The sunn Forum
Sunn Musical Equipment => Q & A => Topic started by: Walt-Dogg on August 11, 2010, 02:05:39 pm
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It just came to mind that there's the possibility that the speakers might not be wired right in my 412L. Could anyone tell me how they should be wired (series or parallel, or some crazy design Conrad came up with) and a diagram? So I could check myself and see?
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There could be several ways that the cabinet could be wired. If you have 4 - 16 ohm speakers, the wiring could be either all in parallel to give you a 4 ohm load, or series / parallel for a 16 ohm load.
If you have all 8 ohm speakers, the wiring is usually in a series / parallel configuration to give an 8 ohm load.
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It has the original 4 - 8 ohm speakers for an 8 ohm load (8 ohm load to my knowledge that is). You know it's probably in the catalog... *checks catalog* ...Doesn't say... Hmm, I guess I should just pull it open and see how it is wired as opposed to how it should be wired. So how should a stock 412L be wired?
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Mr. Sundholm had been "done with Sunn" for the better part of a decade before your 412L was designed, so it's pretty unlikely that it's "some crazy design Conrad came up with". :-D
The only 4x12 during his era was the 42" high X 24" wide Sceptre cab AFAIK.
If you have all 8 ohm speakers, the wiring is usually in a series / parallel configuration to give an 8 ohm load.
Series/Parallel is indeed probably the most common four driver cabinet wiring, and the 1979 catalog shows the cabinet as being 8 ohms, so if it has 8 ohm drivers in it, series/parallel it is.
If they are indeed 8 ohm drivers, and intend to keep the power distribution even across all drivers, you have the choice of 32, 8, or 2 ohms.
What is the impedance of the drivers, and what impedance do you want the cab to be?
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My mistake, I'm not too versed in the history of Sunn.
It's the original 8 ohm speakers and the cab is supposed to be 8 ohms, which I want it to be.
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i have that cab and i witnessed GregAnderson in GoatSnake using one lastnite and it killed!
four 8 ohm spkrs in two's wired in par= 4ohm plus two spkrs wired in par-add them in series 4&4 to get 8 0hms.
(i think thats how its done-i could be wrong and i'll eat a bug)
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So what kind of diagram am I looking for then? If I want an 8 ohm load from 4 - 8 ohm speakers/
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have a look here, http://www.colomar.com/Shavano/spkr_wiring.html or if you have a multimeter you can save yourself the hassle of removing any speakers...
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Well I cross checked my speakers' wiring to a series/parallel diagram I found. They matched. So I guess the cab just doesn't sound that good.
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There are only three eras of Sunn history;
Sundholm - Inception to '71?
Hartzell - '71 until '86 or '87?
Fender - late 80's until the end. Fender still owns the name.
IMO the quality, tone, and collectabilty dropped from era to era.
Here's a chart;
(http://i626.photobucket.com/albums/tt341/EdBass/SeriesParallel8ohm.jpg)
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That one's a bit more confusing than the one I used, but yeah my cab's wired correctly for an 8 ohm load.
And EdBass I'll keep that in mind. Thanks.
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The big difference here is if you wire the cab series/parallel,and one driver fails,you also lose the one it's in series with,so now you're running on two drivers.If you wire it parallel/series,and one driver fails,the other three keep working,except one will be lower in volume because it's parallel "mate" is now open and the impedance will double on that leg,good luck,Mel.
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have a look here, http://www.colomar.com/Shavano/spkr_wiring.html or if you have a multimeter you can save yourself the hassle of removing any speakers...
I recently acquired myself a Beta Bass, but with only one 410 (each speaker rated at 8 Ohms, presumably wired in series/parallel to give an overall impedance of 8 Ohms), I was wondering how I could rewire the 410 to 4 Ohms to get the full use of the amp (100W at 4 Ohms).
The document that Ed provided the link to doesn't show this to be possible (at least, not with only 4 speakers), though in theory it must be - presumably if there are two sets of 2 speakers wired in parallel, and those two sets then wired to the other in series?
Jon.
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"in theory it must be"? Why? In fact, it is theory that says it is not.
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My "theory" was premised on what I read in the link that Ed took us to, under the heading "8 Speakers - Series/Parallel Wiring; In Phase".
There, albeit with 8 speakers rather than 4, we are told that individual speakers rated at 8 Ohms will create a total load impedance of 4 Ohms if wired in series/parallel.
I therefore theorised that the same wiring could be applied to 2 sets of 2 speakers in my quad, with the result that four 8 Ohm speakers wired in series/parallel would give a total load impedance of 4 Ohms.
Would you care to elaborate on why this is not the case?
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As I posted before, with four 8 ohm drivers you have the choice of 32, 8, or 2 ohms. It's not really a "theory" at all, it's just the way it is. The reason that eight 8 ohm drivers can be wired for 4 ohms is best described by thinking of the 4 ohm 810 as two 8 ohm 410's wired together in parallel.
Theoretically, you could wire it for 2 ohms and put a resistor in the circuit to obtain 4 ohms; but that is such a terrible idea on so many levels it's not worth explaining. :wink:
It also would be counterproductive to the reason you want a 4 ohm cab in the first place, it wouldn't be louder than an 8 ohm cab, probably quieter in fact.
As far as getting "full use of the amp", the difference between running the amp at 8 ohms vs. 4 ohms isn't really that great.
A lot of people assume that just halving the impedance will make your rig about twice as loud.
I'm not real sure about the Beta output with an 8 ohm load; I'm going to guess about 60 watts or so. If that is correct, you might pick up a decibel or two in volume by running the same cab but at 4 ohms.
IMO not worth messing with; you probably won't even be able to tell it's louder without using a dB meter, and the amp is much happier and cooler running at 8 ohms.
If you want louder, add another 8 ohm 410. That will pump things up! :-D
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Thanks Ed.
I'm not actually looking for louder - I was simply concerned about the mismatched impedance between the amp and speakers. Since the Betas are rated 100W at 4 Ohms, and there is no switch on the amp to raise the impedance to 8 Ohms, other people on this site had me worried that an 8 Ohm load was not optimal (and therefore potentially bad) for this kind of amp.
Rest assured, I am happy to know that "the amp is much happier and cooler running at 8 ohms"!
How about this then: There are two jacks on the back of my 410. There are also two output jacks on the back of my amp.
Is there any reason why I can't, inside my 410, wire a set of two speakers in parallel and connect them to a jack on the 410, and do the same with the other set of two speakers. The impedance of each of the two sets of 8 Ohm speakers would then halve to 4 Ohms. I could then run a lead from each output on the amp to each jack on the back of the 410.
Cheers
Jon.
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Thanks Ed.
I'm not actually looking for louder - I was simply concerned about the mismatched impedance between the amp and speakers. Since the Betas are rated 100W at 4 Ohms, and there is no switch on the amp to raise the impedance to 8 Ohms, other people on this site had me worried that an 8 Ohm load was not optimal (and therefore potentially bad) for this kind of amp.
Rest assured, I am happy to know that "the amp is much happier and cooler running at 8 ohms"!
I think you may be confusing tube amps with transistor amps.
Tube amps use transformers to match the load impedance with the impedance of the output stage of the amp, they make the same power with any speaker impedance but you need to select the output transformer output (referred to as output “tap”) that matches the load with the output stage.
Transistor output stages don’t need to be matched, they will also put out increasingly more power the lower the load impedance gets down to the point where the amp fries. With an 8 ohm load your Beta is more stable than with a 4 ohm load, but will make less power with the 8 ohm load.
How about this then: There are two jacks on the back of my 410. There are also two output jacks on the back of my amp.
Is there any reason why I can't, inside my 410, wire a set of two speakers in parallel and connect them to a jack on the 410, and do the same with the other set of two speakers. The impedance of each of the two sets of 8 Ohm speakers would then halve to 4 Ohms. I could then run a lead from each output on the amp to each jack on the back of the 410.
The reason you can’t do that is because there is really no way to circumvent Ohm’s Law.
There is only one actual output on your amp. Those two jacks on the back are that single output split, and when you spilt the output like that the jacks have to be either in series or parallel. The jacks on the back of your amp are in parallel so you need to factor that into your impedance calculations, using your idea would actually be showing 2 ohms to the amp, which I believe is below what a Beta is rated for.
There are lots of threads about both of these issues; a search is your friend!