wiring up a foamy 4x12"

[nyazzip]

i'm making a somewhat temporary 4 x 12" speaker box. i had the brainstorm this winter to make one out of "Foamular" foam insulation...you know, the rigid pink stuff made by Dow-Corning, to insulate houses? i'm just goofing around.
it should weigh about a tenth of what a standard 4x12 cab weighs, i figure. i don't intend to bring it on an international stadium tour, so it ought to stay together for a few hours at least. i'm VERY curious to hear how it sounds...heh heh
here's the issue: i have three 8 ohm speakers, and one 4 ohm speaker to use.
i calculated that a series/parallel wiring scenario would produce a 6.8 ohm speaker box.
is there any way to get a nice clean 4 or 8 number? if not, it should be kosher to use the amplifier's 8 ohm tap to power the "6.8 ohm" cabinet.... right...? also these are low powered speakers, some maybe as low as 8 or 10 watts each. will the oddball speaker drink up more juice than the other 8 ohm speakers? Yellow_Light_Colorz_PDT_07
the caulking ought to be hard by tomorrow

[Geek]

Hi,

We had a thread on Guitars Canada about this... you can't mix different ohms without one speaker hogging more power. One guy ended up with a dead speaker in an attempt.

They need to be all the same ohms for round ohm number and full power capability.

Cheers!

[nyazzip]

well, i'm gonna try it out anyway i guess. i don't plan on cranking it, i just want to hear some big full sounds. i made a mistake, i actually have three 4 ohms and one 8 ohm. same problem, different values

[EWBrown]

You can connect an 8 ohm (or 10 ohm) 25W (or greater)resistor across the 8 ohm speaker, to make it look like 4 ohms, then connect the speakers in series-parallel for 4 ohms total.

THe 8 ohm speaker (and resistor) will be less loud than the other three, but it will work well enough.

If anything this will be a good test the foam box's rigidity and strength :o

/ed B

[nyazzip]

ain't she a beaut. doesn't sound too bad, maybe a lil upper-midrangey. i question the SPL ratings of those 40 year old speakers though, seems a bit quiet, which is ok, because i can open up the amps a bit more than normal. they also have lackluster bass response. again no surprise
the final impedance using (3) 4 ohm speakers with (1) 8 ohm in series parallel is just over 4 ohms. close enough for rock and roll
if i end up liking it i might cover it in some fake brick paneling i saw at a home improvement store. now Yellow_Light_Colorz_PDT_05 that would be goofy lookin...

[EWBrown]

What vintage is that Strat?

Looks nice Yellow_Light_Colorz_PDT_11

I sold a 1965 vintage Jazzmaster for some "crazy money" last year. Yellow_Light_Colorz_PDT_06 Had it for 40 years (bought it in 1968 for about 5-6% of that it sold for. Better than the Dow-Jones, fer shure Yellow_Light_Colorz_PDT_01 Yellow_Light_Colorz_PDT_08

/ed B

[nyazzip]

What vintage is that Strat?

nothing exotic, it's a 1987. i got it new when i was about 16; i'll never part with it, its been a good friend