Mark IIB Problems...Suggestions?

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gitapik
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Mark IIB Problems...Suggestions?

Post by gitapik » Fri Dec 31, 2010 12:45 pm

Hi. I've got a 1980 Mark IIB. EVM12L. Great sound. I've got three issues that I'm looking for help with. One of them's probably not fixable, but I figure I'll throw it out there, anyway:

1) When I'm in Lead mode, the reverb begins to cut out as I dial down the amount of distortion in the Lead Drive pot. Volume 1 is at "8", so there's plenty of break up there, if I want it. The cut becomes really noticeable when the pot's at 6 or below. It's bothersome when I switch from the clean channel, as the loss of reverb's pretty noticeable. I've been getting around that by using a RealTube pedal for the subtle overdrive (reverb stays constant) and the Boogie Lead drive at 8 for the heavier stuff, which keeps the reverb constant there.

2) I've got the stereo footswitch for EQ and Gain (wish it was the treble pull out pot and not the gain...anyone know if I can do that?). Sometimes I get an annoying *POP* when I switch into the EQ. Sometimes not. I'd love to get rid of that.

3) Along the same lines, I get a pop when I switch in and out of lead mode. This doesn't seem fixable, though...so I make sure I blunt the strings before making that change, which gets rid of the pop. Be nice if someone knew a different fix for that.

I had a mod done to the lead drive which kicks it up a couple of notches. I love both channels.

Thanks for your time, people.

Bob
'57 AVRI Strat
'11 G&L ASAT Classic
'69 Les Paul Custom
Boogie Mark IIB
Blues Jr (BillM mods)
Peavey Backstage
Lotsa Stomp Boxes
Martin OM-21
National Radiotone reso
Fernandez Classical
Mainland Tenor Uke
Schertler "David" Amp

RR
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Re: Mark IIB Problems...Suggestions?

Post by RR » Fri Dec 31, 2010 8:04 pm

gitapik wrote:Hi. I've got a 1980 Mark IIB. EVM12L. Great sound. I've got three issues that I'm looking for help with. One of them's probably not fixable, but I figure I'll throw it out there, anyway:

1) When I'm in Lead mode, the reverb begins to cut out as I dial down the amount of distortion in the Lead Drive pot. Volume 1 is at "8", so there's plenty of break up there, if I want it. The cut becomes really noticeable when the pot's at 6 or below. It's bothersome when I switch from the clean channel, as the loss of reverb's pretty noticeable. I've been getting around that by using a RealTube pedal for the subtle overdrive (reverb stays constant) and the Boogie Lead drive at 8 for the heavier stuff, which keeps the reverb constant there.
First of all, you do realize that the "rhythm channel" does effect the drive on the lead channel. Just want to make sure you are aware how to set these amps because I've seen guitar player that just bought a used Mark IIB don't really know how to use them. They don't read the manual and they don't realize that they have to "juggle" the three volumes (yes, there's actually 4).

As for the reverb, the Mark II, IIB reverb and effect loop should be upgraded. This is a standard modification done by MESA's head chief technician Mike Benedelli. This will great improve the performance of your reverb.
gitapik wrote:2) I've got the stereo footswitch for EQ and Gain (wish it was the treble pull out pot and not the gain...anyone know if I can do that?). Sometimes I get an annoying *POP* when I switch into the EQ. Sometimes not. I'd love to get rid of that.
It possible to do that modification of the treble pull but that's medium modification done by amp technician. He'll probably discourage you from doing this modification anyway.
gitapik wrote:3) Along the same lines, I get a pop when I switch in and out of lead mode. This doesn't seem fixable, though...so I make sure I blunt the strings before making that change, which gets rid of the pop. Be nice if someone knew a different fix for that.
This amp runs on relay so there will be some pop sound. Also your footswitch are old and a bit faulty which cause this loud pop. Those footswitch buttons should be replace. I''ve replaced all of mine dual (gain & EQ) and the channel switching and the pop was not as noticeable.

Hope this help. Yes, Mark IIB is one of my favorite MESA.

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gitapik
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Re: Mark IIB Problems...Suggestions?

Post by gitapik » Sat Jan 01, 2011 11:19 am

RR wrote:
gitapik wrote:Hi. I've got a 1980 Mark IIB. EVM12L. Great sound. I've got three issues that I'm looking for help with. One of them's probably not fixable, but I figure I'll throw it out there, anyway:

1) When I'm in Lead mode, the reverb begins to cut out as I dial down the amount of distortion in the Lead Drive pot. Volume 1 is at "8", so there's plenty of break up there, if I want it. The cut becomes really noticeable when the pot's at 6 or below. It's bothersome when I switch from the clean channel, as the loss of reverb's pretty noticeable. I've been getting around that by using a RealTube pedal for the subtle overdrive (reverb stays constant) and the Boogie Lead drive at 8 for the heavier stuff, which keeps the reverb constant there.
First of all, you do realize that the "rhythm channel" does effect the drive on the lead channel. Just want to make sure you are aware how to set these amps because I've seen guitar player that just bought a used Mark IIB don't really know how to use them. They don't read the manual and they don't realize that they have to "juggle" the three volumes (yes, there's actually 4).
Great to meet another Mark IIB admirer. Your point about the different channels is well taken. I've had this amp for a while and have gotten them down. Blows me away how many different tones I can get. I think a lot of people give up on the Mark Series because it's easy to lose patience. I know it took me some time...
As for the reverb, the Mark II, IIB reverb and effect loop should be upgraded. This is a standard modification done by MESA's head chief technician Mike Benedelli. This will great improve the performance of your reverb.
Thanks for the tip. Mike's great. He definitely knows these amps. I'll ask my techie here about it. If he can't do it, I'll send it out. Costs $$$ to ship from NY to CA.
gitapik wrote:2) I've got the stereo footswitch for EQ and Gain (wish it was the treble pull out pot and not the gain...anyone know if I can do that?). Sometimes I get an annoying *POP* when I switch into the EQ. Sometimes not. I'd love to get rid of that.
It possible to do that modification of the treble pull but that's medium modification done by amp technician. He'll probably discourage you from doing this modification anyway.
Yeah...that was just a flyer, but thanks for addressing it. I just like that midrange boost a lot more than the Gain boost that's provided. It's easy enough to just walk over and pull it out or in, though.
gitapik wrote:3) Along the same lines, I get a pop when I switch in and out of lead mode. This doesn't seem fixable, though...so I make sure I blunt the strings before making that change, which gets rid of the pop. Be nice if someone knew a different fix for that.
This amp runs on relay so there will be some pop sound. Also your footswitch are old and a bit faulty which cause this loud pop. Those footswitch buttons should be replace. I''ve replaced all of mine dual (gain & EQ) and the channel switching and the pop was not as noticeable.
I do have the original boxes. What did you replace them with?
Hope this help. Yes, Mark IIB is one of my favorite MESA.
Very much so, thanks! Much appreciated. Happy New Year!
'57 AVRI Strat
'11 G&L ASAT Classic
'69 Les Paul Custom
Boogie Mark IIB
Blues Jr (BillM mods)
Peavey Backstage
Lotsa Stomp Boxes
Martin OM-21
National Radiotone reso
Fernandez Classical
Mainland Tenor Uke
Schertler "David" Amp

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