did - this will help!

I bought my MarkV back in 2010 on a holiday trip to cali and since then, I had to learn how to set it up - before, I played a dual recto 3CH which could never meet the tone I was expecting and I hated to use any pedals. The MarkV on the other hand came much clother to the tone I heared in my head, but there where always some fizzy or cold treble frequencies that I couldn't dial out.
The amps FX loop section is bright and adds brightness to everything you play. In the meantime I understand the reason and know how to get rid of that. This is what I want to share with you.

The ice pick or fizz issue is always there, mainly in CH3. The simple cause, that makes it nearly impossible to dial out is that it is generated late in the signal chain, at the end of the preamp. To disable the FX loop makes it better, but I didn't want to lose the solo function and the FX loop. The only thing you can do with standard tube configuration is to keep the chanel master low (I wrote about that secret tone control in another threat), but there is a far better solution:

There is one preamp tube that is golden and perfect to me - back in the days, it cured all troubles I had with my laney, peavey or orange and it cures my MarkV trouble as well. It is the Jan Philips 12AT7. And on the MarkV it belongs on V6, the last stage just before the PI. One triode of V6 contains the last gain stage of ch3, the other triode is the fx loop/solo stage. Compared to 12AX7 it sounds big, fat and nothing but sweet in the higher frequencies and never harsh or cold. It has only 60 percent of gain - and that is maybe the main reason why it will not generate any further treble distortion or ice pic - it just fatens up the tone and lets you dial in more usable sustaining gain that you could think of. It simply cuts out all the harshness.
The funny thing is that you can still dial in more high frequencies than you would ever need. Just use the EQ. The missing level can easily be compensated by turning up the send level (mine went from 10:30 to 02:00).
With the 12AT7 in V6, the highs are not longer dominant. The consequence is that you can dial in more gain, which adds so much sustain and brutality to the sound. The MarkIV mode as well as the MarkII mode can deliver heavier tones then before.

Here is a video I shot just half an hour before my bandmates arrived to rehearsal - random noodeling, so please be patient with my playing

Unfortunately, I don't have any high quality recording equiptment at my rehearsal space, but when you listen to the video I think you get the idea of the tone.

https://pl.vc/1ksxbg setting

https://www.youtube.com/watch?v=PbTDvYfRMwI video

Mesa MarkV (2010) - Mark IV Mode // 90 Watt // Full Power
Preamp: V1-V5: EH12AX7 // V6: Jan Philips 12AT7 // V7: Sovtek 12AX7LPS
Poweramp: TAD 6L6GC-STR // JJ GZ34 (for a heavy 10 Watt Mode)
Mesa 412 std slant & Mesa 112 Thile EV Speaker [Clone]
Ibanez RG Prestige 3620 (Mahagoni with DiMarzio D-Sonic) thru Sommer Spirit XXL Cables

Tell me what you think - greetings from bavaria!

Well Apeman my Mark V doesn't have icepick.
But then I use different guitars than you.
I can't hear any icepick on your video noodling but if you do it's probably a pup issue

 

[bandit2013]

My Mark V does have the ice pick. The simple and cost effective 12AT7 in V4 was all I needed to be happy. However I wanted a bit more equal footing on all channels through the combo speaker. EV may be a better choice as once I put the MC90 back it I lost interest. The Red Back was just willing to be stuffed into the combo so why not take a break, break in the RB in the combo and make use of the new piezo guitar I recently got. Still had the hum on CH1, CH2 is always quite and a similar hum can be heard on CH3 (however not as apparent with the 12AT7 loaded into V4). I thought about the tubes I had used in the V in the past that well, fixed most of the issues and the non-signal noise. I liked them so much but decided since they are not longer available to find something else. Once I gave up on them Doug's tubes has an inventory or them, probably unbranded. These are the same tubes that came stock with my Mesa Mark III (blue strip). I am still kicking myself for giving away more than half of the preamp tubes I had saved from the band days when I sold the Mark III. Never thought to use them in the Mark IV. When the power tubes needed replacement I replaced everything. Tubes were more affordable back then.

Actually it was the Mark V that prompted me to get into tube rolling, not to find the holy grail tube, it was an attempt to correct the terrible ice pick tone that only got worse the more I played the amp. The old mesa tubes worked well with the SED =c= 6L6 tubes but ripped like new evil with the Gold Lion KT77.

I will find out soon enough if the Beijing tubes sound as good as the old stock Mesa tubes. (Fingers crossed).

I actually do not have an issue with the 12AT7, I was just getting tired of the Mark V in general. The old Mesa tubes sort of re-sparked my interest.

 

[Bankim]

Bandit, it might be just better to sell off your Mark V. Between the JP2C and the Tc-50, you probably have all your bases covered. Have a nice drink and Think about it; weigh your options and make the best choice..

You could always spring for a Mark V later , if you end up missing it..

Cheers!!

 

[Dreamtheaterrules]

Yeah, a head, to play with your 2x12 vertical recto cab!

 

[bandit2013]

Sorry if I was coming off as complaining. The 12AT7 mod is awesome and would recommend it to anyone. I like the Mark V for what it is and yet it may not be the ideal amp for me.

There is yet another avenue for getting awesome tone from the Mark V. Since I have some old Mesa tubes from the Mark III, I found them to be ideal for all channels relative to noise levels, clarity, and gain response. Since I was able to find them (without Mesa sorting or branding) I will have to see how things pan out.

 

[Bankim]

No need for apologies.. just saying it as I see it.. I might have come across a bit harsh, so my apologies for that too..

It would be fun to be in your position though.. ha..

 

[Dreamtheaterrules]

Sorry if I was coming off as complaining. The 12AT7 mod is awesome and would recommend it to anyone. I like the Mark V for what it is and yet it may not be the ideal amp for me.

There is yet another avenue for getting awesome tone from the Mark V. Since I have some old Mesa tubes from the Mark III, I found them to be ideal for all channels relative to noise levels, clarity, and gain response. Since I was able to find them (without Mesa sorting or branding) I will have to see how things pan out.

I'll be watching for your response on the new tubes. If they are what you think, we might run Doug out of them quickly! 8)

(To the point that I already had a tube order made out for Doug's, and didn't check out. Waiting to hear what you find out before I order).

 

[bandit2013]

Sorry if I was coming off as complaining. The 12AT7 mod is awesome and would recommend it to anyone. I like the Mark V for what it is and yet it may not be the ideal amp for me.

There is yet another avenue for getting awesome tone from the Mark V. Since I have some old Mesa tubes from the Mark III, I found them to be ideal for all channels relative to noise levels, clarity, and gain response. Since I was able to find them (without Mesa sorting or branding) I will have to see how things pan out.

I'll be watching for your response on the new tubes. If they are what you think, we might run Doug out of them quickly! 8)

(To the point that I already had a tube order made out for Doug's, and didn't check out. Waiting to hear what you find out before I order).

I will be honest on how I feel they sound when the come in. I got shipping notice yesterday.

 

[Dreamtheaterrules]

I have an update. I'm almost hesitant to post this. I went to my Mesa dealer today and he had one Mesa 12AT7 in stock. Mine. I came home tonight and put it in the big boy. When I dropped the Mullard in the V25, it was immediate clear significant improvement. No questions asked, no magic blind tests, it just sounded better! Several follow up listens have shown it to be even better than I first thought.

When I put the new Mesa AT7 in V4 tonight, it was not the immediate major change I got with the V25. I played it for over 30 minutes. All three modes got a shot. I'd say it was a little better, but not the immediate beautiful crunch I got with the V25.

I'm wiling to write this off as a new tube that needs breakin. I might even take the Mullard out of the V25 and swap them. And I will put the time in on the new tube. So many theories on how long it takes to break tubes in. I've had other new ones that initially sounded no better than the old and a few weeks later sounded much nicer. We'll see. Not blown away like I was with the V25 V2 change. Hopefully, a couple weeks form now I'm recanting this. IF not, I'll go ahead and make my new tube order and replace the rest, which could be the issue anyway as the amp is a couple years old now.

 

[Markageddon]

Remember that this mod gives you a lot more potential, but its in the dialling. Was the FX loop active? If so what was it set at? There are a more variables and perhaps setting requirements on the big head. Rest assured, the brutality is there to be had.

 

[bandit2013]

I have not given up on the V yet. I will do some tube rolling with the amp today and see if the 12AT7 will have merit with the old Mesa tubes. I think I will go back to the EV speaker so I can run a pair of them as I have one to put back into the extension cab. (again....I have some much practice taking the Mark V apart I can do it blind folded). It is much easier in Combo form that it was in head form. At least the combo is easier to swap speakers than a 412 cab. I am trying to explore the possibilities. After running some Mesa NOS Siemens EL34 tubes in the TC-50 (among some others I have tried out) make the Mark V obsolete in some respects. I still like the Mark V but times I get tired of it. Also the Red Back speaker needs to be pushed harder and I do not want to run the amp that loud all the time. It does sound great but my hearing is more important than feeling it. Time to do some experiments and see what comes of it. (If I do end up selling the V, at least the tubes can be used else where including the Beijing tubes I ordered from Doug's as they should be great in the RA100 if they are anything like the old Mesa tubes).