Mesa MarkV / Saturation 'mod'

[Markageddon]

I've sussed out the Mark III a little more and found common ground with the V. I disengaged the pull shift on 'Bass', and suddenly I felt I was back on the MkV with mod.
Even with 'Deep' engaged. The similarity remained.
Shows you just how good that tubeswap really is in the V.
I don't think I could have gotten the same tones/action from the stock tubes.
Colour me impressed.
The sounds from these amps had in the last few months have been the best I've ever had/played through, and possibly ever will.
Real tone on tap. All day long.

(And the combination of openback EV speaker on top of the 1x12 ported cab really let all that shimmer, complexity and 3Dness breath beautifully. Massive rich and smooth. A combination that works equally well with the V and 25 too.)

 

[Wayno]

A bit more live 'At7 in 4' on the 90w malarkey.

More Sabbath for Wayne.

https://www.youtube.com/watch?v=_t-_m5UT-ds

Sounds great man, nice rhythm tone from Ch2 Crunch. Solo sounds spot on too. Do love me a bit of Sabbath :twisted:
Where you playing there? You're in England right? Venue looks familiar.

 

[Wayno]

Getting very itchy over the C29 removal. Been working like a dog for last month or so, 7 days a week 14hr days :shock: so no boogie time. Still, be nice when the wage comes in at the end of the month! So haven't had no time at all to play, or tweak. May well give this Cap Mod a go though if i can sometime soon. May well be the icing on the very delicious cake that is the Mark V now.

Surprised there's still no voice from Boogie over all of this? Especially now the thread has evolved as far as it has?

 

[Markageddon]

A bit more live 'At7 in 4' on the 90w malarkey.

More Sabbath for Wayne.

https://www.youtube.com/watch?v=_t-_m5UT-ds

Sounds great man, nice rhythm tone from Ch2 Crunch. Solo sounds spot on too. Do love me a bit of Sabbath :twisted:
Where you playing there? You're in England right? Venue looks familiar.

Cheers. Thats it on the 25 and the V now... soon the Iommi test for the III too.
This was in Essex..a fair bit south of you.
May have just a production 'generic look pub' from ACME. haha

 

[bandit2013]

Getting very itchy over the C29 removal. Been working like a dog for last month or so, 7 days a week 14hr days :shock: so no boogie time. Still, be nice when the wage comes in at the end of the month! So haven't had no time at all to play, or tweak. May well give this Cap Mod a go though if i can sometime soon. May well be the icing on the very delicious cake that is the Mark V now.

Surprised there's still no voice from Boogie over all of this? Especially now the thread has evolved as far as it has?

You have the wrong capacitor as C29 is the cathode resistor bypass cap on V4A which is the reverb circuit. The capacitor in question is C39 which is on the other half of the tube V4B. Just for smiles and grins I did manage to install one so I can have a point of reference. It acts as a low pass filter and will affect the midrange as well as treble. I prefer the tone without it so I am waiting for the tubes to cool down so I can remove them in order to place the amp on the bench (also allows for the stored energy to dissipate). A smaller capacitance value may have more merit say a 47pF or perhaps a 10pF than the 120pF. With the C39 installed, the amp sounds squished and a bit lifeless as far as note articulation is concerned. Without it adds some note definition and seems to raise the midrange as well as the upper frequencies too. It may appear like a minor change in simulation but the difference is audible.

Did you say yours was a 2009? There was a minor change on the tone circuit for CH3 that started in 2010. I tried to look for the thread but could not find it.

 

[Wayno]

A bit more live 'At7 in 4' on the 90w malarkey.

More Sabbath for Wayne.

https://www.youtube.com/watch?v=_t-_m5UT-ds

Sounds great man, nice rhythm tone from Ch2 Crunch. Solo sounds spot on too. Do love me a bit of Sabbath :twisted:
Where you playing there? You're in England right? Venue looks familiar.

Cheers. Thats it on the 25 and the V now... soon the Iommi test for the III too.
This was in Essex..a fair bit south of you.
May have just a production 'generic look pub' from ACME. haha

Work in and around Essex a lot so probably had a cheeky "knock off early on a friday" pint in there at some point :lol:

Looking forward to hearing the iii :mrgreen:

 

[Wayno]

Getting very itchy over the C29 removal. Been working like a dog for last month or so, 7 days a week 14hr days :shock: so no boogie time. Still, be nice when the wage comes in at the end of the month! So haven't had no time at all to play, or tweak. May well give this Cap Mod a go though if i can sometime soon. May well be the icing on the very delicious cake that is the Mark V now.

Surprised there's still no voice from Boogie over all of this? Especially now the thread has evolved as far as it has?

You have the wrong capacitor as C29 is the cathode resistor bypass cap on V4A which is the reverb circuit. The capacitor in question is C39 which is on the other half of the tube V4B. Just for smiles and grins I did manage to install one so I can have a point of reference. It acts as a low pass filter and will affect the midrange as well as treble. I prefer the tone without it so I am waiting for the tubes to cool down so I can remove them in order to place the amp on the bench (also allows for the stored energy to dissipate). A smaller capacitance value may have more merit say a 47pF or perhaps a 10pF than the 120pF. With the C39 installed, the amp sounds squished and a bit lifeless as far as note articulation is concerned. Without it adds some note definition and seems to raise the midrange as well as the upper frequencies too. It may appear like a minor change in simulation but the difference is audible.

Did you say yours was a 2009? There was a minor change on the tone circuit for CH3 that started in 2010. I tried to look for the thread but could not find it.

Yeah you're right, C39 not C29. Too much work and not enough play had skewed my memory, was late on a school night too. Seriously considering your cap mod if I get the time, might have to wait though as will probably use any little time I get to play rather than tinker. Yeah my V is a 2009 so I almost definitely have the original tone stack. Will look and check if I do get round to the cap mod. Think it was one of APEMAN's threads on the tone stack.

Here's the thread, APEMAN's input is on first page about 10 or 15 posts down

http://forum.grailtone.com/viewtopic.php?f=33&t=73457

I would guess the small difference in simulation on the cap mod compared to in actuality would be due to the small change there having a larger effect on the preceding and post gain stages because of changes to impedance and loading etc?

 

[Dreamtheaterrules]

A bit more live 'At7 in 4' on the 90w malarkey.

More Sabbath for Wayne.

https://www.youtube.com/watch?v=_t-_m5UT-ds

Good job man! :!:

 

[Markageddon]

90w malarkey.

Work in and around Essex a lot so probably had a cheeky "knock off early on a friday" pint in there at some point :lol:

Looking forward to hearing the iii :mrgreen:

Nice one! You see me in there next time come say hi I'll buy you a beer.
You may be able to catch the jam live, by employing a seismic monitor for the south. hahaha
I'll post a link to clip or two on Sunday or Monday.

Good job man! :!:

Cheers DTR...! \m/

 

[bandit2013]

I was thinking on shifting the V4 midrange a bit with change in bypass cap. If I do the C39 may be necessary to retain. Very tight quarters to restore if you do remove it. A 100pF or smaller cap across the anode resistor may compensate for the removal of C39 (do not go too large as that will kill the top end). Why I am willing to modify is beyond me. Amp sounds great if just left alone as is. Oh yeah, I know why.... it is that JP-2C that has inspired me to do so. If only I can get the Mark V to sound closer to that in some respects on CH3 that would make the V ideal. Unfortunately there is far more to it than one or two components. Heck, I already have the JP-2C so that should be enough to keep me happy (but that amp is a beast when it comes to volume levels where as the V is easier to run at lower volume levels. At least the Vertical 212 cab helps in the loudness control of the JP-2C, the 412 cab is over the top and too much for me. Perhaps that is what is compelling me to do the unthinkable to the MKV...modification :roll: definitely beyond the scope of this thread and at best probably not recommended, especially if that is not your daily job or part of your skills as it is mine but not exactly for audio circuits. The high voltage part of it does not fear me as I am always cautious even with working on the live circuit under full power).

I think the change to the AT7 improves the tone considerably in V4 and or V6. Still have not tried just V6 by itself yet. Perhaps I should do so before tinkering with signal gain characteristics as this may be a fools errand, even for me. Actually the slight difference in tone compared to the JP-2C is fine with me as I have no need to attempt to achieve with one amp to what I already have in another. Keep in mind if this had seeded any ideas, once you change one part, you may have to change other things like the coupling capacitors to compensate...... Having a good understanding what components do what to a tube amp circuit is of great value and best left to someone who can do that sort of thing in there sleep.

 

[Markageddon]

Looking forward to hearing the iii :mrgreen:

There ya go. You're catching the amp close and off to the side.
And its messy room noise city. But heres the III with AT7 in PI through the EV speaker cab and the 1x12 ext cab stacked. It was a rowdy affair and audience members were hijacking mics and it was getting a bit silly so there may be that all over it.

https://www.youtube.com/watch?v=YCO_XtrtGE4

Some of the more mellow rhythm parts were channel2/rhy2 sometimes boosted sometimes not. And the heavier rhythm stuff and all the lead was channel3/lead. Chain was Flying V>Smartgate>535q Wah>Ts9>Boogie. Had a TC looper in the loop too, but it wasnt really used on this occasion..

Presence was set real low to 2 and a half out of ten. Would have opened that up a little in hindsight.
Especially with all that pull deep and big 80hz/240hz going on in that room sound. Also with the mod making it more big vintage warm and liquidy raw like it does for the V. It needs definition.

But this was a hurried stripped kinda vibe that night and many crazy things were happening so it was all a bit 'on the fly'...

 

[bandit2013]

Sounded great Markageddon! That brought me back to my band days in the early 90's when all I had was guitar and Mark III. Great playing too (as well with the other clips. Image was a bit washed out in darkness so I would assume that you were playing the Flying V again...

 

[Markageddon]

Sounded great Markageddon! That brought me back to my band days in the early 90's when all I had was guitar and Mark III. Great playing too (as well with the other clips. Image was a bit washed out in darkness so I would assume that you were playing the Flying V again...

Thanks Bandit...! I was indeed. Seemed apt from attempting a Heartbreakers tune. Cam was in a really crap viewpoint and just had people's backs and stuff, so thought it looked less aggrovating in black. (Faster YT upload time too, with no image to process...!)
Yes it did give me a classic 80s/90s vibe too...!! Covers of Stiltskin and Sandman were potentially only moments away from happening again... lol Thanks again for the kind feedback. \m/

 

[Wayno]

Uh oh...

Clipped out the C39 leg furthest away from the relay, plugged back in and nothing! On Ch2 10w power i get a really quiet fuzz if i touch the guitar cable with my finger but nothing at all in any other mode or power setting? Very strange. Tried swapping out a few of the preamp tubes to no avail. Did them all apart from v5 and v6. I do get pops and clicks like normal when switching between channels and the usual pop when switching from 10w to 45w or 90w on all channels so im guessing the power amp section is ok. Tried a cable in the loop return but nothing there, no buzz when touching it, even with a jack in the send as well to make sure the loop is active. Tried with the reverb cables both connected and not connected, nothing. Gotta feeling, at least i hope so, that ive missed something really stupid here but cant for the life of me think what it could be. One thing i did do was disconnect the ribbon cable from the switching board to the main board to allow easier access to C39 in order to clip the leg. Then when i powered back on and the channel selector wouldnt work, nor the pedal. Realised what id done so took amp back apart, reconnected the ribbon cable and turned back on. Its almost like the amp is stuck in mute, could this be my problem? Amp is also super quiet, but you can hear a slight noise increase like normal when you turn the mute switch off on the pedal. Bizarre...

 

[bandit2013]

I did the same thing. But I had clicking noises when I left the large ribbon cable out. I would double check the cable to verify it is indexed properly on the connector..... if it is the correct part that would not cause sudden loss of all channels.

Remove chassis again... this time leave it out and invert it on a speaker cab. Before you set it up, check the cables again. You should also confirm that there is no lead or other metallic parts on the PCB that could be connecting the anode resistor as it is right next to the cathode resistor.

Also did you remove any tubes? Take a picture of the area you did the mod and post it or PM me. If all is plugged in, tubes in place and speaker connected to proper load you should not have this problem. Also check to see if the solo control is pulled out as that is also a mute. The amp may be stuck in mute. Confirm all ribbon cables are seated properly (no exposed pins showing). You did just cut one leg on C39 right, not C29....which is also on V4 but is not a disk capacitor and is also on the other side. C39 should be between V5 and V4. This should be on a Mark V 90W on V4 side b, cap is on pin 7 and pin 8, also inline with the 0.22uF cap and a JFET just below that.

Another thought, try turning off the FXloop on the back panel (hard bypass) as it could be stuck in tuner out position.

 

[Wayno]

https://drive.google.com/file/d/0B_NBQ4NZ9lM4S1Y2QnRfb3BWZUk/view?usp=drivesdk

Pretty sure I got the right cap. Hadnt tried the pull mute on the solo control, will try that when I get home from work as I could easily have accidentally pulled that when putting the chassis back in the cab. Did try hard bypass though, thought that bypassed the hole master volume and mute section?

 

[APEMAN]

-

 

[bandit2013]

Wayno,
That appears to be the correct capacitor. I also noticed an extra component in the view. There is a 3.3M resistor connected to a Zener diode and the other side is out of view. I know it is there in the circuit and should be across the two Zener diodes on the Reverb circuit. I had thought the resistor was on the other side of the ribbon header. Leave it there as it may be necessary if the pattern was not on the PCB version.

Removal of the grid to cathode capacitor should not cause the issue you are having. You may want to check the continuity of the ribbon cable from end to end to verify a wire is not loose as it is an insulation displacement style of connection. Ribbon cables of this type usually require care in removal and never pull on the wires to remove the connector as it has a lock on the header. It may be possible there is a poor connection on the ribbon cable if nothing else can be discovered. Also since V4B is not used anywhere else in the preamp but CH3 you could pull it and you would still have signal on CH1 and CH2 but without the reverb. You can even do the same for V5 with the same effect. The reverb circuit runs parallel to the channels.

When you get the time test the ribbon cable (there should be pin access on the side of the connector (they are small but a meter probe should be able to touch them if you need to confirm if you have a poor connection or broken wire on the ribbon cable. You can even use a component lead with alligator clips to test continuity if needed (you will need to remove the ribbon cable completely to check point to point connections.

The Mark V is not that easy to mess up where the speaker gets connected. JP-2C has the speaker jacks extremely close to the FX loop and I have already plugged into the loop thinking it was the speaker jack (TC-50 is similar and have done it with that amp too when hooking up in the dark or poor lighting.... flashlight helps sometimes).

 

[mace]

Hope you get it up and running soon! Hopefully it is something simple.

Question: In Bandit’s photo there is a yellow component next to the two resistors and in the Wayno’s photo there is a black componenet. Are these the same components?

 

[Wayno]

Hi Guys,

Yeah I noticed mine was slightly different to bandits when I was clipping the cap leg. I had bandits photo up on my laptop for reference and noticed the difference.

I haven't touched or added anything since I experimented with the eq coupling cap a couple years ago. And that was put back to stock. However, the amp was bought second hand so someone could possibly have done some mods but I wouldn't have thought so.

I will try your suggestions when I get home from work and report back.