Boogie MKIIB Rev Eq 60/100W head

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Very interesting. I knew, that the reason for core lamination and isolation is to cut eddy currents.
Well yes, it's well known !

So probably the tie rods form shortcut, if the holes in the core are too small and the tie rod can touch the core inside.

Exactly. But the "total magnetic shortcut" occurs between the 1st and the last lamination if the ends of the tie-rods are not insulated by nylon (or so) washers : this is the most important.

And I never thought about the rust thing. Maybe thats the reason why in one of my old Kitty Hawk Amps the Xfo gets quite hot after a while: it is indeed a little rusty outside.

Well, it is a possibility. I suggest you then to clean from rust as best as possible you transformer's lamination edges, and treat it with anti-rust coating (in France, we have the RUSTOL OWATROL, which is very convenient for that), but I won't say that it is the absolute cure. On most of my old Fenders - which have no or minor/non significant rust traces - the transformers get very hot but works well... Till one day where they will die by overheating, may be. A surface temperature of 50°C for a transformer on nominal duty is common, in fact.

To summarize, what kills transformers is :

- excessive humidity, which ruins coil insulation. I tried to save transformers of a friend's amp (a 2x75W Mickaelson & Austin TVA-1 HiFi tube amp of the 80's) which was immerged by accident in a water flood for one night : it was useless - even with a prolonged stay in an oven (1 week at controlled temperature with hot air drying) - the transformers were dead definetly. Neddless to say that we were upset !

- excess heat due to long "little" overload exposition. The windings "roasts" slowly but surely, performances decreases by losses in insulation, and one day there's an arcing or a cut and it's over.

-and we discussed it : magnetic short circuits, by unacceptable design issue, or with the time, damage to the laminations or tie-rods .

A+!
 
BTW: how is the sound? very different to your Mk IIA? More gain?

Only an accurate A/B comparaison will tell us exactly, but again I find it similarly sounding and a little more gain than my IIA on a fast sound test yesterday... Remember that my Boogies are not stock anymore, so...

For the moment, I still have one small funny parasitic noise issue to eradicate on a perticular setting... Work is still in progress and still coming to end... Soon :mrgreen: !

A+!
 
This morning I could compare side to side my MKIIA and IIB :

- my IIB has more gain, what is probably called "liquid" gain, the reverb is balanced correctly between lead and rhy, but the amp is still too much noise ridden : remaining hum, buzzy little guitar sound when M1 is at 0 or 1 instead of silence. The FX loop is hummy too. The sound is very good but the noise is still unacceptable...

- my IIA has less gain, but is dead quiet at any setting compared my IIB. The sound is very good and there is NO hum or noise issue...

If my IIB had the signal/noise ratio of my IIA, it would be Le Saint Graal. As I will probably never use a noise ridden Fx loop (and maybe never a loop), I will study the possibility to simplify the circuit (by sacrifying the loop unfortunately) in order to stay with the gain and tone, but not the noise...

Wait and See...

A+!
 
I have a stock January 1980 Mark IIB combo. I'm really happy I found this post. Some observations:

> I've never used the reverb above 4. Usually at 3. Any higher and it sits out in front too much for my taste. The effects loop is a dud, too. The mod on yours is supposed to fix that. So I've always played my effects straight into the front.

> The clean tones are the best I've ever heard. They are why I still have the amp after all these years. I was going to sell it and buy a lighter combo but couldn't find anything I like as much. Got close in the $2500 and up range. So I've decided to convert it to short shell head.

> I never thought about the proximity of the reverb tank to the transformer in a head. I just researched it and found that it's only in the short shells. That's why Mesa stopped making that size. Sounds like I'll be using my WET reverb pedal or getting the larger head.

> I honestly can't decide whether to go for the effects loop mod or not. I love the cleans as they are and am getting very much into the Lead channel with Vol 1 and Treble pots pulled and the Presence knob and/or EQ set right. Especially through a closed back speaker (my Thiele rocks!). I'm told that the mod will change those tones, which really makes me pause. And if it creates noise, why bother? The IIB has a distinctive voice which I'm reluctant to mess with until I've heard and played through one with the mod.

> I think you said there's a way to set the amp so You can play it as though it's stock or modded. If so, I'm curious about your comparison between those two, as opposed to comparing to your IIA. I know you've modded it...but I'm curious.

> Do you know how to eliminate that *POP* when changing from Rhythm to Lead (other than blunting the strings?

Btw: like your IIA, my stock IIB is dead quiet. No hums or crackles. I don't know if that's due to it's being a combo vs head or that it's not modded?
 
Hi gitapik & thanks for your constructive advice,

> I never thought about the proximity of the reverb tank to the transformer in a head. I just researched it and found that it's only in the short shells. That's why Mesa stopped making that size. Sounds like I'll be using my WET reverb pedal or getting the larger head.

Reverb is part of my sound arsenal, so it is important to me to have a good and quiet reverb at any level, and it's what my MKIIA combo does after I modified it. I made the test of my MKIIA chassis installed in the headshell of my IIB with the stock mounted 9AB2A1B reverb, and found it was hummy, but quite acceptable if I was in the need of a headshell mount. But the combo is quiet, thanks to the reverb distance from the power transformer, that's a fact.

honestly can't decide whether to go for the effects loop mod or not. I love the cleans as they are and am getting very much into the Lead channel with Vol 1 and Treble pots pulled and the Presence knob and/or EQ set right. Especially through a closed back speaker (my Thiele rocks!). I'm told that the mod will change those tones, which really makes me pause. And if it creates noise, why bother? The IIB has a distinctive voice which I'm reluctant to mess with until I've heard and played through one with the mod.

You're right : the FX loop mod is hummy/noisy. It's a pity because it can work well in term of tone and efficiency... But that hum is not acceptable to me. There is no significant difference between my MKIIA and my FX loop factory modded MKIIB in term of tone : they both have that distinctive clean tone, IF we neglect that my MKIIB is a hum factory . That hum is a Pest...

think you said there's a way to set the amp so You can play it as though it's stock or modded. If so, I'm curious about your comparison between those two, as opposed to comparing to your IIA. I know you've modded it...but I'm curious.

I am not sure to understand clearly what you mean (sorry I am French), but my MKIIB came to me with the FX loop mod already done at Mesa in 2007, ordered by the previous owner along with a compete check-up. So I can't compare with a "standard" MKIIB like yours... The instruction notice coming with the FX loop mod explain how to set the amp to use an effect or to use it without effect connected, with the same performance as if it was not modded. Nonetheless, IMHO there is not much difference between stock IIA and IIB, and the FX loop mod doesn't alter it significantly. Again, I forget the "hum disease"...

> Do you know how to eliminate that *POP* when changing from Rhythm to Lead (other than blunting the strings?)

No. I didn't found any miracle in that field, unfortunately... I attenuated it by a thorough cleaning of the relay contacts, and by building an independent and correct DC supply to the relay to have a frank switching, but it is impossible to eradicate the remaining pop.

Btw: like your IIA, my stock IIB is dead quiet. No hums or crackles.

It's very difficult to believe that for me !!! All the MKII, III, IV I've had at home for service were hummy, no exception, but NOT for the same reasons. I have today a MKIIC here and I can confirm it again. It would be very interesting for me to hear your amp along with mine, since I think that it has the same misconceptions concerning the ground distribution scheme inside, which makes it hum unbearably...

A+!
 
Hi gitapik & Co,

This morning I could compare side to side my IIA and IIB extensively, paying attention to have comparable settings each time to be fair. So :

- My IIB has a bit more gain than my IIA, but IMHO the Fx loop Mod has minimal or no influence there : the number of stages involved is the same.

- the lead tone is more "modern" on my IIB.

- the cleans are comparable, but a bit deeper/warmer on the IIA (it's reputedly the main quality of the IIA models versus the others).

- I set the FX loop as best, with a Carl Martin Red Repeat echo and minimum lenght cables, adjusted at the maximum allowable send level before clipping the FX, in order to have the best signal/noise ratio.

Then :

> Does the FX Loop Mod changes the sound of the amp ? I think that there is many other parameters which can influence as well, but maybe the loop makes the amp a bit brighter, I am not really sure, and it can be corrected by the presence control, so that's why I say "comparable".

> Is the FX Loop Mod bringing hum ? Yes, indeed. At any setting my IIB is noisier than my IIA, but it is more hummy when you plug an effect, and it even makes no difference if you plug a 4" patch cable between Send and Return...

The trial is done for me, and the FX Loop Mod is losing, arguably. It works well, but the noise is as unacceptable as unbearable - at least to me. On lead mode, at equivalent settings and volume level (set high), there's no picture : You think that the IIA is on SBY mode compared to the IIB...

So the next step is removing all that interesting but occasional and very noisy feature, and go for simplicity and quietness !

Wait and see...

A+!
 
Very nice of you to keep us up on these developments, mark2. Thanks.

I've got a broken wrist that's just now healing, but I can still check sounds by tuning my guitar to a chord and checking stuff out that way. Here's what I've come up with on my IIB:

1) You're right. It hums. I never really even thought about it, to tell you the truth. I guess it doesn't bother me that much. It would be nice if it didn't, though. Wish I had your smarts in that area.

2) If I dial the reverb down all the way, the effects loop works fine. I'd never tried that and it's a nice discovery. So, basically: if I want to use the effects loop and like reverb, I need to use a reverb pedal on my IIB. I don't know that it's any noisier than any other effects loop...but it's nice to know that it's there. I don't know, though...I've been putting the effects through the front for so long that I'll probably just keep doing that.

3) I spoke with Mike B about how the mod changes the tone of the Lead channel on the IIB and you're right: he said that it gives it a smoother, more modern tone. A "poor man's C+". In fact, I've heard some say that the 60/100w version comes very close to a C+, but I wouldn't know about that. Once again: I'd really like to hear it for myself before changing anything. Also: there's a "raw" quality to the Lead on my IIB which I like. I'm not sure I'd want to change it. I can get some fantastic modern tones with my pedals...but haven't found a pedal that can do the IIB tones.

4) Both the IIA and IIB are known for their clean tones. I know that I'd never have held onto mine this long if not for that. It wasn't until the IIC/C+ and III series that they really started to get into the higher gain stuff. What you're saying about the difference in clean tones between the IIB and IIA is exactly what I don't want to happen. There's a depth and warmth to my amp's clean channel that I would really miss if I lost it with a mod.

And that's what's up in BoogieLand, NYC. Too bad we can't get together and compare/play, dude. But this is nice, too.
 
Hi gitapik - thanks for your useful (and honest) information here +++

About the hum on MKIIA/B, I suggest you to have a look to my topic : Boogie MKIIA Rev Eq 60/100W , located on page 2 of the Mark Series subject. Otherwise, here is the link :

http://forum.grailtone.com/viewtopic.php?f=27&t=54614

But stay wise if you're a beginner :wink:

Beside that, reading your last post explanations draw me to think that you should simply discard the FX Loop Mod idea : you would certainly be disappointed... You'd better stay with your MKIIB "As Is", IMHO. It is no coincidence that I decided to remove the FX Loop Mod from my MKIIB to install a very simple AND QUIET circuit of my own instead, moreover preserving the original tonal qualities of the amp as best as possible.

A+!
 
Well, I think Australia is a nice eqi-distant destination between you two..

And so it's only fitting that I offer my place for U guys to get together and compare notes.

Naturally, we'd be forced to drink beer and tell lies, but that's the price of the pursuit of tone..

I'll leave the porch light on...

Dave
 
A very tempting idea, some boogie talk with a couple of cold beers, a couple of old guitars and MK II amps on a nice australian porch...
hope they invent teleportation quite soon, that would help :wink:
Thomas
 
One of my goals in life is to visit the Great Barrier Reef. I have some friends from Down Under and just sold my MusicMan Silhouette to a bloke in Bathurst.

I'm really looking forward to converting my combo to a head. Got a nice Thiele and plan on getting an open back cab next.
 
gitapik said:
One of my goals in life is to visit the Great Barrier Reef. I have some friends from Down Under and just sold my MusicMan Silhouette to a bloke in Bathurst.
Sounds good. My uncle lives in Perth and I never visited him, so that's also on my list.
gitapik said:
I'm really looking forward to converting my combo to a head. Got a nice Thiele and plan on getting an open back cab next.
I have a Thiele myself with a MK IIB combo. But I like the sound of the combo with it's open back plus the Thiele much more than the Thiele alone. For my taste it sounds more open and roomfilling if there is one open back speaker. The closed Thiele alone lacks a bit treble for my ears.

on the other side the big advantage of a cab plus a top is the transport issue. The combo is really heavy!
 
TiPiMods said:
gitapik said:
I'm really looking forward to converting my combo to a head. Got a nice Thiele and plan on getting an open back cab next.
I have a Thiele myself with a MK IIB combo. But I like the sound of the combo with it's open back plus the Thiele much more than the Thiele alone. For my taste it sounds more open and roomfilling if there is one open back speaker. The closed Thiele alone lacks a bit treble for my ears.

on the other side the big advantage of a cab plus a top is the transport issue. The combo is really heavy!
the weight is the issue. Not that I CAN'T...more that I don't WANT to carry it. I agree that the open and closed back, together,are optimal. But I like both separately, too. I'd actually love
a 4x10...but that's the weight factor all over again.
 
Gitapik/USA > Mark2boogie/France > TiPiMods/Austria > McBarry/Australia... Yes, good idea.

Is there enough room in your garden for my spaceship to land, guys ?

435949empiredesmillesplanetes1.jpg


The Thiele cab gives much more bass than the combo. In retrospect, an open cab would have been my preference...
The weight issue is less critical to me since I have always young tough volunteers on hand to carry the flycase of my combo...

A+!
 
Exit the MESA Factory FX Loop Mod...

Here's what will probably be my Custom FX Loop Mod, when I'll have the time to continue that job :

1 - the Send/Return jack of the amp will be simply re-inserted in the signal path just before the phase splitter stage, and I'll return the rest of the circuit close to the original MKIIA schematic.

2 - to match the signal level correctly, I'll built a LOOP BOX to be connected there :

679546LOOPBOX02082012.jpg


3 - when I will not need the FX Loop facility, I'll connect nothing to the S/R jacks of the amp itself... having then the simplest and the shortest signal path with de facto the best Signal-To-Noise ratio possible.

Wait and See...

A+!
 
mark2boogie said:
Gitapik/USA > Mark2boogie/France > TiPiMods/Austria > McBarry/Australia... Yes, good idea.

Is there enough room in your garden for my spaceship to land, guys ?

435949empiredesmillesplanetes1.jpg


The Thiele cab gives much more bass than the combo. In retrospect, an open cab would have been my preference...
The weight issue is less critical to me since I have always young tough volunteers on hand to carry the flycase of my combo...

A+!
Every home I've ever lived in has come equipped with a spaceport...

I like the tightness of the bass in my Thiele and have found some nice ways to compensate for the loss of the highs through changing my settings.

I do plan on getting either an open back or convertible cab, though. Anybody have any recommendations...?
 
@ mark2boogie: yes, great idea, you could call it the "Brunolater" :wink:
Some time ago I thought about buying one of this "Dumbleater" kind of thing. I think somebody in this forum wrote about the one from Ceriatone. But the longer I play (and the older I get, haha) the more I like the pure sound of an amp with maybe some pedals in front and a little reverb. In the 90ties I had this huge rack with a drawer for all the pedals, a 19" looper and the 19" delays and reverbs with a Bradshaw switching so you could have a different reverb and delay for each amp channel...sounded great, but a lot to carry, a lot of cables and a lot of things which could go wrong. Now I have a small case with some pedals and take whatever amp I need for the venue and thats it.

@gitapik: I had once a boogie 1x12 open cab with an EV12, which sounded great, I sold it, cause I didnt have a boogie at that time and I rarely used it with other amps. As I remember the size was like the thiele, so you can staple it and it looks good.
I think, this must be a gorgeous sounding solution: the MK II head with one open back and one Thiele.
 
TiPiMods said:
@ mark2boogie: yes, great idea, you could call it the "Brunolater" :wink:
Some time ago I thought about buying one of this "Dumbleater" kind of thing. I think somebody in this forum wrote about the one from Ceriatone. But the longer I play (and the older I get, haha) the more I like the pure sound of an amp with maybe some pedals in front and a little reverb. In the 90ties I had this huge rack with a drawer for all the pedals, a 19" looper and the 19" delays and reverbs with a Bradshaw switching so you could have a different reverb and delay for each amp channel...sounded great, but a lot to carry, a lot of cables and a lot of things which could go wrong. Now I have a small case with some pedals and take whatever amp I need for the venue and thats it.

@gitapik: I had once a boogie 1x12 open cab with an EV12, which sounded great, I sold it, cause I didnt have a boogie at that time and I rarely used it with other amps. As I remember the size was like the thiele, so you can staple it and it looks good.
I think, this must be a gorgeous sounding solution: the MK II head with one open back and one Thiele.
I usually bring both the Thiele and the combo to shows. It's a noticeable improvement over the combo (on it's own) when playing at low to mid volume. But when you crank it, the combo's a monster on it's own. In either channel, though you really don't need the Lead channel in those situations.

I used to have a lot of outboard stuff, too. I'd sit the Boogie on a rack in a very durable anvil case, connect that to the floor pedals, etc. It was fun. Great sounds but a pain to lug around and, as you said: lots of things could go wrong.

I almost sold the Boogie, recently, in my search for a lighter, great amp. What I ended up discovering was that, at 3x the price that I could get for the Mark IIB and Thiele (I got bites for $1000), I wasn't getting any better of an amp in the clean tones. And with the ones with strong cleans and an OD that I liked more than mine, the weight was the same. Seeing as I started the whole search because I wanted a lighter amp...

But I have to say that I did (and still do) like the Port City Pearl as a pure, clean sound. I considered selling the Boogie and getting that when, once again, I realized that the sound was great, but no better than the IIB...and that I like the option of bringing the IIB, with only a compressor, to sessions. Just the amp's pedals. I can't do that with the Pearl. That's when I decided to convert the combo to a head.

Thanks for the tip on the Boogie open back cab, TiPiMods. Here's a shot of my current board. It's nice and compact and packs a wallop. The compressor was modded by Mark Humphrey. I like it a lot, but am considering swapping it for a Wampler Ego for the Blend function. I once a/b'd them and found that was the only thing lacking on the Boss unit, with the mod.

IMG_1127.jpg


IMG_1128.jpg


I love the sounds I can get off this board. I've got an even smaller one that I put into an old Boss case (BCB-6?) for the real on the fly stuff...but this is nice for gigs if I want a lot of options.

I miss flanger and phaser stuff, and consider getting a tc electronic Nova Mod, but I really love the Boss CE-2. It was my first effect pedal and there's a reason I've still got it.

It would be nice to have a Timmy on there, too...but that's another reason I'm holding onto the Boogie. It does the light breakup really, really well. I think that's why a lot of people are turned off by the stock IIB. The Lead Channel isn't thick and creamy. But for the more transparent stuff, it kicks arse!
 
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