Re-wired my Ashton Quad Box.

Hey Everyone,

Last night I did some re-wiring work on my Ashton 4X12 Quad Box, basically re-wiring the speakers from it's stock wiring to what's called a series-parallel wiring where I have two 8 Ohm speakers wired in series which are then connected in parallel with another two 8 Ohm speakers that are wired in series, the original stock wiring of the speakers was two 8 Ohm speakers wired in parallel which were connected in series with another two 8 Ohm speakers which were connected in parallel, this is what I call parallel-series wiring, here's a diagram to illustrate the differences between the two methods of wiring-up the speakers, note that both methods result in the same total impedance of 8 Ohms.

Attachment 44002


Here's why we end-up with a total impedance of 8 Ohms for each of the two wiring methods, in the case of the stock Parallel-Series method of wiring, if we wire two 8 Ohm speakers in parallel we get a total of 4 Ohms, if we wire 4 Ohms in series with another 4 Ohms we get a total of 8 Ohms because the two 4 Ohm speaker loads add-together.

On the other hand, if we wire two 8 Ohm speaker loads in series we get a total of 16 Ohms (they add together), if we then wire two 16 Ohm speaker loads in parallel we get a total of 8 Ohms because two identical impedances in parallel will always result in a total impedance of half of one of the impedances.

Remember, resistances in series add, and if you put two identical resistances in parallel, the result is always half the resistance value of one of the resistances.

In the past, I have tried my Ashton Quad Box out with my Marshall amp by unplugging the internal speakers from the socket and plugging the Quad Box into the 8 Ohm speaker out, and I remember my Marshall amp sounding a bit weak and thin as well as low in volume, well, I noticed a dramatic difference when I tried the Quad Box out with my Marshall amp after I had re-wired it to a Series-Parallel configuration, the Marshall sounded much fatter, louder, and more dynamic too, all the speakers in the Quad Box measured fine on my multimeter, no coil rubbing either, I was really surprised at the difference, literally day and night, very happy with the results I got from the re-wiring.

Each of the four speakers are Celestion Rocket 50s which I presume are rated at 8 Ohms/50W each.

I wonder if when your speaker cabinet was originally wired, the speakers were out of phase, and when you rewired it you corrected this and fixed the sound. Just a thought, as I can't see how the parallel-series method would cause any issues if done correctly.

Quote:

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Originally Posted by ian_macpherson

I wonder if when your speaker cabinet was originally wired, the speakers were out of phase, and when you rewired it you corrected this and fixed the sound. Just a thought, as I can't see how the parallel-series method would cause any issues if done correctly.

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It is entirely possible that at least two of the speakers may have been inadvertently wired out of phase at the Ashton factory, and I corrected it when I did the wiring, the cab did sound good before doing the wiring when I tried it out with my Super Twin amp, and I didn't notice any phase issues with it before.

I have tried the cab out with my Super Twin amp and the Marshall after doing the re-wire and it seems to work really well with both amps, there's a low-end resonance that I never noticed before, and yes, I did make sure I had all the speakers correctly phased while doing the re-wire, I used a blue sharpie to mark the + and - terminals on each speaker.

Both the Series-Parallel and Parallel-Series wiring methods should result in the exact same speaker load impedance, assuming that all four speakers in each case are 8 Ohm speakers, it's possible that with the re-wiring both my Super Twin and Marshall amps are seeing the proper load impedance being reflected back into the output transformer, although yes the phasing of the speakers may also have something to do with it too.

I've decided to keep a very open mind about the whole thing.