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Topic: How do I wire jack panels |
Ken Campbell
From:
Ferndale, Montana
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Posted 14 Jun 2014 6:30 am |
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I have two 4 ohm speaker cabs. I will need to be able to run them both from a single output on an amp. Currently they both have a single 1/4 input. How would I wire one to have a two jack panel and still run them at 4 ohms?
Thanks all...... |
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John Owen
From:
Seattle, Washington, USA
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Posted 14 Jun 2014 2:31 pm
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If each cabinet had an 8 ohm speaker in it, you just add a second jack (wired in parallel with the existing jack) in one of the cabinets and daisy chain the cabinets with a second speaker cable. That would give you a 4 ohm load if I'm not mistaken.
If all you have is 4 ohm speakers, it gets a little more complicated. I guess you could add a 4 ohm resistor in series with the 4 ohm speaker in each cabinet to make each cabinet 8 ohms and then proceed as described above. I've never heard of anyone doing that but seems like it could work.
Good luck,
John
_________________
Williams S-10, Beard R-model, Gibson BR-4 lap steel, Fender lap steel, Brownface Princeton, Goodsell Custom 33, 70's Tele Thinline, Fubar Twangmaster, Fubar Custom Buckarooster, Collings CJ Mh flattop |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 14 Jun 2014 5:44 pm
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With two 4ohm speakers you are left with either 8ohms or 2ohms... unless you get an expensive box that transforms the impedance (using a big transformer).
http://taweber.powweb.com/store/zmatch.htm
So we need to know the capabilities of your amplifier... can it handle 2ohms? If so, you're in luck, and you can just parallel the speakers + to +, - to -, to get 2ohms. You would install a second jack in one of the cabinets that was connected to the other jack tip to tip, sleeve to sleeve.
If your amp can't handle 2ohms, then you'd have to go with the 8ohm setup (or buy the box above). You'd need a special jack, one with a switching contact. Also, the jacks have to be mounted to a plastic plate, since they'll be in series and you can't mount them both to a metal plate (unless you get insulated jacks). For this connection you have a normal jack and the series jack... the series jack has to short itself out when unplugged, so the normal jack would work as it should (when you don't use two cabs). The jack connection for this would be:
Normal jack tip to speaker +
speaker - to shorting jack tip
shorting jack sleeve to normal jack sleeve
so when the shorting jack is not used the cabinet is normal, but when the shorting jack is used (not shorted!) the thing plugged into it (the other cabinet) is in series with the first one.
There are several disadvantages to this, depending on your amp, which we know nothing about. You could create a special series Y-cable to use... all three connections are in series, tip to sleeve, tip to sleeve, etc.
Putting dummy load resistors is not recommended, mostly because not only does the volume go down, but the tone gets sucked away too... and 4ohm 100W resistors are expensive, heavy, and get hot. Nobody does this.
So good luck... we need to know more about your amp to make a judgement call here.
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Lane Gray
From:
Topeka, KS
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Posted 15 Jun 2014 4:08 am
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| Stephen Cowell wrote: |
Putting dummy load resistors is not recommended, mostly because not only does the volume go down, but the tone gets sucked away too... and 4ohm 100W resistors are expensive, heavy, and get hot. Nobody does this.
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Well, Tom Scholtz (of the group Boston, if you remember the 70s) did. Sold a bunch of dummy loads, called "power soaks".
But they don't work for THIS application. His aim was to allow you to get that sound of an amp good and cranked while playing at a nice reasonable volume. So a big bucket of transformer oil (IIRC) ate up most of the amp's power so that the amp worked hard but you didn't drive everybody out of the studio/bedroom.
But that gives you reduced volume, not any increase.
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Ken Campbell
From:
Ferndale, Montana
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Posted 15 Jun 2014 5:58 am
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| K. So i bought a gk mb200 which will handle 4 and 8 ohm loads. Its 200 w @4 and 140 @ 8. Worst case is I'll wire one of the cabs and run em @ 8. Thanks for the heads up on the jack..... |
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