NAD- Mesa Mark IIB Coliseum, Loop Modded insanity!

GJgo

Well-known member
Hey guys,

Thanks to a hot tip a couple months ago by Racerxrated I (we both, really) scored a SUPER clean 15" Coli combo from the collection that sold out of L.A.. Of course the call came 2 days before I left on a 2 week vacation to HI so the timing was poor, but when you gotta buy an amp you gotta buy an amp! I've had pretty much all Mark amps but a Coli and V, so I had to jump on this one. Once I got it I sent it in to Mike B. for a full service and decided to take a leap of faith on his loop mod.

I just did a tone vid, check it out. https://youtu.be/A-ATYsY8IMc

First impressions- 540 plate volts is AWESOME. Playing notes, it makes it feel like my picking is spring loaded. I fully expect to smoke the STR440s that came with it.

It is sensitive to preamp tubes for sure. I've rolled a couple types of Russian, some Chinese, JJ and also a Tunsgram. The right combination makes a big difference. When Mike modded it, the 12AT7 preamp slots all turned into 12AX7 slots.

The gain, once I figured some things out, I'd say is between the C+ and the C++, and closer to the latter. The character of the gain isn't quite as smooth as a C+ but most guys would never know the difference unless you were A/B-ing them. I actually have to be careful with the various masters now if I want a sparkly clean tone as it starts to break up much earlier than when the amp was stock. TBH the stock cleans were amazing so that's a bit of a bummer, but there should be so much headroom in its 200 watts that it won't be an issue.

A few years ago I had a guy come over with a IIB & a IIB loop mod. At the time I had IIC+s and IIIs. Everyone online always talks about "what's the closest thing to a IIC+ since I can't afford one?". The internet seems to think it's a III, specifically red stripe which I've had. Don't get me wrong it's a great amp, and close, but the IIIs are a little more raw & aggressive than a IIC+ because that's what the hair metal bands at the time were looking for. C+s are smooooth, and a lot of the gain is in your fingers because they are so touch sensitive. My opinion has always been that the closest thing to a IIC+ in terms of feel & character was a loop modded IIB, and this amp isn't changing my mind.

Every one of these old Mesa amps I've picked up I've sent back to the mothership to have Mike refurbish them. Beyond needing a cap job, they have all had problems- even this one which was in as close to showroom condition as they come. They're ~30 year old amps! Thus, all of my comparisons have been done from a level playing field. When you just go pick one of these older amps up and try to make some comparisons odds are that the amp has some issues & you're not hearing its full potential, so be cautious.

This is the first Mark amp I've played that legitimately has the balls to keep up with the hugeness of my Rectos. Big, tight bottom end. Now, it is a different character than the Recto but still awesome. They definitely sit in a different spot in the mix.

I've always thought that the IIB was a better classic rock amp than the IIC+ in terms of the medium gain tone structure, and this amp isn't changing my mind. So, with the loop mod we have an amp that:
- Has huge, sweet clean headroom.
- Has a killer classic rock tone.
- Has a high gain tone that's DAMN close to my C++. There is much metal inside.
- Has the sweet Mark II character as opposed to how the III and IV got a little more aggressive & harsh.
- Is so loud that it can kill your neighbor's cat.
- Has the Limit board so it can easily be run, sounding good, at bedroom levels.

WHAT IS THIS?!?!?!?!

The one place I will give the nod to the C+ is that the gain structure is more complex and lead tone is smoother, which is part of why they are what they are. The other reason, of course, is MoP.
 
I have serious doubts. I know Mike and not just over the phone. He's personally spoke to this and no way did the words he use about the loop mod put that amp in C+ territory, and it's a far cry from ++ status. A C+ board as you know has way more gain than the RP9A preamp board. The loop mod helps but never will attain C+ type gain. The C+ with a ++ mod is 20db more on top of that...I'm sure your amp is nice and I know it's ultra clean. I know the deal that went down and was aware of it to the point that I was part of it. Dave has the same amp and has plans to add the loop mod but that's the extent of what can be done to that amp internally but externally...a clean boost will make that amp burn like no other brother.
 
Exo- did you watch the video? All amp. No boost. Possibly all the voltage from the Coli power section makes a difference?

I've had a C, two C+ and two C++s. (HRG / DRG) All Mike modded. When I asked him about doing the loop mod to this amp I got the impression that the gain would end up somewhere between the C and the C+. Imagine my surprise when that was not the case- at first I was actually a little put off by how much it dirtied up the cleans.

For my metal settings I'm running the lead drive at 4 on my C++ and on this IIB. (The C++ Volume 1 does run hotter, though.) On both of my old C+s I ran the gain at 6-7 and never felt it was quite enough for metal.
 
exo-metal":2upbhjqq said:
I have serious doubts. I know Mike and not just over the phone. He's personally spoke to this and no way did the words he use about the loop mod put that amp in C+ territory, and it's a far cry from ++ status. A C+ board as you know has way more gain than the RP9A preamp board. The loop mod helps but never will attain C+ type gain. The C+ with a ++ mod is 20db more on top of that...I'm sure your amp is nice and I know it's ultra clean. I know the deal that went down and was aware of it to the point that I was part of it. Dave has the same amp and has plans to add the loop mod but that's the extent of what can be done to that amp internally but externally...a clean boost will make that amp burn like no other brother.
The one thing I will say is that both of these Coliseums have the RP9C board, not the A or B. My Coli is going to go in and become a true C+ very soon, as I have acquired a 2C for a good price. But this 2B Coli that I have is WAY different than the previous 2B Coliseums I owned, which were very loose on the bottom even with a boost. The second 2B Coli I sent in for the loop mod, and it definitely had C+ gain and maybe a bit more. But the feel is not there like a C+.
The Coli I have now is the RP9C and is as tight as a frogs ass with no boost needed. Almost like a Mk III tight and the gain is very near a C+. So Jeremys amp after the mod would be quite different than a standard 2B Coli with the previous board revisions, as I can attest to the difference myself. No, it's not a 2C+ but it's very different than the previous pre board. Almost like a bridge to the RP10 as they are more similar to that than they are different.
 
I don't know jack about these early mark series mesa amps,but threads like this rule. You guys that know so much about them,and can articulate both knowledge and amp "feel" and such make it worth my wifi bill. Thanks to all three of you for this post. I love learning stuff like this.
 
I spent some quality earplug time today with the Coli & my Rev G Triple Recto, playing, and slaving. Both amps have a huge bottom end, but they sit in a different place so not really comparable. That said, the Coli is definitely the bigger power section. The amount of volume & force it has is insane.

The Recto slaving into the Coli didn't sound as good with the native power section when the Coli's GEQ (post-loop) was off. When it was on it sounded really good, but the traditional V makes it disappear in the mix. This could be tweaked of course.

The IIB slaving into the Recto power section also didn't sound as good as with the native power section, in part because it loses the GEQ.
 
With that type of plate voltage, I strongly suggest getting a set if Ruby EL34BHT. They are the only current production tube that can consistently take that abuse. As for the tone, the high plate voltage give more headroom
 
Well, this is a 6L6 amp so..

I've spoken to Mike B. about this. For new production he advises the TAD 6L6GC-STR which is rated to 550v. I have them in my IIC++ with the 105 PT running 505 PV.
 
Jeremy, if you want the beast u need a C+ preamp from one of your other amps as a donor. I know it is a total mind fuck but hey in the end nothing can touch it.
 
GJgo":6zrcivaa said:
Well, this is a 6L6 amp so..

I've spoken to Mike B. about this. For new production he advises the TAD 6L6GC-STR which is rated to 550v. I have them in my IIC++ with the 105 PT running 505 PV.
I had this same conversation with Mike a few weeks back, and in addition to the TAD I asked him about the Sovtek Wafer 5881s and he agreed that they also are a tube to consider as they will take the plate voltage as well.
 
GJgo":2t104mss said:
I spent some quality earplug time today with the Coli & my Rev G Triple Recto, playing, and slaving. Both amps have a huge bottom end, but they sit in a different place so not really comparable. That said, the Coli is definitely the bigger power section. The amount of volume & force it has is insane.

The Recto slaving into the Coli didn't sound as good with the native power section when the Coli's GEQ (post-loop) was off. When it was on it sounded really good, but the traditional V makes it disappear in the mix. This could be tweaked of course.

The IIB slaving into the Recto power section also didn't sound as good as with the native power section, in part because it loses the GEQ.
But....
Please tell me you've slaved your C+s to the Coli....that experience for me is the main reason I'm going through the expense of the C+ Coli. It was mind blowing.
 
I've sold all of my C+ except for my factory DRG that Mike ++d, and it's in a remote location at the moment. I'll get it back & slave to the Coli in due time. :)

Racer, I would love to A/B mine vs. yours when it's done. :) I will agree that this KRG has something special in the bottom end that none of my HRG / DRG have had.
 
For the last ten years I've watched people buy Mesa amps and try to "upgrade"or mod them to get them to sound like original IIC+ amps. I am talking fully loaded long heads. Never seen one that came out better than an original or should I say "heard". Not boasting as I have clips of my IIC+ on my Youtube to back up my statement.
 
EXPcustom":1ma42v8t said:
For the last ten years I've watched people buy Mesa amps and try to "upgrade"or mod them to get them to sound like original IIC+ amps. I am talking fully loaded long heads. Never seen one that came out better than an original or should I say "heard". Not boasting as I have clips of my IIC+ on my Youtube to back up my statement.
With all due respect, and I do respect your opinion, how many have you heard? And I mean in person, not just some clip that may or may not suck. I've heard clips of amps that suck complete ass and sound like a transistor radio version of the amp. I talked with Mike B for 45 minutes not long ago and he laughs and laughs at the original vs upgrade BS as he calls it, those aren't my words. I did have an original and I compared it to my upgrade and off went the original as my newly upgraded sounded better. I think your amp sounds great through your clips...but the proper comparo would be your original long head to an upgraded short head DRG with the 105. In the room. Jeremy is stating that the CLOSEST amp to a real C+ is his loop modded 2B Coli. He isn't saying that it's an exact match, just the closest. In his opinion.
On another note, I did see your post on the Boogie Board on the rarest of the rare...the export Coli? All Coliseums CAN be run in Europe, they just have to be re wired that way. There are no export Coli transformers. And my soon to be upgraded Coliseum IS one of the rarest, as it is a fully loaded 1X15 combo which someone suggested is probably the rarest Boogie out there because of the configuration. I can ask Mike to make it Simul as all the Coli simuls are hard wired that way, not switchable like the regular DRGs. But you lose power (150 vs 180w) and I liked my Mark IIIs with all 6L6 anyway.
 
Racer- our Colis with the pentode / triode switch I think in this case is more valuable than making it Simul, and I LOVE my DRGs. Also, I'm pretty sure these are the Sovteks he speaks of. Reading the description they might be nice in the IIB. I'll keep my TADs in the IIC++, though.
https://store.mesaboogie.com/products/power-tubes-5881-str-425-matched-pair.html

Let me be clear- I've owned or played most Mark amps at this point, and for any tone where rock or metal gain is involved, there is not better tone & feel than my IIC++ DRG RP11 105. Especially for leads. There are a few tricks that it absolutely does best, and you're paying north of $4K to get there. I don't care about original vs. upgrade so long as Mike does the service work but I do care about the preamp board & PT. However, my opinion at this time is that this loop modded IIB is the best OVERALL Mark I've played per my reasons above, all for under $2K. The one caveat here would be if this was purely a gigging amp- in that case I think I'd have to lean towards a V for the pure versatility.

Let me also clarify- in terms of recorded tone, I think the closest to a real C+ is actually the JP2C. It has limitations though. In terms of tone in the room & feel under your fingers, closest to a C+ this loop modded B. That doesn't come through on the mic. Recording is not my strong point, however I try to capture my frame of reference here..
https://www.youtube.com/user/fast13b/videos

Mark IIIs and IVs are in the same price point but they are not as smooth as the IIs. They do have a third channel that's decent in the III and kind of sucks on the IV. The III has a harshness that's hard to dial out- I've had 3 of them & they all gave me ear fatigue. That said the IIIs do record very well, their raw aggression really comes through. The IV is hard to dial in even for a Mark and to me had a very narrow sweet spot, and still a hint of ear fatigue.

The V and JP are fantastic gigging amps but lack the rawness & 3 dimensionality of the older amps. The JP is a 2 trick pony- uber clean pedal platform and really high gain. The V can cover a ton of ground but it doesn't have the same feel under your fingers as the older Marks.

To be honest after Racer prodded me about getting an old Rev G Triple Recto which led to me getting a MW Dual Recto my Marks have been sitting. I sold all of them but my DRG++, and it's collecting dust. In my band mix (metal) the Rectos wipe the floor with the Marks. (flame suit on...) I do look forward to our next rehearsal with this IIB though just because the tone is so incredibly thick.
 
EXP your wet dry rig sounds great. I'm not very good at recording what I hear in the room, but I do try to record gear as-is so a guy can hear what to expect out of the box as opposed to heavily massaged. I at least try to be internally consistent. :)
 
Sounds cool. Here's my issue with the idea of modifying a IIB to get it closer to a IIC+ tone... the reduced filtering of the power section. The IIB (all IIB series amps and earlier) only have 2 220uf/300V filter caps for the power section... not 4 caps... which is why the IIB series amps and earlier sound softer, mushier, saggier, and flabbier. This is why Mesa went with separate power filter printed circuit boards in the Mark IIC and later amps, which all have 4 220uf/300V (2 on top and 2 more on the bottom)... and they definitely sound tighter because of it. Ask Mike B. he will tell you the same. I'm sure the 150W Coli PT/OT set add a certain something, and maybe a little extra oomph... but it's not going to be as tight as a IIC+, III, and definitely softer, saggier than an original IIC+ Coli or III Coli... no way. The feel and response alone. There is only 50% of the power section filtering present. Not even taking in to account the differences in the preamp section. I own multiples of these amps, both original and modified, so I am also very familiar with them.

And as for any long chassis Mark IIC+ sounding better than a short chassis version... applesauce. Extra chunky applesauce. Nuff said there.
 
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