Jumbo Sunshade - Ezine

Speaker Wiring Diagrams for 2-speaker & 4-speaker guitar and bass cabinets (for use with tube amplifiers)
 

Wiring your guitar or bass cabinet incorrectly, or, using a mis-matched combination of cabinet and tube amplifier; will at best cause excessive wear on your power tubes, or at worst could result in damage/failure of your tubes, speakers or transformer.

Below are parallel, series, parallel/series & series/parallel configurations for 2-speaker and 4-speaker cabinets.  But first...

1.  4-ohm, 8-ohm or 16-ohm cabinet(s): which is best?
Resistance is measured in Ohms.  A 4-ohm cabinet offers less resistance than a 16-ohm cabinet (allowing more wattage to the speakers) and is therefore a GREATER load on your amp than the 16-ohm cabinet.
Up to an amplifier's limit, using a lower ohm cabinet will deliver more power to your speakers (although not necessarily more volume), but the trade-off in working your amp harder and hotter may not be worth it:
When amplifiers suffer shorts in their output power transistors, they often deliver raw voltage into the speakers, immediately cooking the voice coils.  In my early days of tinkering with electronics, i destroyed two mint JBL speakers (Earth solid-state power amp) - the smoke and smell and feeling of horror is something i will probably never forget!

That being said: you might be able to get more desirable speaker distortion by going 4-ohm if you use speakers that facilitate this (Celestion), and/or you might be able to get a noticeable boost in volume if you're using speakers that facilitate that (EV).  The bottom line is that you won't really know unless you try (or find somebody with your amp who has tried it).
Just bear in mind that the difference can sometimes be imperceptibly subtle.  The most dramatic change i've personally experienced was with a 50-watt Marshall half-stack that i rewired (the cabinet) from 16 to 4 ohms.  I did this again a few years later with a different 50-watt Marshall half-stack and none of us could hear any difference at all.

2. If you purchased your speakers new, or otherwise have access to the manufacturer's wiring instruction, use it.  This seems like a no-brainer, but it is the case that some manufacturers suggest different wiring configurations for the same speaker combinations (number, ohm, watt).
Obviously it wouldn't hurt to wire your 8-ohm 150-watt EV's with the Carvin instruction for their 8-ohm 150-watt drivers, but it certainly will not help you with your warranty!

3. Don't assume that the operational characteristics of one amplifier will be the same as  (or even similar to) another.

Example 1:  You can plug two 16-ohm cabinets into your 1971 Marshall Super Lead by simply setting its Ohm selector to 8 ohms.  But if you want to hook those cabinets up to your 1971 Fender Twin Reverb you have to rewire them because that amp is hard-wired for a 4 ohm load.

Example 2:  Just about every manufacturer in the world warns you not to fire up your (tube) amplifier without a cabinet plugged in or you risk damaging the amp.  But you can do just that with an early 90's VHT UL-100 head because jack #1 shuts down the output when not in use.

4.  If at all possible, use the exact same speakers (brand/ohm/watt) for each cabinet.  If you have to mix and match brands, fine - but both (or all four) of the drivers should have the same ohm/watt specs!

5.  If you want to go louder but fear the risk of blowing your speakers, or, if you just can't go any louder: you have to add speakers (assuming your amplifier's power isn't the problem).
A Carvin four-speaker cabinet will facilitate higher volume levels than a Carvin two-speaker cabinet.  Four 25-watt Celestions will be harder to ruin than two 25-watt Celestions.  Etc.

 

Ok, ok - here are the wiring diagrams!

 
Parallel wiring diagrams for 2-speaker and 4-speaker cabinets
 

two 8-ohm speakers wired in parallel

This illustrates two speakers wired parallel.

I've always pictured it this way: the circuit load is equal to the speaker ohm divided by the number of speakers in the circuit.

In this case, 8 (ohm speaker) divided by 2 (speakers) equals a 4-ohm load.

Thinking of it that way makes it really easy for me to remember.

 

two 16-ohm speakers wired parallel

This is the same as the previous diagram but with 16-ohm speakers.

16 (ohm speaker) divided by 2 (speakers) equals an 8-ohm load.

 

four 16-ohm speakers wired in parallel

Here we have four speakers wired parallel.  This very configuration can be found plugged into older Fender amps.

Yes, you could do this with 8-ohm or even 4-ohm speakers, but unless your amp allows it, why would you?

Again, i remember it this way: 16 (ohm speaker) divided by 4 (speakers) equals a 4-ohm load.

 
Series wiring diagrams for a 2-speaker cabinet
 

two 4-ohm speakers wired in series

Here we have two speakers wired in series.

I think of this as the circuit load being equal to the speaker ohm multiplied by the number of drivers in the circuit.

In this case, 4 (ohm speaker) multiplied by 2 (speakers) equals an 8-ohm load.

 

two 8-ohm speakers wired in series

This is the same as the previous diagram, but with 8-ohm drivers.

8 (ohm speaker) multiplied by 2 (speakers) equals a 16-ohm load.

 
Parallel/series wiring diagrams for a 4-speaker cabinet

Remember, this is parallel/series, as opposed to series/parallel (which is covered next).  The way we arrive at the term "parallel/series" is like this: two parallel circuits combined together in series.  That's why these speaker wiring diagrams are limited to 4-speaker cabinets.

 

four 4-ohm speakers wired in parallel/series

Picture the speakers on the left as a single two-speaker circuit that is wired in parallel thus: 4 (ohm speaker) divided by 2 (speakers) equals a 2-ohm load.

This single load is then connected to another single load (the two right speakers) that is exactly the same.

These two 2-ohm loads are connected in series thus: 2 (ohm load) multiplied by 2 (the number of loads in the circuit) equals a 4-ohm total load.

 

four 8-ohm speakers wired in parallel/series

This speaker wiring diagram is the same as the previous, but with 8-ohm speakers.  As above, i think of each set of speakers (left; right) as their own parallel circuit, which are then connected together in series.

As individual parallel circuits they are: 8 (ohm speaker) divided by 2 (speakers) equals a 4-ohm load.

Now combined in series thus: 4 (ohm load) multiplied by 2 (loads in circuit) produces an 8-ohm total load.

 

four 16-ohm speakers wired in parallel/series

This final parallel/series wiring diagram is the same as the previous two, but with 16-ohm speakers.  Ends up being a 16-ohm load.

 
Series/parallel wiring diagrams for a 4-speaker cabinet

Finally, there are the series/parallel configurations.  Yes, this really is "six of one - half dozen of the other", but there are cabinets out there that are wired both ways.  The difference is exactly what you'd think it would be: two series circuits combined together in parallel.

 

four 4-ohm speakers wired in series/parallel

Again, consider the speakers on the left as being wired in series as a single two-speaker circuit thus: 4 (ohm speaker) multiplied by 2 (speakers) equals an 8-ohm load.

This single load is connected to another single load (speakers on the right) that is exactly the same.

These two 8-ohm circuits are connected in parallel thus: 8 (ohm load) divided by 2 (loads in the circuit) equals a 4-ohm load.

 
four 8-ohm speakers wired in series/parallel Yep, same as above but with 8-ohm speakers.  If you've read everything else you've GOTTA be sick of it by now...

Four 8-ohm speakers wired series/parallel equaling an 8-ohm load.

 
four 16-ohm speakers wired in series/parallel And finally, the same series/parallel circuit using 16-ohm speakers.

Four 16-ohm speakers wired series/parallel equaling a 16-ohm load.

Yep, it's just that easy!

 
FYI: these speaker wiring configurations aren't just for 2x12 and 4x12 cabinets; they also work with 2x10, 4x10, 2x15, 4x15, etc.
 

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If you're trying to figure out how to wire a guitar speaker cabinet then this is maybe the page for you. If you specifically need a guitar speaker wiring diagram then this is *definitely* the page for you!