#1
Hey guys, I need help again with wiring my cabinet. I finally found a set of cheap speakers locally (not the best, but not the worst either). I tried to wire up the cab today based on a diagram I found online. But after I got it all put together it didn't work. I ran my amp for about 10 seconds, but when I couldn't get any sound out of the cab I shut everything down because I was afraid of damaging my amp.

The cab is set up to run as either mono or stereo (I will only run it as mono, if that matters). Here are some pics of the jack plate on the back of the cab, and the wiring on the inside. I have the red wires going to the positive terminal of each speaker, and the black wires going to the negative terminals. I don't have any wires connecting the speakers together because it looks (to me) like the wires are jumpered together at the jack plate.

Is there something I'm doing wrong? Please help!

EDIT: each speaker is rated at 16 ohms, and my amp is able to run a cab at either 8 or 16 ohms (if any of that helps...)








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Last edited by 57Goldtop at Apr 16, 2014,
#2
What you have there is some switched jack sockets. The terminals on one side are connected to the input jack and the terminals on the other side disconnect when the jack is inserted. You have probably wired them all the wrong way round (maybe).

P.
Last edited by PSimonR at Apr 16, 2014,
#3
So, here is the diagram I was following when I wired it up. I figured this was the way to go since I have two input jacks on the back of the cab (one for mono, two for stereo):




But is that wrong? Should I only use the mono side of the jack and wire it up like this (the parallel example)??

Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#4
Quote by PSimonR
What you have there is some switched jack sockets. The terminals on one side are connected to the input jack and the terminals on the other side disconnect when the jack is inserted. You have probably wired them all the wrong way round.

P.

So what should I do to fix it? The cab was wired like this from the factory, I didn't do any of that wiring myself (I just soldered the wires to the speakers).
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#5
Quote by 57Goldtop
So what should I do to fix it? The cab was wired like this from the factory, I didn't do any of that wiring myself (I just soldered the wires to the speakers).


Well, now I look more closely it actually looks correct, what you have done. So, did you check that the speakers actually work?

If you only need mono, it might make sense to simply wire the speakers in parallel as per you second diagram, and don't use the switches on the jacks. These switched jacks are often unreliable especially after someone over-enthusiastic with the soldering iron has been at them.
Last edited by PSimonR at Apr 16, 2014,
#6
Quote by PSimonR
Well, now I look more closely it actually looks correct, what you have done. So, did you check that the speakers actually work?

If you only need mono, it might make sense to simply wire the speakers in parallel as per you second diagram, and don't use the switches on the jacks. These switched jacks are often unreliable especially after someone over-enthusiastic with the soldering iron has been at them.

Ok, maybe I'll try that. Probably won't get to it until tomorrow so if anybody has any other thoughts please feel free to jump in.

And unfortunately I have no way to test the speakers. I bought them used and they look fine to me. Is there a way to test them with a multimeter? I don't have another amp or speaker cab to run them through as a test.
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#8
I'm not sure I did that right, but I didn't notice any movement in either speaker. But the terminals are too far apart to hit both sides of a 9-volt at the same time (and too close to get both sides with a AA battery).
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#9
Ok, I had a minute so I just broke out my multimeter. I'm getting a reading of 7.4 - 7.5 ohms for each speaker (they are both rated at 16 ohms). I know the ohms reading will probably read less than 16 ohms when I measure it, but does 7.5 seem too low??

(sorry for the double post, trying to do 100 things at once over here...)
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
Last edited by 57Goldtop at Apr 16, 2014,
#10
Are they still wired in parallel when you're measuring? If so, that's about right. If they're separate, then that's definitely not right.
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#11
Quote by mmolteratx
Are they still wired in parallel when you're measuring? If so, that's about right. If they're separate, then that's definitely not right.

I didn't undo the wires, everything is still set up like the pictures above. So yeah, I guess that makes sense - two 16 ohm speakers wired parallel for an 8 ohm load (so the 7.5 ohm measurement isn't far off).

But does that mean the wiring for the cab should be working as is?
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#12


That says 8 ohms, same thing but all those 8's are 16's in your case.
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#13
Quote by 57Goldtop
I didn't undo the wires, everything is still set up like the pictures above. So yeah, I guess that makes sense - two 16 ohm speakers wired parallel for an 8 ohm load (so the 7.5 ohm measurement isn't far off).


Plus it probably isn't impedance that's being measured, but rather DC resistance (impedance takes into consideration resistance as well as inductance and capacitance).
"Practice doesn't make perfect. Perfect practice makes perfect." -some dude
#14
DC resistance ALWAYS reads lower than impedance, it has to. It's not a lot lower but is has to be lower. An 8 ohm speaker will read somewhere around 7.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#15
Quote by 57Goldtop
I'm not sure I did that right, but I didn't notice any movement in either speaker. But the terminals are too far apart to hit both sides of a 9-volt at the same time (and too close to get both sides with a AA battery).


Well obviously you have to connect both terminals at once! (with a short bit of wire)
Last edited by PSimonR at Apr 17, 2014,
#16
I think I was right first time then - given the multi-meter reading.

You have connected your speakers to the wrong side on the input jack socket. When you insert the plug the connections open and the electricity goes nowhere.

P.
Last edited by PSimonR at Apr 17, 2014,
#17
Well... it turns out I'm just a big idiot. This is the first time I'm using this new amp. There's a knob on the back to set the reverb level and a button next to it to turn it on. There's also a button on the OTHER side of the knob that activates the FX loop. Apparently I had turned the FX loop on instead of the reverb, and since there wasn't anything in the loop it killed the whole signal.

So all is good now, the wiring was right from the start. Thanks for the help. And on the plus side, my new amp sounds AMAZING!
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2
#18
Quote by 57Goldtop
Well... it turns out I'm just a big idiot. This is the first time I'm using this new amp. There's a knob on the back to set the reverb level and a button next to it to turn it on. There's also a button on the OTHER side of the knob that activates the FX loop. Apparently I had turned the FX loop on instead of the reverb, and since there wasn't anything in the loop it killed the whole signal.

So all is good now, the wiring was right from the start. Thanks for the help. And on the plus side, my new amp sounds AMAZING!


It's funny how electricity can make fools of anyone - seen it before many times. I don't think its common to have a switch on the FX loop. We have a desk with a all-mute button that has caught me out more than once - I've now bypassed it!

P.
#19
Well, serves me right for leaning over the top of an unfamiliar amp and pressing buttons without looking closely! When it didn't work I just assumed I screwed up the wiring. I never even thought to check the FX loop. And I only noticed it by accident when I was plugging in a new speaker cable
Current Gear:
2002 Gibson Les Paul Standard
'57 AVRI Fender Stratocaster
MIJ Fender Jaguar Special HH
Marshall JVM410
Vox AC15 C2