Possible Mark VI Directions

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I was under the impression that only 90W was SimulClass(Class AB outside tubes paired with am extended Class A pair). 45W disables the outside tubes, and just runs the Extended Class A tubes. Then the 10W mode runs a true single-ended class A. So you could possibly toggle a 100/120W true Class AB power section, but that would involve some Bias changing, wouldn't it?
 
Keep in mind the 45W power mode is a Class A/B power amp, it is just biased differently. Also, with that in mind, the signal also flows though the same grid circuit, the signal path into the outer tubes only has a series resistor to limit current flow, the inner pair has a voltage divider on each grid (pulls the bias voltage more towards ground which in result drives the inner pair hotter (extended class A region, does not mean the amp is class A in 45W).

It would not be difficult to alter the Simul-class extended class A to a traditional push-pull A/B circuit with a few relays and a few extra parts. This could be done with the same bias circuit as once the voltage divider resistor connected to ground is disconnected, the bias voltage on all 4 tubes would be very much the same (however the series resistor on each grid may be different as well as the screen resistor, would not be too difficult to use relays to switch in additional parts to balance things out).

What I would like to know if this be true, does the JP2C sound as good in the clips as it does in first person point of view?. I found that I do not care for the Mark V tone when the EQ is off. What I have seen in some of the demo videos, turning on and off the EQ did not seem to make the amp sound worse with it off. In case of the Mark V, it sounds lifeless and lacking power without the EQ (preset or sliders), but with it on, it sounds much better. In pale comparison to the RA100 or Roadster, both sound incredible without EQ. I have the Mesa 5BEQ pedal and I actually prefer the amps without it. Sure, it is all about tone stack, how it is managed, where in the circuit is it, etc... Roadster drives it with a Cathode Follower, RA100 does not (closer to the Mark V in method).

I have been looking into the JP2C more now, I believe that may be what I have been looking for, but yet still want to wait and see what comes out of Mesa next (if anything).
 
bandit2013 said:
What I would like to know if this be true, does the JP2C sound as good in the clips as it does in first person point of view?. I found that I do not care for the Mark V tone when the EQ is off. What I have seen in some of the demo videos, turning on and off the EQ did not seem to make the amp sound worse with it off. In case of the Mark V, it sounds lifeless and lacking power without the EQ (preset or sliders), but with it on, it sounds much better.

The clips do the amp no justice. I've yet to hear any clips really truly capture the magic in the JP2C. I agree 1000% with you on the V without the GEQ. In fact, imho, the V sounds god awful without the GEQ. When I bought the JP2C, I assumed it too would sound like crap without the GEQ engaged. I was very wrong. It sounds wonderful without it. I can't belive how well I get along without the GEQ on the JP. Basically, the character of the JP2C is very different from the V. The V has that honky nasty midrange, the JP has none of this. It's more scooped, so it sounds smoother and feels bouncier, which, to me, feels more lively. Where that nasally, honky midrange in the V makes it feel tighter, or stiffer, and that makes it more unforgiving to play. And I agree with you that that sounds lifeless, and I think it feels lifeless. The JP2C was truly refreshing to play. No more fighting with my V to get it to loosen up its midrange stranglehold and trying to get it to breathe. Now I've got the JP2C, and it sounds like the mark tone has been perfected.
 
I have experimented with many different preamp tubes, 12ax7: From EH, TS, Mullards (both LP and short CV4004), Preferred series and a few others, 5157 NOS JAN GE, also including 12AT7. Same with Power tubes. My issues with most of the tubes brokered by New Sensor seem to create more noise in certain positions than others. If I can get past the low frequency hum or high hiss I would love them. What was noise free (almost) were some old Mesa Chinese tubes I have (square foil getter) that really liven up the amp. Best tube for V2 if you want that heavy healthy punch for the crunch. I tried a few of the ECC 803S JJ tubes (very nice sounding and not as dark as the ECC83s used by Mesa. The Mark V does react quite well to different preamp tubes. If you want to change things up, NOS 12AT7 in the V4 and V5 pushes CH3 into a different world. Perhaps less gain but quite a different character. If I play without the EQ I could get used to it, but turn it on and its Nirvana.

Speaker choice is another thing that helps. I converted to a Combo so I could experiment with different speakers and love the Celestion Crème ALNICO 90W. Sounds really great with stock Mesa Power tubes, could not stand them in the V before the change. JJ 6CA7 or Gold Lion KT77 are also amazing. Will have to try some other brands of the 6CA7 as the JJ tube had some issues that were not related to plate voltage, more so quality issue due to open lead wires inside the tube causing intermittent function.

I still want to get a JP2C, would like to get one before they become discontinued as it seems that Mesa drops the amps that I like. I have no plans now to let go of my V, it is a keeper at the moment. What I would love to get my hands on would be a JP2C combo 2x12 but doubt that would ever become a reality.
 
What would be cool is two FX loops, each buffered with their own tube circuit as well as independent switching and volume control. There are times you want to run a parallel patch especially with delays and reverb pedals. When they are run in series, it gets muddy but in parallel it sounds much better (had to do this with the TASCAM recorder and did not use any effects on the amp for that reason alone). Also you could assign each loop to a specific channel or use both simultaneously or just one. If two loops are not enough, add a few more (similar to the Line 6 helix).

Add midi control as requested by the OP, Cab clone (would be better with improved cab simulation based on assumption as I do not have the cab clone, perhaps some DSP with down loadable IR ).

Let's not forget about the coffee or beer dispenser while we are at it. Okay I can do without that, it is the thought that counts. I can understand wanting to be challenged with a set of what may seem impossible to pack into a small enclosure along with preamp and power tubes. Perhaps we have not given enough challenge to the master amp engineer. Preserve what was done and add what was not done. Why only stick with 3 channels, when we can have 4. Blend the JP2C with the Mark V ;Perhaps use the JP2C clean on CH1 but add the tweed for some grit, CH2 could be the IIC CH2, CH3 with same features as JP3C CH3 and CH4 the Mark V (mkIV, extreme, and little Mark III blue stripe). What ever would make sense and be yet feasible to accomplish. Still have to find the place to put in the Mark 1. recap that, Mark 1, Mark IIC(in the form of the JP2C), Mark III, Mark IV, Mark V (tweed and extreme) with the possible power amp switching for pure class A (10W), Simul-Class power (45w/90w) and more traditional A/B power used on JP2C (50W/100W) with a twist to include two 5U4GB that can be used at all power settings.

As always, I am looking forward to what ever it is that will be released to production.
 
I think Mesa will try and get at least 10+ years out of the Mark V before we see a Mark VI. The Mark V has been out for 7 years which is not very long for a flagship tube amp. I can imagine a revision at some point but not the next generation of the Mark Series.

With that said, I think integration with pro audio equipment is something Mesa has wisely deemed important. I think they will continue in that direction as long as guitarists want to record music.
 
Perhaps you are right about the time line when a new Mark would be in the works. I am sure something is in the planning stages for a new product.

I have one last request and this would be applicable to all Mesa amps,
A footswitch chassis that does not vibrate at low frequencies. The Mark V footswitch controller seems to resonate the most at certain low frequencies when compared to that of the RA100 or Roadster. If you have the space to distance the footswitch away from the speaker enclosure it is not an issue.
 
bandit2013 said:
Perhaps you are right about the time line when a new Mark would be in the works. I am sure something is in the planning stages for a new product.

I have one last request and this would be applicable to all Mesa amps,
A footswitch chassis that does not vibrate at low frequencies. The Mark V footswitch controller seems to resonate the most at certain low frequencies when compared to that of the RA100 or Roadster. If you have the space to distance the footswitch away from the speaker enclosure it is not an issue.

I do not think it is hard for Mesa to create a new product. I think the challenge is making that product affordable, marketable, and profitable.

Mesa redesigned the Rectifier Recording Preamp's footswitch fairly recently. The only reason I know that is because I happen to need a new footswitch for that Preamp. The new one looks really nice! The only pieces of plastic on it are the LED covers. So you never know, maybe Mesa is redesigning all their footswitches as we speak.
 
Given To Fly said:
I do not think it is hard for Mesa to create a new product. I think the challenge is making that product affordable, marketable, and profitable.

Mesa redesigned the Rectifier Recording Preamp's footswitch fairly recently. The only reason I know that is because I happen to need a new footswitch for that Preamp. The new one looks really nice! The only pieces of plastic on it are the LED covers. So you never know, maybe Mesa is redesigning all their footswitches as we speak.

Designing a product to meet the demand and yet make it affordable, marketable, and profitable is every engineers challenge. That is one of the difficult challenges I face every day at work. Shoveling a load of features and functions and control surfaces into a small box in attempts to meet a cost target. "wait a minute here, you want this and expect it for that? Are you nuts? I may think that but usually respond with " I will see what I can do to meet the cost target, but if we are dealing in low annual quantities that may not be possible".
 
Think about Class definition.
Taken from Duncan Amp pages.

CLASS A
"The distinguishing feature of class A is that the valve is conducting current at all times. Note the the "Out" current never drops down to the zero line at any time....."

CLASS B
"What about class B? In the diagram on the right, we have set the bias point to where the valve has almost stopped conducting.

Note that the input signal is a lot larger now in order to drive the valve hard enough. Also, the output current is only for half of the waveform.

To make any use of this, we have to have a "push-pull" output stage which employs two valves (or two banks of valves) so that each side amplifies each half of the waveform. While the first output valve provides the output current as shown on the right, the second valve fills in the gap which follows it."

CLASS AB

"By now, you have probably guessed what class AB is - it's somewhere between class A and class B. Where exactly, is up to the imagination!

In our class AB diagram, a small amount of bias current is flowing through the valve. For the output valves in a typical class AB guitar amplifier, this would amount to around 30-40mA, with peaks of approximately 250-300mA.

In the push-pull output stage, there is a little overlap as each valve assists it's neighbour during a short transition, or crossover period."

So in class A, the valve is conducting all of it's current all of the time. Whether that is a single valve or six of them. If that valve ever shuts off, it's not class A, it is then class AB.
Where a class B valve conducts no current unless needed, it completely cuts off and lets it's partner do the work for half of the time.
A class AB valve conducts some current all of the time, not all of it's current like a class A circuit would.

http://www.duncanamps.com/technical/ampclasses.html

Therefore, there is no extended class A, there is simply hotter class AB bias, where the valves are on more than the regular class AB, outer pair.
What I won't do is deny the results of it, no matter how Mesa dress it up in words. It sounds really good. I wasn't a fan till tonight. When I plugged my amp into a Peavey Valveking 4x12. Cheapo speaker cab and the thing sounded divine. If their 2x12's sound as good, I'm having one.

Those readings of 42ma on the inner valves in Variac mode is about 65% bias, colder than I'm used to, firmly class AB.
The 30ma reading of the outer pair in Variac mode is stone cold but still class AB at 45%.
 
bandit2013 said:
Given To Fly said:
" I will see what I can do to meet the cost target, but if we are dealing in low annual quantities that may not be possible".

:lol: I love this response! Every profession has its own unique way of saying "No."
 
I think that progressive linkage thing would be great. I'd love to be able to run CH1 and 2 EL34 and CH3 6L6. Or any other options it may reveal. Is that what it does? Love tweed with EL34's and CH2. CH3 is also great with EL34's but the option would be incredible. The bigger coupling cap for iic+ mode is a no-brainer along with the bigger transformer too. MIDI as well. And the drive control. Could drop my clean boost then! I like Bandits multi fx loop idea as well. Series and parallel loops both have their pros and cons. Big form factor head as well, changing Pre amp tubes is a nightmare.
 
bandit2013 said:
Is it really that important to debate the method by which Mesa biased the Mark V? The only time the Mark V operates in pure class A mode is in the 10W power setting, amp is reconfigured to operate at a cathode bias and uses one inside tube and the outside tube next to it. In 45W mode, the amp is operating in class A/B (push pull) but the operating point of each side is biased closer to class A than it should be for class A/B. 90W mode just pulls in the outer pair also in Class A/B. Quite similar to the Mark IV but does not have a 10 W mode. If I recall, the differences were in the plate voltages, screen resistors, and the voltage divider network on the pair of tubes. Too bad I deleted the schematics for the Mark IV after I sold the amp (you can find that one doing a search). I still have the schematics for the Mark V (not complete as it is missing the relay control circuits and logic for the footswitch, but is good enough for simple repair if needed). In essence, the Mark V in 45W and 90W is operating Class A/B. If you consider each portion of the Class A/B amplifier, each is composed of a push pull format, extended class A refers to the operating point or load line characteristic of the inner pair of tubes that is closer to that of a Class A but is not a true class A amplifier, it is a push pull or A/B. How this differs from a traditional class A/B amp is that the inner pair of tubes have a lower bias voltage than the outer pair. Inner pair of tubes have a -43.6V on the grid, outer pair have -46.6v on the grid. If you feel the Mark V is operating in Class A in the 45W mode, you are mistaken.

If you want it in writing by the manufacturer, look at bottom of page 3 of the Mark V manual.

copied from the manual:
45 WATTS turns off the outer pair of 6L6s so only the middle two are running. These are the ones with the lowered bias so, while they are still Class AB, their Class A region is extended. In Channel 3, they can be switched to run in Triode configuration which cuts their clean headroom roughly in half.
Combining these two opposite styles of wiring in one amplifier gives you the best of vintage and modern amplifier styles. Headroom and power are there when you need it… but there is always a naturally pleasing and musically curvaceous quality to the sound that
Overview: front panel (Continued)
PAGE 3
is magic to your ears and to your hands. Simul feels great and is inspiring to play!
10 WATTS reconfigures the whole set of 6L6s so that the two nearest the 5U4 run pure Class A, single-ended—no longer push-pull. This is the ultimate low wattage output circuit that duplicates the essence of the best really old vintage circuits. Here, the second harmonic (an octave above the note played) is NOT cancelled out (as it is in push-pull circuits) and provides a magical halo surrounding the notes. Onset of clip is so gradual that it’s hard to pin down the transition from clean to overdriven.

I was under the impression that the 45W mode was class A as well. It is not.

What about the other mark amps with the "class A" switch? If it's anything like the simul-class circuit the V uses then it's not class A, it's still A/B. Isn't that a bit misleading if that's the case? I thought the V was the first Mark with a true class a circuit. Is mesa telling the truth with that class A switch on the other marks?
 
The other Mark Amps that have the Simul-Class use the same circuits. Class A is in reference to the push/pull only. In essence it is two class A circuits each out of phase. What it should state Class A push/pull. When I think of Class A, I think single ended, not in terms of push/pull circuit. All of the preamp tubes operate class A single ended, including the PI tube. Most of the products I design do not use negative power supplies as there is not much of a need for that so I have forgotten most of what I learned back in college. I can still remember most of it so I have not lost what was learned. Having a good definition what is Class A, what is Class A/B, what is push/pull and single ended Class A. How does it all work....? This can be found on the internet if you are interested. Perhaps I too should read up on it as it has been more than 23 years since I had designed any audio amplifier circuits.

I think I am getting a better understanding of all of this....
Mark V operates in true class A only in 10W mode only. However, the 45W mode is not a single ended class A, it is a push/pull similar to A/B but not. Center tubes will be operating class A (sort of) but will be 180 degrees out of phase of each other. Still class A as it were but the cross over point when signal is above or below the load line that tube will be amplifying the signal, there is no cut-off at the cross over region, actually there should be no cross over region with the push/pull Class A circuit. In essence this will require the center pair to have a hot bias compared to the outer pair of tubes. Class A/B works differently as such that signal above the bias voltage will cause one tube to conduct and the other will be off, and when the signal drops below the bias voltage the roles switch. This will result in cross over regions. When mixed together, the outer pair of tubes will be operating in A/B mode and the inner pair is class A push/pull. It is finally making sense to me know.

If you ever had any background in electronics and amplifier circuits, term called load line is used. I simplified this by stating bias voltage but it is more in depth than that. In other words, the traditional A/B amplifier uses a horizontal load line (not it will have a slight angle but it is more horizontal) signal that drops below the load line is cut off. Consider it as a half wave signal. For simplicity the A circuit amplifies the positive going signal, and the B circuit amplifies the negative going signal. Class A or extended Class A uses a load line that is ideal at 45 degrees. It will amplify positive and negative swings (signal above load line would be positive, below load line will be negative) Extended class A may refer to push/pull as once circuit is 180 degrees out of phase to the other. Both tubes in the 45W mode are always amplifying the signal and there should be no cross over distortion. The outer tubes when turned on (90w), will only amplify part of the signal. Simul-class blends both together. Sort of neat trick once you mull it over. I never really bothered to understand all of this as it was not important to me.

Now when it comes to the JP-2C, characteristic is very similar to the 90W simul-class sound. I beg to wonder if it is a traditional Class A/B circuit or is there something different in it. I guess I have read over the manual and read the stuff I skipped over as it was the same story provided with all the manuals. Roadster and RA100 are traditional Class A/B amplifiers. Both seem to have their own character that has been difficult to replicate with the Mark V and vice versa. Perhaps the monstrous OT of the JP-2C may have a major role in its character. Now I wonder.....
 
Working on my gig rig and just wishing that Mesa would drop a Mark V update with the JP-2C features. ESPECIALLY MIDI CONTROL.

At the moment I'm trying to figure out how I'm going to fit a mini amp gizmo (which I do not own yet) on to my pedal board. It's looking grim.

PS: Midi-selectable channel modes would be hot.
 
dlpasco said:
Working on my gig rig and just wishing that Mesa would drop a Mark V update with the JP-2C features. ESPECIALLY MIDI CONTROL.

At the moment I'm trying to figure out how I'm going to fit a mini amp gizmo (which I do not own yet) on to my pedal board. It's looking grim.

PS: Midi-selectable channel modes would be hot.

Here is my RJM unit cable tied to the metal screen. I connect the proper cable (RJM cable) when needed between the Gizmo and the amp's switch jacks. I think I need to attach the cable permanently by tying it down with cable ties rather than connecting / disconnecting.


Something you may want to consider for you setup (I'm assuming your pedal board is away from you amp):

With the Gizmo attached to your pedal board, the RJM cable will be a long run back to your amp. Considering the RJM cable is 'specially made' I'd protect this cable as priority and keep it as a short run by attaching the Gizmo to the amp instead, similar to how I have. Having the Gizmo attached to the amp the RJM cable is short and tucked away. You only need to run one standard midi cable from your pedal board to the Gizmo. A standard midi cable is a lot cheaper if it get's damaged with overly excited feet.


RJM unit cable tied. Power lead shown with hooks that I installed. The hooks are simple clothes hooks I bought from a hardware store. I don't understand why Mesa doesn't have hooks to wrap the power lead nice and neat. My Peavey JSX has moulded hooks as standard.
 
Blaklynx said:
dlpasco said:
Working on my gig rig and just wishing that Mesa would drop a Mark V update with the JP-2C features. ESPECIALLY MIDI CONTROL.

At the moment I'm trying to figure out how I'm going to fit a mini amp gizmo (which I do not own yet) on to my pedal board. It's looking grim.

PS: Midi-selectable channel modes would be hot.

Here is my RJM unit cable tied to the metal screen. I connect the proper cable (RJM cable) when needed between the Gizmo and the amp's switch jacks. I think I need to attach the cable permanently by tying it down with cable ties rather than connecting / disconnecting.


Something you may want to consider for you setup (I'm assuming your pedal board is away from you amp):

With the Gizmo attached to your pedal board, the RJM cable will be a long run back to your amp. Considering the RJM cable is 'specially made' I'd protect this cable as priority and keep it as a short run by attaching the Gizmo to the amp instead, similar to how I have. Having the Gizmo attached to the amp the RJM cable is short and tucked away. You only need to run one standard midi cable from your pedal board to the Gizmo. A standard midi cable is a lot cheaper if it get's damaged with overly excited feet.


RJM unit cable tied. Power lead shown with hooks that I installed. The hooks are simple clothes hooks I bought from a hardware store. I don't understand why Mesa doesn't have hooks to wrap the power lead nice and neat. My Peavey JSX has moulded hooks as standard.

I agree that this is the way to go. I'm planning on ordering one by the end of the month.
 
dlpasco said:
Working on my gig rig and just wishing that Mesa would drop a Mark V update with the JP-2C features. ESPECIALLY MIDI CONTROL.

At the moment I'm trying to figure out how I'm going to fit a mini amp gizmo (which I do not own yet) on to my pedal board. It's looking grim.

PS: Midi-selectable channel modes would be hot.


I solved the problem for my small-ish/backup rig by putting the RJM switcher into a small, 4U rack that also houses the effects that go into the loop and are also switched via midi.

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For a "Mark 6" I think there have been plenty of suggestions here. I personally figured the Mark V wasn't for me so I'd like to see something that is closer to the Mark IV again. Maybe with a Mark IIC+ mode from the JP2C. And yes, Midi would be great. Dual EQ would be the winner. So basically a 4-channel JP2C with the 3 channels from the Mark IV plus one of the JP2C gain channels. And all that in a more traditional Mark design, skirted buttons, wicker and all. And no famous-person-endorsement logos and stuff please.
 
Here is my idea for the Mark VI: The Mark Modular.

This would be a Mark "chassis", that would accept preamp "modules". The chassis would contain the power amp, fx loop, GEQ, and reverb. There would be slots which would allow you to pop in preamp modules, with each module being its own preamp channel. There might be several versions of the chassis, which would allow either one, two, three, or (why not?) 4 modules, depending on how many channels you wanted. They could also have a "high power" chassis (6L6/EL34) and a low power (EL84). There could be many preamp modules available, allowing the user to customize their setup, and even change it around, based on different needs.

Remember the Seymour Duncan convertible amp back from ~20 years ago? I had one of these for a while, and I think it was a brilliant design. Mesa could go crazy offering various preamp modules, having a module for every sound from every amp they've ever built. (Speaking of signature amps, they could have signature modules...) Imagine having 30 preamp modules to choose from! Also, you could have a stereo setup by adding a simple 1-module-chassis, similar to the Satellite amps they built in the 90s.

I really feel that this would be the best of all possible worlds. The flexibility would be amazing. No more compromising! You could choose the exact preamp sounds you like, the exact number of channels you want, and could change it around from gig to gig, depending on the needs. And Mesa could spend the next 10 years developing new and exciting preamp modules!
 

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