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Topic: Dumb question.............. |
David Mullis
From:
Rock Hill, SC
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Posted 15 Jan 2003 6:42 am |
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| How can you check the speaker leads on a Twin to find out what the polarity is? I know on a SS amp you can meaure the resistance from each lead to ground and the one with the least resistance is negative, but when I tried this on my Twin, they both read about the same. Am I hallucinating? |
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CrowBear Schmitt
From:
Ariege, - PairO'knees, - France
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Posted 15 Jan 2003 6:56 am
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David try this:
take a 9v battery w; 2 wires hooked on it
apply to speaker connections
if speaker pushes forward then + is on the +
if speaker pushes back then + is on -
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Steel what?
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C Dixon
From:
Duluth, GA USA
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Posted 15 Jan 2003 7:13 am
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CrowBear is correct. I would suggest your just touching the 9v battery to the terminals. Not leave it on. DC current is anathema to a speaker's magnetic powers. IE, some magnetism can be lost if DC current flows thru a voice coil for more than just an instant.
But the test is still valid if you just touch the terminals while watching the direction the cone moves.
God bless you in your quests,
carl |
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Jim Smith
From:
Midlothian, TX, USA
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Posted 15 Jan 2003 7:21 am
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I think David is asking about the speaker leads from the amp, not the speaker itself. From what I remember, Fender uses white and black wires which would be hooked up to the positive and negative terminals respectively.
If yours aren't colored, you can set the amp at very low volume, plug a guitar cord into the input, and touch the tip with your finger. If the speaker pushes out it's set up correctly. If not, reverse the speaker wires. |
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Joey Ace
From:
Hamilton, Ontario, Canada
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Posted 15 Jan 2003 9:19 am
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| moved to ELECTRONICS |
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David Mullis
From:
Rock Hill, SC
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Posted 15 Jan 2003 9:32 am
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Thanks Joey, I though I had posted this under electronics, but I guess the caffeine hadn't kicked in!  |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 15 Jan 2003 7:08 pm
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| Unless you're using two amps, the polarity of the (pair of) speakers is inconsequential. As long as the two speakers in the amp are polarized correctly (the same), you won't notice any difference by changing the polarity of the speaker wires at the amp. |
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David Mullis
From:
Rock Hill, SC
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Posted 15 Jan 2003 8:40 pm
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| Thanks guys, I've got a single 15 in this one |
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Terry Downs
From:
Wylie, TX US
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Posted 15 Jan 2003 9:26 pm
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Donny is correct, it doesn't matter what the polarity is unless you are running the same signal through another amp ..i.e. a stereo rig.
However, the wire that is negative on any tube amp should be the least resistance to ground. The negative speaker lead should be connected to the chassis. The + side to the output transformer will also read very low (less than 1 ohm) but should still be slightly greater resistance to ground than the negative lead.
Touching your finger to the tip or an input cord injects a 60Hz (50Hz if in Europe) signal into an amp. The human body acts as an antenna to the 60Hz power fields near electrical wiring. This is an AC signal, so you cannot tell polarity by doing this. Your amp just reproduces the 60Hz AC body tone and its harmonics.
Also a 9V battery will not damage any speaker with a wattage rating conducive to live music.
Regards,
Terry
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David Mullis
From:
Rock Hill, SC
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Posted 16 Jan 2003 8:39 am
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| Interesting, I had heard that measuring the resistance on the leads only worked with SS amps. I'll have to look at it again. |
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