What is this strange adapter?

[calkew5]

The question is simple.

I am a lighting designer at a small professional theatre that has survived long enough to accumulate decades of random stuff.

The other day, I found a strange little sort of adapter. It's a female edison plug connected to a 1/4" TRS jack by about four feet of 18 gauge copper wire, a red strand and a black strand.

What is this for? Any thoughts?

 

[jfleenor]

I know this response is of no real use, but:

Perhaps it's meant to create a heat/fire source, for the purpose of burning down important stage props and curtains, or shorting out audio boards?

I wouldn't trust it...

Janell

 

[Van]

What ever it was originally it needs to be garbage now.

 

[epimetheus]

I would guess some poor mis-guided soul decided it would be convenient to create an adapter to allow a common extension cord to be used as a speaker cable. The disastrous adapter you now question is the result.

Cut it up into many small pieces immediately.

 

[seanandkate]

What is this for? Any thoughts?

Um . . . the remnants of a contract hit?

 

[Footer]

Its an extension cord adapter. I have seen them before. I have also seen a house that used to have all twistlock lighting move over to stagepin only to have the sound dept. take ALL of the old twistlock connectors and started putting them into speakers....

 

[calkew5]

I suspected the device in question might not have...traditional applications. Out of curiosity, can you actually transmit sound over extension cord?

 

[Footer]

I suspected the device in question might not have...traditional applications. Out of curiosity, can you actually transmit sound over extension cord?

Yup. Its copper.

 

[MNicolai]

I suspected the device in question might not have...traditional applications. Out of curiosity, can you actually transmit sound over extension cord?

Can you? Yes. Sound is transmitted as electricity.

The most serious issue is that all it takes is for one cable to be unplugged that connects to some equipment and someone who thinks they're being helpful then plugs that extension cable in, now someone's electrocuted, a speaker is blown up, or an entire audio system is destroyed.

The reason people like to do this is because extension cords are everywhere. It's very easy to get a hold of more if you run out, and in this case if you don't need as many power cords for a gig, then you have extra speaker cables. That is, until your sound system literally explodes like a hand grenade at which point you'll really wish you had just bought the right cables the first time.

 

[SHARYNF]

Back in the Day as the saying goes, there were not a lot of options for connecting speakers to panels and amplifyers. on the Speaker side you have Standard 1/4 jacks and on the amp side typically binding posts. Speakons were not even Designed at that time, and so a lot of setups used a lot of weird and potentially dangerous setups. Twist locks were used a lot, and on the amp side of things I am guessing someone decided to use edison males for the AMP outlet. Sounds Insane today, BUT in those days a lot of crazy things were done. So I am betting someone had an amp rack where the Binding posts were connected to a set of edison females, and then standard extension cords to 1/4 inch jacks were used to connect to speakers.

we Laugh today, but a lot of really unsafe things were done in those days, Just look at the whole ground issue with Tube Guitar Amps... Lethal current could easily flow from the Amp to the performer/mic/stand when the Guitarist touched both the guitar and the amp at the same time

It was quite common during sound check to very carefully check to see if you the guitarist got a shock when touching the mic stand, if so, then you switched the ground switch.

Old Amps

http://www.fender.com/community/forums/viewtopic.php?p=263798&sid=8f7d634099480210b807a32e2287eb00

Sharyn

 

[derekleffew]

...The problem is that extension cords are not shielded like speaker cables are. This makes for a lot of extra noise in the signal. ...

Um, Mike, no.

 

[epimetheus]

Um, Mike, no.

My thoughts exactly...

 

[Chris15]

Yes you can be shocked by a speaker line. Consider that say a lab Gruppen FP14000 has a peak output voltage of 195V. And a peak output current of 83A. More than enough to kill you.

Extension cord makes great speaker cable, when and only when its plugs are replaced with something appropriate, say Speakon.

As to the original adapter, at least it wasn't a male mains connector (you'll find that half soon no doubt)

 

[MNicolai]

Post cleaned up.

Please, do tell me why I'm wrong. I've asked electronics teachers before and haven't ever been given reason to think getting shocked by touching a 1/4" TS connector is possible, or at least likely. (I'm not being cynical, I actually do want to know the physics and logic behind it.)

 

[fx120]

Back in the Day as the saying goes, there were not a lot of options for connecting speakers to panels and amplifyers. on the Speaker side you have Standard 1/4 jacks and on the amp side typically binding posts. Speakons were not even Designed at that time, and so a lot of setups used a lot of weird and potentially dangerous setups. Twist locks were used a lot, and on the amp side of things I am guessing someone decided to use edison electric outlets for the AMP outlet. Sounds Insane today, BUT in those days a lot of crazy things were done. So I am betting someone had an amp rack where the Binding posts were connected to a panel of edison outlets, and then standard extention cords to 1/4 inch jacks were used to connect to speakers.

we Laugh today, but a lot of really unsafe things were done in those days, Just look at the whole ground issue with Tube Guitar Amps... Lethal current could easily flow from the Amp to the performer/mic/stand when the Guitarist touched both the guitar and the amp at the same time

It was quite common during sound check to very carefully check to see if you the guitarist got a shock when touching the mic stand, if so, then you switched the ground switch.

Old Amps

Fender Community

Sharyn

At my shop, we still have 4x Renkus-Heinz SR-1's, 12x SR-2's, and 12x LR-2's which all came from the factory with male L14-20 twist locks on the back for input.

It was actually quite the ingenious solution for high current multi-conductor speaker cables back in the days before the NL4 Speakon connector. All of our cable was shared with our split phase 20A A/C distribution system, and all of the the cable is 10AWG so it was great for driving those heavy subs and high power bi-amped top boxes. Of course all of the amplifier cube racks built for the system had L14-20 outputs.

To my knowledge at no point did the power and speaker lines get crossed on any of our events.

Somewhere buried deep upstairs in our shop we have parts of our old Perkins system, which used actual Cannon-branded 3-pin XLR's for the speaker level inputs, although I believe only the subs are still intact. Nothing like driving a pair of 18" subs off of a single 14 AWG XLR cable...

 

[Chris15]

Post cleaned up.

Please, do tell me why I'm wrong. I've asked electronics teachers before and haven't ever been given reason to think getting shocked by touching a 1/4" TS connector is possible, or at least likely. (I'm not being cynical, I actually do want to know the physics and logic behind it.)

Honestly the likely reason is your teachers don't know what they are talking about in this instance.

Consider say a "1000w" amp driving say a 4 ohm load. Say you have 400w RMS being drawn. By Ohms law, you have 40V and 10A (both RMS). Change this to an 8 ohm load and the voltage goes up to 57 volts. Make it 800w and 8 ohms and you get 80 volts.

Derivation: P=v^2/R so V=SQRT(P*R).

Making sense?

 

[Les]

Post cleaned up.

Please, do tell me why I'm wrong. I've asked electronics teachers before and haven't ever been given reason to think getting shocked by touching a 1/4" TS connector is possible, or at least likely. (I'm not being cynical, I actually do want to know the physics and logic behind it.)

Heck, I was shocked by a 50w home theater speaker. It wasn't major, but it was there!

 

[MNicolai]

I'll admit that it's stupid, that I, the electrical engineering student, would let myths of my early theatre days get the better of me and electricity is still electricity, be it for a power cord or an audio signal. It's probably never been an issue (at least for me and the people I regularly work with) been because the likelihood of messing around with the TS connectors while pumping a loud signal into the speakers is rather low.

Still, getting shocked being possible, how did 1/4" TS connectors ever make it to market for amplified signals? Especially given how most of them even have metal jackets to them. (to which now that I think back, I do remember a couple occasions getting shocked by these connectors)

 

[Anonymous067]

As to the original adapter, at least it wasn't a male mains connector (you'll find that half soon no doubt)

Funny how that works usually...

 

[gafftapegreenia]

The 1/4" TS connector is very, very old. It's original application was in telephone board switch panels.

Much like the Edison screw base socket, which is clearly a shock-hazard, its just something that has been "grandfathered" in even if it has inherent hazards.