Speaker Wiring Issue

[Lazarus1140]

I have an early 80's Mitchell CELE GB 4-12 speaker cabinet. I removed the original speakers many years ago and want to re-install them, but I can't figure out how to wire them. The original (4) speakers are 15 Ohm Celestion G12-80s, and the cabinet label at the input socket says 8 Ohms. How is that possible? I could wire them in series for 60 Ohms, parallel for 3.75 Ohms, or series/parallet for 15 Ohms. But how is it possible to get near 8 Ohms?

Did the manufacturer put the wrong speakers in the cabinet or the wrong label on it?

 

[ehdwuld]

Assume they are a ,, b ,c, & d

Wire a and b in parallel for 4 ohms
Wire c and d in parallel for 4 ohms

Then wire the first pair in series with the second pair for 8 ohms

 

[Lazarus1140]

Assume they are a ,, b ,c, & d

Wire a and b in parallel for 4 ohms
Wire c and d in parallel for 4 ohms

Then wire the first pair in series with the second pair for 8 ohms

I tried to edit my post, but the edit wouldn't stick. The speakers are each 15 OHMs.

 

[Artie]

Yup. What he said. Also keep in mind, a speakers actual impedance is all over the map, relative to frequency. Here's the graph of an Eminence Cannabis Rex. It only hits 8 ohms a about three spots. The light orange line:

 

[Artie]

I tried to edit my post, but the edit wouldn't stick. The speakers are each 15 OHMs.

Then, they are effectively, 16 ohm speakers. You can wire them as ehdwuld said for 16 ohms, or all in parallel for 4 ohms. There's no way to get 8 ohms.

Hard to say what the original cab was doing.

 

[Lazarus1140]

Well then, let me ask this. Which would appeal to more potential users - 4 or 15(ish) Ohms? Or would it be smarter to try to sell the speakers and trash the cabinet? I'm a 1-12 combo guy, so it's all just useless clutter to me.

 

[ehdwuld]

Then, they are effectively, 16 ohm speakers. You can wire them as ehdwuld said for 16 ohms, or all in parallel for 4 ohms. There's no way to get 8 ohms.

Hard to say what the original cab was doing.

What i posted is 8 ohms combined with 4 16 ohm speakers

Says so right in the post

Combining two 4 ohm pairs in series
results in 8 ohm load

 

[ehdwuld]

Old geezers

 

[Artie]

What i posted is 8 ohms combined with 4 16 ohm speakers

Says so right in the post

Combining two 4 ohm pairs in series
results in 8 ohm load

Yup and yup. My comment was in reference to his correction of them being 15 ohm speakers.

 

[ehdwuld]

Someone got confused as I read down through it

 

[ehdwuld]

If you had 8 ohm speakers

Two 8s in series = 16

Two 16 ohm pairs in parallel = 4

-----------

Two 8s in parallel = 2

Two 2 ohn pair in series is 4

Four eight ohm speakers will end up 4 either way

 

[ehdwuld]

I had this issue when I was wiring my HB 2x12

It spec'd at Two 16s and all i had were 8s

I jumper the 8s to make a 16 load

Then got a wiring harness from sound town that would make it do the
Parallel 16 in one jack
Single 8s in two orther jacks

And a fouth jack I put tape over that goes to 4

 

[Lazarus1140]

I appreciate all the input and fully understand the three wiring options and their results. I was just baffled by the manufacturer having labeled the cab 8 Ohms. That will remain a mystery. But I need to reinstall and wire the speakers. Between 4 Ohm and 16 Ohm - what total resistance do you think would be most preferrable to most players who use separate heads and cabs?

I am most certainly an old geezer, and I prove it almost daily.

 

[ehdwuld]

8 ohm is the most common output for a head


What speakers were in it?

It may be better to sell the speakers separately

And then the unloaded cab

Or if they have no value
Sell it as a kit


If you want to use it there are jack plates on Amazon that will switch back and forth from 8 ohm mono and 4 ohm stereo

 

[Artie]

If you had 8 ohm speakers

Two 8s in series = 16

Two 16 ohm pairs in parallel = 4

-----------

Two 8s in parallel = 2

Two 2 ohn pair in series is 4

Four eight ohm speakers will end up 4 either way

Two 16 ohm "pairs" (assuming the pair in series) = 16

Two 8's in parallel = 4

Four 8's can either be 2, all parallel, 32, all series, or stay at 8, series-parallel.

 

[Lazarus1140]

The "original" speakers were the 15 Ohm Celestions. I can only suppose that the cabinet that I thought was new was actually pre-owned and someone switched out the original speakers.

 

[Artie]

So, you have three choices:

All in parallel, for 3.75 ohms. Not ideal, but will work if your amp has a 4-ohm setting.

All in series, for 60 ohms. Not recommended for a tube amp, but ok for a SS amp, but with reduced wattage out.

Series / parallel, as my diagram shows, to stay at 15 ohms total. This works fine if your amp has a 16-ohm out or is SS.

 

[Seashore]

16 (or 15) ohms total is more useful than 4. Most guitar heads are rated for 16, and two 16 ohm cabinets can be run in parallel for an 8 ohm load. A 4 ohm cabinet means you're stuck with just that one unless your amp can handle a sub-4 ohm load, which is rare for guitar heads IME.

 

[Seashore]

If you had 8 ohm speakers

Two 8s in series = 16

Two 16 ohm pairs in parallel = 4

-----------

Two 8s in parallel = 2

Two 2 ohn pair in series is 4

Four eight ohm speakers will end up 4 either way

I'm not a wiring expert guy, but I don't think all of this is right. Two 8 ohm speakers in series do add up to 16, but two 16 ohm pairs in parallel divide back down to 8, right? Not 4. If you had four 8 ohm speakers all in parallel the load would be 2 ohms, but in series-parallel it would be 8. I thought the formula for parallel resistance was 1/total resistance = 1/(load A) + 1/(load B) + etc etc.

Or to put it in context for this cab: each speaker is 15 ohms. Two 15 ohm loads in series is 15+15 = 30 ohms. Two 30 ohm pairs in parallel is 1/30 + 1/30 = 1/total, so that's 2/30 = 1/15. 15 ohms would be the total load in series parallel.

If that math is wrong, please let me know, because that's the way I've been adding up my speakers and I would hate to be wrong when it counts.

 

[ehdwuld]

What is two 16 ohm speakers in parallel?

Is it 4 or 8 ?

I have two 16 ohm at the house and I will check when I get back

But I believe my math is correct