a quick lesson in speaker wiring and impedence

muttonchopsrule

muttonchopsrule

New member
there's been quite a few threads lately regarding ohms, impedence, and speaker wiring. hopefully this can clear up a few issues.

let me first say that you should ALWAYS match the impedence of your cabinet to your amplifier. mis-matching can damage your amp! not having any speakers connected to your amp while it is on can be damaging also.

with that said, here are the most common wiring schemes for guitar cabinets.

series:
speakersseries.jpg


the formula for finding the total impedence for a cabinet wired in series is simply R1+r2+R3+R4 = Total. if you have four 4-ohm speakers, then you'll have a total impedence of 16 ohms (4+4+4+4 = 16). 8 or 16 ohm speakers wired in series will typically have too high of an impedence to be useful in a guitar amplifier.

4 ohm speakers - 4+4+4+4 = 16 ohms
8 ohm speakers - 8+8+8+8 = 32 ohms
16 ohm speakers - 16+16+16+16 = 64 ohms

parallel:
speakersparallel-1.jpg


the formula for finding the total impedence for a cabinet wired in parallel is impedence of speakers/# of speakers. if you have four 16-ohm speakers, this means your total impedence will be 4 ohms (16/4 = 4). using speakers rated lower than 16 ohms will give a total impedence that is typically too low to be useful to a guitar amplifier.

4 ohm speakers - 4/4 = 1 ohm
8 ohm speakers - 8/4 = 2 ohms
16 ohm speakers - 16/4 = 4 ohms

series/parallel
speakerss-p-1.jpg


this is probably the most common way to wire a 4x12. whatever the impedence of each speaker is is what the total impedence of the cabinet will be.

4 4-ohm speakers = 4 ohms
4 8-ohm speakers = 8 ohms
4 16-ohm speakers = 16 ohms

if you're ever having trouble wiring up a cabinet or you aren't sure what the impedence of your cabinet is, then these are the diagrams you want to follow. also, you should never use speakers with a different impedence in the same cabinet. if you change the wiring in your cabinet, it is also helpful to have a multimeter handy so you can measure the actual resistance to double check your work.
 
Re: a quick lesson in speaker wiring and impedence

Pictures%2Funtitled.bmp


theres a diagram of mine, which one does that match? i cant really follow it
 
Re: a quick lesson in speaker wiring and impedence

As you say, as long as you're using the same impedance speakers in the cabinet. Then your parallel formula will work. But it's actually:

1/Spkr1 + 1/Spkr2 + 1/Spkr3 + 1/Spkr4 = 1/Final Value

These are all mathematical inversions. Best done with a calculator. Then you invert the solution one more time to get the final impedance.

e.g. 1/8 + 1/4 = 3/8

then 1/(3/8) = 2.66 ohms

Pretty wierd, isn't it?

Like the man said, stick to same value speakers!!

Noth
 
Re: a quick lesson in speaker wiring and impedence

Thanks man that was really helpful. I'm getting two eminence speakers for my 2x12 cab. I was going to get 8 ohm speakers but i'm also thinking of upgrading to a 4x12 later on, so if i'll get 2 more 8 ohm i'll get a 8 ohm cab, and i'd rather get a 16 ohm cab. Is there a way to wire 2 16 ohm speakers to get a 16 ohm cab?
 
Re: a quick lesson in speaker wiring and impedence

LooseCannon said:
Thanks man that was really helpful. I'm getting two eminence speakers for my 2x12 cab. I was going to get 8 ohm speakers but i'm also thinking of upgrading to a 4x12 later on, so if i'll get 2 more 8 ohm i'll get a 8 ohm cab, and i'd rather get a 16 ohm cab. Is there a way to wire 2 16 ohm speakers to get a 16 ohm cab?
Click to expand...

with two 16 ohm speakers, your only possibilities are wiring them in series to get 32 ohms, or wiring them in parallel to get 8 ohms.

if you want to be able to add another cabinet later, you have to plan out the impedence combinations now. how many speaker outputs does your amp have, and what is the impedence on each?
 
Re: a quick lesson in speaker wiring and impedence

muttonchopsrule said:
with two 16 ohm speakers, your only possibilities are wiring them in series to get 32 ohms, or wiring them in parallel to get 8 ohms.

if you want to be able to add another cabinet later, you have to plan out the impedence combinations now. how many speaker outputs does your amp have, and what is the impedence on each?
Click to expand...

This is all correct. Do we know our stuff or what?!? Damn if I could play 1/10th as good:chairfall

Noth
 
Re: a quick lesson in speaker wiring and impedence

muttonchopsrule said:
with two 16 ohm speakers, your only possibilities are wiring them in series to get 32 ohms, or wiring them in parallel to get 8 ohms.

if you want to be able to add another cabinet later, you have to plan out the impedence combinations now. how many speaker outputs does your amp have, and what is the impedence on each?
Click to expand...

I have one amp with 8 and 4 ohm outputs and another with 4\8\16 ohm. So I guess it's either getting two 8 ohm and wiring them to get 16 ohm now, and 8 ohm on a 4x12, or getting two 16 ohm and wiring for 8 ohm now and 16 ohm on a 4x12, right?
 
Re: a quick lesson in speaker wiring and impedence

Vault Worthy.

If I may butt in: Never completely trust your eyes for the wiring, and never trust an expert/tech if his @$$ is not on the line. Whenever possible...get a multimeter, and check the Ohm reading at the output jack BEFORE the amp is ever plugged in, and fired up!

This only takes a second, and folks who do not know how to use a multimeter should be able to find a tech willing to show them the static Ohm reading. If a tech wants to charge cash to give you the concrete answer, so be it. Pay the man, or find another tech. No whining allowed. The choice is yours. He may have given some well-intentioned free advice over the telephone before, and got burned!

Every bit of wire, and every solder connection need to be 100% electrically correct, and physically strong. There are some heinous wiring jobs out there to fixed.

I got a used cab off ebay this month, and a mulltimeter was used before it was ever connected to the amp. It was also used after each speaker change at the output jack. One needs to preserve the integrity of the amp. Speaker wiring may be "easy", but there enough variables in the execution of a "simple" speaker wiring job to screw things up.
 
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