Mark V 90W combo speaker change

[MarkV User]

I was unhappy with my Mark V after playing a 1987X 50W Plexi and a very special Bassman. The Mark V sounds sterile, shrill, and harsh. Despite this I don’t think my amp is broken. I think all or many Mark V amps are like this. I tried some things to help understand the problem.

Changing tubes to EL34s helped some.

Playing a different preamp into the loop return of my 90W combo still sounds bad.

Huge surprise: playing the Mark V preamp into the power amp of my $200 solid state 30W Bogner Ecstasy mini amp with a 4x12 Marshall 1960A cab with the 75W speakers sounds awesome! Much, much better than the Mesa amp end to end.

Playing the Mark V into the 4x12 cab or a Bogner 2x12 cab still sounds bad, but not nearly as bad as through the Mesa black shadow 90W speaker in the combo.

Playing the Bogner mini amp into the Black Shadow sounds bad. Whereas the mini amp into the 4x12 sounds good. Note that I’ve never played the Mark V at high volume for any extended time. After almost ten years do I still need to break in that speaker??

So it seems the Mark V preamp absolutely rocks but the speaker in the combo and power amp are both lacking to my ears.

1) What speaker should I put in the combo? Or alternatively what is the cheapest way to put my amp in a head shell? I dont want to give Mesa more money for an official head shell at this point.

2) What mods can I make to fix the power amp? And do the other 25 and 35W Mark V amps have the unpleasant power section? I feel like those are good amps because I played one or the other in a music store once and really loved it.

I get the hearing loss feeling every time I play the Mark V. My old oscilloscope has stopped working, but I wonder if the root cause of my issue could be a high frequency chirp or fast ringing from the power stage distortion. I haven’t done it yet but I’m thinking now that I need to mic the amp and use a spectrum analyzer plugin to search for the problem.

I know Bandit and others here have tried chasing this problem too. I might not have read all the important history. Folks here have already been really helpful! Does anyone have further hints or ideas? Thanks!

 

[rarebitusa]

Couple of questions cause there's alot of configuration choices with the V:90. What power modes do you typically run? 90W, 45, 10? What chans and voicings? Have you run the variac mode much?

Yes the V:25 & 35 have el84s vs the 6L6s in the V:90.

 

[MarkV User]

Thanks for your reply. I’ve been running all three power modes and favor the 10W and 45W modes most often. I can never decide which power modes I like most.

I’m always using variac mode now with the EL34s. With 6L6GC tubes I ran either mode. I like channels 2 and 3 best and probably use the Mark I voicing on 2 and the IIC voicing on 3 most often. In channel I the tweed voicing gets the most use. When I was trying to isolate the shrillness I switched through several channel/voicing combinations for each experiment.

I usually have the effects loop and MV on but also run it off sometimes for a slightly more open sound. I used to always run EQ but now bypass it when I can for the same reason.

I did try two EL84s in the V90 and liked them ok but went back to 4 EL34s. I didn’t have adapters on hand for four EL84s but could try that at some point. The EL84s seemed to help but did not make the problem go away. I also feel like it should be possible to correct this problem independent of the tube choice. And switching power tubes helped but didn’t make the problem disappear.

Words sometimes fail me in trying to describe the nuances of amp sounds. People talk about looseness and tightness in different frequency ranges and the amp feeling organic or fluid and I feel some of that but I’m not sure if I’m hearing the same things other people talk about. The Mark V feels less organic and fluid and much tighter than the Bassman/Marshall family. I think maybe organic means power rail dynamics and tight means phase-accurate. So the Mark V sounds crisp. Separate from that it seems to have a high frequency resonance almost above my hearing that is not very responsive to the tone controls. I hear that in things like the fret noise and power amp distortion. These are all subjective impressions about the sounds. I’ll be much happier if I can get this down to something I can measure.

Because there are really several issues. The Bassman/Marshall family really adds its own volume dynamics, which maybe is from B+ sag. But the Bassman, Marshall, Shiva, and even the XTC mini amp all have a percussive feel. I really like that but the Mark V is different, not wrong. Then there is the organic/fluid thing that I don’t exactly understand. I think maybe the Bassman family has a phase transfer that changes enough with frequency that attack sounds are spread out a little in time. I don’t know how to describe the sound but I think of classic overdriven Plexi sounds and warm Soldano sounds like the Kurt Kirkwood guitar on Too High to Die. It is like the distorted amp tone has its own life separate from anything that came from the guitar. I personally really like this, but again it is a matter of taste.

The thing I’m trying to get at with the Mark V is subtle but feels like something wrong on top of those differences. And maybe the thing to do is just figure out how to measure it objectively since I have such a dim understanding of what is sounding so bad. I know already that it is not just one thing because part of the problem comes from the speaker and part from the amp. I know the Mark V makes my ears ring and that I can never seem to find the right volume, and that tiny noise sounds become unpleasant in a way that doesn’t happen in other amps. I’ve seen other people describe these Mark V problems and I think we are hearing the same things. Many people also don’t have these issues.

 

[Eevil]

I was unhappy with my Mark V after playing a 1987X 50W Plexi and a very special Bassman. The Mark V sounds sterile, shrill, and harsh. Despite this I don’t think my amp is broken. I think all or many Mark V amps are like this. I tried some things to help understand the problem.

Changing tubes to EL34s helped some.

Playing a different preamp into the loop return of my 90W combo still sounds bad.

Huge surprise: playing the Mark V preamp into the power amp of my $200 solid state 30W Bogner Ecstasy mini amp with a 4x12 Marshall 1960A cab with the 75W speakers sounds awesome! Much, much better than the Mesa amp end to end.

Playing the Mark V into the 4x12 cab or a Bogner 2x12 cab still sounds bad, but not nearly as bad as through the Mesa black shadow 90W speaker in the combo.

Playing the Bogner mini amp into the Black Shadow sounds bad. Whereas the mini amp into the 4x12 sounds good. Note that I’ve never played the Mark V at high volume for any extended time. After almost ten years do I still need to break in that speaker??

So it seems the Mark V preamp absolutely rocks but the speaker in the combo and power amp are both lacking to my ears.

1) What speaker should I put in the combo? Or alternatively what is the cheapest way to put my amp in a head shell? I dont want to give Mesa more money for an official head shell at this point.

2) What mods can I make to fix the power amp? And do the other 25 and 35W Mark V amps have the unpleasant power section? I feel like those are good amps because I played one or the other in a music store once and really loved it.

I get the hearing loss feeling every time I play the Mark V. My old oscilloscope has stopped working, but I wonder if the root cause of my issue could be a high frequency chirp or fast ringing from the power stage distortion. I haven’t done it yet but I’m thinking now that I need to mic the amp and use a spectrum analyzer plugin to search for the problem.

I know Bandit and others here have tried chasing this problem too. I might not have read all the important history. Folks here have already been really helpful! Does anyone have further hints or ideas? Thanks!

Howdy

I’ve been in that C90/open back rabbit hole couple of times and every time the remedy has been closed back cab with V30

The combo idea is promising but doesn’t deliver in a way I’d enjoy the act of playing

One little device that’s helped a lot for my purposes have been the Torpedo Captor X.. dropping the decibels helps the power amp to even out the freq response a bit.

With this setup (Mark V head -> Captor -> Mesa 4x12) I’ve been 90% of time happy with the tone and feel the system produces.. which is actually a lot

 

[Eevil]

For me the combo cab was the culprit for most feel and tone issues in all the combo amps I’ve had.. tried different speakers and everything yet it all turned to be that I personally prefer the feel of a closed back cab in all the tones I want

Personal journey and realisation about what I prefer

 

[rarebitusa]

There's a wealth of info and past discussion in the V forum. You are certainly not alone in your take. Some folks just can't get on with the V:90, it's just not their cup of tea. Others it took time until they figured out something that worked for them.

You reference the Bassman, I had one with 4x10 and it was indeed very different then the V no doubt. I'd agree "less organic and fluid and much tighter than the Bassman". The tone on "Too High" is a good reference and no surprise the preferences on your V configuration so far underscore where you'd like to go.

Just one man's opinion personally I think you could get there with a V, but it may take more effort with signal path tweaking and speaker rolling. The V:90 is however fairly tube responsive and lots of info WRT that here. But perhaps a Badlander is a better fit.

 

[bandit2013]

(edit): I just wanted to add that this is my perspective on the Mark V90. I may get negative on the subject so please do not let that influence your thoughts or likes on the amp in question. Mark V90 can be a great amp, and some of them are. Mine was loaded with issues from the start so my opinion on the amp is not favorable.

Yeah, I was hesitant to get in volved with this. I would have recommended a change of venue and move to a Badlander. Love that amp. Then there is the Mark VII which has some similar flavors of the Mark V90 but sounds so much better, more back to the Legacy sounds of the IIC+, Mark III. I feel the IV mode just sounds better than the IVB I had a few years ago. Sold it so I did not have a change to compare it directly.

My 2012 Mark V90 is brittle, harsh, ice pick on most modes in all three channels, and it has a boxy tone that is hard to evade. I loved it so much was I was willing to part with it at the curbside next to the garbage can when it was trash day. I would not go that far but the thoughts have crossed my mind several times. Change in preamp tubes will fix many of the issues of brightness. V1, V3 and V7 are the critical positions to address. V4, V5 and V6 will aid in any harsh tones for CH3. Then there are the power tubes. I thought the STR441 actually sounded better than the STR440 or SED =C= 6L6GC tubes. The =C= tubes were the only tubes that added in that 3D character. Everything else is on the flat side. When I changed to the STR441 tubes not that long ago (actually it was after getting the Mark VII) is when I realized there is more potential to the Mark V90. My 20 minute tolerance changed to 1.5 hours or longer. This was also with a preamp tube swap. I have an EVM12L speaker loaded in my Mark V90 combo but may change it back to the MC90 since the EV brings out the boxy tone of this amp too much. It is quite the contrary with the Mark VII or JP2C, that speaker sounds epic. Just not a favorite with the Mark V90, come to think of it the Mark IVb combo did not favor the EV speaker either.

Another Mark trait that crosses boundaries of all of the models including the legacy versions, the 8 ohm output will be much brighter than say if you ran two 8 ohm speakers powered from the two 4 ohm jacks. This is true with the Mark V90, Mark VII and JP2C. Running the amps with two cabinets, or the combo speaker with an extension cabinet does cut back on the brightness of the amp but retains the characteristics that make the amp sound desirable. For example, running the combo with a 112 open back wide body cab with another MC90 sounds really good. I ran that for a short time period with the Mark V90 before I changed the extension cab to an EV speaker so I can pair it up with the JP2C. I just do not have much luck with the MC90 speaker as I seem to have the issue with the dust cap popping off. The only survivor I have left is one I reattached. The other ones I burned out. (this was before I realized the bias on the Mark V90 was way off). Dust cap pops off due to cone distortion since the voice coil is much smaller than the dust cap diameter, there is no coil former to provide support and pushing the volume limits tends to do weird things to doped paper.

Preamp tube rolling can be a *****, but it is possible to find a combination of preamp tubes that work for you. I usually found that the low end would get muddy, or the top end is too rich. Depends on the preamp tubes and where they are located. Not all Mark V90 amps are equal. Mine basically sounds like . I do tend to be pessimistic on the MKV90. Even with preamp changes and such, I barely ever use the amp as that in the room sound is not much to my liking. Sure, it records well as the mics will not capture the overtones and such. Since I got the JP2C and more recently the Mark VII, I see no purpose on torturing myself with the MKV90 any longer. May as well be water-boarding.

 

[MarkV User]

Thanks to all three of you for this. Taking things in order, first it is helpful to know that I should give up on the combo and do the head conversion.

Second, I tried running the 1960A cab from the Mark V at 4 Ohms and it makes a big improvement by reducing whatever that resonance is.

The attenuator I have here is an 8 ohm THD hot plate and I tried it just now. It seemed to hurt instead of help things when I use it with the Bogner 2x12 cab, and my ears started ringing right away. I might try the hot plate from the 4-Ohm output, and I guess before that should capture some audio for analysis. I need to stop doing experiments that always end with my ears ringing.

One thing I notice as I keep testing the amp is that I love some things it does and always have. The biggest problem is that it hurts my ears in a way that other amps don’t. And now I know that problem comes from the power section and speaker rather than the preamp. Once I can measure it I’ll locate the source.

I think I most love the sounds that come from a cranked old Marshall or a Bogner or Soldano. But the Mark V does wonderful things in the preamp section and if I can get it to sound tolerable I would like to still have that big tonal palette.

And Bandit don’t worry about being negative. You have been consistently helpful to me and to everyone else too. My experience is that I bought this thing new as my only amp after moving to a new city and ditching some old gear. It took me a long time to realize there was something wrong with the amp that caused me to play less. I couldn’t be more pissed at Mesa for putting this thing over on me. It is also my fault for playing one Mark V in a store and then buying the “flagship” amp that I thought was even better. On the other hand we put in our time and figured out what kind of sound we wanted to make. Maybe it works out in the end.

 

[bandit2013]

I did the same thing, the Mark V was the next best thing and found it was not. Should have held onto my Mark III comb. That amp was always a pleasure to play though.

What power tubes have you used in the Mark V90 in terms of 6L6GC?
What I have used that sounded epic: SED =C= 6L6GC, they are a bit bright but really help with the sterile effect. It is too bad they are out of production and very difficult to find. The Mesa STR441 were also a huge improvement over the STR440 tubes. I have tried many other power tubes to no avail of any satisfaction. STR448 did not work out. I know for a fact my Mark V90 is not on par with the other amps out there. It started out as a head but got replaced by a Roadster, so I converted it to a combo with the intent of using an EVM12L speaker with it. This also helped with the chassis overheating issue which was related to the bias being way off. I could not run any of the STR440 tubes in the amp as it would result in red plating the center pair. Sometimes it would take 20 minutes or longer and sometimes it was an instant kill of the tubes. SED=C= 6L6GC would survive and never failed, I still have those tubes and they work fine and test like new. I did change the one bias resistor 82.5k to a 91k (measured at 86k ohms). It was not until I saw how the power meter on the rock crusher was pegged at 150Wrms peak constantly when I was running with that. No wonder why I kept blowing out speakers in the combo or red plating most tubes I tried with it. I do not have much faith in the amp as it is, so many issues to mention, blown screen resistors, a few JFETS died, lost the reverb and now I cannot use the amp without the footswitch connected, before it was the other way, if I used the footswitch it did weird stuff. Ground issue in the cable and other problems. Variac power mode usually resulted in tube death so had to run at full power. Just do a search on my username in the Mark V forums, I still wonder why I have it to this day. I should have sold it and got another if that was what I was after.

Good old sounds of a cranked Marshall, yep. Me too. That is why I have the Badlander, RA100, Marshall Silver Jubilee 2555x. The EVH 5150 IIIs EL34, a bit noisy but had it out not too long ago and though it sounded good. I did not like it much when I first got it.

This rig is all in parallel. Two BADS in stereo with the RA100 as a dry channel. This sound like no other amp, has that full mod Marshall sound but only better.

This combination actually sounded good too. I just do not have much room to set all my gear up.

Perhaps I am deaf and need to have more than one amp. Not sure. I can hear quite well. I just have more fun with blending amps. Two RA100 and a Silver Jubilee. I am surprised how close they sound.

But I have also gone to the dark side and this is what I am working with at the moment. 2BAD, one Mark VII and the JP2C. This is a wall of sound. This was after a jam session so the cables were disconnected because the guitar player could not handle the 4 amp array. I play the drums when the group is together but I am more of a guitar player than a drummer or bassist. I play the bass too.

This was all because I could not bond with the Mark V90. Had to find the right amp and now I have a few. The Mark V does not get much use if any.
Heck even this amp is superior to the V. Flux drive and grid slammer. That is all that is needed and I have a Mark sound on tap. The GEQ did not do much for the California tweed though. Fun amp, I should play through it more than I do. I think I got around to pulling the tags off of it.

 

[rarebitusa]

FWIW just adding some V:90 musings. The swap of preamp V4 to a 12AT7 made a big difference in taming the harshness of Ch3. There was certainly an abrasiveness in the upper frequency response with the 12AX7 that disappeared. Next, on a Bandit suggestion, pulled the set of original, tired STR-440 YELs, replaced with new STR-441s GRYs in the outer sockets, STR-440 GRNs in the inner sockets. That also was also a major improvement, it made the SimulClass 90W mode come alive. Never could get along with Edge mode until that upgrade as it smoothed out the brightness. I used to use 45W mode with Edge and realized after the swap that it also was adding to the upper end brightness.

Also use a vert cab with an EVM in the closed bottom and a v30 in the semi open top. I agree with Eevil the cab makes a major impact. By far that cab with the V is much more to my liking then my others, which have different speakers and cabinet formats.

Have swapped around power amps with preamps and will admit running the V preamp thru the LSS el84 power amp (same as a V:35/25) is a very different experience. It's not as fat, dense or stiff sounding, much more rounded and smooth. But have never tried the el34s.

Full disclosure... I liked the V:90 when it first arrived but it has only gotten alot better with time, experimentation and input from folks on the forum. So I'm a fanboy... But when compared to my others IIC+. LSS, Stiletto, it is a very different sounding amp, no question.

 

[MarkV User]

I did the same thing, the Mark V was the next best thing and found it was not. Should have held onto my Mark III comb. That amp was always a pleasure to play though.

What power tubes have you used in the Mark V90 in terms of 6L6GC?

Wow Bandit, you have a great amp collection.

It makes me a lot happier to understand that you and others have gone through something similar to me.

My only other tube amp before the Mark V was a 100W Yamaha designed by Soldano that I sold, and kind of wish I’d hung onto it and modded it to perfection. It was a cool amp with great transformers I think and some flaws, and I had 6L6s in it and we didn’t get along. Then I had the Mark V with the 6L6GC set it came with and I was so convinced it was going to be the perfect thing. And as I found I couldn’t play for a long time without hurting my hearing I ended up having this bad association with the 6L6 tubes. I’ve found now that my high frequency hearing is impaired on the side the amp was on during those years. And I wasn’t playing super loud or for very long. In a very simpleminded way I ended up deciding incorrectly that the tube type itself was the cause of my ears ringing after playing. I tried the EL84 adapters early on but they don’t make everything better, nor do to JJ EL34s, even though I like the sound a little better that way. I mean I think the different tubes cause the amp to have a different frequency response in broad terms, but the real issue has got to be more than that.

I’ve briefly put those sweet Tung Sol 5881 tubes in the amp and they sound good but the mystery problem is still a mystery. I have some chores to do and when I finish, as a reward, I’m going to record the Boogie and search for the problem with the spectrum analyzer. I also have a kind of crude USB oscilloscope and I’ll try to record with that in case the problem frquency is too high for the audio interface. I have a function generator too, and the amp’s square wave response might be revealing.

I am going to make the preamp changes for sure, and find the best power tubes. Because to my ears the preamp could sound better. But the priority has to be the mystery problem. I hope to make some change to the power amp circuit to fix this. Then maybe I really should add bias test points and bias adjustment pots, and voice the amp just the way I like it best. It is never going to sound like a Marshall anyway so maybe I will like the 5881 tubes or a great 6L6 or even a quad of 6V6 tubes, or some simul-mixture of those. It could still become an amazing amp.

What I have used that sounded epic: SED =C= 6L6GC, they are a bit bright but really help with the sterile effect. It is too bad they are out of production and very difficult to find. The Mesa STR441 were also a huge improvement over the STR440 tubes. I have tried many other power tubes to no avail of any satisfaction. STR448 did not work out. I know for a fact my Mark V90 is not on par with the other amps out there. It started out as a head but got replaced by a Roadster, so I converted it to a combo with the intent of using an EVM12L speaker with it. This also helped with the chassis overheating issue which was related to the bias being way off. I could not run any of the STR440 tubes in the amp as it would result in red plating the center pair. Sometimes it would take 20 minutes or longer and sometimes it was an instant kill of the tubes. SED=C= 6L6GC would survive and never failed, I still have those tubes and they work fine and test like new. I did change the one bias resistor 82.5k to a 91k (measured at 86k ohms). It was not until I saw how the power meter on the rock crusher was pegged at 150Wrms peak constantly when I was running with that. No wonder why I kept blowing out speakers in the combo or red plating most tubes I tried with it. I do not have much faith in the amp as it is, so many issues to mention, blown screen resistors, a few JFETS died, lost the reverb and now I cannot use the amp without the footswitch connected, before it was the other way, if I used the footswitch it did weird stuff. Ground issue in the cable and other problems. Variac power mode usually resulted in tube death so had to run at full power. Just do a search on my username in the Mark V forums, I still wonder why I have it to this day. I should have sold it and got another if that was what I was after.

That is all fascinating. I’ve read some of your accounts of your initial excitement for the amp and your gradual disillusionment and eventual disgust, and it seems very reasonable given the series of things that happened. You had that red plate problem that I never have, and other problems too.

Because I decided not to put Mesa tubes in my amp again I just run variac mode and EL34s and have the bias meter to double check. In variac mode the EL34s are looking about right. Maybe 35mA for the hot pair? I don’t remember exactly now, but it seemed ok in Variac mode and too hot in Normal mode, and I think variac mode was what the manual said to do for EL34s anyway.

So far I’ve just played around with the Bogner Ecstasy mini as a substitute power amp. But I‘m going to try also with my Shiva 80W 2xEL34 amp. It has direct power amp input separate from the effects loop, and it’s a beautiful, dark-voiced thing. It should give some confirmation of previous observations. If it makes everything good then I know all I need to do is rework the part of the Mark V circuit after the effect out or line out, etc.

One thing I know about analog circuit design is that the stack up of component tolerance differences is one of the biggest obstacles. Because even when purchased components meet all their specs the tolerance variations are often not random but systematically skewed in some way. For example sometimes 5% resistors and 1% resistors come from the same manufacturing runs, so in that case no 5% resistor is within +/- 1% of the stated value. Or maybe a whole run of parts will be skewed the same direction. This ends up meaning that unless the designer is very careful the finished products will not always work correctly without testing and rework.

Old tube amps don’t have to worry so much. They have few parts and the stack up of errors is not too bad. Also the compensation schemes were established long ago and everyone knows about them. Things like bias pots and matched tubes will make everything good. The Mark V really pushes into a place of normal/modern amounts of complexity and the designers just might not be up to the task or might have to learn new tricks before they can ship a reliable product. JFETs in particular just have a huge spread over some of their parameters. And they notoriously do assign part numbers after testing those.

And there are decisions in the Mark V that I think are just design errors. Like using a 1000V 1N4007 diode with a very low current rating in the 12V supply. I didn’t try to work out the 12V power budget, but looking at what happens there I thought it might be good to have something with a better current rating. Mesa says the problem was a bad batch of parts, but I replaced those with 1N4003 diodes in my amp. I didn’t necessarily analyze everything correctly to make that decision, and there would have been better diodes that I didn’t happen to have on hand, but I no longer have confidence that Mesa analyzed the component selection either.

That is why I am willing to bet that so many Mark V amps sound great and others have problems, and a few just try to cook their tubes. It is no secret that some of these amps are lemons, and the resale values reflect that. If Mesa would have documented what they learned after shipping then we would have fixed our amps already and the value-sucking cloud of uncertainty around them would dissipate. It is a bit of a challenge for us as customers to diagnose and fix these complex problems. This is as much of a support issue as a collection of design mistakes. To me the question about a company like this is whether they are a trustworthy partner for their customers. And I feel like my amp can potentially be saved, but if I gave Mesa any more money in the future I’d feel like a real sucker.

Good old sounds of a cranked Marshall, yep. Me too. That is why I have the Badlander, RA100, Marshall Silver Jubilee 2555x. The EVH 5150 IIIs EL34, a bit noisy but had it out not too long ago and though it sounded good. I did not like it much when I first got it.

Those are so great. That RA-100 in particular just sounds like a kingly amp. Yet another Marshall that is better than the real Marshall it most resembles.

If you could only have either the Silver Jubilee 2555X head or the RA-100 head, or one Badlander, which would you keep?

Every one of those amps you have seems wonderful to me. I feel right now like I can meet all my needs with the Shiva alone, but every one is special.

Something you are doing that I’d also like to try are stereo side or rear channels. Did you see the Bogner Duende Seco Mojado in earlier times? Super wonderful living room amp with tube tremelo on two 6x9 square speakers for side channels (maybe 5W each?) and an improved 2x 6V6 Fender Delux in the center. It looked like a labor of love. I’ve sometimes set up a second amp behind me with delay-only for an echo but that is all I’ve tried. The hot way to do that would be with stereo mic pair, preamps and a stereo delay, to enhance the actual room echo. And it would take compression or some other active dynamics to keep the echos under control. Maybe the mics are carotids that face the center cab. The idea would be to get the particular room sound, which is so recognizable to our ears, but expanded.

 

[MarkV User]

FWIW just adding some V:90 musings. The swap of preamp V4 to a 12AT7 made a big difference in taming the harshness of Ch3. There was certainly an abrasiveness in the upper frequency response with the 12AX7 that disappeared. Next, on a Bandit suggestion, pulled the set of original, tired STR-440 YELs, replaced with new STR-441s GRYs in the outer sockets, STR-440 GRNs in the inner sockets. That also was also a major improvement, it made the SimulClass 90W mode come alive. Never could get along with Edge mode until that upgrade as it smoothed out the brightness. I used to use 45W mode with Edge and realized after the swap that it also was adding to the upper end brightness.

Also use a vert cab with an EVM in the closed bottom and a v30 in the semi open top. I agree with Eevil the cab makes a major impact. By far that cab with the V is much more to my liking then my others, which have different speakers and cabinet formats.

Have swapped around power amps with preamps and will admit running the V preamp thru the LSS el84 power amp (same as a V:35/25) is a very different experience. It's not as fat, dense or stiff sounding, much more rounded and smooth. But have never tried the el34s.

Full disclosure... I liked the V:90 when it first arrived but it has only gotten alot better with time, experimentation and input from folks on the forum. So I'm a fanboy... But when compared to my others IIC+. LSS, Stiletto, it is a very different sounding amp, no question.

That tube swap experience sounds great. Which are hotter, the 440GRN or the 441GRY? I see the inner pair getting a higher grid voltage and more grid current in SimulClass operation (if I remember that right). If the outer tubes are more sensitive to bias voltage that would make the amp break up more like other 100W amps.

I have the Bogner 2x12 and it is closed back and horizontal, but almost certainly loaded with V-30 speakers. But I could just set it on its end at least to try the vertical cab concept. It already sounds really good, but I could try different speakers there. I was curious about the EVM’s but also about Redbacks, Goldbacks, the G12-65 (for the 1960A), and Creambacks. It makes sense if the EVM is almost a reinforcement speaker that it will make nice interference patterns with a more relaxed guitar speaker of similar sensitivity and still retain good clarity. Is that what you feel is happening? It looks like they are both 100dB speakers. Do you run two 16 ohm speakers in parallel to make an 8 Ohm cab? Is the cab on the floor or on casters, and hard floor or carpet?

I feel like my Mark V amp might be able to be saved. Since yours is working right it is no surprise if you love it! It should be a great amp. I loved it and then it broke and by the time I fixed it I’d found that mine compared poorly with other amps and always had. And that is when I also realized that it has caused me to play less by beating up my ears. But to be fair I picked amazing amps to compare it with. I’m sure that because you have other amps you know your Mark V is a good one.

Running through the Shiva power amp helps for sure. I had to use the reamp function to get the level right though, so I’ll try again later with a clean boost from loop out on the V. The other experiments are still pending.

 

[MarkV User]

By the way Bandit, I found your thread where you talk about the Badlander and TC and RA amps. That is good info.

 

[bandit2013]

If I had to choose between three, 2555x, Badlander or the RA100. I think some may have an idea what amp I would go with. The king of the pile is the Royal Atlantic RA100 on a Mesa recto standard 412 cab loaded with the UK-60W V30 speakers. One is just not enough, better make it two.

The RA is quite unique in its own way. Sure, it has a similar sound to the 2555x as well as the Triple Crown but the dynamics are just amazing. I can use that amp for anything. However, to get there does require a few tube changes. The RA runs a 400VDC plage voltage so NOS EL34 tubes are on the table for use. At the moment, I am running both RA100 with the SED=C= EL34 tubes (Mesa STR442). They were available for a short time period, so I bought a few sets. Best tube for the multi-soak feature that actually works as it was described. I also have some Mesa STR450 Siemens EL34 waiting to be used but have not tried them yet. I did try a pair in the TC-50, not a good thing, poof went the magic dragon and damaged the mute circuit when the fuse blew out. Mesa said it was unrelated but I beg to differ. Amp stopped producing sound after going back to the STR447 tubes and new fuse. Had to ship it to Mesa for repair. TC runs a little bit too high for NOS EL34 tubes, 450VDC plate voltage, not safe for the STR450 Siemens EL34. Sure, the TC is a fun amp but the dynamics on the hi/lo gain channels suffer from the op-amp circuits that follow the gain stages. I do not want all that gain characteristic when I roll back on the guitar volume. No fun. For those who keep the volume up all the way it works great. The RA100 on the other hand I can roll back on the guitar volume, sound level remains about the same and it cleans up from a heavy or moderate gain setting. No other amp does it this well. However, the other trick with this amp, change the hi/lo gain tubes (V1 and V2) to something other than the Mesa (JJ ECC83s) 12AX7. Why? the low end can get muddy with the JJ tubes in this amp. My fix was an RFT ECC83/12AX7 in V1 and an Ei long plate CV492 in V2. I forgot what I have in the phase inverter, it may be another CV492. The Ei tube is a Mullard 12AX7 copy of sorts and was often used as a counterfeit Mullard. Still a really good tube, just not as expensive. The RA does not have a presence control and the one used on the TC is more of a high pass filter, so it is not a true presence control either. Bass and midrange are the key, drop the treble and this amp rocks. Toss in a Boss EQ-200 in the FX loop and that adds more awesomeness to the tone. Works well with the 7-string axe too. I could write a book on the RA100 on how much I like it, and probably did that already. As for the RFT, it sounds very similar to the JJ ECC83s at a low to medium gain setting but once you push it, the characteristic changes with a slight effect of sub harmonic content as if there was a cold clipper in the amp. It remains tight on the low end. Sure, there is still power sag at gig levels. Not like a Recto amp on spongy mode and tube rectification.

I love the Badlander for much the same reason. All stock tubes, no need to change anything and will sound epic with the current production tubes. It only gets better with the red base TAD EL34 that Mesa is now offering as the STR446. I need to get another quad so I can stuff them in the other BAD. What also sounds really good in that amp is the STR448 but in the gray bias color. Probably one of the better sounding 6L6GC tubes for the BAD. I still prefer the EL34 power as that was the primary tube choice.

If I understand the bias colors, starting with the most headroom to the onset of early distortion:
Red, Yellow, Green, Gray, Blue, White. Green is typically in the center point and is based on a standardized test using the STR415 as a benchmark. Just note that different tubes in the same family like the STR441 vs STR440, STR443, STR445, STR448, STR415 will have different characteristics. Different amps may favor one 6L6GC variant over the other as well as a specific bias color range.

Mark V90 may work well with the Red to Green bias range. Gray may be over the top. When it comes to the Simul-class power, the extended class A will have the hotter characteristic. That basically defines the tone and character of the amp. The Class A/B power tubes in 90W mode just provide an enhancement over the extended Class A section. The Class A will have more influence than the Class A/B. This was more notable with the previous amp, Mark IVB. I could run a pair of the SED =C= 6L6GC and a pair of the TAD 6L6GCSTR tubes and get an amazing grind that was hard to replicate with other amps. Well, I did find that sound, it was with the JP2C loaded with the STR415 tubes. The Mark V90 just can't seem to get there. Sure, you can use different pairs of tubes if you stay in the same family. One matching pair in the Class A and the other in the Class A/B. The Mark V90 cannot run an integrated quad though. Meaning a pair of EL34 with 6L6GC. The Mark IVB could do that but the extended class A circuit was operating at a different point, so it was possible. The Mark V90 will not work with that arrangement. I am sure it could be modified but then the 10W power mode will be out of whack or imbalanced. It may not be running with the bias voltage on the control grid but a combination of EL34 with the 6L6GC may not work well. Never tried it. I do not recommend it either.

There is a means to tune the Mark V90, that is with the preamp. The issue with this amp, it broke from tradition and complicated things with extra gain stages that so not serve any purpose. Perhaps it was necessary for the Mark I mode but not essential for CH3. Mesa did a much better job with the Mark VII in my opinion. Not only is the midi control much better than the old school method used with the Mark V for channel changing, it does not have added gain stages that do nothing for sound quality. Not more ice pick, or boxy overtones. It is more on par with the JP2C, Mark III and Mark IVA. This is one caliber of amp I only wish the Mark V90 could have been. Sure, very similar character tones but no more sterile blandness. I am sure you could find one at guitar center or Mesa Dealer of your choice to try out. For me, I just bought it from Sweetwater without playing it first. So far it has been a joyride through the park. I do not feel something has to change, like tubes or what not. I did explore some power tube changes and mixed a pair of different 6L6GC tubes, almost close to the Mark IVB effect but not quite there. At least it is on par with the JP2C (loaded with the STR415) and the Badlander 100. So, for me it was a win-win for the 4-amp rig. I said too much already.

 

[bandit2013]

I will admit I have a love/hate relationship with the Mark V. I kept it for some reason. I may go back and do some of the mods I did from the saturation thread. I did restore it as I contemplated on selling it. The EVM12L is coming out of that combo, may just install the Red back or Jensen Blackbird. Not sure what speaker will go with. May have to experiment now that the STR441 tubes made a difference.

 

[MarkV User]

That is all so useful to know. It sounds like less simul-class and more conventional distortion makes the Mark V sound best.

I feel like you already kind of wrote a book on the Mark V at least. It is sort of a tragedy at the moment though! It would be fun if there could be a happy ending.

It would be cool if there were a schematic for the Mark VII. That amp might be better because of schematic level changes (one hopes) or because they got better about testing and rework during manufacture. You said they got rid of extra preamp stages which sounds like a big change. I wonder what is different in the power amp.

 

[mace]

Not sure if it matters but the Mark V 5 band EQ is before the FX SEND where-as the other Marks have the EQ after the FX RETURN. This could make a big difference when comparing the power amp sections of various amps if just running FX SEND of one amp into FX RETURN of another.

Thanks for talking about comparing power sections, I’ll play around with that someday. I’m curious about the difference you heard.

 

[bandit2013]

When I slaved the Mark V90 into the Roadster, I got much of the same thing, brittle and ice pick tones on CH3 (IV and Extreme were the worse), CH1 tweed and Ch2 edge were also terrible. Not to mention that the Mark V GEQ circuit is used to create the send signal level, it has an impedance issue which can make things difficult with most FX processor buffers. The only products that actually worked with the Mark V were made by Strymon, DIG, BigSky, Brigadier were all good. Line6 DL4 was nasty, compressed the signal considerably, sure it sounded cool but it was not how it was supposed to sound.

When I was looking at the send levels I did take some pictures, I was running a 750 Hz signal if I remember correctly from a function generator. Here is what the signal looked like with the GEQ turned off. All of the controls were placed in their center positions.

The image is hard to see on the scope, here is a close up. The green trace is the FX Send output, note the leading edge marked with the arrows. This was CH3. Since the lead drive circuit comprised of the V5A -> V4B creates an asymmetrical waveform as I was led to understand, the sharp edge has more frequency content, If it had a slope or rounded corners like the portion of the waveform in the negative swing it would be a really good sounding amp. The sharp leading edge is ice pick tone.

Now to compare that to a Legacy amp, lets just say a modern version of such, the JP2C. Same frequency and the GEQ was turned off (not that it mattered since it follows the FX loop). Since I was looking at the signal amplitude to determine the signal level, I only took a picture with the amp in the view on the clean channel. It had no distortion. The next picture was on CH2 with some moderate gain dialed in.

Again with the CH2 controls at their center position. This is the difference in the distorted signal.

There is a sharp leading edge but the not a large spike. The Lead drive circuit is asymmetrical so the bottom portion has more of a normal distorted appearance The 2nd harmonic is visible. The top waveform has 4 ripples in it so that would be from the 4th harmonic. The leading edge having that sharp hook would be the higher order harmonics. My company will not fork out the money for a good signal analyzer as they generally start at $100k for an entry level.

Anywas, the reason the JP2C sound great, it does not push the limits on the upper harmonics that leads to ice pick tone. May as well call it shot-noise. Yes, that term goes way back to the tube days when the masters were creating their theory on design, mostly for the small signal analysis, Miller effect, and all that jazz. If you ever had any engineering courses on electronics and amplifiers in general (limited to the transistor), it all came from tube circuits. Some say the tube amp has a natural sound and will not generate odd order harmonics. That is BS. Class A/B is not as bad as a Class B amp. They may look similar (yeah, Class B does exist but not used) Class A/B will generate some nasty harmonics of the odd order but is corrected with negative feedback often called presence. The Simul-Class (combination of Class A/B and extended Class A) will create more harmonic content than a Class A/B, again corrected with the use of negative feedback.

I did have all the gear I needed to use to measure the output power except for hearing protection. No ear plugs or sound blocking headphones. Running a single frequency through an amp at elevated levels is pure punishment. 750 Hz was bad enough, 1KHz would have been much worse. Also would have had to use the clean channel as the power test is done without distortion. No thanks. Still tempted though.

 

[bandit2013]

That is all so useful to know. It sounds like less simul-class and more conventional distortion makes the Mark V sound best.

I feel like you already kind of wrote a book on the Mark V at least. It is sort of a tragedy at the moment though! It would be fun if there could be a happy ending.

It would be cool if there were a schematic for the Mark VII. That amp might be better because of schematic level changes (one hopes) or because they got better about testing and rework during manufacture. You said they got rid of extra preamp stages which sounds like a big change. I wonder what is different in the power amp.

Sure it would be interesting to see it. Since it only has a total of 5 preamp tubes, one is consumed as the phase inverter. So that leaves just 8 triodes. The basic circuit can be found on any schematic, best to use the Mark III for your search as that is easier to read than the IIC+ schematic. Mark IV is not that much different. With just the 4 tube positions, I mapped out the tube task chart in a graphical representation. The top row is the JP2C, Mark VII, may as well include Mark IV, Mark III, and Mark IIC+ in that group. I did not map out the clean modes, only the gain modes. The crunch and VII are just rerouted signals using relays so the lead drive circuit can be moved to a different location in the signal path. The Mark V90 does not reassign the lead drive circuit signal path as it is only used on CH3. Different amp design but lead drive design is the same circuit but different tube positions V5A ->V4B 7 preamp tubes vs 5. JP2C only has 5, as do the IIC+, Mark III and Mark IVB. Mark V had to add triodes for the Mark I mode I assume. The extra triodes used does not make it better, there are many attenuator voltage dividers between some of the gain stages for CH3, between V3A and V6A and the feedback circuit is also quite different from V4B to V5A. It is more of an RC network and not as simple as the traditional design. More does not make it better. Heck a Marshal 2204 circuit only uses 3 or 4 triodes and a phase inverter. So you are lucky if you get more than three preamp tubes in that design. Same for the 2555x. Now if you were to look at the EVH, they have more preamp tubes than needed. Probably why the noise floor is so bad on that amp.

 

[KRichter]

I use a closed back 2/12 deep cab with 1 shadow and one EM Texas Heat. That did it for me. Tight with a huge thump. Perfect for the stage, but that's just me. Good luck.