How to properly wire a 4x12 speaker cabinet
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So, this week I received an email from Scott, a WGS aficionado who was inquiring as to how he should wire his Marshall-style 4-12 cabinet. To be honest, I hadn’t given that one any thought in a couple of decades, and it made me think. In essence, there are two ways to wire up a 4 speaker cabinet that both wind up with the cabinet having the same impedance as any one of the individual drivers, or in other words, a cabinet with four 8-ohm speakers that ends up with a total cabinet impedance of 8-ohms.
The two main methods of arriving at this means are as follows:
Okay, so let’s talk about the difference between the two.
Here is my reply to Scott, which I will … until proven wrong … stick by:
I opened up a couple of my vintage Marshall cabs (a 4-12 and a 4-10), and both are wired "series/parallel". I really like these cabs, and so I think I’d go with that. Plus, if you do it in the "parallel/series" style and one speaker fails with a full open voice coil, all four speakers will be down, and your amp will see a no-load impedance. I know this is unlikely with your ultra low-power amp, but I’d still term it a "consideration".
Scott replied that a fellow by the name of Jim at an amp shop in his area felt as though "the parallel-series method provides a darker tone". Hummm ... I had not heard that before, and I have not been able to substantiate it. So, I’ll stick by my suggestion to go with the "vintage" Marshall series-parallel wiring method when wiring a 4-speaker cabinet. However, I am always ready to hear another point of view. If you have any experience or input in this, email me, and I’ll be sure to share the information on this blog! Oh, and as for the modern Marshall mono-stereo switch, well, let’s just say no to that little bit of absurdity (please)!
Until next week... -Vaughn-
**UPDATE**: Scott has just checked in; he tried the wiring both ways, and could discern no difference in tone - that's kinda what I would have suspected. He went with the series-parallel method for the reasons I described above. Here is a pic of the wiring in his Marshall cab, with the new WGS Green Berets installed. Looks like a good clean wiring job!
- VAUGHN SKOW's blog
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Worked just fine.
Hello,
Thank you for a good article. I'm trying to re-wire a cabinet that I just got (used), and one thing strikes me though:
In the picture, both of the two blue wires are connected between + and - straight across horizontally, but I can't seem to find those connections in the upper two illustration graphics (from jumbosunshade.com). So I was wondering which model I should follow to end up with a series-parallell wiring.
Best,
Andreas Lorentsen
Norway
Hello,
As I mentioned earlier, there's some differences in wiring between the upper two illustrations and the photo.
When I wired my cab according to the Series-Parallel illustration, I only had sound in 2 of 4 speakers (one half/side).
However, when I used Scott's photo as reference, I got sound in all speakers at 8Ω. Just thought I'd mention that.
Thanks,
Andreas
The GREEN wires in the diagram are the same as the BLUE wires in Scott's photo ... it just looks different because of the way the diagram is drawn !
Thanks for reading ... and for being a valued customer :-)
Hello,
You say the cabinet shown in the photo is wired "series-parallel" but it looks to be drawn parallel-series per the diagram. Am I seeing this right?
If you lose a voice coil in "parallel/series" as drawn above, you still will hear the other three speakers. You have the two left speakers in parallel and the two right speakers in parallel. If you lose any of the four, the one in parallel with it will still work in series with the other two parallel pair, resulting in a 12 ohm load
In the "series parallel" circuit as drawn above, you have the left two speakers in series with each other paralleled with the right two speakers in series with each other. If you lose any of the four speakers, you also lose it's series mate, but you will still have the other two functioning series pair, resulting in a 16 ohm load.