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PostPosted: Fri Aug 24, 2012 9:58 am 
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Donating Member

Joined: Sat Oct 01, 2005 2:27 pm
Posts: 5420
Location: Maui Wowee!
He has a Revision A. His Reverb circuit is quite a bit different from the Revision B.
On the A, V4 is a 12AT7. This is a lower gain, but higher current tube. I have seen several vintage Fender amps that have blown Reverb transformers because someone used a 12AX7 tube instead of a 12AT7.

I would say that it is worth it to install a new or good AT7 and see if the Reverb comes back. I have a copy of the Mark IVA manual if anyone needs it too. Can't remember who sent it to me, but I would be happy to email it to anyone that needs it.

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Elvis said.......
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Amp techs do get shocked. :shock:


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PostPosted: Wed Dec 12, 2012 4:37 pm 
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Mark I

Joined: Tue Dec 11, 2012 9:56 am
Posts: 50
Monsta-Tone wrote:
He has a Revision A. His Reverb circuit is quite a bit different from the Revision B.
On the A, V4 is a 12AT7. This is a lower gain, but higher current tube. I have seen several vintage Fender amps that have blown Reverb transformers because someone used a 12AX7 tube instead of a 12AT7.

I would say that it is worth it to install a new or good AT7 and see if the Reverb comes back. I have a copy of the Mark IVA manual if anyone needs it too. Can't remember who sent it to me, but I would be happy to email it to anyone that needs it.



I have the old one done on a typewriter and Mesa Boogie stationery! Is that the one you have?


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PostPosted: Wed Dec 12, 2012 7:08 pm 
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Location: Maui Wowee!
That's the one. I think someone here scanned it and emailed it to me years ago.

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Elvis said.......
Quote:
Amp techs do get shocked. :shock:


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PostPosted: Thu Dec 13, 2012 11:02 am 
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Mark I

Joined: Tue Dec 11, 2012 9:56 am
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I got my amp in '92 and thought at the time it was very "mom and pop". Very cool.


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PostPosted: Sat Aug 03, 2013 5:40 pm 
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Mark III

Joined: Sun May 11, 2008 12:23 am
Posts: 244
Monsta-Tone wrote:
He has a Revision A. His Reverb circuit is quite a bit different from the Revision B.
On the A, V4 is a 12AT7. This is a lower gain, but higher current tube. I have seen several vintage Fender amps that have blown Reverb transformers because someone used a 12AX7 tube instead of a 12AT7.

I would say that it is worth it to install a new or good AT7 and see if the Reverb comes back. I have a copy of the Mark IVA manual if anyone needs it too. Can't remember who sent it to me, but I would be happy to email it to anyone that needs it.



I don't believe using a 12ax7 is going to hurt the amp in any way. I don't know the reason for using the 12at7 over the 12ax7. I have never had a problem with any of my amps that I've owned using a 12ax7, but i'm sure there's a reason why mesa chose to use that type of tube for the reverb.

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GIbson 30th Anni Gold Top ,Classic w 57/JB , 93 Studio w Jazz/JB, 07 Studio Fender Highway One Telecaster
Mark V, Marshall DSL 100, Mesa Rocket 44
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http://www.reverbnation.com/cradlefish


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PostPosted: Sat Aug 03, 2013 6:34 pm 
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Joined: Sat Oct 01, 2005 2:27 pm
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Location: Maui Wowee!
The AT7 is higher current, less gain.
The AX7 may result in not enough reverb.
I've repaired a lot of vintage Fender amps where someone put an AX7 in the reverb driver slot. It blows the reverb transformer most of the time......

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Elvis said.......
Quote:
Amp techs do get shocked. :shock:


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PostPosted: Sat Aug 03, 2013 10:46 pm 
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Mark III

Joined: Sun May 11, 2008 12:23 am
Posts: 244
Monsta-Tone wrote:
The AT7 is higher current, less gain.
The AX7 may result in not enough reverb.
I've repaired a lot of vintage Fender amps where someone put an AX7 in the reverb driver slot. It blows the reverb transformer most of the time......


thanks for shedding some light on the differences. I'll test out a at7 and check out difference.

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GIbson 30th Anni Gold Top ,Classic w 57/JB , 93 Studio w Jazz/JB, 07 Studio Fender Highway One Telecaster
Mark V, Marshall DSL 100, Mesa Rocket 44
Whitebox 2x12, Whitebox 1x12
http://www.reverbnation.com/cradlefish


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PostPosted: Sun Sep 01, 2013 9:16 pm 
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Joined: Wed Jun 26, 2013 3:56 pm
Posts: 1044
Location: Norfolk, CT
CudBucket wrote:
fdesalvo wrote:
I just don't get how ppl can honestly say their MKIV can't get super tight, saturated, or lacks low end


+1

If I had a Mark IV with any of those symptoms I'd do the following:

1) Preamp tube swamp and if that didn't work,
2) Poweramp tube swap and if that didn't work,
3) package it up and send it to Petaluma for a checkup.


That about sums it up, but I'll add that your guitar and pick-up choice will make a huge difference. Today our bass player couldn't make it to practice and I noticed the low end of the amp was super tight when I used the bridge pick-up compared to the neck pick-up. I never really noticed that there was that much more tightness because the bass guitar picked up the slack. I did make some changes in EQ and gain structure as the practice went on and now I wonder how it will sound when we get together this week and if I'll resort back to the earlier settings.

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Hendrix/Dimebag influenced, JP2C, Mark llC++, Steinberger GR4's


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PostPosted: Sun Oct 20, 2013 2:18 am 
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Mark I

Joined: Sun Apr 21, 2013 7:43 pm
Posts: 32
Location: Fife WA
Today my other guitarist found a Mark IV A compact head on craiglist (without pedal) for $800.
I have the Mk IV B head and we played both heads through the same cabinet using the same guitar with exact same settings. The tone differences was very minimum.
Later on we are going to do some side by side recording comparisons.


Image

Image

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'94 Jackson Kelly Pro Std w/ DiMarzio
'99 MiJ Ibanez RG7621
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Mesa Mark IVb
Mesa 212 Recto Cab V30 and Vet30


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PostPosted: Sat Oct 26, 2013 9:23 pm 
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Mark II

Joined: Tue Sep 04, 2007 2:10 pm
Posts: 64
Hi everyone. Got an issue with my Mark IV and I was hoping someone could steer me in the right direction. I created a thread outside of this one. Basically, my volume dropped considerably across the board, gain channel also sounds like it's crapping out, and now the signal seems sort of intermittent.

Thread: http://forum.grailtone.com/viewtopic.php?f=3&t=65570

I'm guessing it's in need of a re-tube. But that leads to all sorts of other questions, mainly, what kind. :?

Anyway, any help is appreciated. Thanks guys.


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PostPosted: Mon Dec 02, 2013 9:24 am 
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Joined: Wed Jun 26, 2013 3:56 pm
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Location: Norfolk, CT
I put new tubes in my Mark IV on Saturday. Someone gave me a pair of Mesa STR 420's so I tried them in the outer sockets at first along with the GT 6L6's in the middle. That sounded awesome, nice and tight. Next I tried the =C= el34's in the outer sockets and that had the typical "jangly" sound associated with Marshall amps. Next I put the 420's in the middle, 34's in the outer sockets and have been playing it that way trying different settings. I'm using the amp in simil-class, triode, full power, and I think that is what I'll use. My band is on holiday break, and I love my other Mark amps when I play with the band, so I never really use the Mark IV live unless it is at an "open mic," home practice or playing at a friend's house. I'd say the combination of 6L6 & el34's is best all around, but a quad of 6L6's would be my choice for metal only, the amp sounds less spongey and much tighter with 6L6's. I have different pre-amp tubes on the way.

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Hendrix/Dimebag influenced, JP2C, Mark llC++, Steinberger GR4's


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PostPosted: Sun Jan 05, 2014 9:59 pm 
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Joined: Sat Aug 26, 2006 2:16 pm
Posts: 695
Location: Dahne, AL
I sent you a Mark IV manual or something like that last year, I think.

Monsta-Tone wrote:
That's the one. I think someone here scanned it and emailed it to me years ago.

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Guitars: HamerUSA T-62 and Centaura
Amp: Mesa DC-5a
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PostPosted: Wed Oct 08, 2014 7:07 pm 
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Bottle Rocket

Joined: Wed Dec 15, 2010 2:50 pm
Posts: 6
Hi everyone, I just got my used wide body mesa boogie mark IVB 2 days ago. It's a beautiful combo and I'm thinking of make as head cab which I'm looking for head shell now.

I tried to call Mesa the other day and they quoted me with $356. Does anybody here have any idea for cheaper solution ? I heard there is member here "gts" who can make it happen for less than Mesa quoted me. Does he still make head shell these days ?


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PostPosted: Tue Nov 18, 2014 6:20 am 
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Bottle Rocket

Joined: Tue Nov 18, 2014 6:05 am
Posts: 1
hey there,
new to the forum and I just picked up a Mark IV last week.
amazing amp! so far I was able to play it only at bedroom levels,
but even pretty quiet it does sound incredible.

apparently it's a pretty early on, too.

Image

Image

Image

Image

does anyone know what the jack in the last image is for?


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PostPosted: Tue Nov 18, 2014 8:19 am 
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Mark III

Joined: Tue Nov 20, 2007 3:36 am
Posts: 185
No, but congratulations on the amp!


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