Mark IV A/B & B photos of back showing difference

Mark I's, II's, III's and the almight IV

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Markedman
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Mark IV A/B & B photos of back showing difference

Post by Markedman » Sat May 26, 2018 7:20 am

ImageMark IV A/B back by John Bazzano, on Flickr

ImageMESA/Boogie Mark IV-B wicker by John Bazzano, on Flickr

Pretty close, not the same. Does someone have a photo of the back of an A version?
JP2C, Mark llC++ DG, Mark IV-A/B.

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Silverwulf
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Re: Mark IV A/B & B photos of back showing difference

Post by Silverwulf » Sun May 27, 2018 9:47 pm

I can take a IV (A) pic tomorrow if it's still needed. There's 2 loops on the back, and depending on when it was made, there were a few different sets of transformers used during the production of A.
Boogie user of 20+ years, previous owner of 150+ Rectos, author of the previous "2 Channel Recto User Guide" and current "3 Channel Recto User Guide" (if I ever stop being lazy and finish it)...

JCB1980
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Re: Mark IV A/B & B photos of back showing difference

Post by JCB1980 » Sun May 27, 2018 11:03 pm

AFAIK there really isn't an A/B. It's just what some people have ended up calling an early B with an attached power cord. The B changed the effects loop, added a reverb footswitch jack, and introduced the satellite output. The other changes were tweaks on the inside. Not saying A/B isn't a thing for certain, just that the only ones that aren't As I have ever seen are Bs with or without an attached power cord. When they switched to the detached cord it dropped the ground switch from the back of the amp.
If your A/B one has a 12ax7 for it's reverb I dont think there is anything that distinguishes it from any later B other than the attached cord. But I have been wrong before.
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