Author Topic: Please help me with Sceptre 4x12 speaker wiring  (Read 3394 times)

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Offline 57classics

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Please help me with Sceptre 4x12 speaker wiring
« on: March 02, 2011, 06:01:12 pm »
Hello folks,  I removed my original sunn transducers from my tall sceptre cab to try and sale, but then changed my mind.  So now I want to put them back in.  However, I did not make a note of which wire goes to which terminal.  I know that they are wired series paralell so my 4 8ohm speakers will give me an 8ohm load.  I have found lots of diagrams on how to wire series paralell but I am confused about the different wire colors.  There are white, green, black and red wires.  I have found some pics of the inside of some of your cabs (EdBass) on this site and I have the bottom 2 speakers figured out but the top 2 is where I get confused.  I should also mention that besides being a newbie on this stuff, I am a complete moron, and if anyone has any close up pics of the top 2 speakers I will be in debt to you for life!!!!!!  Please help!!!

Offline 57classics

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #1 on: March 02, 2011, 06:38:18 pm »
Ok, so I went ahead and made a guess.  Im still to scared to plug my laney in but I do have a multimeter.  So when I check the 2 wires that go to the speaker jack with the multmeter I get a 7.6 ohm reading.  Is it safe to assume that I wired it right based on that reading?

Offline Isaac

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #2 on: March 03, 2011, 04:12:20 pm »
Yes.
Isaac

Offline 57classics

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #3 on: March 03, 2011, 04:35:08 pm »
Thank you Isaac.  Now that leads me to another question. If I am getting a 7.6ohm reading on the cab does that mean I should run the head at 4ohms or is it safe at 8ohms.  I also need to replace the speaker jack, but how do I know what wire goes to what terminal on the speaker jack? So I have a black wire and a white wire and there are no markings on the speaker jack.  And last but not least, is my 100watt head going to kill those speakers?  I was wondering if I should look for a 50watt laney aor to match with this cab.

Offline Isaac

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #4 on: March 04, 2011, 04:27:57 pm »
8 ohms. What you're measuring is the DC resistance of the wire in the voice coils. The AC impedance will be higher. 7.6 ohms is not an unusual DC measurement for an 8 ohm speaker, though it is, in fact, a bit on the high side.

Most drivers are made such that a positive voltage applied to the + terminal (often red) will cause the drivers to move out. Having wired the cabinet yourself, you should check this. Apply a 9 volt battery to the wires, noting two things. One, that all of the drivers move in the same direction when voltage is applied, and which wire is connected to the + battery terminal when they move out rather than in. Connect that wire to the center post terminal of the jack, the other to the sleeve terminal.

The Sceptre was rated at 60 watts. Many folks say they got more like 80 watts. In general, I'd say you'd be fine with your 100 watt head. However, if you're playing with everything on 10 all the time, then there could be a problem with drivers that old, and 50 watts would be better. With drivers that old, though, there can't be any guarantees about anything.
Isaac

Offline 57classics

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #5 on: March 05, 2011, 10:07:29 am »
So I tried the 9volt battery test and all the drivers move in the same direction.  When the positive wire(white) is applied to the positive terminal on the battery the drivers move out(push).  And when the negative wire(black) is applied to the negative terminal on the battery the drivers move in(pull).  So This is good right?  Is it normal to get a scratchy popping sound when doing the 9volt test?

Offline Isaac

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Re: Please help me with Sceptre 4x12 speaker wiring
« Reply #6 on: March 06, 2011, 09:57:33 am »
Yes, this is all good, and as it should be. Good job!
Isaac