#1
I'm rewiring my 4x12 cab with different speakers. I had a mish mash of 8ohm speakers & got a reading of just over 7ohms when wired with 2 in-series pairs running in parallel. I'm fitting 4 vintage G12H30's, which are 16ohms, so I've fitted an impedance selector, just a 5amp DPDT rocker switch, so I can change between 4 & 16 ohms.

When on low setting, it reads about 4.5ohms, but on the high setting it reads just over 21ohms! All the speakers individually read around 14.7ohms, so is this 21ohm reading average, or have I got a problem somewhere? Been checking the wiring for the last 2 hours & can't find why this should be

Please help!!!! Thanks in advance
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#2
You sure you don't have one of the speakers wired wonky?

You should be getting pretty close to 15 ohms if you have the four wired two each series and then the combination of the two sides parallel (or vice versa).
You should be getting around 3.5 ohms if you've got them all four wired in parallel.

ONE speaker is wired bassackwards.
Last edited by dspellman at Aug 3, 2015,
#3
Quote by anguskilminster
I'm rewiring my 4x12 cab with different speakers. I had a mish mash of 8ohm speakers & got a reading of just over 7ohms when wired with 2 in-series pairs running in parallel. I'm fitting 4 vintage G12H30's, which are 16ohms, so I've fitted an impedance selector, just a 5amp DPDT rocker switch, so I can change between 4 & 16 ohms.

When on low setting, it reads about 4.5ohms, but on the high setting it reads just over 21ohms! All the speakers individually read around 14.7ohms, so is this 21ohm reading average, or have I got a problem somewhere? Been checking the wiring for the last 2 hours & can't find why this should be

Please help!!!! Thanks in advance


Sounds about right to me. Speakers rated at 16 ohm are often measured higher or lower by 1-2 ohm. If you want to run 4x16 run them all parallel for a 4 ohm load.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

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#4
I've rechecked the reading, it's actually 19.6 ohms. I think I was jiggling one of the speakers, which makes the reading fluctuate. I guess I'm most worried about blowing the output transformer in my amp, rather than anything else. Hopefully this won't be the case
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#5
Thanks Cajun, I was hoping that was the case
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#6
Finally got it sorted, it was a bad solder joint on one of the speaker tabs!!!
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!