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Author Topic: 70-volt speakers  (Read 4761 times)

Mike Sokol

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70-volt speakers
« on: February 25, 2019, 07:10:17 PM »

Just a reminder that 70-volt sound systems actually make 70-volts AC when you shout into an RF microphone while you're also twisting the speaker wires together with your other hand to test the connection. Ouch!  :o

Dave Garoutte

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Re: 70-volt speakers
« Reply #1 on: February 25, 2019, 08:05:17 PM »

Speaking from experience? ;)
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Chris Hindle

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Re: 70-volt speakers
« Reply #2 on: February 25, 2019, 08:27:33 PM »

Ouch!
I'm really surprised you didn't see that coming Mike.
Well, at least it won't ever bite you again.

My first job out of High School (1976) was as an electrical technician for a security company. Got sent out to make repairs, upgrades, and modernize systems.
The normal operation was 30ma and 15ma current loops at (I think) 6 volts.
Pretty much invisible when making splices and hooking stuff up. When the office wanted to get your attention, they threw 48V "ringing current" on the line. That sure got your attention if you were holding onto something....

Also used Ringing Current to find intermittent failures on the window foil.
A couple of minutes applied would burn the poor connection.
Chris.
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Mike Sokol

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Re: 70-volt speakers
« Reply #3 on: February 25, 2019, 11:10:25 PM »

Speaking from experience? ;)

Yes, I had that reminder this morning and nearly "dropped the mic".  ;D

Mike Sokol

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Re: 70-volt speakers
« Reply #4 on: February 25, 2019, 11:15:19 PM »

Ouch!
I'm really surprised you didn't see that coming Mike.
Well, at least it won't ever bite you again.

Yeah, I should have known better, and a little voice inside my head said "don't do it". But I didn't have any wire nuts in my pocket and I was confirming which wire was which after the drywall people rerouted everything. Just a little reminder that any wires can have significant voltage, even speaker wire.

John Roberts {JR}

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Re: 70-volt speakers
« Reply #5 on: February 26, 2019, 12:00:13 AM »

Just be glad you weren't using the 100V tap...

JR
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Re: 70-volt speakers
« Reply #6 on: February 26, 2019, 06:47:38 AM »

Just be glad you weren't using the 100V tap...

JR

That would have been an even bigger ouch.  :o :o

Dave Garoutte

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Re: 70-volt speakers
« Reply #7 on: February 26, 2019, 12:38:49 PM »

Over the years most of my 'stupid mistakes' were preceded by a little voice or funny feeling which was promptly ignored instead of investigated.
Intuition is the smart part of your brain trying to tell the stupid part of your brain to pay attention. >:(
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Chris Hindle

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Re: 70-volt speakers
« Reply #8 on: February 26, 2019, 01:04:21 PM »

Over the years most of my 'stupid mistakes' were preceded by a little voice or funny feeling which was promptly ignored instead of investigated.
Intuition is the smart part of your brain trying to tell the stupid part of your brain to pay attention. >:(
"I wonder if I could just....." usually ends with "Nope, that was a bad idea"
So, why don't we just listen to ourselves ?
Chris.
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John Roberts {JR}

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Re: 70-volt speakers
« Reply #9 on: February 26, 2019, 01:20:42 PM »

IIRC school installations used 35V tap.

Make that 25V correction noted.

JR
« Last Edit: March 01, 2019, 09:57:28 AM by John Roberts {JR} »
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ProSoundWeb Community

Re: 70-volt speakers
« Reply #9 on: February 26, 2019, 01:20:42 PM »


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