How to wire a guitar cabinet with 2 x 12 8ohm speakers to get an 8 ohm load

[RicardoS]

Hi!

I bought a Marshall MX212A cabinet which comes with 2x Celestion Seventy Eighty speakers, 16 ohm each speaker, with parallel wiring (2x 16ohm speakers = 8ohm load).

I've got a Marshall DSL20H amp which can work with a 8ohm or 16ohm output, but I've got a Two Notes Torpedo X 8 ohm in between the amp and the cab, serving purely as an amp attenuator.

I replaced the original speakers by a Celestion G12K-100 8ohm and a Celestion Vintage 30 8ohm, and used the same wiring as before, parallel wiring.

I've been playing it for a couple of weeks but I've only now noticed that 2x 8ohm speakers = 4 ohm load...

So I currently have:
8ohm amp output ==> 8ohm Torpedo X ==> 4ohm cabinet

I'm not very knowledgeable of electronics or cab wiring, so I've got a couple of (probably) basic questions:

1. Am I in risk of burning the speakers or the Torpedo X, or even the Amp?
   
   
2. How can I wire the speakers so the cab takes an 8ohm load? Judging by this youtube video here, if I wire them in parallel I get a 4 ohm load cabinet, if I wire them in series I get a 16 ohm load cabinet...

Thanks!
Ricardo

 

[bubucci]

rewire cab for 16ohm for using without loadbox. 8ohm is not possible.
But even 4ohms are fine because amp “see” load of 8ohms of Captor. There are different dB values of attenution but I dont think it is matter too much.

 

[RicardoS]

Thanks Bubucci.

That makes sense. Out of curiosity and for me to understand, sounds like the amp is safe but, I've got the Volume switch on the back (here) permanently set to low, so is the Captor still at risk of burning? If I switch the Volume on the Captor to High, would the Captor then be at risk of burning?

But I think what you suggested is the best solution, rewire the cab for 16 ohm, and use a different attenuator (I found this one here) to take the 16 ohm load.

 

[bubucci]

Captor is safe until You punish it with 100W plexi at full bore With DSL20 it is a breeze and totally safe.
You can still use 8ohm Captor for 16ohm cab , no problem and no need for another attenuator.

 

[TheToneDig]

Send the speakers back for the 16 Ohm versions. 2 x 16 = 8 Ohms out to match your Captor X.

 

[bubucci]

even 16ohm cab is safe mismatch when you run Captor in Full mode. In Low or Club mode is still 8ohm load for amp so not worth the hassle with speaker changing (packing, shipping etc...).

 

[TheToneDig]

even 16ohm cab is safe mismatch when you run Captor in Full mode. In Low or Club mode is still 8ohm load for amp so not worth the hassle with speaker changing (packing, shipping etc...).

This is true because they can run a several hundred-watt bass amp through the thing and nobody has damaged anything which tells me it can handle more than what it's rated at. I just use 2x16 with it or a single 1x8.

 

[GlideOn]

There is no physical way to wire a pair of 8ohm speakers for an 8ohm load short of disconnecting one speaker.

New speakers at 16ohm can do 8ohm but that's the most expensive route.

Find a cheap Weber Z matcher instead of replacing your speakers.

You gain the ability to plug into whatever head and cabinet combination you want plus extra speaker outs. Win / win

 

[RicardoS]

There is no physical way to wire a pair of 8ohm speakers for an 8ohm load short of disconnecting one speaker.

New speakers at 16ohm can do 8ohm but that's the most expensive route.

Find a cheap Weber Z matcher instead of replacing your speakers.

You gain the ability to plug into whatever head and cabinet combination you want plus extra speaker outs. Win / win

Thanks GlideOn, and thanks everyone else as well!

I can't find a Weber Z Matcher for sale here, I'm based in the UK. Do you know any alternatives to the Weber?

I'm planning to re-wire the speakers this weekend to have 16 ohm instead of 4 ohm. Meanwhile, I bought a Bugera PS1 to use the 16 ohm amp output (the Captor I have is only 8 ohm), but the tone with the Bugera is really different from the tone I'm getting from the Captor, it's not as good... The Captor shouldn't be changing the tone when acting just as an attenuator, I'm not sure why the tone is different between the Bugera and Captor, both currently at 8 ohms still. Any thoughts on what may be changing the tone between the two attenuators?

 

[GlideOn]

Thanks GlideOn, and thanks everyone else as well!

I can't find a Weber Z Matcher for sale here, I'm based in the UK. Do you know any alternatives to the Weber?

I'm planning to re-wire the speakers this weekend to have 16 ohm instead of 4 ohm. Meanwhile, I bought a Bugera PS1 to use the 16 ohm amp output (the Captor I have is only 8 ohm), but the tone with the Bugera is really different from the tone I'm getting from the Captor, it's not as good... The Captor shouldn't be changing the tone when acting just as an attenuator, I'm not sure why the tone is different between the Bugera and Captor, both currently at 8 ohms still. Any thoughts on what may be changing the tone between the two attenuators?

Attenutors suck tone. Unless you have the legendary $1300 OXBOX that is.

Other factors aside, mismatching ohms greater than a span of 4ohm in either direction audibly results in a thinner, less punchy tone.

I don't know of any other device than the Weber (he has a rep for making clever devices), the best bet would be wiring for 1 8ohm speaker.

This might be a debated item, but I would lean towards the camp of stating that a single, well designed and matched speaker is greater than a hodgepodge of several, ill-suited speakers.

There is such a thing as a "detuned" 2x12 which is a pretentious way of saying take out one speaker and leave a giant hole in place for bassier tones. This would of course be the fastest and most reversable way of meeting your goal to "match" the amp to the cab, I have tried it and it genuinely does sound bassier with no perceived beaming or loss of volume but less tighter overall.

 

[knjaxefx2]

There is no physical way to wire a pair of 8ohm speakers for an 8ohm load short of disconnecting one speaker.

New speakers at 16ohm can do 8ohm but that's the most expensive route.

Find a cheap Weber Z matcher instead of replacing your speakers.

You gain the ability to plug into whatever head and cabinet combination you want plus extra speaker outs. Win / win

Actually I think there is. So if I took two 8ohm speakers and put them in two 1x12 cabinets running mono I am effectively running in stereo in 8ohms. That’s dual mono!

Take the same two 8ohm speakers put them in one 2x12 cabinet, but using same 2 dual mono jacks. That is still dual mono! The only thing you did was put the speakers in one cabinet instead of two. Now you are running stereo 8ohms with dual mono in a 2x12 cabinet.

You don’t need to wire a 2x12 in series or parallel since you do dual mono [which is stereo in 8ohms with two 8ohm speakers].


Mind blown. Boom.