Mesa MarkV / Saturation 'mod'

[sherrillsml]

Many users from earlier models complain about ice pick and an overall thin CH3 and many users from newer models hear no problem at all.

So many people can't be wrong.

It's a shame mesa is silent about revisions/changes. At least we, as (hard paying) customers, know that they don't want to offer help.
I guess they want us to buy more amps/caps/tubes instead.

I don't get it - if that would be my company I would give my very best to bring every product out there with my name on it to top performance level. Anything else would cause harm to the company and on the long hand destroy its reputation.

EXACTLY I purchased mine new in 2010 and it definitely has the ice pick which the AT7s have negated somewhat but I am very, very disappointed that Mesa has not made any effort to provide some kind of path for me to have as good an amp as the newer models! Circuit revision details should be provided or at the very least an inexpensive method to send it back to Mesa for an upgrade option. My dollars helped Mesa launch the success of the Mark V and I feel left out.

 

[user 83127]

I would agree that Mesa should at least acknowledge changes made. However you could look at it differently....at least they are somewhat responsive to the critiques of their users. They found a perceived problem, and fixed it with no fanfare. The more I look into it, the more I think some change must have been made to the circuitry of my amp as I do not experience the same problems. (it could all be the cabs, but as stated earlier, my Studio Preamp had icepick highs so I kinda think it was a circuit fix). And not to be thick, but maybe they had problems with constantly updating circuits(think mark ii and its various revisions, A, B, C, C+, how many people screamed about that as probably a constant marketing plan to milk users for constant revisions.) I am sure Mesa works with people to get them the best equipment, but at a certain point they have to let product go and just deal with what they have released. I would think that you would be glad there is a fix for the problem(at7 mod). I had a Marshall TSL100 and believe me, there was no fix from the factory on that one. Bad board design, bad transformers, bad effects loop connections, all repairs on me as well. I spent hundreds(did the work myself, or it would have been thousands) on those repairs and not one single shred of "mea culpa" from Marshall. Finally have a stable amp, but I can tell you, the problems with this Boogie are minimal compared to that one.(not mine, obviously, but yours at least can be fixed with a tube roll)

 

[Wayno]

Pretty sure mine is a 2009 model, and I'm sure Mesa did some revision at some point to the Mk V. Also, there's many factors at work here, such as no 2 tubes are ever equal, no components are ever 100% equal, no cabs and speakers regardless of brand are ever equal, let alone different brand cabs and speakers ( and this is probably the biggest difference of them all) and, last but most importantly, no 2 pairs of ears are ever equal. One man's tone heaven is another's hell! I say good on ya, you tried it and it's maybe not needed for you. Happy days either way :twisted:

 

[Wayno]

Hey guys,

Been busy for a while. Whats happened to APEMAN?

 

[mace]

Seems he took his toys and went home. And cleared all his good posts in the process. A true shame, I think.

Bandit also seems to have disappeared a while back after the ‘it’s not your amp, it’s your playing’ thread.

 

[Wayno]

That is a shame, lots of great information for everyone lost there. I did see a post on one of apemans threads from boogie saying that it was misinformation being spread about the ferrite bead. I dunno, thin skin maybe? Shame if bandits gone too. Lots of great info there as well.

 

[mace]

Yeah, I jumpered the ferrite bead in mine and will keep it jumpered out of honor for the Apeman's AT7 advice. I still like the AT7 in the V4 position.

Since jumpering the ferrite bead, I can engage the bright switch now on Channel 3 whereas before it was always off because of the grind/icepick-i-ness. Now, I'll be the first to admit, maybe it's just in my head that jumpering the bead made a difference. Maybe I run the presence lower nowadays? or maybe the 6600 kHz slider is a little lower? I don't know. But the amp has been hugely big sounding without being fatiguing. so, what's not to like with a jumpered ferrite bead? Maybe there quality issue with them back in 2011?

I'll have to do an A/B and some recording to really definitively see if the jumpering has made a difference. For now, I'm just playing!

 

[Wayno]

Hard to say if the ferrite bead thing is a placebo or not. I see Authorised Boogies response on his thread stating it was miss-information and only suppresses very high and ultra high frequencies well beyond human hearing, but, it could also have an effect on the lower audible frequencies as a consequence of things being different. I don't know, either way it doesn't really matter if its placebo or real, the result remains the same for you. Thinking of maybe seeing of I can find the time to collate all the information regarding the AT7 from this thread and starting a new thread to make it easier to find and understand for any newcomers, dunno, what do you think?

 

[stewiecopeland]

Can't really imagine what would make someone take the time to go back and edit out all of their posts from a site.

Odd.

 

[LesPaul70]

Can't really imagine what would make someone take the time to go back and edit out all of their posts from a site.

Odd.

I know a couple of people who have done that. Or wish they could have done so.

Me, I typically print every interesting/useful piece of information I see. Never know when it's going vanish from the 'net. Not saying that my method is foolproof, but I'll say this...deleting my paper copies will take a little bit more effort and determination from the original poster. 8)

 

[skoora]

The best “mod” I did to my 2009 was to use EL34’s. Made the amp good to go for me.

 

[stewiecopeland]

If people are interested, here's the post that started this thread, which the OP deleted a few years later, c/o the Wayback Machine.
----------------------------
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!

 

[chris osborne]

Figured I would update this thread with my experience. I have a late 09 Mark V and I'm pretty sure it was made before the update to the tone stack. When I first plugged this amp in I was immediately taken aback by this shrill, metallic frequency that I did not remember from either my first Mark V nor the V25 I had. I immediately started researching what might be causing this and found this mod. I had two groove tubes 12at7s lying around and decided to give it a try. When I put it in the v4 position I was absolutely blown away with the tone. Completely fixed the harsh frequencies in channel three. I also tried it in the v6 position and the results were also good but somewhat less pronounced in channel three to my ears. I did however like what it did for crunch in channel two. So I decided to try both at7s in v4 and v6. I was worried from some comments that using both would lower the gain too much but what I found is that the gain wasn't reduced any more than having just the one in the v4 position. Now channel two and channel three both sound absolutely perfect to me! The gain is definitely more usable across a wider range. While it is necessary to increase the gain to get the same amount of drive after this mod it's also possible to go higher with it while still retaining a tight low end. Speaking of which, this mod seems to increase the low end while also tightening it up! God only knows why this amp didn't come from the factory like this. The tone stack revision may have sorted the harshness issue out but I don't remember my mk11c+ mode having this much girth on my first Mark V. Anyways, thanks for all the input from everyone in this thread, really helped me sort this amp out.

Chris

 

[bandit2013]

I am still around. I noticed mention of the ferrite bead bypass? Why would one do that? If it was an experiment, great. It is just a small filter that I doubt is making much of a difference. It is not a choke or wound inductor (assumed) so it may not have much influence on the guitar signal. Think of it as a radio suppressor, nobody likes RF interference and your guitar makes for a good antenna for this. It helps to some extent but there are still other ways you end up with RF signals. At frequencies below 20k, I doubt the bead will do much if anything.

I got involved with the thread as I hoped it was a cure for the ice pick CH3. I have a 2012 model so it does have the tone stack change Mesa did in 2010.

V4 seemed to be the best candidate for the ice correction since it has the highest gain (V4B circuit has a 220k plate resistor). This really should not be an issue with the 12AX7 preamp tube as it is the basic lead drive circuit used in practically all Marks before it. Beside that, the lead gain stages are the same as the Mark IVB. (Some one had shared them with me). The schematics for the mark IV is different and easy to find doing a simple search. The same thing could be used in a Mark IVb. V4 has the same use (high gain stage of lead, other used for reverb driver). Instead of V5, the V3 of the MKIVb has the same role (gain drive stage of lead, other used for reverb return). As for the Mark IVa, the lead circuit is all of V3. You cannot take advantage of the 12AT7 in that one.

MKV90: lead gain stages V5A->V4B, reverb driver is V4A, reverb return is V5B
MKIVb: lead gain stages V3A-> V4A, reverb driver is V4B, reverb return is V3B

Mark IVa: lead gain stages V3A -> V3B, reverb driver is V4A, reverb return is V3B. 12AT7 mod will not work to any benefit since the lead gain stages are contained in one preamp tube.


I have tried just about every current production 12AX7 tube available in the Mark V90 , some were better than others.

I think when I dropped out of all this, I was using some NOS 12AX7 tubes in my RA100 that became my desired amp. I have tried some of those tubes in the Mark V. Well, that was an eye opener. RFT 12AX7 (ECC83) has similar characteristics to the Mesa 12AX7A (JJ ECC83) but with more attitude when you raise the signal or gain level it becomes something else. Yes, I tried the NOS RFT 12AX7 in V4. I also paired it with the NOS Ei CV492 in V5 (long plate 12AX7/ECC83 similar to a Mullard 1980. Now that was interesting. No ice pick either. It sounded really sic in a good way. I should dust off the Mark V and start tinkering with it (mainly preamp tubes). Have not given up on this but took a long vacation due to work and other amps that were more to my liking.

I would not bother with any of the circuit mods I may have suggested in the past. There are only two I have retained and one I restored. (mods still in effect: Removal of C39 on V4B and the 3.3k resistor coupling between the RMY7 contacts. I restored the removal of C44 as it sounded better with that in the circuit). I have all stock preamp tubes in it now. Have not used the Mark V for several years as I found other interests. JP2C, Royal Atlantic and my recent poison is the Badlander.

A few weeks ago I thought about running the Mark V again but notices some oily film on the power tubes. Will have to open it up and see if I had a cap leakage. The 12AT7 fix for V4 does work out well for a different characteristic. I did try it in V6. Oh yeah, I did go back to the Gold Lion KT77 for a short period, the 12AT7 in V4 was of no help. If you are into that EL34 sound, not sure the 12AT7 mod will be as desired. I believe with my Mark V, there are other issues to be addressed than its preamp. I still feel the bias is off some. I will have to take a deeper dive into that before going any further. At least the amp is not red plating power tubes or blowing out speakers like it was long before this thread became active.

 

[mace]

Yeah, I remember doing that ‘removal of the ferrite bead’ thing to try it out. It wws easily reversible so what the heck? At first I thought that it seemed to maybe have tamed some fizz in Channel 3. After a while I realized it really didn’t do anything. In the end I put a bead back on that input wire (actually Mesa did when repairing some other stuff).

I never tried your more ‘permanent’ mods since I’m a reversible kind of guy.

At any rate, I still have the JAN 12AT7 in V4. That has worked well over the years.

 

[notch269]

Apparently I was in the wrong place to write.

 

[bandit2013]

That is a bummer. I see some posts have faded away. There was a lot of valuable information in this thread. Right or wrong, it is all about learning.

As for any hard mods, it is not necessary. I was exploring the possibilities of the Mark V90 and did some experiments with mods, I even changed a few cathode bypass caps to evaluate how that would change characteristics. Also tried a few plate bypass caps (obviously the metal film type with high voltage ratings). Any mods to an amp is best left undone and not worth attempting regardless of the outcome. I can easily restore what I did as I have the knowledge and proper tools to do so. The potential voltages, stored energy or complexity of the design is not that far off of what I do at work.

If I were to delete anything in this thread, it would be the hard mods as I do not want to influence others to make a mistake or expose them to risk of shock due to stored energy. Besides that, if your Mark V90 sound like an amazing amp to you, do nothing! If you have ice pick characteristics on CH3, by all means try the 12AT7 in V4. There are other alternatives to a change in gain structure of the tube in question. The Mark V90 does respond surprisingly well with change in preamp tubes of different variations in the 12AX7 family (short plate, medium plate, long plate). It all becomes subjective at a point. Change of a preamp tube does not require you to make any changes to the circuitry so hands off on that stuff.

 

[Aftermath Studios]

So this is now a massive thread...and I regrettably do not have time to read 44 pages worth of conversation.

However, for a long time I struggled with the harshness of my MkV.



Here's a video I made of tones I was able to get with my stock MkV which I'm pretty ******* happy with...

...but seeing a 44 page thread on a simple tube swap has me curious.

For those who have done the mods, what would be different about the tones here?

 

[Wayno]

So this is now a massive thread...and I regrettably do not have time to read 44 pages worth of conversation.

However, for a long time I struggled with the harshness of my MkV.



Here's a video I made of tones I was able to get with my stock MkV which I'm pretty ******* happy with...

...but seeing a 44 page thread on a simple tube swap has me curious.

For those who have done the mods, what would be different about the tones here?

Hi,

Very, very long story short, 12at7 in v4 (and to my ears with my amp also in v7, I do seem to be one of very few with this though) will tame the harshness and allow much more usable sweep from the controls. Added girth and tightness minus the ear ache. Lots of experimenting and comparing discussed over the 44odd pages but that's the short and skinny of it.

 

[bandit2013]

So this is now a massive thread...and I regrettably do not have time to read 44 pages worth of conversation.

However, for a long time I struggled with the harshness of my MkV.



Here's a video I made of tones I was able to get with my stock MkV which I'm pretty ******* happy with...

...but seeing a 44 page thread on a simple tube swap has me curious.

For those who have done the mods, what would be different about the tones here?

The saturation mod is just a tube swap. I had a slew of other issues with my Mark V that some have experienced so the 44 pages ended up exploring other avenues to fix the ice pick issue. Then those with the Mark V:25 and V:35 wanted to join in only to find out their amps are different than the Mark V90 and the trick does not work.

JAN/Phillips 12AT7. Original OP used one in V6 in attempt to cure the FX loop issue but found he got some saturation effect that came with it. I suggested to use it in V4 and tried that myself and found it fixed most of my ill-will with CH3 but did nothing to cut the ice on tweed or edge modes on the other two channels. the JAN 12AT7 in V4 made it possible to dial in more treble and gain without the ice pick being the issue. Perhaps some Mark V90 have different components that are not up to par.

Another trick is the phase inverter, 12AT7 does help to swamp out some top end if that is the issue. It will also cut on output level at the same time.

From your video, it sounds like you are one of many that have a good one. I am one of the few that just have ice-pick mode built into mine.

Most of this thread pre-dates the changes Mesa set into motion with the Mark V90. The obvious being the change in power tubes from the STR440 (now out of production) to the STR441 tubes. That alone makes a huge difference in the amp's performance. I tried them and found the 12AT7 trick was no longer a necessity. What is buried deep within the pages may be some hard mods. I doubt any of my images lasted over the years. If so, do not bother with any hard mods. Not necessary. I have long given up on the Mark V90 and moved on. I still have it and found some other means to make the amp perform better in all 3 channels, all modes and features. The key ingredient was the STR441 power tubes. The rest was tube rolling the preamp with a variety of 12AX7 tubes, most of them are NOS I had on hand. The only thing left to do is correct the impedance issue with the FX send. That is the weakest link in the amp unless Mesa corrected that in later production runs.