The Mark IV thread....!!

Mark I's, II's, III's and the almight IV

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Monsta-Tone
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Re: The Mark IV thread....!!

Post by Monsta-Tone » Fri Aug 24, 2012 9:58 am

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

HBob
Mark I
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Re: The Mark IV thread....!!

Post by HBob » Wed Dec 12, 2012 4:37 pm

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?

Monsta-Tone
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Re: The Mark IV thread....!!

Post by Monsta-Tone » Wed Dec 12, 2012 7:08 pm

That's the one. I think someone here scanned it and emailed it to me years ago.
Elvis said.......
Amp techs do get shocked. :shock:

HBob
Mark I
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Re: The Mark IV thread....!!

Post by HBob » Thu Dec 13, 2012 11:02 am

I got my amp in '92 and thought at the time it was very "mom and pop". Very cool.

cradlefish
Mark III
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Re: The Mark IV thread....!!

Post by cradlefish » Sat Aug 03, 2013 5:40 pm

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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Monsta-Tone
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Re: The Mark IV thread....!!

Post by Monsta-Tone » Sat Aug 03, 2013 6:34 pm

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

cradlefish
Mark III
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Re: The Mark IV thread....!!

Post by cradlefish » Sat Aug 03, 2013 10:46 pm

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.
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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Markedman
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Re: The Mark IV thread....!!

Post by Markedman » Sun Sep 01, 2013 9:16 pm

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.
JP2C, Mark llC++ DG, Mark IV-A/B.

mazzith
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Re: The Mark IV thread....!!

Post by mazzith » Sun Oct 20, 2013 2:18 am

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.


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Aaron M
'94 Jackson Kelly Pro Std w/ DiMarzio
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Mesa Mark IVb
Mesa 212 Recto Cab V30 and Vet30

darkalone
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Re: The Mark IV thread....!!

Post by darkalone » Sat Oct 26, 2013 9:23 pm

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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Markedman
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Re: The Mark IV thread....!!

Post by Markedman » Mon Dec 02, 2013 9:24 am

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 simul-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.
Last edited by Markedman on Thu Apr 05, 2018 9:11 am, edited 1 time in total.
JP2C, Mark llC++ DG, Mark IV-A/B.

boogietone
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Re: The Mark IV thread....!!

Post by boogietone » Sun Jan 05, 2014 9:59 pm

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.
Guitars: HamerUSA T-62 and Centaura
Amp: Mesa DC-5a
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andrewraharjo
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Re: The Mark IV thread....!!

Post by andrewraharjo » Wed Oct 08, 2014 7:07 pm

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 ?

philip
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Re: The Mark IV thread....!!

Post by philip » Tue Nov 18, 2014 6:20 am

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.

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

tonejam
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Re: The Mark IV thread....!!

Post by tonejam » Tue Nov 18, 2014 8:19 am

No, but congratulations on the amp!

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