Series / Parallel switching for Speaker Cabinet

[andyg_prs]

Hi,

I have a 2 x 12 speaker cab that is 16 ohms. It is two 8 ohm speakers in series. I use it with an Engl Ironball that has a 16 ohm output.

I also want to use the cab with an amp that only has 4 and 8 ohm outputs. Putting the two 8 ohms in parallel will give me 4 ohms.

So, I can re-wire for impedence matching for either amp, but not both.

I've tried to sketch out the wiring for a switch to flip from one mode to the other.....can anyone confirm if this is correct? And does it matter whether the tip or ring of the speaker cable goes to positive on the speaker?



Thanks,
Andy

[IM4Tone]

Re: Series / Parallel switching for Speaker Cabinet

This doesn't look right to me, but maybe I'm just not following your diagram correctly. HERE (7th from top) is a diagram for a DPDT switch to achieve 16 or 4 ohms (8 ohms isn't available with this configuration). Switch boxes are available for sale that are pre-wired.

Regarding "And does it matter whether the tip or ring of the speaker cable goes to positive on the speaker?" .....If you are using this cab as a stand alone only, the importance is that both speakers are wired +/- the same to eliminate phase cancelling. If you plan on using this cab with another, tip is +, barrel is -. So, best to wire tip to +.

[ArtieToo]

Re: Series / Parallel switching for Speaker Cabinet

The way to switch two speakers between series and parallel, is exactly the same as how to switch a humbucker between series & parallel. Use the Duncan diagram and pretend one speakers wire is +black and -white, and the other speaker is +red & -green. Use a slightly heavier duty switch, however.

[Dave Locher]

Re: Series / Parallel switching for Speaker Cabinet

What kind of switch should one use?

[Darg1911]

Re: Series / Parallel switching for Speaker Cabinet

Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

https://www.tubesandmore.com/product...lay-monostereo

[IM4Tone]

Re: Series / Parallel switching for Speaker Cabinet

Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

https://www.tubesandmore.com/product...lay-monostereo

This doesn't look right to me, but maybe I'm just not following your diagram correctly. HERE (7th from top) is a diagram for a DPDT switch to achieve 16 or 4 ohms (8 ohms isn't available with this configuration). Switch boxes are available for sale that are pre-wired.

Exactly!

[ArtieToo]

Re: Series / Parallel switching for Speaker Cabinet

What kind of switch should one use?

Simple DPDT on-on. But, obviously, rated for the power. A typical AC power switch would be more than sufficient.

[regan]

Re: Series / Parallel switching for Speaker Cabinet

So long as the impedance of the cab is greater than the impedance of the amp you can use it.

If you wire the cab at 16 ohms you can use it with 4,8, & 16 ohm amp outs

[regan]

Re: Series / Parallel switching for Speaker Cabinet

Depending on the existing input type/size, this could be your easiest solution. It was virtually a drop in for one of my cabinets. If the input dish is smaller, the cabinet back can pretty easily be enlarged to accomodate.

https://www.tubesandmore.com/product...lay-monostereo

this is just giving you one (2 speakers together) load at 16 ohms or 2 individual loads (2 speakers in stereo) at 8 ohms each

[devastone]

Re: Series / Parallel switching for Speaker Cabinet

this is just giving you one (2 speakers together) load at 16 ohms or 2 individual loads (2 speakers in stereo) at 8 ohms each

It's 4 ohms mono on the left top jack.

[regan]

Re: Series / Parallel switching for Speaker Cabinet

Oh so it is,I missed that sorry

[PFDarkside]

Re: Series / Parallel switching for Speaker Cabinet

So long as the impedance of the cab is greater than the impedance of the amp you can use it.

If you wire the cab at 16 ohms you can use it with 4,8, & 16 ohm amp outs

This is only true with solid state power amps.

[regan]

Re: Series / Parallel switching for Speaker Cabinet

This is only true with solid state power amps.

Nope, It's quite OK

https://mesa-boogie.imgix.net/media/Amplitudes/2013/June/Speaker%20Impedance%20Matching%20and%20Hookup.pdf

[PFDarkside]

Re: Series / Parallel switching for Speaker Cabinet

Nope, It's quite OK

https://mesa-boogie.imgix.net/media/...d%20Hookup.pdf

You’ll notice in the documentation that it states at maximum a doubling of load impedance is ok. (4 ohm amp and 16 ohm speaker is not OK). For solid state this is ok.

Also, I’d trust this advice for manufacturers that explicitly mention you can mismatch impedance. Not all amps are built with the robustness of Mesa Boogies.