8 or 16 ohm ?

[guitarcase]

Just got a tiny terror. It can take a 8 or 16 ohm speaker. As I am only going for 1 x 12, prob g12m, which would be best? (and why?)

[HogmanA]

Hi,
here is some info regarding your question - it was copied from an old thread posted on here, not by me. But it sounds good! And actually, what I've heard through trying different speakers backs this up, but only with 4x12's - don't know how much difference you'd hear in 1x12.


'The primary side of the OT does see the same load at all impedances, yes - but it's the difference in inductance ratios between the speakers and the OT secondary that's important.

When you double the impedance of a speaker, you also (roughly) double its inductance. But the impedance ratio of a transformer is proportional to the square of the turns ratio, and the inductance is only directly proportional to the turns ratio, so doubling the impedance of the OT secondary does not double its inductance, it only raises it by 1.41 (square root of two) times.

So, when running at 8 ohms, the speakers have more inductance proportionally relative to the OT than they do at 4 ohms. Then, since in a circuit the high frequencies are distributed more toward high inductance than low, this means that at 8 ohms the speakers receive proportionally more highs than they do at 4 ohms - hence, brighter sound.

The effect is then exaggerated because at higher impedances, the current is reduced (as well as the voltage raised), compared to at lower impedances. This makes the damping effect of the inductance less important, so the response is more 'peaky' at higher impedance, and you hear the speaker characteristics a little more.

So, the higher impedance you run at, the brighter and less damped the tone.

Series vs. parallel wiring for the speakers multiplies the effect even more, because the inductances of the speakers divide in parallel and add in series (like resistance), so a series-wired pair running at 16 ohms have even greater inductance relative to the OT than a parallel-wired pair at 4 ohms - and speakers in parallel damp each other more heavily than in series.'

[rocknhorse1]

I would bet you wouldn't be able to even hear the difference, maybe a dog can. Once the rest of the band kicks in, no way you will hear it. I wouldn't really spend a lot of time worrying about it, but that is just me.

It won't be like a pickup change, or a tube swap, much, much less of a difference.

[dwagar]

I'd suggest a 16ohm, just in case you want to add a second cab sometime in the future (2 in parallel would then be 8 ohm)

[guitarcase]

Originally Posted by dwagar

I'd suggest a 16ohm, just in case you want to add a second cab sometime in the future (2 in parallel would then be 8 ohm)

Thanks all. Ok. Looks like I will go for 16 ohm, as I could always draw on another 16 for a 2x 12 as an option, at later date.

[snaredrum]

i run at 8 as it was easier for me to get attenuators at that impedance or whatever the word is.