The Mark IV thread....!!

[stephen sawall]

The effects loop is always after the preamp. There isn't any option to have the effects loop before the preamp on the Mark IV.
As for why I have no idea.

 

[Claude Lambelain]

I Stephen sorry to answer so late, but haven't been there since long time.
THanks for your answer but i think I wasn't clear : My main concern si to be able to use "normal loop" and "switcheable" loop in the same time.

I did came with whawha and compression before preamp. THat's ok (also with tuner at first)/

Then I have a few effects as Phaser, Chorus and delay in switchable loop

I'd like to put only phaser and chorus in "normal loop" (after preamp right?) and only delay in "switchable loop" (also after preamp right?).

But apparently it is not possible to use both "switchable" and "normal" in the same time. It is either switchable OR normal but not both of them in the same time...

I just wanted to knox if someone has already found the solution to be able to wire "switchable" separated and "normal" separated to be able to keep normal activ (all the time of course) and switchable drived by the foot switch of course....

Many thanks in advance to all of you and sorry if it is still not clear!!!

Best
Claude

 

[stephen sawall]

I never heard of anyone doing that modification.

 

[Claude Lambelain]

Hi,

Ok anyway thanks for answer!
Best

CL

 

[user.39921]

Something I found out while repairing a Mark IV B that I haven't seen posted.

As we know - basically Mark IV A serial numbers span from 0001 to 6000 and Mark IV B start after that.
I have a really early B version (low 6100s) and while comparing the schematics I found some things that carried from the A version.

One particular spot: The official IV B schematic show a 3rd relay switch after the PI that switches between two ceramic capacitors (filtering fizz/fizz cap). One is 120p (schematic shows 180p, PCB is printed 120p - some amps had 120p, some 180p installed), the other switched value is 250p. Most IV Bs I've seen have that relay, but it seems like very early B's don't.

The IV A versions had a fixed 250p (no relay) as well as my IV B.

Also my chassis is still bare steel like the A's with separate face plates. Newer B's are painted black and there are no separate face/back plates (everything printed directly on the painted chassis).

I don't know if it's common knowledge, but I wanted to share in any case.

 

[user.39921]

Another interesting thing I found about this super early IV B.
The Power Transformer is still "561137" from "A" models (export version) and not the later "561141".

The 561141 has a center tap on the filament tap and the 561137 does not.

This explains why I see two balancing 100R / 2W resistors on the actual PCB but not on the IV B schematic.
I am fascinated by this crossover model!

 

[sduck]

It sounds like you have one of the transitional models, like mine. Nice to know about these other little differences!

 

[BoogieBaron]

Hi all,

First time poster here, glad to be part of the vintage boogie community.

I've got a Mark IV b version long head that I would like to hook up to my Marshall 1960BV 4x12 (280w) cabinet but I am unsure which speaker jack on the amp to use and which on the cabinet to connect it to. The Mark IV has an 8 ohm and two 4 ohm jacks while the Marshall cabinet has a 4 ohm input and a 16 ohm input, the 4 ohm also being labelled 8 ohm right and the 16 ohm being labelled 8 ohm left. There is also a switch on the cabinet for 'Mono' or 'Stereo', and the stereo side also says 140w. The cabinet contains four 16 ohm speakers, two of which are V30's and two are the original Marshall Vintage G12's. Please see the attached photos for clarification.

Cheers!

 

[Markedman]

Think of water, you want more at the spigot. The lower the ohm, the more water, 4 ohms is a 1/4 & 16 ohms is a 1/16. You wouldn't want a 1/16 feeding a 1/4.

4 ohm out from amp to 4 ohm in to speaker cabinet is proper but I would bet 8 ohm amp out into the 16 ohm speaker input would sound the tightest.

 

[user 21540]

Mesa Mark IV Manual -- Speaker jack info on page 13:
https://mesa-boogie.imgix.net/media/User%20Manuals/Mark%204.pdf

Tones And Tips
MESA/Boogie® Speaker Impedance Matching and Hook-up ~ Part 1:
https://www.mesaboogie.com/amplitudes/2013/June/mesaboogie-speaker-impedance-matching-and-hook-up-part-1.html

Mesa FAQ --What is the best way to connect speakers or cabinets?
https://mesaboogie.zendesk.com/hc/en-us/articles/218267437-What-is-the-best-way-to-connect-speakers-or-cabinets-

 

[BrokenAlleys]

First time MB owner. Got a '91 IVB the other day.

After reading all 700 plus posts here and in other forums I'm almost afraid plugging it in again. I suspect the brown Sprague 10,000 needs to be changed before they make an expensive mess. What can I get instead?

Lead drive is a bit scratchy, cutting in and out. I have it some cleaning last night. Maybe it gets better. Otherwise I assume I have the get a new potentiometer, getting in there seems like a huge hassle though.

Can someone tell me which pot that is the Lead Drive on a MKIV?



Here's the board.
https://imgshare.io/image/pzUEDq
https://imgshare.io/image/pzUiO7

 

[El Rey]

First time MB owner. Got a '91 IVB the other day.

After reading all 700 plus posts here and in other forums I'm almost afraid plugging it in again. I suspect the brown Sprague 10,000 needs to be changed before they make an expensive mess. What can I get instead?

Lead drive is a bit scratchy, cutting in and out. I have it some cleaning last night. Maybe it gets better. Otherwise I assume I have the get a new potentiometer, getting in there seems like a huge hassle though.

Can someone tell me which pot that is the Lead Drive on a MKIV?



Here's the board.
https://imgshare.io/image/pzUEDq
https://imgshare.io/image/pzUiO7

Send it to Mesa before Mike Bendinelli before he retires, which is soon.

Pull all the tubes and send in just the chassis.

I promise you he can get that amp back to new spec faster than anyone, and it is worth every penny!

I promise you no one, and I mean no one does better, neater, cleaner work.

Just got mine back from major service. New electrolytics and tubes, and general cleaning of pots, jacks, switches and minor tweaks.

 

[BrokenAlleys]

I'm sure he does unfortunately I live in Sweden so the shipping plus the work he'd do ...might as well use those money for a new amp.

 

[Lights Out]

Hi All
After several years without a Boogie
I recently bought another Boogie MK IV , My third one
Good to have a Boogie back in the house

This is my first REV B , looking back throught my threads on the forum
I bought my first one was back in 2005 . How time flys by ....

Anyway since I cant remember exactly how my old Boogies sounded .
I have a few questions about R2

Has anyone focused on trying different 12ax7s to get the most tight gain out of R2
Im assuming V1 and V2 are the tubes to focus on

The top strings sound tight and crisp but the A and E strings sound too boomy even with the bass off

Back in the day I got the JJ High gain set and remember thinking it was an improvment over the original old tubes
and I got close to the sound I was looking for

AC/DC through to Scorpions , Dokken , Accept .
But that Boogie was an early REV A . Reading throught the forum most people say it is more Raw sounding

Does that mean Its tighter sounding as well ?


My current MKIV is a serial 0083xx with an attached power cable ( early REV B) ?

I have done all the tweeking and variations on the amps functions . Still a work in progress
The last thing im looking into is the preamp tubes

Sorry for the long post :roll:

Any advice from experienced MK IV users would be appreciated 8)

 

[woodbutcher65]

I'm now a Mark IV owner and I'm thrilled.

Got it at the Orlando guitar show, Jan 29-30, 2022, Orlando Fairgrounds, Orlando FL.

I traded a 3 channel Dual Rec straight across to get it. Actually I sold the Rec, and for the same amount of money bought the Mark IV.

I like the Mark IV better, I could tell that in minutes. Seconds, really.

My last Mark was a blue stripe Mark III loaded widebody head. It was pretty much the last word in aggressive metal crunch.

The Mark IV is very competitive with it, but with the added benefit that Rhythm 2 is MUCH more usable than it is on a Mark III.

 

[BrokenAlleys]

Hi All

Has anyone focused on trying different 12ax7s to get the most tight gain out of R2
Im assuming V1 and V2 are the tubes to focus on

The top strings sound tight and crisp but the A and E strings sound too boomy even with the bass off

Back in the day I got the JJ High gain set and remember thinking it was an improvment over the original old tubes
and I got close to the sound I was looking for

My current MKIV is a serial 0083xx with an attached power cable ( early REV B) ?

I have done all the tweeking and variations on the amps functions . Still a work in progress
The last thing im looking into is the preamp tubes

Sorry for the long post :roll:

Any advice from experienced MK IV users would be appreciated 8)

I've done quite a bit of tube rolling in my Rev B. Even the power tubes. JJ's are an improvement imo. Get one of those expensive ones for V1 and V2.

 

[El Rey]

Hi All

Has anyone focused on trying different 12ax7s to get the most tight gain out of R2
Im assuming V1 and V2 are the tubes to focus on

The top strings sound tight and crisp but the A and E strings sound too boomy even with the bass off

Back in the day I got the JJ High gain set and remember thinking it was an improvment over the original old tubes
and I got close to the sound I was looking for

My current MKIV is a serial 0083xx with an attached power cable ( early REV B) ?

I have done all the tweeking and variations on the amps functions . Still a work in progress
The last thing im looking into is the preamp tubes

Sorry for the long post :roll:

Any advice from experienced MK IV users would be appreciated 8)

JJ's are an improvement imo. Get one of those expensive ones for V1 and V2.

Yeah right......don't count on it these days.

The psychotic tube rolling is just stupid.

But besides that, getting noise free dependable tubes from the resellers is more of a crap shoot today than it's ever been in some years. People keep forgetting there are few places in the world that continue to MFR them. Don't take my word for it, just do some searching. And now that the Shuaguang factory in China is gone, and probably wont be coming back on line, there's one less major source for the extremely low profit margin audio tubes for guitar amps.

So what are we left with? Reflektor and JJ (Russia & Slovakia)?

Add to that not all resellers test as diligently. I've just sent back counting 4 quads of the supposedly glorious TAD Red base 6L6's. TAD's coming from China used to be decent, and were for quite a while.

I gave up on JJ and TAD EL34's for my Wizards last year after suffering thru that mess of the same thing. Thankfully I still have some of the long out of production Winged C's.

And what have I ended back up on my Mesas?

Mesa branded tubes. People hate to admit that Mesa does a pretty damned good job of screening and testing the tubes they sell.

And yeah, they may not sound all that great compared to what you could get back before the all this supposed "supply chain issues".

But every single quad of STR 440's I've got in the last month (4 quads), are quiet, and don't raise holy hell crackling and popping when you put power to them and to the task at hand.

I've never liked the fact that Mesa hard fixes the bias on their amps. But with the stupid Simulclass power sections, I'm just better off buying their branded tubes, and could care less where they get them because in my experience, they do a much better job screening the tubes they sell, and as good a warranty as anyone if you happen to get a bum set (which is extremely rare in my experience).

 

[BrokenAlleys]

Is there a more quiet fan nowadays to use instead of the original Howard fan in a Mark IV REV B?

 

[domglop78]

Hello
here is the configuration of the tubes on my mark 4 b
https://imgur.com/gallery/J89mjJu

V1 is very important. I have a Mesa 12ax7 setup with STR 440s.
I often play with the R2 for a creamy sound and on Lead to boost the sound. (similar sound with more boost)
small reverb on and no GE.
type of sound: bluesy with a "santana" grain
HP: Altec 417 8h.
Note: The tubes play an important role in the final sound.You have to systematically matched the power tubes and use the best 12ax7 preamps.

POWER:
4 x STR 440
https://imgur.com/gallery/fTnZm9g

PREAMP:
V1: STR 12AX7 MESA
https://imgur.com/gallery/FA37kKK
V2:12AX7 MESA
https://imgur.com/gallery/A6it0Pq
V3:12AX7 MESA
https://imgur.com/gallery/nWr1NV2
V4:12AX7 MESA
https://imgur.com/gallery/NjdBp6e
V5:12AX7 MESA
https://imgur.com/gallery/Fl2hPka

dom

 

[Feedbacker]

Hi all - first time post (and apologies if I'm derailing this chat, but this seems to be the best thread to request this info)
I see from the Mesaboogie.com write-up that the Mark IV combo was available in two sizes, the Compact and the Wide Body combos.
I've tried to find info on the actual size/dimensions, and weights of these - to no avail. Please could any owners here confirm?
Thanks in advance...