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Marshall Polarity Switch


 
8/29/2000 12:48 PM
Bryce.Y.
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Marshall Polarity Switch
Looking at buying what Im told is a 80's MKII 1959 Super Lead reissue, serial number W29527 and Im after some opinions please. Also wondering what the polarity switch located next to the standby and mains switches is all about.  
Thanks, Bryce.
 
8/30/2000 12:50 PM
Bryce.Y.
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More Information
Trying to date this amp. I dont know much about old Marshalls but Ive got a feeling this might not be an 80's model at all. It has got a PCB but the pots aren't attached to it like later stuff, it has huge transformers, at least compared to what Ive seen in Marshalls of late. The switches are like flat plastic toggles but they do seem to be of good quality. Also, although I don't know if it means anything, but the knobs are held on by grub screws rather than splined. The chassis layout is pretty well identical to the photo on page 267 of AP's Tube Amp Book, although it has four outputs and the mains socket and selector switches are a bit different. It also sounds amazing.  
I'd really appreciate any thoughts on this and advice on dating Marshalls in general  
Thank-you, Bryce.
 
8/30/2000 1:38 PM
Richie{~}==:::
What you describe is correct.. they made 3 different reissuies of the 1959..Pretty cool amp.  
The polarity switch, its used to reverse polarity. If you hook two amps together it will put them in phase so you don't get a shock.. and if useing as one amp.. you know how you take your hands off the strings.. you may hear a buzz.. flip the polarity switch and it will eliminate this buzz. Some wall plugs may be wired wrong , and this helps switch it, like the old amps where you only had a 2 prong plug.. you had to unplug and turn the plug over and plug back in to do what this switch does.Hope i'm explaining this right. The one thing it is best for. is if you ever been playing and you step up to the mic to sing ..and you see sparks fly off your lips.. then you learn real quick what this switch is good for.makes it so you don't get a shock.Almost as bad as playing on concrete barfoot..OUCH.. that can be a shocking experience..Hope this helps.. This is a pretty great amp..The amp should have a sticker inside with code date attached on the chassis. They are harder to date before 69.. they don't have the sticker..or if it has come off. You just have to know what to look for. Usually the later MK II amps come with 6550 tubes.. The older Marshall you just have to learn the cosmetics of them and circuts, transformer layout and filter cap arrangement..to tell the year of them.  
Richie{~}==::
 
8/31/2000 12:03 PM
Bryce.Y.
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Thanks Ritchie, your explanation of polarity switch was very helpful. I actually got to put it into practice today after plugging in an old Vox wah and picking up some horrible squeeling signal that sounded like radio Moscow or something, I flicked the switch and it came good straight away. Interestingly it stayed quiet on flicking switch back again too. This amp doesn't have a date code sticker inside so Im still in the dark about its vintage, would you care to guess? Other possibly distingushing features are : EL34 valves, but I think all Australian exports were. Gold piping around cabinet and appliance type mains socket, similar to current stuff. Probably doesn't help much but thanks anyway.  
Bryce.
 
8/31/2000 12:32 PM
Richie{~}==:::
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Bryce: Well what you describe is probably the first reissue.. came out in 1988..and made for 3 years.. then they went to the plexi panel reissue..So close as i could tell you it was made between 88 to 91 when the plexi came out.And you are correct, the EL34 amps were almost always across the ocean amps,or English type.. Seems like the ones they ship to USA are 6550.. In those days anyway.. now they have EL34s. I don't remember if all the reissue amps came the same.. I'd say they did..This amp was modeled after the early 70s type amps.  
Richie{~}==:::
 
8/31/2000 1:16 PM
Bryce.Y.
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Thanks again Ritchie, its all starting to make sense now.  
Bryce.
 
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