Sunn 6x12 ohm issue (using with other cabs)

[beebassdude]

So my guitarist recently picked up a sunn 612 that looks like its dated 1967, which is pretty awesome. he was originally planning on running it with another cab but it turns out the ohm rating on this thing is something like 5.5 (assuming its rated at 6, if theres 2 sets of 3 8 ohm speakers).

im wondering if anyone has experience with these behemoths and if theyve ever run multiple cabs with them, and if so, how did you run it without overloading or underloading the head? i gotta imagine that these things are capable of running with another cab but were trying to figure out how. any info would be helpful, thanks dudes.

[beebassdude]

cmon, somebody has to have some experience with this cab.

[Bmorefoozler]

Run a 16ohm(2 8 ohm drivers in series) 2x12 on top of it for a full stack. you will be at 4ohms.

[Nightlyraider]

Using that cabinet by itself off a 4 ohm tap would be OK. Similar resistance rating to that of a 310.

[fu22ba55]

Originally Posted by beebassdude

it turns out the ohm rating on this thing is something like 5.5

Hey, Bee.

I'm assuming that's what you got when you checked at the output jack with an Ohm meter? (since you said it's rated at 6?)

All the vintage guys are going to swoop in here and tell you that back then, impedance was an "inexact science" to put it mildly.

Many "4 Ohm" cabs hover around 4.8, or 5.3 when checked with a meter. I think 5.3 was universally accepted as 4 Ohms back in the 70's. (Heaven knows what was acceptable in '68)

Some of my 8 ohm cabs read 8.6 ish on the Ohm meter.

My guess is that it was rated at 4 Ohms. Erring on the higher side for impedance (setting the amp's output impedance to 4 Ohms, leaving cab at 5 Ohms) is probably safer than setting the Amp to 8 ohms and running at 6.

And you could double check to make sure all speakers are connected and original. Maybe something was swapped out in the 42 years the cab has been pushing air.

[beebassdude]

Originally Posted by fu22ba55

Hey, Bee.

I'm assuming that's what you got when you checked at the output jack with an Ohm meter? (since you said it's rated at 6?)

All the vintage guys are going to swoop in here and tell you that back then, impedance was an "inexact science" to put it mildly.

Many "4 Ohm" cabs hover around 4.8, or 5.3 when checked with a meter. I think 5.3 was universally accepted as 4 Ohms back in the 70's. (Heaven knows what was acceptable in '68)

Some of my 8 ohm cabs read 8.6 ish on the Ohm meter.

My guess is that it was rated at 4 Ohms. Erring on the higher side for impedance (setting the amp's output impedance to 4 Ohms, leaving cab at 5 Ohms) is probably safer than setting the Amp to 8 ohms and running at 6.

And you could double check to make sure all speakers are connected and original. Maybe something was swapped out in the 42 years the cab has been pushing air.

the multimeter read 5.5, which could either be 6 or 4 depending on which way you swing. the issue is connecting it with another cab and running them both off of one head. were trying not to get any strange loads going from one or the other (loads with decimal points lol).

if you are correct and 5.3 or 5.5 was accepted as 4 ohms, then we're in business. the issue is just making sure that were not damaging any heads/cabs by doing this. i guess we wanna make sure that this is not like running an 8ohm cab and a 4ohm cab with the same head, where the loads are unequal. hopefully im making sense, and i really dont like typing load this much lol.

[fu22ba55]

Originally Posted by beebassdude

if you are correct and 5.3 or 5.5 was accepted as 4 ohms, then we're in business.

5.5 Ohm cab and 4 Ohm cab wired parallel yields 2.32 Ohms. I would call that a safe 2 Ohm load. (Since 2 Ohms is usually the MINIMUM you want to attain running a 2 Ohm load.)
(same cabs in series would yield 9.5 Ohms. Yikes)

5.5 Ohm cab and 8 Ohm cab wired parallel yields 3.25 Ohms which is too high for a 2 Ohm tap, too low for a 4 Ohm tap.
(cabs in series would yield 13.5 Ohms. Yikes again.)

What you have to be careful of at that point is how many watts each cab is rated for. I've had a 100% legit 4 Ohm load brutally cook one driver when one of the drivers was rated at 200ish watts, and the other was rated at 280ish watts. Even though impedances were correct, the 280 W rated speaker could handle way more load, so when in parallel, the lower rated speaker cooked.

I'd be careful. Math doesn't always tell the whole story.

You could also disconnect two of the speakers, but I know that sucks. Still looks cool, but carrying around two dummy 12s is a drag.

[BassmanPaul]

Originally Posted by fu22ba55

You could also disconnect two of the speakers, but I know that sucks. Still looks cool, but carrying around two dummy 12s is a drag.

The two disconnected cones would act as passive radiators and alter the cabinets tuning.

Paul

[KramerBassFan]

What kind of amps is he running, and what other speaker cabinets are in the equation?

[beebassdude]

i was just hoping someone had run one of these cabs with another cab and had some experience with this exact cabinet. good info so far tho guys.

[fu22ba55]

Originally Posted by beebassdude

i was just hoping someone had run one of these cabs with another cab and had some experience with this exact cabinet. good info so far tho guys.

Can you snap a pic of the cab? I remember seeing a Sunn cab here locally (that I might be able to see again if I hunted it down) that I believe was 6x10. I believe it was this one, where the two rows of speakers face inward to form the V of death and hearing loss... I've never seen the 6x12 though...



The Sunn Forum should have tons of info on it too.

http://sunn.ampage.org/

http://sunn.ampage.org/sdp/

[KramerBassFan]

Originally Posted by fu22ba55

Can you snap a pic of the cab? I remember seeing a Sunn cab here locally (that I might be able to see again if I hunted it down) that I believe was 6x10. I believe it was this one, where the two rows of speakers face inward to form the V of death and hearing loss... I've never seen the 6x12 though...



The Sunn Forum should have tons of info on it too.

http://sunn.ampage.org/

http://sunn.ampage.org/sdp/

Here.


That one is a late 60's, the one you posted is a late 70's early 80's model. Hartzell corp.

[Stumbo]

http://sunn.ampage.org/site/catalogs/1968/1200s.jpg

Check out the weight.

There's also a V shaped front face cab: http://www.richbriere.com/images/1972cat3.gif

[billfitzmaurice]

Originally Posted by beebassdude

the multimeter read 5.5, which could either be 6 or 4 depending on which way you swing..

5.5 ohms DCR translates to 8 ohms impedance.
As for running with another cab, I can't imagine a good 6x12 needing any assistance. But whether this is a good 6x12 or not depends entirely on the drivers, and with cabs of this vintage that's a 50/50 proposition.

[fu22ba55]

Originally Posted by billfitzmaurice

5.5 ohms DCR translates to 8 ohms impedance.

I wish I knew more about what I'm talking about. Thank you Bill.

[beebassdude]

Originally Posted by billfitzmaurice

5.5 ohms DCR translates to 8 ohms impedance.
As for running with another cab, I can't imagine a good 6x12 needing any assistance. But whether this is a good 6x12 or not depends entirely on the drivers, and with cabs of this vintage that's a 50/50 proposition.

so just in theory if we wanted to, we should be treating this cab as an 8 ohm cab? so if we had another 8 ohm cab (412 cab) both could be run by a 4 ohm head? without damage in terms of unequal amounts being spread across both?

[billfitzmaurice]

Originally Posted by beebassdude

so just in theory... both could be run by a 4 ohm head...without damage in terms of unequal amounts being spread across both?

Yes, but as to how the power would be distributed to the two cabs and to the drivers within them, and how they'd all be able to deal with it, is far too complicated an issue to predict. All you can do is try them.