8 Ohm 2X12 Guitar Speaker cabinet - 2X4 Ohms in series or 2X16 Ohms in parallel? - Page 4 - diyAudio
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Old 15th September 2013, 06:48 AM   #31
ivan H is offline ivan H  Australia
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Thanks again for the responces. I want the cabinet wired for 16 ohms (I was aware of the all parallel @ 4 ohm etc choices). The amp running thru the cab is a M@rsh@ll 1987 50W clone with a Tim Caswell #39 added triode mod(all triodes cascaded, 4 gain stages + cathode follower), so any volume loss isnt really a problem. The reason for wiring the 2 different speaker types in series is for the "exagerated anominallies" effect Cyclecamper mentioned earlier. I was just wondering if there is a more correct way to place the 25W/16 ohm speaker & the 60W/16 ohm speaker in each series wired pair (eg, jack tip connection to 25W's + & jacks sleave connection to 60W's -, or the other way around) but as no one has commented on I take it that it doesnt matter either way. Thanks again. Cheers

Last edited by ivan H; 15th September 2013 at 07:02 AM. Reason: Add to
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Old 15th September 2013, 03:22 PM   #32
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The order of the speakers makes no difference in series (which is nearer the + supply versus the -).

In series, or in parallel, the wiring also must operate the drivers in-phase. Otherwise drivers will not be pushing out (or in) together at the same time and you get a huge loss of output (especially bass) and projection. Well, really the correct word for the wiring is "polarity" but it's commonly called "in-phase" or "out of phase".

So in series, between drivers you always connect a + terminal to a - terminal.

In parallel you always want to connect all + terminals together, and all - terminals together.

When you're done, put a battery on the input. If all the cones move in the same direction when you connect the battery then the speakers are phased OK with respect to each other. If you are going to occasionally (ever) use the cabinet with other cabinets, then you also want the cabinet phased the same as them. Hmmm, I don't know what the correct "standard" phase is for a guitar cabinet, but I'm sure someone will tell us. It is worth wiring it "standard", in case someday you plug in different bottoms to work together. I never remember because I just wire them all to work like my Fender cabinets: Battery + on the tip of the 1/4" plug, - on the sleeve, and when I connect the battery all of the cones move (which way, in or out???).
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Old 15th September 2013, 03:30 PM   #33
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by cyclecamper View Post
(which way, in or out???).
positive is out, in my book
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Old 15th September 2013, 08:33 PM   #34
ivan H is offline ivan H  Australia
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Thanks for the tip with regard to phasing. Their both Celestion drivers, both designed for 4x12 application so I would expect them to have the same phasing, Celestion list the 2 as a "recommended mix n match pair", even tho there's about a 3db SPL difference between the 2 types. At some point in time Marshall appears to have changed the way in which they wire their cabs as I've seen both 2 seried pairs paralleled at the jack as well as 2 paralleled pairs seried at the jack.
So in a series wired pair there id the same power across both drivers regardless of power handling capability, right? Thanks again. Cheers
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Old 15th September 2013, 09:08 PM   #35
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Originally Posted by tinitus View Post
positive is out, in my book
I would agree, positive to positive makes cone move out.
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Old 16th September 2013, 02:13 AM   #36
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Quote:
Originally Posted by ivan H View Post
Thanks for the tip with regard to phasing. Their both Celestion drivers, both designed for 4x12 application so I would expect them to have the same phasing, Celestion list the 2 as a "recommended mix n match pair", even tho there's about a 3db SPL difference between the 2 types. At some point in time Marshall appears to have changed the way in which they wire their cabs as I've seen both 2 seried pairs paralleled at the jack as well as 2 paralleled pairs seried at the jack.
So in a series wired pair there id the same power across both drivers regardless of power handling capability, right? Thanks again. Cheers
As far as same phasing, yes some mfgrs have in the past labelled + and - backwards to the standard, but nowadays they're pretty standardized.

Yes, I think early Marshall were 2 seried pairs paralleled at the jack (which exaggerates anomalies) and later 2 paralleled pairs seried at the jack (the hi-fi way).

How you arrange them in the cabinet will alter the directions different frequencies will disperse. You may want something symmetrical in one direction or another.

How the power divides in series depends on how the impedances compare. The listed impedance is really just a 'mininal' or minimum value for computing load, but one model of driver will actually have a complex impedance curve with peaks and dips at different frequencies (and one big dip at resonance).
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Old 16th September 2013, 04:51 AM   #37
ivan H is offline ivan H  Australia
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Well thanks for the answers guys, I've definitely learnes from them. I also definitely prefer the sound of the cab wired the "old way" with 2 seried pairs in parallel, (I tried it the other way too), & it seems from looking online that I'm not alone in this with people rewiring newer cabs to the old way even with all the same speaker types, just to get that "good sound". Thanks again. Cheers
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Old 16th September 2013, 09:03 AM   #38
sreten is offline sreten  United Kingdom
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Hi,

If you wire two different drivers in parallel and then wire them
in series with the same, there is no "exaggeration" effect.
Driver bass resonances will not interact due to impedance.

If you wire two different drivers in series and then wire them
in parallel with the same, there will be a difference in sound,
the higher inductance unit will effect the lower inductance one,
the result likely being an overall somewhat darker tone.
Driver bass resonances will interact due to impedance.

(Assuming significant driver differences.)

I'd go for the first wiring method.

rgds, sreten.
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Last edited by sreten; 16th September 2013 at 09:17 AM.
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Old 16th September 2013, 11:00 PM   #39
ivan H is offline ivan H  Australia
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Thanks for the tips Sreten. Caswell's #39 mod is a very bright sounding circuit so a little darkening up isnt a bad thing. I prefer the sound of the different drivers in series , with the series'd pairs paralleled at the jack, at least with this amp. My other 50 watter is running thru a later 4x12 so I imagine (havent looked) it is wired the way u suggest. Cheers

Last edited by ivan H; 16th September 2013 at 11:08 PM. Reason: Add to
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