How do i identify a 105 transformer in my Mark III?

[rgx612a]

I have a red stripe Mark III simulclass, from '87. I have heard that a few amps from this time have the Mark iiC+ transformer, but how do i figure this out? and which transformer am i looking at, the one on the left side of the amp, or right??

 

[Buster Leggs]

I have a red stripe Mark III simulclass, from '87. I have heard that a few amps from this time have the Mark iiC+ transformer, but how do i figure this out? and which transformer am i looking at, the one on the left side of the amp, or right??

M/B is known for being a frugal company. They had a some C+ power transformers left over at the start of the Mark lll production and a hand full of the earliest lll's got a C+ trans. On occasion one would show up on a Mark lll randomly after the initial few hundred (or what ever the quantity was) of the leftover C+ transformers were seemingly gone. A red stripe is too far into mark lll production it's not going to have a C+ trans unless someone replaced the Mark lll power transformer with a C+ trans. Unless you have some reason to think the PT was replaced, it's not worth even taking the chassis out to look. From the back it would be on the left side and have the numbers 105-162318 stamped on the bottom. A 105 transformer measures 3 1/2 inches from where it attaches to the chassis, to the very bottom - the cap the numbers are stamped on. The mark lll trans is about an inch shorter ( I'm guessing I no longer have a Mark lll ). If this doesn't clear it up for you snap a photo and post it and I'm sure someone here will clarify what ya got.

 

[megavoice]

What sound-influences would a C+ transformer have on a redstripe ???

 

[fretout]

I believe the OT trans is what you are trying to identify, and it will be the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located.

As far as what the difference in sound will be like, it's not really a "sound" difference as much as it's a "feel" difference. Mark III OT Trannys are still pretty desirable (ask anyone that owns a 2 channel Rectifier). You can get the Mark III to scope EXACTLY like the Mark IIC+, but there is a difference, and that difference is in the responsiveness or the "feel" of amp. Most of the talk revolving around OT Trannys is in regard to the "bass response" or the "depth of the low end". I find my standard Mark III is just fine in this department.

There's always been a lot of debate around whether Mark IIIs, IVs, and Vs can compete with the "Gold Standard" Mark IIC+, so don't feel like you're alone. I personally love the Mark III for what it is, and after playing a Mark IIC+, I don't feel like I'm missing too much (at least right now). And, there has always been a part of me that wants quality sounding (and feeling) gear, but there's also a special feeling by getting a great tone out of something that costs a fraction of what others use. I guess that's the "punk rock" side of my personality...

I will say that the Coliseums have a different feel that is more touch-responsive than my normal, simul-class Mark III. It would be interesting to see what OT the Mark IIC+ Coliseums used to determine if the Mark III Coliseums used the same OT Transformer. Maybe that would explain the "feel" of this series more.

 

[megavoice]

I believe the OT trans is what you are trying to identify, and it will be the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located.

As far as what the difference in sound will be like, it's not really a "sound" difference as much as it's a "feel" difference. Mark III OT Trannys are still pretty desirable (ask anyone that owns a 2 channel Rectifier). You can get the Mark III to scope EXACTLY like the Mark IIC+, but there is a difference, and that difference is in the responsiveness or the "feel" of amp. Most of the talk revolving around OT Trannys is in regard to the "bass response" or the "depth of the low end". I find my standard Mark III is just fine in this department.

There's always been a lot of debate around whether Mark IIIs, IVs, and Vs can compete with the "Gold Standard" Mark IIC+, so don't feel like you're alone. I personally love the Mark III for what it is, and after playing a Mark IIC+, I don't feel like I'm missing too much (at least right now). And, there has always been a part of me that wants quality sounding (and feeling) gear, but there's also a special feeling by getting a great tone out of something that costs a fraction of what others use. I guess that's the "punk rock" side of my personality...

I will say that the Coliseums have a different feel that is more touch-responsive than my normal, simul-class Mark III. It would be interesting to see what OT the Mark IIC+ Coliseums used to determine if the Mark III Coliseums used the same OT Transformer. Maybe that would explain the "feel" of this series more.

Well,well,well...............very interresting...............
I'm also pretty happy about and kinda proud of, of the sounds of my reds after listening to the C+s on youtube.......
But my upper question derrives mostly from curiosity................

 

[Buster Leggs]

The original question was "how do I identify a 105 transformer in my mark lll. The 105 was the production power transformer in factory Mark ll C+'s. A hand full of Mark lll"s got leftover 105 power transformers. The PT (power transformer) on a C+ is the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located. The OT (output transformer) is next to the V1 preamp tube on the other side . It's been a little bit since I've owned a Mark lll but I'm pretty sure the transformers are in the same location as a C+. I don't know if any left over output transformers were put in the lll's , I've never thought about that. Seems they would have had some leftover C+ output transformers also unless they weren't compatible.

 

[fretout]

The original question was "how do I identify a 105 transformer in my mark lll. The 105 was the production power transformer in factory Mark ll C+'s. A hand full of Mark lll"s got leftover 105 power transformers. The PT (power transformer) on a C+ is the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located. The OT (output transformer) is next to the V1 preamp tube on the other side . It's been a little bit since I've owned a Mark lll but I'm pretty sure the transformers are in the same location as a C+. I don't know if any left over output transformers were put in the lll's , I've never thought about that. Seems they would have had some leftover C+ output transformers also unless they weren't compatible.

They had some leftover C+ output transformers, but they were delegated to early Mark IIIs, usually no stripes/black dot/black stripes. Once Mesa got into the purple stripes, I believe they were all gone.

The only way I could see a C+ tranny getting installed on a red stripe is if a previous owner decided to swap the Trannys, and I don't know any such instances.

 

[gts]

The original question was "how do I identify a 105 transformer in my mark lll. The 105 was the production power transformer in factory Mark ll C+'s. A hand full of Mark lll"s got leftover 105 power transformers. The PT (power transformer) on a C+ is the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located. The OT (output transformer) is next to the V1 preamp tube on the other side . It's been a little bit since I've owned a Mark lll but I'm pretty sure the transformers are in the same location as a C+. I don't know if any left over output transformers were put in the lll's , I've never thought about that. Seems they would have had some leftover C+ output transformers also unless they weren't compatible.

They had some leftover C+ output transformers, but they were delegated to early Mark IIIs, usually no stripes/black dot/black stripes. Once Mesa got into the purple stripes, I believe they were all gone.

The only way I could see a C+ tranny getting installed on a red stripe is if a previous owner decided to swap the Trannys, and I don't know any such instances.

Fwiw the Simul OT in a Simul Mark III has the exact same specs as the Simul OT in a Simul C+

Fretout, with all due respect you have it backwards.
The 105 PT used during C+ production was also used in some early MkIII's (not the OT's).

As BusterLeggs has pointed out Mesa was frugal and never wasted anything.
If a 105 PT was found in the back room later on during MkIII production, they'd use it/ put it in that amp.
So it's possible one could have been put in MkIII red stripe. Not all that probable but it is possible.

As far as how to identify a 105 PT:
The numbers stamped on the PT will literally start with the number "105"
The full number is "105-162318"
Here's a pic - not the best but you can see the "105" right under the word Mesa:

 

[fretout]

The original question was "how do I identify a 105 transformer in my mark lll. The 105 was the production power transformer in factory Mark ll C+'s. A hand full of Mark lll"s got leftover 105 power transformers. The PT (power transformer) on a C+ is the big block located on the underside of the chassis, underneath where the power cord and power cord plug are located. The OT (output transformer) is next to the V1 preamp tube on the other side . It's been a little bit since I've owned a Mark lll but I'm pretty sure the transformers are in the same location as a C+. I don't know if any left over output transformers were put in the lll's , I've never thought about that. Seems they would have had some leftover C+ output transformers also unless they weren't compatible.

They had some leftover C+ output transformers, but they were delegated to early Mark IIIs, usually no stripes/black dot/black stripes. Once Mesa got into the purple stripes, I believe they were all gone.

The only way I could see a C+ tranny getting installed on a red stripe is if a previous owner decided to swap the Trannys, and I don't know any such instances.

Fretout, with all due respect you have it backwards.
The 105 PT used during C+ production was also used in some early MkIII's (not the OT's).

As BusterLeggs has pointed out Mesa was frugal and never wasted anything.
If a 105 PT was found in the back room later on during MkIII production, they'd use it/ put it in that amp.
So it's possible one could have been put in MkIII red stripe. Not all that probable but it is possible

I meant PT, not OT. It was a pretty late when I posted and was trying to post and get to sleep. I won't edit my previous post, I'll leave it in all it's mistaken glory so that this thread makes sense. :lol:

Everything else I wrote regarding the 105 PT was as accurate as far as I know though. I 100% agree that if Mesa had a random 105 tranny left over they would use it (M/B themselves have stated this), but I'm almost certain that by the time the Red Stripes, the 105s would have been accounted for.

This is my rational: when the first red stripes were born, M/B at that point had moved about 6,000 units of the Mark III, so at that point, any leftovers would have been used up.

I agree with you, it could absolutely, definitely happen given Mesa's "frugality", but I have never seen a red stripe with a 105, and I believe the "leftovers" would have been used up on the earliest Mark III revisions. I can't say with certainty, because I don't work at Mesa, but I thought the 105s were used up during the "black stripe" series, and going from memory, I want to say that I saw a purple stripe with a 105, but are you aware of any occurrence of any red stripe that had a 105?

Sorry again to Buster Leggs and gts. I was describing the location of the PT, but mistakenly referred to the PT as an OT.

 

[Buster Leggs]

I figured as much when I saw the posting time. My intention was not to "call you out'. Initially I wasn't even going to comment but then thought, I don't want the OP to become confused.

 

[gts]

Here's a MUCH better pic:

(Fwiw this pic is taken from this thread where the seller has a MkIII with the 105 for sale.
http://www.grailtone.com/forum/viewtopic.php?f=9&t=59524 )