Coliseum Mark II C/C+ production number research

[Elpelotero]

Got a call back. They said there were no simul-class IIC+ coliseums ever made.
This one was made by MB in October 1984. (date 10/84 and initials hand written on chassis)
There is a plus above the power cord and the same initials on the back just above the power supply.

That's very interesting research! For a C+ nerd, at least. This debunks what Hetfield has said in interviews where he mentions he used a Simul Coliseum to record Metallica in the 80s

 

[AL-X]

Yeah I was kind of surprised to hear that also. I think he might have meant IIC/C+ coliseums and not mark III. I guess the question is does anyone have a Mark II C/C+ Coliseum that is simulclass?

 

[zachman]

Yeah I was kind of surprised to hear that also. I think he might have meant IIC/C+ coliseums and not mark III. I guess the question is does anyone have a Mark II C/C+ Coliseum that is simulclass?

There was a IIC+, and a MKII Coliseum, but not a MKIIC+ Coliseum Simul-Class, if I recall correctly. Hetfield used a MKIIC+ Simul-Class head, not a IIC+ Coli

 

[gts]

This is worth repeating:

With all things Boogie back when the Coli's were being made and in their early days as a whole (the first 10+ years) nothing was normal.
If I remember correctly the serial number was stamped onto the chassis early in the process.
If say for some reason the buyer bailed out that stamped chassis would be used for whatever amp was next on the production line.
According to Mike B. there are likely 40-50 five digit serial numbered IIC/C+ Coli's out there.
He also estimates there are 40-50 five digit serial numbered MKIII Colis' out there too.
So while my 5 digit IIC Coli is not common, it's likely not alone.

Ian's website gathered much of (if not all) it's serial info from another Mesa users website (pretty sure that website is now gone).
Here's another Coli serial number anomaly.
On Ian's website it states the MKIII Coli numbers are from K423 to K500.
But I have seen a Mark III Coli with the serial number K535!

Mesa anomalies while not the norm have been seen more than a few times.

Fwiw Mesa wasted/ threw out nothing. So you'll see IIC faceplates on some IIC+'s
But perhaps even more odd we've seen a IIC+ faceplate on a IIC!

We've also seen four or so IIC+'s with serial numbers below 12500. I personally know of 12,399, 12400 and couple with 123xx numbers.
And I'm pretty sure no one has see a IIC+ serial number above 14400 (except Ian's which is 15000)

In any case back to the IIC/ IIC+ Coli's and production number research.
Coli's don't pop up too often so trying to track down each and every one could take a lifetime. And even then all may not be found.
Mesa didn't keep great records back then. Even they don't even know the exact numbers and/ or to whom they sold each amp.
Pretty sure they didn't start keeping decent records until around '90-'91.

But keep looking it would be fun to find them all (that's kind of why I started that other poll / thread on the Coli's.)

 

[JimmyB]

We've also seen four or so IIC+'s with serial numbers below 12500. I personally know of 12,399, 12400 and couple with 123xx numbers.

The lowest IIc+ s/n I've seen is 12376... I'm looking at it right now. And, nope, it's definitely not a Coli!

 

[fretout]

On Ian's website it states the MKIII Coli numbers are from K423 to K500.
But I have seen a Mark III Coli with the serial number 535!

Hey Boogie Brothers! I'm not sure if this would be of any help for you guys, but I was recently sold a Coliseum serial numbered K533. This Coliseum was sold to me as a Mark IIC+ Coliseum (fully-loaded with GEQ and Reverb), but based on the circuit boards inside the amp, this appears to be a Mark III No Stripe Coliseum. It's so new to me, I still haven't identified if this Coli will run simul-class, but it has the same transformers and choke as my 5-digit Blue Stripe Coliseum.

I haven't seen many no-stripe Mark III Colis, so if you wanted to "bookend" the Mark IIC+ Coli serial numbers, this could be one...

On a side note, thanks for everyone contributing in this thread so far. I think we need more threads that record the genealogy of Mark series, and I think it would be great to update the first post of this thread with the facts and findings this thread uncovers. Maybe we could contribute some photographic evidence of anything from boards and caps, to the stock preamp and power amp tubes these great amps came with...

 

[zachman]

On Ian's website it states the MKIII Coli numbers are from K423 to K500.
But I have seen a Mark III Coli with the serial number 535!

Hey Boogie Brothers! I'm not sure if this would be of any help for you guys, but I was recently sold a Coliseum serial numbered K533. This Coliseum was sold to me as a Mark IIC+ Coliseum (fully-loaded with GEQ and Reverb), but based on the circuit boards inside the amp, this appears to be a Mark III No Stripe Coliseum. It's so new to me, I still haven't identified if this Coli will run simul-class, but it has the same transformers and choke as my 5-digit Blue Stripe Coliseum.

I haven't seen many no-stripe Mark III Colis, so if you wanted to "bookend" the Mark IIC+ Coli serial numbers, this could be one...

On a side note, thanks for everyone contributing in this thread so far. I think we need more threads that record the genealogy of Mark series, and I think it would be great to update the first post of this thread with the facts and findings this thread uncovers. Maybe we could contribute some photographic evidence of anything from boards and caps, to the stock preamp and power amp tubes these great amps came with...

Mine is S/N# K513 No stripe MKIII Coliseum Simul-Class. Simul-Class was an option, and on the MKIII Coli is always in that mode of operation. There is no Simul-Class/Class A switch like on the normal MKIII.

 

[gts]

Mine is S/N# K513 No stripe MKIII Coliseum Simul-Class. Simul-Class was an option, and on the MKIII Coli is always in that mode of operation. There is no Simul-Class/Class A switch like on the normal MKIII.

By "Normal" do you mean like on a short head or short Chassis?

Fwiw Long heads/ widebody chassis (regardless of they are a Coli or not) typically do not have a switch labelled Simul" as well.
They have a "1/2 power" switch which is well documented as a "mis-labeling".
These "1/2 power" switches on long heads were for switching between "Simul/Class A" or "60/100 watts" depending on the amp in question.
The only way to know which it is doing is to look and find out which Output Transformer is on the amp in question.

But then again what I think you are saying is what Scott posted awhile back in this thread (and quoted below).

Hey
Learned something new from Mike B.

He said that the simul coliseum has about 120 watts full power and about 80 watts on half power. In either configuration all 6 output tubes are used. To drop the power, another screen resistor kicks in to drop the plate voltage by about 50 volts thus reducing the output power. I could never imagine they would only use the class A tubes in half power, it just seemed like too big a drop in power. That also means it always running simul and never in class A.
Interesting

Scott

This is what is done to drop the output wattage but the Coili never stops to use all six power tubes.
Unlike non-Colis which stop using the 6L6 sockets when in "Class-A" mode (or in "1/2" power" on Long heads/ Widebody amps).

 

[zachman]

Mine is S/N# K513 No stripe MKIII Coliseum Simul-Class. Simul-Class was an option, and on the MKIII Coli is always in that mode of operation. There is no Simul-Class/Class A switch like on the normal MKIII.

By "Normal" do you mean like on a short head or short Chassis?

Fwiw Long heads/ widebody chassis (regardless of they are a Coli or not) typically do not have a switch labelled Simul" as well.
They have a "1/2 power" switch which is well documented as a "mis-labeling".
These "1/2 power" switches on long heads were for switching between "Simul/Class A" or "60/100 watts" depending on the amp in question.
The only way to know which it is doing is to look and find out which Output Transformer is on the amp in question.

But then again what I think you are saying is what Scott posted awhile back in this thread (and quoted below).

By 'Normal', I meant 75 watts in Simul-Class mode operation, and 12 Watts in Class A operation, as opposed to the much more powerful Coliseum.

The Coliseum was only available as a long chassis and does not have a Simul-Class/Class A switch like a ' normal' MK w/ the Simul-Class option.

 

[gts]

By 'Normal', I meant 75 watts in Simul-Class mode operation, and 12 Watts in Class A operation, as opposed to the much more powerful Coliseum

Got ya ;-)
Fwiw Class-A on a "Normal" Simul is is 15 watts

 

[zachman]

By 'Normal', I meant 75 watts in Simul-Class mode operation, and 12 Watts in Class A operation, as opposed to the much more powerful Coliseum

Got ya ;-)
Fwiw Class-A on a "Normal" Simul is is 15 watts

Oops, my bad. Too early in the morning. lol Thanks for the correction. :wink:

 

[kippiejr]

There are C+ Coli Simulclass. I have two. One factory and one was a C>C+ upgrade.

 

[gts]

There are C+ Coli Simulclass. I have two. One factory and one was a C>C+ upgrade.

A C+ Coli?!? This is news to me and all here.

Post pics, gut shots etc.

 

[Elpelotero]

There are C+ Coli Simulclass. I have two. One factory and one was a C>C+ upgrade.

A C+ Coli?!? This is news to me and all here.

Post pics, gut shots etc.

Yes, please! The output transformer is the way to know!

 

[Boogiebabies]

I've seen one Coli C+ Simul. It's in Switzerland. Four 6L6 outer sockets and 2 EL34 inner sockets.
Long head in Imbuya.

 

[kippiejr]

GTS I have tried to post via bucket and it did not work so I gave up trying but email me and I will sent the pics. But I am not dragging that beast to the bench. Its not as simple as a short head. Have you seen the tranny on these things. And for the record the output tranny tells nothing. They do not have a simulclass tranny. They are not like a traditional simuclass amp in many ways. All tubes are always on even in 1/2 power. You can not isso the EL34's, therefore no need for simulclass tranny, the are hard wired off the production tranny.

 

[dodger916]

Is it possible these are post-factory modded Simul Coli's?

 

[SpongeRob]

From my Records....

Simul IIC+ Coliseum OT: 0160 322 EIA 606-401
IIC+ Coliseum OT: 0180 322 EIA 606-806

But from the IIC+ Guide for Dummies

Pricing September 1984

THE COLISEUM SERIES 300

Coliseum Series 300, 180 Watts, 6 Power Tubes, Half Power Switch,
Vinyl Cabinet, 23” Wide only (specify Black or Cream) & Slip Cover,
(Can be wired for 117 or 230 volt operation.)

Mark II-C Type Series 300 Amplifer Head, includes Footswitch… $ 1000
Reverb ………………………………………………………………$ 150
Graphic Equalizer …………………………………………………..$ 150

Cabinet Options Each Extra

Hardwood Cabinet with Wicker Grille ……………………………..$ 155
Hardshell Road Case without wheels, Black……………………….. $ 130

There is not Simu Class Option listed. Maybe a custom Order back in the days.....

 

[gts]

I've seen one Coli C+ Simul. It's in Switzerland. Four 6L6 outer sockets and 2 EL34 inner sockets.
Long head in Imbuya.

I stand corrected.
Is it Roberts?
Not to discount kippiejr stating he has two but this is the first IIC+ Simul Coli I've heard of....

 

[gts]

GTS I have tried to post via bucket and it did not work so I gave up trying but email me and I will sent the pics. But I am not dragging that beast to the bench. Its not as simple as a short head. Have you seen the tranny on these things. And for the record the output tranny tells nothing. They do not have a simulclass tranny. They are not like a traditional simuclass amp in many ways. All tubes are always on even in 1/2 power. You can not isso the EL34's, therefore no need for simulclass tranny, the are hard wired off the production tranny.

Yes I know how they work all six power tubes being in use all the time.
Not sure about how the OT could not be a Simul and allow the EL34's to be used along with 6L6's.
Ed you know more about this than I do. Is running El34's and 6L6's together possible without a Simul OT?
Then again Spongerob's records indicate there was/ is a Simul OT for the IIC/IIC+ Coli....
Now I'm starting to feel a bit confused.

But yeah kippiejr the 1/2 power switch drops the PT voltage and thus the wattage/ output so the Simul Colis never real go to just using the two EL34's.