How do I wire a speaker cab?

[Mr French]

Fellas, I cannot figure this out!

I have a 4x12 cab and only using 2 speakers on purpose & will always be that way.
Here's my issue, I have a WGS Reaper that has those T-Tab/4 connection & a black back with J hooks.
ALL SPEAKERS 16OHMS

Here's how I have it wired:
Black back + into WGS +
Black back - into WGS -
= + going to the output jack
& - into the output jack.

Is that the correct way for this set up?

2nd mix of speakers are Dual Black back with Hooks & I don't know how to wire them. NOT A CLUE.

Again I'm only operating in a 2x12 configuration. Even though it's a 4x12 cab, we do not want to run all speakers as it sounds better.

Pictures would be very helpful!

Thanks gang.

***UPDATE AS OF 6/7/24
As you'll see I have no clue of what I am doing as this was all new to me. You will find some mixed information. However, some information is correct and most importantly the correct information is coming from James of ReWind. He's not letting me off easy with my short cuts & I thank him.

Again I didn't know that I was doing it wrong all along even though this speakers setup sounds killer. I don't want to be playing with fire and ruin any gear. These G12m 55hz are tuff to find & not cheap.

Next step is to rewire the speaker cab in the 4x12 configuration with soldering all wires onto each tab. James made multiple points with the danger of spade connectors and I agree. They can easily fall off especially with 3 of the 4 speakers being 55hz/bass cones.

Thanks.

 

[Note Milker]

Depends if you have 8 ohm or 16 ohm or 4 ohm speakers. And if you want to match them with 4 ohm or 8 ohm output of your amp. Parallel conection, plus to plus minus to minus will give you half the impedance. Two 8 ohms in parallel will give you a 4 ohm load.

Series will double the load. Plus from the input jack to plus of the first speaker, a jumper wire from minus of the first to plus of the second speaker, then out of the minus of the second speaker to the minus of the input jack. That will double the load, 2 8 ohm speakers will give you a 16 ohm load. Works the same way with all speakers.

Hope that helps.

 

[ReWind James]

Assuming you have 16 ohm speakers, you’ve made an 8 ohm load by running them in parallel.

Also, assuming you have vintage blackbacks (sounds like it) they can only handle 25-30 watts, which means two of them (no matter how you wire them) is only suitable for about a 25-30 watt amp (assume double the stated capacity for your speakers is required of the stated power of the amp).

 

[Mr French]

Depends if you have 8 ohm or 16 ohm or 4 ohm speakers. And if you want to match them with 4 ohm or 8 ohm output of your amp. Parallel conection, plus to plus minus to minus will give you half the impedance. Two 8 ohms in parallel will give you a 4 ohm load.

Series will double the load. Plus from the input jack to plus of the first speaker, a jumper wire from minus of the first to plus of the second speaker, then out of the minus of the second speaker to the minus of the input jack. That will double the load, 2 8 ohm speakers will give you a 16 ohm load. Works the same way with all speakers.

Hope that helps.

ALL SPEAKERS 16OHMS ADDED

 

[Mr French]

Assuming you have 16 ohm speakers, you’ve made an 8 ohm load by running them in parallel.

Also, assuming you have vintage blackbacks (sounds like it) they can only handle 25-30 watts, which means two of them (no matter how you wire them) is only suitable for about a 25-30 watt amp (assume double the stated capacity for your speakers is required of the stated power of the amp).

ALL SPEAKERS 16OHMS
Using JTM 45 and yes all vintage black backs.

 

[ReWind James]

ALL SPEAKERS 16OHMS
Using JTM 45 and yes all vintage black backs.

I wouldn’t run a vintage JTM45 with any less than four vintage G12Ms. I bet they do sound good, though. Gear always sounds best right before it blows.

 

[NotScott]

I am not sure exactly what you are trying to do but this should help.

1) Wire your second set of speakers exactly as you did the first set.
2) Disconnect the - from the first set from the output jack and connect it to the + of your second set.
3) Connect the - from your second set to the - of the jack.

Plug a cable into the speaker jack and touch the tip and ring of the cord end to a 9V battery and watch the speakers. They should all move in the same direction. If anything moves in an opposite direction, reverse the + and -.

You should now have a 16 ohm cab using all 4 speakers. If you want to just use 2 speakers at 8 ohms, just pick the pair you want, attach to the jack and test with the battery for proper polarity.

 

[Big John]

You currently have two of the four speakers running in parallel for an 8 ohm load. You stated that you will only operate 2 speakers at a time in this cab. From what I'm reading, you don't need to do anything. What am I not getting?

 

[Mr French]

Q

You currently have two of the four speakers running in parallel for an 8 ohm load. You stated that you will only operate 2 speakers at a time in this cab. From what I'm reading, you don't need to do anything. What am I not getting?

There are 2 questions listed.

1st, if It's wired correctly using the first set of speakers.

2nd question is how would I wire two speakers with j hooks.

Dang I really need a crash course on this load and wiring stuff. We've been running this cab at 16 ohms setting from the amp with no issues, now I'm wondering if I have to set the ohms to 8? Etc.....

 

[Mr French]

I wouldn’t run a vintage JTM45 with any less than four vintage G12Ms. I bet they do sound good, though. Gear always sounds best right before it blows.

We've been running this cab like this for years with no issues. It's now becoming confusing.

 

[ReWind James]

We've been running this cab like this for years with no issues. It's now becoming confusing.

If you’re running the amp at 16 ohms into 8 ohms, it’s running extra hard on the amp and inefficiently. It’s probably a good amp so it’s just taking it, running hot, and is being hard on the output section. Not ideal but, as you see, it didn’t kill it. I wouldn’t push it into further mismatch with 4 ohms, though. You’re having a combination of luck and tough gear.

Now, when you switch the amp over to 8 ohms, to properly run your two 16 ohm speakers in parallel correctly, your amp will be much happier (and probably sound better, personal subjectivity not accounted for) and be more efficient. That extra efficiency could be the end of your speakers because your two 25-30W speakers are not sufficient to take the 60W or so that a JTM45 can put out.

If you blow a coil in a speaker and the circuit opens up, giving you a 0 Ohm load, that’s the absolute worst situation for your output transformer. It would rather see a full short than an open load of nothing.

Look up photos of any old Marshall cab and just copy the wiring. They were wired with 4 16 ohm speakers in a series / parallel combination, resulting in 16 total ohms for all four and with 4 25W speakers, a power rating of 100W, which is real-world-suitable for a 50W Marshall.

 

[ReWind James]

Here’s one of mine. You can zoom in (at least on the link below, maybe not the thumbnail above) see where each wire goes to each terminal. Just copy this for four speakers at 16 ohms, exactly the way Marshall did it.

IMG 0207 | ReWind Electric, LLC

IMG 0207 - IMG_0207.jpeg

www.re-wind.net

Then, at the jack, both reds to tip and both blacks to sleeve.

 

[Mr French]

Here’s one of mine. You can zoom in (at least on the link below, maybe not the thumbnail above) see where each wire goes to each terminal. Just copy this for four speakers at 16 ohms, exactly the way Marshall did it.

IMG 0207 | ReWind Electric, LLC

IMG 0207 - IMG_0207.jpeg

www.re-wind.net

Then, at the jack, both reds to tip and both blacks to sleeve.

If I'm seeing yours correctly that is parallel wiring. I'm guessing our cab was originally in series as nothing was soldered to the output jack.

 

[Mr French]

If you’re running the amp at 16 ohms into 8 ohms, it’s running extra hard on the amp and inefficiently. It’s probably a good amp so it’s just taking it, running hot, and is being hard on the output section. Not ideal but, as you see, it didn’t kill it. I wouldn’t push it into further mismatch with 4 ohms, though. You’re having a combination of luck and tough gear.

Now, when you switch the amp over to 8 ohms, to properly run your two 16 ohm speakers in parallel correctly, your amp will be much happier (and probably sound better, personal subjectivity not accounted for) and be more efficient. That extra efficiency could be the end of your speakers because your two 25-30W speakers are not sufficient to take the 60W or so that a JTM45 can put out.

If you blow a coil in a speaker and the circuit opens up, giving you a 0 Ohm load, that’s the absolute worst situation for your output transformer. It would rather see a full short than an open load of nothing.

Look up photos of any old Marshall cab and just copy the wiring. They were wired with 4 16 ohm speakers in a series / parallel combination, resulting in 16 total ohms for all four and with 4 25W speakers, a power rating of 100W, which is real-world-suitable for a 50W Marshall.

If I'm understanding, the only time you'd set the amp speaker ohms at 16 is if using a 4x12 configuration with 16ohms speakers.

Running a 2x12 16 ohms speakers, you would need to set the amp at 8 ohms setting.

If that Is accurate I don't know how I've gotten away with this after all these years and I'm pushing the amp and been running with an attenuator all those years at 75% full.

 

[redking]

If I'm understanding, the only time you'd set the amp speaker ohms at 16 is if using a 4x12 configuration with 16ohms speakers.

Running a 2x12 16 ohms speakers, you would need to set the amp at 8 ohms setting.

If that Is accurate I don't know how I've gotten away with this after all these years and I'm pushing the amp and been running with an attenuator all those years at 75% full.

It depends on the impedance of the speaker outputs of the amp. Some have one output option, some have multiple options. Ideally you want to match the impedance of the output on the amp with the input on the cabinet. If you are unsure about the impedance of how you have wired up the speaker cabinet, you can easily test it with a multimeter to double check that you got it correct. From time to time I will test the jacks on the cabinets to make sure none of the connections inside have shaken loose on the push-on connectors.

 

[Note Milker]

Attenuator is soaking up power, so protected your speakers. Even running it into the speakers with mismatched output won't just smoke everything right away.... You'll be really loud! I mismatch mine sometimes just to change the tone a little. Never have to crank it, it's way loud. And I do use pedals....

Been doing stuff like that for years, so far so good. Old original caps from '76. They sound best right before they blow, that's right where I need it. Live dangerously. And when they finally go.... More stories to tell, and throw money at it. Again.

You haven't smoked yours.... Yet. So.... What are you going to do?

 

[redking]

Attenuator is soaking up power, so protected your speakers. Even running it into the speakers with mismatched output won't just smoke everything right away.... You'll be really loud! I mismatch mine sometimes just to change the tone a little. Never have to crank it, it's way loud. And I do use pedals....

Been doing stuff like that for years, so far so good. Old original caps from '76. They sound best right before they blow, that's right where I need it. Live dangerously. And when they finally go.... More stories to tell, and throw money at it. Again.

You haven't smoked yours.... Yet. So.... What are you going to do?

I think I recall Dave Friedman saying a "one level" mismatch (i.e. 8 vs. 16 or 4 vs. 8) shouldn't damage the amp, but a "two level" mismatch (i.e. 4 vs. 16) is asking for trouble.

 

[Mr French]

It depends on the impedance of the speaker outputs of the amp. Some have one output option, some have multiple options. Ideally you want to match the impedance of the output on the amp with the input on the cabinet. If you are unsure about the impedance of how you have wired up the speaker cabinet, you can easily test it with a multimeter to double check that you got it correct. From time to time I will test the jacks on the cabinets to make sure none of the connections inside have shaken loose on the push-on connectors.

We only own 16ohms speakers

 

[Mr French]

Attenuator is soaking up power, so protected your speakers. Even running it into the speakers with mismatched output won't just smoke everything right away.... You'll be really loud! I mismatch mine sometimes just to change the tone a little. Never have to crank it, it's way loud. And I do use pedals....

Been doing stuff like that for years, so far so good. Old original caps from '76. They sound best right before they blow, that's right where I need it. Live dangerously. And when they finally go.... More stories to tell, and throw money at it. Again.

You haven't smoked yours.... Yet. So.... What are you going to do?

Jesus Christopher.

Fellas at times for months like now I'm running all at 10 with bass at 0.

 

[ReWind James]

If I'm seeing yours correctly that is parallel wiring. I'm guessing our cab was originally in series as nothing was soldered to the output jack.

No. It's series AND parallel. That's the only way to get a 16 Ohm total load from four 16 Ohm speakers.

Two pairs in series making 32 ohms each pair, but those two pairs are paralleled making them 16 ohms total. That's how Marshall has always done it on vintage cabs.

Forget what your cab may have been or what you've been getting away with. What matters is what you do with it now.

As for your attenuator, that throws a whole other wrench into things. They are not all the same. Some can have different input and output impedance settings. That's all case by case. With an attenuator, you are probably protecting your speakers (strictly regarding power which is unrelated to matching impedance), as long as the output of your attenuator isn't more than 25W for two 25W speakers.