612S Impedance

[Where's Uranus?]

Hi,
    Just acquired a 612s cabinet, I had a question about the impedance of it. It says on the back it's a 6 ohm 360W cabinet, however, I see people on this forum selling Sunn transducers from a 612s that are 8ohm, is the cab really only 5.333' ohms, with 3 parallel pairs of 2 8ohms in series, or is it a true 6ohm with 2 parallel triples of 4ohms in series?

I mainly asking as I want to impedance match it with a 2x15 with 2 8 ohm transducers, ideally if it's 3 sets of 8+8 then another set of 8+8 makes exactly 4 ohms, if it's 2 sets of 4+4+4 then that comes out at a slightly funkier 4.3636' ohms.

oblig smiley for breaking my Sunn virginity

[Isaac]

I wish I could say for sure.

Without having one handy to open up, I'm as sure as I can be that it's actually 5.3 ohms, with 8 ohm drivers, three parallel sets of two drivers in series. Why don't you grab a couple of tools and find out?

Ultimately, though, what difference does it make? Impedance isn't a single number. It's a moving target, depending on several factors, and your amp isn't going to notice the difference between a nominal 4 ohms and 4.36 ohms.

[JoeArthur]

If the speakers are 8 ohms, then the overall impedance would be 5.33 for 3 parallel strings of 2 speakers each.

I really don't know if Sunn used them, but 12 and 24 ohm speakers were used by other manufacturers during this era - for those odd-number of driver speaker systems. IIRC, Fender used 3-12 ohm 12" speakers all in parallel with the solid state Bassman.  The Fender Bassman 10 used 4-10" 32 ohm speakers in parallel during the 70s.

But I agree with Isaac, it's not that much of a difference to worry about and I wouldn't hesitate to use it with either a 4 or 8 ohm output impedance setting with a tube amp.

And of course solid-state wouldn't care.

[Where's Uranus?]

Very true, I guess it was a case of pedantry and laziness, well that and I don't want to open the cab up unnecessarily, which is the only real way to find out, as you say. I thought maybe someone else had already opened their cab up. Plus with mixing another cab in, the power distribution will change slightly depending on the configuration of the drivers.

As I'm driving it with a solid state SVT right now, and not a tube head, it really, really doesn't matter.

To add to JoeArthur's list, the original SVT810's used 8 32ohm drivers in parallel for 4 ohms.