MK1

[fugazi]

HI all,

First off.....yep I'm a nOOb to this forum. So go easy on me guys.

I just recently got my paws on what I believe to be a blonde tolex, with cloth speaker cover, 1977 MK1 that could have possibly been modified during it's some 33 years of life. I received it yesterday. first thing I noticed....WOW is it heavy :shock: !! Second thing i noticed....certain areas had multiple layers of dust on them and it had that "old piece of electrical equipment smell" to it. I began with inspecting the whole thing. No obvious character flaws, so after it set for a couple hours, to make sure the tubes were up to room temp before powering it up. On went the power switch! Smooooth! Started off with input 2 just to see what kinda cleans I can get out of her. Warm, rich, creamy...yep, all of that. Aside from it being a vintage amp, I originally purchased cause I wanted that original Boogie clean tone (I do believe I'm well on my way to finding it). With the option to use input 1 for some gain. I'll probably stick with my Single Recto head through a 4X12 recto cab for the really heavy rhythm stuff that I so love. But who knows...maybe I'll find a voicing on the MK1 that I'll really like for those soulful yet heavy leads.

So gents, what do ya think? Did I get the real deal? On the bottom of the chassis (all in green Sharpie) are what I am assuming are Mr. Smiths initials and 7/77 along with several of the pre-amp tube inputs (there are 5) being marked either 12AX7 (2) 12AT7 (1) Unmarked (2). There is a concoction of pre-amp tubes in it. 3 Mesa 12AX7-A's, 1 Groove-Tube 12AT7 and 1 Groove-Tube 7025.



Pics of said amplifier are ready to roll........

See ya!

 

[fugazi]

No comments/suggestions? Did I register AND donate in error? :?

Maybe I wasn't thorough enough in my description of my (what I believe to be original) MKI. Or I didn't ask any legitimate question.

So here ya go:

I did some visual investigating and here's what I came up with.

The Power Transformer EIA # is 606702 with "MESA 60-162318" above the EIA #. Am I translating the EIA # correctly? The "606" is the manufacturer code (Woodward-Schumacher) and the 702 is the year and week of manufacturing (e.g. "7" being either 1967 or 1977 and "03" being the third week of the year, OR "70" being 1970 and "3" being the third week of the year). Same question applies to all future EIA #'s provided.

The Choke: EIA # 606702 and "MESA 38-15115" above it.

The Reverb Transformer: EIA # 606631 and "MESA - 185225" above it.

The Output Transformer: EIA # not visible without further disassembly (which I'm not comfortable doing myself....YET)

Both the Power Transformer and Output Transformer have a fair amount of rust on them. Which will remain, as I've read on this forum that rust, in mild to moderate amounts will do no harm to the tone.

Three of the five preamp tubes came with the original covers (I'm assuming original) and two have no cover. How critical is it to have all preamp tubes covered, if at all?

Aside from removing the chassis and having it evaluated by a qualified tech, how does one tell if it has had any MOD'ing done to it? When bringing in reverb, the reverb becomes present at approximately 1 on the rotary dial. However, whenever I roll-in the reverb I also experience a significant increase in volume level. Is that normal or could that be an example of a previous MOD?

Just so the forum members know, I have no interest in selling this amp or it's monetary value. I simply would like to determine if the amp I have in my possession is truly a vintage and mostly original Boogie.

Thanks to anyone, for their time and consideration on this.

 

[stokes]

Ya gotta be a little patient waiting for responses,we dont all sit here watching for new posts.I'll try to answer your questions.Is the amp modded?Almost impossible to tell without having the amp in front of me.Nothing you've said indicated to me any obvious mods.The reverb increasing volume could be normal,but again,I dont know what you describe as "a significant increase".When the reverb is off,is the amp weak sounding or anemic? I am guessing not,or you would have mentioned that,right?The reverb being on adds more tubes to the mix,so it would be normal to percieve it to seem louder or fuller sounding.It certainly seems like the amp was assembled in 1977 and such markings are quite common on Boogies,so it would seem to me that you do have a vintage MKI,enjoy it.

 

[Don]

Didn't the title of your post originally say "porn" in it? That implies pics. I thought maybe you'd post some later.

 

[MrMarkIII]

No pix = *Yawn*

 

[miqueas92]

No Pix = Didn´t happen :mrgreen:

 

[fugazi]

Ya gotta be a little patient waiting for responses,we dont all sit here watching for new posts.I'll try to answer your questions.Is the amp modded?Almost impossible to tell without having the amp in front of me.Nothing you've said indicated to me any obvious mods.The reverb increasing volume could be normal,but again,I dont know what you describe as "a significant increase".When the reverb is off,is the amp weak sounding or anemic? I am guessing not,or you would have mentioned that,right?The reverb being on adds more tubes to the mix,so it would be normal to percieve it to seem louder or fuller sounding.It certainly seems like the amp was assembled in 1977 and such markings are quite common on Boogies,so it would seem to me that you do have a vintage MKI,enjoy it.

Apologies for not being patient. Now that I know this is forum, in which, most (if not all) people on it, are employed and aren't mouse-potatoes, I will act accordingly. I meant no disrespect, and I appreciate your input. The "amp sounding weak or anemic when the reverb is off" isn't the case. However, when applying reverb from 0, the volume increase is so significant that I stop adding the reverb at no more than 2-3 for fear of blowing an ear drum or thoroughly annoying the neighbors. It's like the reverb has more of an effect on overall volume than the master. Kwirky, but manageable. Thank you again stokes, for your input.


For ye non-believers (miqueas92, MrMarkIII, Don),

here are some pictures of it:

Is it normal for the tolex to peel back such as represented below?

 

[JOEY B.]

Yes, this is an original Mark I. It has been modified with an Effects Loop and a Boost on the rear of the chassis. You might give MESA a call with the serial # (under the speaker jacks) to see if they have any record of the mods. My '78 was modded with the "Post FX Level" effects loop, and was a beast. The main problem was that the louder I played it, the better it sounded. :lol:

 

[MrMarkIII]

Schweeeet! How could we ever have doubted you?
Yeah, the Tolex peel is normal. Leave it, 'cause if you glue it back down everyone will know you did.
Think of it like wrinkles on your grandma.
If you got rid of 'em, she wouldn't look normal.
Don't all Boogies sound better the louder you play 'em?

 

[Don]

Very cool amp! I love these things!

I had a '68 Princeton Reverb that developed a buzzy rattle. It turned out that it was loose tolex. When I re-glued it the problem was solved.

 

[fugazi]

Yes, this is an original Mark I. It has been modified with an Effects Loop and a Boost on the rear of the chassis. You might give MESA a call with the serial # (under the speaker jacks) to see if they have any record of the mods. My '78 was modded with the "Post FX Level" effects loop, and was a beast. The main problem was that the louder I played it, the better it sounded. :lol:

Thanks Joey B.! I was aware of the location of the s/n but thanks for that. That's why, in the pic of the back of the chassis I strategically placed the speaker jack in one of the 4 ohms inputs instead of the 8 ohms input it normally resides in. Don't wanna go broadcasting the s/n all over the interwebz ya know. :wink:

I seem to have remedied the prob I was having with the reverb increasing the volume significantly. Not sure HOW I did it. Was just messin' around with it while plugged-in to input 2 and was running a stomp-box GEQ through the effects loop. Heard no real audible difference between effected signal and dry signal (except for a bit more amplitude). So removed the stomp-box GEQ and voila! Problem solved! Obviously, I'm no electronics wizard by any stretch of the imagination, but I'm inclined to think that, if I understood the signal path of this particular amp, I would be able to manipulate the parameters in a more effective manner in my quest for the elusive sweet-spot. So yeah, I will definitely call MESA with the s/n. I doubt they'll have it, but wouldn't it be great if they did have, a schematic for this particular amp, and records of possible MOD's? I'm also inclined to agree with you about the Boost on the rear of the chassis being a MOD, but wasn't an Effects Loop an "option" back then?

One additional question for anyone: Is the input in the pic below, for the footswitch that can control the onboard EQ and reverb?

Schweeeet! How could we ever have doubted you?
Yeah, the Tolex peel is normal. Leave it, 'cause if you glue it back down everyone will know you did.
Think of it like wrinkles on your grandma.
If you got rid of 'em, she wouldn't look normal.
Don't all Boogies sound better the louder you play 'em?

:lol: How could you have ever doubted me?!?! After all, it is the interwebz, and anything said on the interwebz is the gods honest truth. I lol'd about your comparison to tolex and grandma! Good stuff, and point well taken. I will leave it as is.

Very cool amp! I love these things!

I had a '68 Princeton Reverb that developed a buzzy rattle. It turned out that it was loose tolex. When I re-glued it the problem was solved.

I'll keep this in mind, should the amp ever develop any buzzy rattles. :wink:

Thanks to everyone for their invaluable knowledge and input!

 

[igfraso]

Sometimes, when the amp is doing something funny, the first thing you do is to plug and unplug a 1/4" plug on the loop jacks a couple of times to wipe off any dust accumulated there.
It happened on my II-B.

Here you have a mod that added a loop to the amp but I guess that you might have cleaned the dust anyway.