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PostPosted: Mon May 08, 2017 6:38 am 
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Mark II

Joined: Tue Nov 14, 2006 8:17 pm
Posts: 113
I have been looking around the site for all kinds of information and it has been very helpful for dialing in my Mark V. In another topic someone posted the tube layout of the Mark V, but when I look at Page 62 of my owners manual the tube layout is different. Are there different versions of the Mark V? Or was there a mistake made in the owners manual at some point.

For example mine shows:
V3A- 3rd gain stage ch1/ch3

V4B- 2nd drive stage CH3
V5A- 1st drive stage Ch3

V6A- 4th gain stage CH3

Everything else is the same


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PostPosted: Sun Jun 04, 2017 8:03 am 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2399
Location: North Carolina
Every time I see the words "Mark V" the only thing that comes to mind is the flagship 90W simil-class amp that uses a quad of 6L6 or EL34 and a single 5U4G rectifier tube. As far as I know there have been no changes to the Mark V over the years since its release with the exception of the aluminum bar vs tube cage. I never really consider the Mark V:25 or the Mark V:35 so the tube positions and functions will be different between those models and the bigger brother (90W version).

The 90W version has not changed to my knowledge. There may be some differences with the 25W and 35W versions which do not use the same design so the tube assignments may be different between the two versions. Your manual that came with the amp should have the preamp tube assignments listed near the back. If the download version is different from Mesa's website I would inquire to tech service if there have been changes and which tube assignments apply to your amp.

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PostPosted: Mon Jun 05, 2017 6:44 pm 
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Mark II

Joined: Wed Aug 04, 2010 10:32 am
Posts: 85
Location: New Jersey, USA
The manual posted online does seem a bit unclear regarding some of the tube assignments. For example, V4B is the 4th Gain stage of channel 3, and V6A is the 6th Gain stage, but nowhere is a 5th gain stage mentioned.

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PostPosted: Mon Jun 05, 2017 7:26 pm 
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Mark II

Joined: Tue Nov 14, 2006 8:17 pm
Posts: 113
The manual was definitely changed at some point. I don't know if mine is the newer version of the manual or the older version.


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PostPosted: Wed Jun 07, 2017 6:03 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2399
Location: North Carolina
Manual does not have V3 listed as a path for CH3 but it is in the CH3 circuit path.

Channel three tube path:

V1A ->CH3 tone stack =>V1B=>CH3=>V5A =>V4B =>V3A =>V6A =>to EQ =>FXLoop send / (or bypass to PI V7) => FXloop Return =>V6B =>V7 (PI)

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Wed Jun 07, 2017 6:52 pm 
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Mark II

Joined: Tue Nov 14, 2006 8:17 pm
Posts: 113
bandit2013 wrote:
Manual does not have V3 listed as a path for CH3 but it is in the CH3 circuit path.

Channel three tube path:

V1A ->CH3 tone stack =>V1B=>CH3=>V5A =>V4B =>V3A =>V6A =>to EQ =>FXLoop send / (or bypass to PI V7) => FXloop Return =>V6B =>V7 (PI)


So my manual is the correct one then and the manual on Mesa Boogies website is wrong. For Channel 3 mine says:
V1A-Input stage
V1B 2nd gain stage ch3
V3A 3rd gain stage Ch3
V4b 2nd Drive stage Ch3
V5A 1st drive stage CH3
V6A 4th gain stage ch3
V6b Effects loop return
V7a &B Phase inverter

Unless I'm misunderstanding something?


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PostPosted: Thu Jun 08, 2017 12:22 pm 
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Mark III

Joined: Mon Sep 29, 2014 12:17 pm
Posts: 180
Location: Canada
It looks to me like method of naming just changed between versions:

The online "V3A- 3rd Gain Stage CH1" just isn't indicating that this tube is ALSO in the CH3 path.

And then these lines:
V4B- 4th Gain Stage CH3
V5A- 3rd Gain Stage CH3

Are really the same as
V4B- 2nd drive stage CH3
V5A- 1st drive stage Ch3

because V4B and V5A are clearly not the first two Gain stages, so when they say "drive" stage they must mean overdriving/saturation stages, which are also gain stages. So the first Drive stage is actually the 3rd Gain stage, and they just decided to label it like that at some point.

Same with
V6A- 4th gain stage CH3
vs
V6A- 6th Gain Stage CH3,

V6A is only the 4th gain stage if you consider V5A/V4B drive stages instead of gain stages, but if you consider them gain stages then it means V6A is the 6th.

So I think at some point they were counting Drive stages separately than gain stages, then they decided it would be clearer to just refer to and count them all as gain stages. Is your manual particularly old? Or perhaps it's newer to help people better figure out which tubes most affect the distortion characteristic of CH3. You don't necessarily know that the 3rd and 4th gain stages are the key ones for distortion character, but the 1st and 2nd Drive tubes certainly would affect the Drive, etc

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formerly: Quad Preamp, Rocket 44 112


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PostPosted: Thu Jun 08, 2017 12:33 pm 
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Mark III

Joined: Mon Sep 29, 2014 12:17 pm
Posts: 180
Location: Canada
huh, just noticed this from the online manual:
Quote:
CHANNEL 3 goes on from there to encompass the best of the MARK Series Overdrive sounds. Beginning with the MK II C+ (switch
up) the sound is pure, blistering focus and this is the classic Boogie voice of the 80’s that became the foundation for players like
John Petrucci, James Hetfield, Kirk Hammett, as well as a staple for L.A.’s first call session players of the day Steve Lukather, Mike
Landau, Dean Parks and many more.
The classic “V” curve on the Graphic EQ became an integral part of this sound and went on to be the sound of choice for some of the
hardest hitting Punk and Hardcore bands of the 90’s and 2000’s and is still currently used by many top acts. The original II C’S bring
many times their original selling price - if you can find one - and this faithful recreation of that burning sound is the cornerstone of
CHANNEL 3. The MARK IV is also represented here in FAT (toggle center) where a dose of thick midrange gain is added combined
with a rounding out of the upper harmonic peak. Finally EXTREME (switch down) unleashes all the aggression and attack of this
circuit for a full gain assault that cuts through any mix. (Beware, the volume jumps up when EXTREME is selected.) There is also a
NORMAL / BRIGHT switch included that affects all three Modes in CHANNEL 3.


Apparently the Center mode of Channel 3 used to be called FAT and not MARK IV, which actually makes a lot of sense because many people looking at the schematic will say the modes are really TIGHT, FAT, and EXTREME, and all are based on the IIC+ (As the Mark IV circuit was).

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Mark V
Studio Preamp
formerly: Quad Preamp, Rocket 44 112


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PostPosted: Thu Jun 08, 2017 3:13 pm 
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Mark III

Joined: Sun Sep 27, 2015 2:50 pm
Posts: 157
Location: Good ole England
I noticed that typo in my manual too calling Mark iV mode FAT. Maybe Mesa would have saved themselves, and the Mark V, a lot of flack if they'd have stuck to TIGHT, FAT and EXTREME as you suggest for naming the modes in Ch3 and said they where all variations of the iiC+ theme. Which looking through the schematic it is very closely matched to the iiC+ typology. As is the Mark iV. I also noticed the omision of Ch 3 from V3 in the tube task chart. I also wonder what Mesa's definition is of the difference between gain and drive stages? Surely they are all gain stages apart from the reverb and fx loop driver stages?

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PostPosted: Fri Jun 09, 2017 10:27 am 
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Mark III

Joined: Mon Sep 29, 2014 12:17 pm
Posts: 180
Location: Canada
Wayno wrote:
I noticed that typo in my manual too calling Mark iV mode FAT. Maybe Mesa would have saved themselves, and the Mark V, a lot of flack if they'd have stuck to TIGHT, FAT and EXTREME as you suggest for naming the modes in Ch3 and said they where all variations of the iiC+ theme. Which looking through the schematic it is very closely matched to the iiC+ typology. As is the Mark iV. I also noticed the omision of Ch 3 from V3 in the tube task chart. I also wonder what Mesa's definition is of the difference between gain and drive stages? Surely they are all gain stages apart from the reverb and fx loop driver stages?


I think they would have. The number of people looking for that IIC+ tone which has PULL DEEP engaged and the larger filter cap but not realizing MARK IV mode is just that could really have been appeased if they didn't think it was wrong to get a IIC+ sound from a mode labelled MARK IV.

MARK TIGHT: Modeled on our famed IIC+ circuit, but using a smaller filter cap that the non-Graphic models had because it provides an immediacy and tightness unmatched.
MARK FAT: The same famous circuit, but with the PULL DEEP engaged and the larger filter cap Graphic EQ models shipped with. Provides a beefier sound at the expense of some immediacy.
EXTREME: I actually don't know how to describe this. But we did some presence shenanigans like the modern mode of our Rectifier line, and it's LOUD.

And as for the stage naming: they are all gain stages, but the 4th and 5th (which they call 1st and 2nd Drive stage) Are the gain stages specifically built to overdrive and saturate, so I assume that was the logic. Without knowing which version of the manual is newer, I can't say which they decided was clearer.

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Studio Preamp
formerly: Quad Preamp, Rocket 44 112


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PostPosted: Sun Jun 11, 2017 5:54 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2399
Location: North Carolina
If you state what the actual circuit is in reality most people will not understand but will be confusing distortion as gain. In essence there is only one area where the tubes get overdriven into hard clip and cut which is the cascaded pair V5a to V4B. It does not really matter, just provide a tube path in graphic form so it is easier to understand what they are looking at. What is interesting, only CH2 has a over drive stage before the tone stack and the other channels have the drive section following the drive. Sure they are gain stages but design to saturate and clip/cut the signal.

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Current amps:
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Old friends I sometimes miss:
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PostPosted: Sat Jun 24, 2017 7:15 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 230
Yes there are changes in the schematic, I think there is at least one big change in CH3 preamp.

Image

The very early amps sound different!


Last edited by APEMAN on Mon Jun 26, 2017 9:41 am, edited 1 time in total.

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PostPosted: Sat Jun 24, 2017 5:08 pm 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 230
After a view hours today in the rehearsal :P my ears are ringing and my fingers hurt and bleed... so I use the time to do this littel simulation to analyse the exact differences. It shows both tone stacks. 2009 vs 2010. Values for treble, mid and bass as resistor values show my favourite settings (Caution, audio taper pots -> you have to think logarithmic!):

Image

You can clearly see the overall gain drop over the whole frequency range as well as the increased treble reduction to tame the ice pick.


Last edited by APEMAN on Mon Jun 26, 2017 9:41 am, edited 1 time in total.

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PostPosted: Sun Jun 25, 2017 10:27 am 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2399
Location: North Carolina
You had my curiosity peaked so I had to look for myself what rev I have in my Mark V.
Note that the actual revision Mark V 1-2A does not appear in a visible area on the top side of the PCB. What is visible if this is code for revision level is this....."the Mark 2 see beyond" just above @2009 Mesa # Boogie LTD as this appears on the edge of the board near the grommet in the chassis for the OT wires. I did trace out the center wire for the treble pot, C18 is marked 180, it feeds into a high precision 82k half watt resistor and the remaining network is the 330k and 220k resistors. If it was the old revision it would have had the 330k and 56k resistors and the 82k would be absent.

In other words, I have the updated board from 2010..... My build date was 7/16/2012 SN number range....MKV-0089xx if that helps. Still with this the amp is terribly brittle when using 90W full power mode on CH3, CH2 edge, and CH1 tweed. However a change in V1 resolves the CH2 and CH1 brittleness. I actually found a Svetlana 12AX7 (new sensor tube similar to tung sol, EHx or the Mullard CV4004). Either that or the Mesa SPAX7. So far the best I have yet to use was the Svetlana (do not confuse this with =c=, at one point in time they actually made a 12AX7 and reports indicated it was of poor quality-performance).

Seems that the only cure for the top shrill or ice tone for CH3 is the Mod you suggested, at least in my case was change of V4 to the tube in the thread. I will take a picture and post it later.

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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PostPosted: Sun Jun 25, 2017 12:32 pm 
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Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2399
Location: North Carolina
Picture will come much later as I already close the amp up and then remembered I wanted to take a picture..... sorry if you were waiting.

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Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


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