2 speaker cabinets wired serial

Tommy Boswell · From: Virginia, USA

My amp only has one speaker out. And I have 2 4-ohm cabinets that I want to run serial for an 8-ohm load. If both speakers were in the same cabinet it would be easy. But I want to keep the cabinets separate for stand-alone use, but also run them serial on occasion. And I don't want to modify the amp to add a serial output jack. I think I can add jacks to one cabinet to allow for this, and wonder if some of you electronics gurus can tell me if I've got it right. Since I can't draw diagrams here, I'll describe in detail what I plan to do with one of the cabinets. It will have 2 normal 1/4 jacks and one switching jack, and 5 wires. You may have to draw this out for yourself to see what I'm seeing:

Normal jack #1 (for stand-alone use), pos terminal wire goes to switch terminal on switching jack, neg terminal wire goes to neg speaker connector.

Normal jack #2 (for patching out to the other cabinet with a normal speaker cable), pos terminal wire goes to neg speaker connector, neg terminal wire goes to neg terminal on switching jack.

Switching jack (for speaker cable coming from amp), pos terminal wire goes to pos speaker connector, and the other 2 wires for the switching jack are described above.

I plan to carefully label the jacks to keep from blowing something up. The stand-alone jack will be in the middle of the cabinet, and the amp input jack and serial-jumper jack for the other cabinet will be over to one side.

How did I do? Do I get an A? And if you draw this out for yourself, you get A+, and a big thank-you!

Les Cargill · From: Oklahoma City, Ok, USA

The simplest way to test this is to use a voltmeter to read the resistance at each point and see if that matches your expectation. Of course, resistance is only half or so of the actual impedance.

Be careful of running the amp to a mismatched impedance. Some can handle it, some can't.

Tommy Boswell · From: Virginia, USA

Thanks Les. My amp has a 4/8/16 ohm selector switch, and I try to check it twice when plugging in a cabinet.

Lane Gray · From: Topeka, KS

Tommy, I think I would leave the cabs alone, and make up a speaker cable with the two plugs in series: the plug in the middle only interrupts one wire.
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Tommy Boswell · From: Virginia, USA

Lane, that's a great idea. I've been known to do things the hard way, only because the simple solution didn't come to mind. Thanks!

Ken Campbell · From: Ferndale, Montana

Can someone describe how to make up said speaker cable? Please?

Thanks
Kc

Tommy Boswell · From: Virginia, USA

You could start with two identical speaker cables. Cut one in half, now you've got one long and two short cables. Assuming the internal wires are black and white, connect the black wire of one short cable to the white wire of the other short cable. Then remove one plug from the long cable, connect the remaining wires black to black and white to white.

Using an ohm-meter, plug the short ends into two cabinets and check the ohms at the long end. If your cabinets are 4 ohms each, the reading should be somewhere in the 8 ohm range. Actual reading is usually lower, like 6 to 7. But that will tell you if the cable is right.

Lane Gray · From: Topeka, KS

Ken, I'm driving and dictating, I'll make a drawing in about an hour.
I STRONGLY recommend coded wire (like AC zipline uses one smooth wire and one ribbed)
For now, start with the amp end. It's normal. The nearest speaker plug, cut one wire only, and solder one end of the cut to the tip, and the other end to the sleeve. Then the far end plug is just like normal.
Wait. If you only cut one wire of the pair, coded wire isn't needed.
Still need the drawing?
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Lane Gray · From: Topeka, KS

Tommy, I think your idea does the same thing but harder.
And if you're gonna make your own cables, I'd use hardware store zip line. Cheaper and perfectly fine for speaker use.
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Ken Campbell · From: Ferndale, Montana

Tommy Boswell · From: Virginia, USA

I'd like to see it too, not sure I understand Lane's solution.

Lane Gray · From: Topeka, KS

I didn't draw the plugs, but polarity doesn't matter, as long as the middle plug comes off the same wire. Let me know if this doesn't make sense.

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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Jerry Jones · From: Franklin, Tenn.

What Lane drew. Wink

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Jerry Jones

Ken Campbell · From: Ferndale, Montana

Perfect. Bing! The lights came in.

Thanks Lane. Got the soldering iron heating up now.....

Tommy Boswell · From: Virginia, USA

Thanks Lane. We're just using different words to describe the same thing. But that's OK, everyone's head is wired a little different too!

But what is AC zipline? A google search brought up some strange-looking stuff.

Lane Gray · From: Topeka, KS

The simple lamp cord. Zip line is a slang term.
I'll search and come back with what I mean
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Lane Gray · From: Topeka, KS

Home Depot and Lowe's call it "lamp wire." 16 ga should be adequate, I'd think
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects

Tommy Boswell · From: Virginia, USA

OK, I've used lamp cord for speakers too. I've also used Radio Shack speaker wire with a stripe down one side to keep things lined up.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Practically all lamp cor or zip cord is marked for polarity (if you look very closely). It may be just a line or score in the insulation jacket, a color stripe, or even a tiny polyester thread around the conductor, but it's there. Wink

Jim Palenscar · From: Oceanside, Calif, USA

I made the same "Y" cord that Lane describes years ago for use w a pair of 4 ohm monitor speakers for our PA which wanted to see a minimum of a 4 ohm load out of one out. Worked like a charm and no alterations to the PA or the speakers.

Kevin Raymer · From: Chalybeate, Kentucky, USA

The drawing above will work, but........

I would go to radio shack and buy a small project enclosure and 3 mono 1/4 jacks.

I'd wire two of them in series and wire "them" to the third as an output jack to the amplifier.

Then when you want to hook up them in series, all you do is pull out this handy dandy box and hook them up.

This way ALL your speaker cables stay STANDARD, and you can place the speakers anywhere your speaker cables will reach.

At least that's what I'd do..

Very Happy

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Kevin Raymer
Zum / Knaggs / Breedlove
Fractal Audio

Ken Campbell · From: Ferndale, Montana

Cool idea. Can you draw out what that would look like inside the box?

Kevin Raymer · From: Chalybeate, Kentucky, USA

With the general disclaimer that you use this at your own risk..

And

If you use this and something goes wrong all damages are your sole responsibility.

The circuit I would use if I wanted to build one for myself would look like this.

Use at your own risk....
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Kevin Raymer
Zum / Knaggs / Breedlove
Fractal Audio

Peter Harris · From: South Australia, Australia

I can remember building one like that a bazillion years ago for just such a need...it worked well!! ...although I haven't got a clue where it is now..... Rolling Eyes

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If my wife is reading this, I don't have much stuff....really!

Jerry Jones · From: Franklin, Tenn.

If you choose to construct the project box above, make sure it is PLASTIC and not metal!
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Jerry Jones

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