speaker wiring for new custom built cab.

  • Thread starter Thread starter Br3n
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Br3n

Br3n

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hey all for those that know about speaker wiring does this work?

i am wanting to build a 3 speaker cab with 2x12s and 1x15 but i need it in to 4 ohms so can i purchase 2x12 as 4ohm and wire them in series to get 8ohms then purchase an 8ohm 15 and wire that in parallel i am thinking this will give me 4ohms but am unsure?
 

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Yes ...... that will give you 4 ohms.

Or you could get two 16ohm 12s and wire everything in parrallel and that will also be 4 ohms total load.
 
thank you mate. the 12" speakers i am looking at only come in 4ohm or 8ohm :/

also if i have read correctly all the speakers need to be the same wattage or can i say do the 2x 12s at 250 watts each and the 15 at 300watt or 500watt. is the wattage a concern?
 
Br3n said:
thank you mate. the 12" speakers i am looking at only come in 4ohm or 8ohm :/

also if i have read correctly all the speakers need to be the same wattage or can i say do the 2x 12s at 250 watts each and the 15 at 300watt or 500watt. is the wattage a concern?
Click to expand...

well ..... that depends on what you're gonna run into them. They should all be able to handle their share of the power.
But as for them needing to be the same power rating ..... I don't see any reason for that as long as they'll handle enough power.
It may be that people saying that are confusing power handling with efficiency.

Let's say that all the speakers are right at their power limits.
lets also say that the 12s are wildly less efficient than the 15. So you hear the 15 but don't hear the 12s ...... so you keep turning it up to get the 12s honking.
Now you've over powered the 15 trying to get the 12s up.
But that's efficiency rather than power ratings.
Ideally you're gonna want them to be within a few db of each other efficiency-wise. If it's a bass rig I'd probably want the 15 slightly more efficient ideally.
 
well .... first, this is getting into personal preferences so YMMV :
I'm assuming this is for bass?

I don't quite get the reasoning behind using a 15 with 12s if they have the same basic freq response. What will you gain? I would want a 15 that went lower than the 12s ...... otherwise may as well just use 12s.

But aside from that ..... the two models you showed do have fairly different sensitivities. The 15 is 98db and the 12s are 94.6. Now ..... 3db is double the volume although that's not the same as percieved volume. So I think you could gestimate that the 15 will be percieved as about 25-35 percent louder than one of the 12s so probably it'll match up fairly well with two of them as far as output goes.

Wanna see how this turns out.
 
i wanted 12's because then i don't need to put a crossover in there. i am hoping the 15 will be a bit more controlled in the low end. i may even put 10" in it yet but i don't like the tones 10" gives out.
 
Br3n said:
thank you mate. the 12" speakers i am looking at only come in 4ohm or 8ohm :/

also if i have read correctly all the speakers need to be the same wattage or can i say do the 2x 12s at 250 watts each and the 15 at 300watt or 500watt. is the wattage a concern?
Click to expand...

If I remember my E.E. classes correctly, your 12" speakers can have half the wattage rating of the 15" and you'll be fine. In theory and practice with series wiring you can add the wattage handling of those 12" speakers together because they have the same impedance, they will dispel the same amount of power each. With the 15" in parallel (and having the same impedance as the 12" in series) in theory the power will be split equally between the two, however in practice these two are not necessarily equal. So while the theoretical max wattage this amp could handle is 1000 watts RMS, I wouldn't let it be driven at more than 750 or 800 watts RMS.
 
i never intend to use an amp head that has any more than 600watts. im undecided on the head at the mo but there are 2 i am looking at a bugera at 550 watt and an eden at 400 watt
 
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