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I have an idea of how I could wire my 4X12 amp cab to allow me to easily switch between 1, 2 or all 4 speakers. But I want to know if I'm missing something in my plan before I jump in.

Instead of just having one 8ohm jack for all four speakers, I also want individual jacks for each of the speakers. That way I could choose to plug into 1 speaker (8ohm out to 8ohm speaker), 2 speakers (using both 4ohm outs to 2 8ohm speakers; but this should be the same as a parallel circuit so each 8ohm speaker is now 4ohm) and then still use the standard series-parallel wiring for all 4 speakers; 8ohm out to the central 8ohm in.

Since electricity chooses the path of least resistance I don't believe the other wiring options would interfere when not in use.

Right?

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  • 1
    What is the rated impedance for the outputs of the amplifier?
    – Theodore
    Apr 5 at 21:48
  • Please draw a diagram showing all the connections. Apr 5 at 21:49
  • 1
    Using switched jack sockets will make all this possible, but if I was doing a gig that needed only one 12" speaker, I'd have a 1x12 cab handy, rather than drag a 4x12 in... Come to think - that's what I've done for decades! Or - use 2 of 2x12 cabs.
    – Tim
    Apr 6 at 6:44
  • 1. Either 8ohm out, or two 4ohm out.
    – Junkrawk
    Apr 7 at 9:28
  • 2. The diagram I drew is at work, but I've already figured out that this will not work the way I was thinking.
    – Junkrawk
    Apr 7 at 9:32

3 Answers 3

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Electricity does not EXCLUSIVELY take the path of least resistance. It takes all available paths, the current that flows in each path will be (inversely) proportional to its resistance.

But with an appropriate - and rather complicated - system of switched jack sockets you could achieve what you mention.

I guess you want just one speaker so that you can drive it harder - into pleasing distortion - without making everything too loud? Well, it's worth a try. But before you construct the complicated multi-jack setup I suggest you snip the wires from just one driver, connect it directly to the present jack, and experiment. You may find it wouldn't be worth the trouble.

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    +1 for debunking the "path of least resistance" misconception. But what comes to pleasing speaker distortion, I've been convinced by seemingly credible sources that speaker cones and cabinets do not exhibit any pleasing distortion. Within the usable range of operation they behave linearly. That's why speaker+mic+room combinations can be reproduced/simulated from their impulse responses. The reasons for using different speaker configurations have to be something else. Apr 6 at 22:31
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    In hindsight that was a silly thing to ask. If Electricity always took the shortest path, parallel circuits wouldn't exist.
    – Junkrawk
    Apr 7 at 9:43
  • Wrong. You clearly do not understand electricity like you think. The path of least resistance IS what is taken, it just happens that the path is not necessarily 1 dimensional as you think.
    – Gupta
    Apr 20 at 15:20
  • @piiperiReinstateMonica Wrong.
    – Gupta
    Apr 20 at 15:21
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As a live performer, what are your on-stage performance goals here?

From a purely electrical standpoint, there's no reason why you can't wire this 4 x 12 cabinet in the manner you describe, but from a practical standpoint, what's the desired end-state?

Surely not a purely Volume/Loudness-centric outcome. And from the perspective of tone and sonic, tonal qualities, are you hoping to achieve some dramatically-different nuances with this modification?

Please clarify, so that these esteemed gentlemen and ladies can respond appropriately.

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  • I'd find it quite interesting to listen to a cab with three wiring options 1. standard 2×2 2. all speakers in parallel, and that in series with a 6 Ω power resistor 3. one speaker in parallel with an 8 Ω resistor, and that in series with a 4 Ω resistor. How different would options 2 and 3 sound? Apr 7 at 22:49
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Generally speaking you can drive a higher resistance load but depending on the quality of the amplifier and type it may cause problems. Specifically with tube amps it can cause excessive heating(this is why they say always have a load connected). Usually though most amps are designed well enough to drive higher and load impedance loads(the lower impedance loads will cause excessive heating too). More importantly you generally want to match your output impedance to the input impedance for maximum power transfer.

Generally speaking an 8 ohm jack for a 4x12 means that you have 4 speakers inside wired up 2x2(2 sets of 2 wired in series then those wired in parallel or vice versa).

Series resistance adds and parallel resistance "multiplies": A + B and AB/(A + B).

So if you have 8+8 = 16 and 8+8=16 then 1616/(16+16) = 8 or 88/(8+8) = 4 and 8*8/(8+8) = 4 and 4 + 4 = 8.

So if your amp has 8 ohms out then generally you want to configure your speakers so that they have a combined impedance of 8 ohms.

Most likely though you can use any combination you want and it will work BUT their may be a reduction in quality and/or power(or potentially an increase).

If you have a pretty beefy modern solid state amp chances are it will drive any load you put on it down to 2 ohms without major issues(although it could get hotter than desired so it could depend on how long you use it).

To be honest though you shouldn't really be trying to jack around with the jacks. It's not going to really change much and could cause you bigger issues if you blow your amp. It's not going to turn you in to Hendrix so better you spent the time playing and practicing.

Electricity doesn't "choose" the path of least resistance. If you have two paths A and B and one is of lower resistance the electricity will split in proportion.

There really is no reason to want to run 1 speaker. Just turn down the volume. If you use 1 and and want more power then you risk burning up the speaker. Even though the ohms is the same the loading is not.

In 4 speaker setup with total 8 ohms each speaker has 1/4 the power on it. In 1 speaker total 8 ohms the speaker has the full power on it. Those speakers generally are somewhat cheap and meant be used in the configuration they are designed.

Of course, if you are not running the amp full blast then it might be ok.

Experiment if you want but just balance that with the possibility of blowing your speaker or amp(it is unlikely unless you go full power and impedance mismatch for a "long time").

But ultimately you will probably not actually gain anything out of it. If you want lower sound turn down the volume or buy a power brake(a resistor) or get a practice amp(the quality of sound generally is due to it being loud so no matter how you try to "cheat" you'll won't get that beefy sound). If you just like screwing around and "learning the hard way" then go for it. As long as you don't short the output you should probably fine if you pay attention and have some "common sense".

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  • Para.7 - with or without major issues?
    – Tim
    Apr 6 at 12:32
  • 1
    Your first sentence generally applies only to solid-state. A transformer-coupled tube (valve) amplifier will be fine with low impedance, but can end up with excessive anode voltages (and damage) when driving a speaker with too high of impedance. This is why the speaker jacks on most tube amps are designed to be shorting. Example schematic: Vintage Fender Bassman
    – Theodore
    Apr 6 at 13:36
  • @Tim without. Your name should be longer
    – Gupta
    Apr 7 at 19:54
  • @Theodore Most modern amps are overbuilt so that if you have no load it will not result in catastrophic damage. Chances are you'll do just as much damage with no load as shorted which is that it will just be more significant wear and tear with a higher chance of catastrophic failure. I wouldn't to either extreme just because it's unnecessary and achieves nothing. Amps, like most things are designed to work in a way that gives them maximum purpose. If one wants to go outside of SOP for "effect" then it should be manifest what that entails.
    – Gupta
    Apr 7 at 19:54

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