There's plenty of domestic equipment in the UK with 'figure of 8' type IEC connections which can be inserted either way, but I can't say if there's a European equivalent of the wall wart I mentioned or whether it's constructed differently to account for non-polarized countries. Quite a lot of equipment has the modern-day equivalent of death caps, but it comes down to the class of cap that's used.
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Lots of older gear had "polarity" switches and what we call death caps. That doesn't mean it's a good idea. Well, it was for getting quietest operation on the fly under less regular conditions. But certainly with higher danger risks relative to that "isolation" Juan was talking about. And lots of things can go wrong. There's a reason changes were made to grounded, polarity specific AC plugs. Of the nine posters on this thread three have reported experiences where something went dangerously wrong because of polarity and ground issues with AC outlets. I'm sure such stories are still happening in places where polarity and grounding haven't been standardized. We just don't hear much about it because it's common, and/or electronics regulations in those regions stipulate greater isolation in electronic designs. It can't be for any other reasons because, of course, electricity has no idea what country it's in."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by Chuck H View PostLots of older gear had "polarity" switches and what we call death caps. That doesn't mean it's a good idea. Well, it was for getting quietest operation on the fly under less regular conditions. But certainly with higher danger risks relative to that "isolation" Juan was talking about. And lots of things can go wrong. There's a reason changes were made to grounded, polarity specific AC plugs. Of the nine posters on this thread three have reported experiences where something went dangerously wrong because of polarity and ground issues with AC outlets. I'm sure such stories are still happening in places where polarity and grounding haven't been standardized. We just don't hear much about it because it's common, and/or electronics regulations in those regions stipulate greater isolation in electronic designs. It can't be for any other reasons because, of course, electricity has no idea what country it's in.Logic is an organized way of going wrong with confidence
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Originally posted by nevetslab View PostI've always been puzzled by a generation of Fender amps having a 3-wire grounded AC Mains cord, WITH the 3-position Grounding Switch, coupled to the Death Cap. I think I've eliminated all of those from our inventory, but, there may be some still lurking about, with so many of them not going out on rentals that often. I know I've nailed all of the Twin Reverbs and Deluxe Reverbs, though they did that on so many models in that era.
This isn't the future I signed up for.
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Originally posted by nevetslab View PostI've always been puzzled by a generation of Fender amps having a 3-wire grounded AC Mains cord, WITH the 3-position Grounding Switch, coupled to the Death Cap. I think I've eliminated all of those from our inventory, but, there may be some still lurking about, with so many of them not going out on rentals that often. I know I've nailed all of the Twin Reverbs and Deluxe Reverbs, though they did that on so many models in that era.
To try and eliminate them all would be a never ending battle.
The caps are there for a reason, and the modern ones are a type considered safe and acceptable. (look at switch mode supplies and line filters)
I think if we get rid of the troublesome (non-safety rated) ones in vintage gear, and install 3 prong if not present, then we have done our part.Originally posted by EnzoI have a sign in my shop that says, "Never think up reasons not to check something."
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Typical death cap rating was 600V DC
Hey!!!! mains is 115/117V !!! (way back then) ... I have a HUGE safety margin!!!
Think again.
To begin with, that mains voltage means 150V peak.
And that IF everything is as in the textbook ... but let lightning hit a transmission line, even hundreds of miles away, and all Hell breaks loose.
Yes, there are spark gaps to deal with that ... but they trigger with scary high voltages ... or they would trigger all the time.
I checked "250 VAC" caps meant for line filtering duty , just quoting from memory they had to stand 3000V DC for 1 hour and 5000V DC for 1 minute, or similar specs.
Or 2000 and 3000 ; in any case the point being that old standard 600V DC is absolutely inadequate by modern standards.
Didn´t check X and Y rated caps, but I bet they at least meet or surpass these specs, adding fail safe failure modes.Juan Manuel Fahey
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I play a lot of venues, but mostly dive bars nowadays. I always ASSUME that ALL outlets are suspect. A brand new recepticale in an old building means nothing. Usually I will run the whole band with a breakout box off of one outlet so everything at least has the same reference and hope for a sturdy breaker. I ALWAYS use a wireless.... only a total cork sniffer will say they can tell a huge difference live. The absolute worst is an outdoor gig with generators. I loath to even plug in. I played a big gig in LV a couple of years ago, I saw the whole back line fried TWICE in one day. Luckily it was all rented by the event. 2 JCM800s, a JCM900, 2 vintage SVTs, and a bunch of other stuff fried.
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Originally posted by olddawg View PostI play a lot of venues, but mostly dive bars nowadays. I always ASSUME that ALL outlets are suspect. A brand new recepticale in an old building means nothing. Usually I will run the whole band with a breakout box off of one outlet so everything at least has the same reference and hope for a sturdy breaker. I ALWAYS use a wireless.... only a total cork sniffer will say they can tell a huge difference live. The absolute worst is an outdoor gig with generators. I loath to even plug in. I played a big gig in LV a couple of years ago, I saw the whole back line fried TWICE in one day. Luckily it was all rented by the event. 2 JCM800s, a JCM900, 2 vintage SVTs, and a bunch of other stuff fried.If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.
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Originally posted by SoulFetish View PostThe guitar player in the last band I ran sound for recently used a wireless setup. The particular unit he used was pretty noisy on this night. But, I've used some wireless systems in playing a couple of large auditoriums and outdoor venues, and if you factor in all the acoustic effects from the physical distance between the mains sound reflections, monitor sound, and location of the amp, I don't know if I could tell any difference at all between a RF and direct cable connection. If there was a "live chassis" fault situation, there is still risk of physical contact with the amp, through an effects loop or controls adjustment. But, it does offer a really attractive margin of safety."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by J M Fahey View PostShielding.Experience is something you get, just after you really needed it.
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Originally posted by nickb View PostSince the shielding is for the electric field I would have thought a suitably rated low inductance capacitor no bigger than 10nf ( approx 1mA at 240V 60Hz) instead of the wire to the case would be almost as effective and would eliminate the possibility of electrocution by touching the mic case. The inductance of the leads would have to be kept as low as possible so think really short.
I remember a couple decades ago, local farmers were complaining after a new 745 kV power line was installed, their cows would not eat grass on fields under the line. There was enough of a field to deliver a mild buzz but that's all it took to set 'em off. The shock was enough to "train" the cows to avoid grass on other fields too. How to convince 'em "it's OK Bossy, no shock here..." Same goes for some vocalists - once you catch a good buzzer it's hard to approach the mic again. Put a big foam "sock" on it !?!This isn't the future I signed up for.
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My thinking was that since "touching the mic" has been a common denominator in the problem often enough that (maybe) some clever manufacturer could have started coating the screen with insulative material or use a secondary plastic guard or some such. I hate spit guards, but I use them. I bought a big, fat bag of them after my shock and changed them every so often when they got smelly or whenever someone of questionable oral hygiene used my mic"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by Chuck H View Postuse a secondary plastic guard or some such.
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Originally posted by glebert View PostIs the metal screen on an SM57 actually grounded? I had a friend in college (where all the houses and bars had terrible wiring) who would only sing with 57's because he got shocked less than 58 style mics.
Yes those college facilities had some very dodgy situations. I remember playing gigs in the basement of an off campus fraternity, crammed into a corner of the room with a steel lolly column in the middle of the stage. Touching the lolly pretty well guaranteed a painful shock no matter where one's "ground" switch was set. Of course that was back in the day when grounded AC outlets were rare, same for grounded AC cables on amps. BZZZZZT - - -OW OW OW !!!This isn't the future I signed up for.
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