Marshall Cabinet Techs - A challenge
- Thread starter Broke
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muttonchopsrule
New member
Re: Marshall Cabinet Techs - A challenge
it appears to be a normal series/parallel wiring scheme, in which both pairs of the speakers are wired in series, then the pairs of speakers are wired in parallel to each other. and according the the label on the speakers, they are 8 ohm speakers. if the above is all correct, you should expect an 8 ohm rating for the cabinet as a whole. however, it is best to verify all this with a meter before you run your favorite tube amp through it.
it appears to be a normal series/parallel wiring scheme, in which both pairs of the speakers are wired in series, then the pairs of speakers are wired in parallel to each other. and according the the label on the speakers, they are 8 ohm speakers. if the above is all correct, you should expect an 8 ohm rating for the cabinet as a whole. however, it is best to verify all this with a meter before you run your favorite tube amp through it.
Rich_S
HomeGrownToneBrewologist
Re: Marshall Cabinet Techs - A challenge
Well, each side is wired in series, so thats 8+8 = 16 ohms on each side.
Then, the two 16-ohms pairs are paralleled where they are soldered to the board, so that puts it back to 16/2 = 8 ohms.
You can confirm this by plugging a speaker cable into the jack and measuring the impedance on the cable's other end. Using a regular DVM set to "ohms" it should read about 5 or 6 ohms if the cab's wired for 8.
However, they perpetrator seems to have bypassed Marshall's tricky stereo/mono, 4/16 ohm switching. I have a rough idea of how it works, but no schematic. There's a bit of PFM that goes on in the traces on that little PC board.
I'm guessing it will give you 8 ohms out, but I don't know if the switch will have any effect. Worst case, the switch could cause an open circuit and blow up your output transformer. Keep the amp turned down low until you're sure whatever combination of switch and jack you're using makes sound come out the speakers.
I highly recommend either: 1) finding a schematic and putting it back the way Marshall intended, or 2) replacing the fancy jackplate/switching assembly with a normal 2-hole jackplate and hardwiring it.
BTW, that cab's blue, isn't it? Extremely cool.
Well, each side is wired in series, so thats 8+8 = 16 ohms on each side.
Then, the two 16-ohms pairs are paralleled where they are soldered to the board, so that puts it back to 16/2 = 8 ohms.
You can confirm this by plugging a speaker cable into the jack and measuring the impedance on the cable's other end. Using a regular DVM set to "ohms" it should read about 5 or 6 ohms if the cab's wired for 8.
However, they perpetrator seems to have bypassed Marshall's tricky stereo/mono, 4/16 ohm switching. I have a rough idea of how it works, but no schematic. There's a bit of PFM that goes on in the traces on that little PC board.
I'm guessing it will give you 8 ohms out, but I don't know if the switch will have any effect. Worst case, the switch could cause an open circuit and blow up your output transformer. Keep the amp turned down low until you're sure whatever combination of switch and jack you're using makes sound come out the speakers.
I highly recommend either: 1) finding a schematic and putting it back the way Marshall intended, or 2) replacing the fancy jackplate/switching assembly with a normal 2-hole jackplate and hardwiring it.
BTW, that cab's blue, isn't it? Extremely cool.
Re: Marshall Cabinet Techs - A challenge
Hey great help man thanks.
8 Ohm would make sense I guess if you wanted to run a full stack with 2 8 Ohm cabs to a 16 Ohm head. They could have just 2 16 Ohm cabs on a 16 Ohm head as well.
I just called a local tech guy and he is going to rewire it back to original. Just so happens he has the same cab from another guy with a blown speaker so he can just copy it.
Thanks a heap!
Hey great help man thanks.
8 Ohm would make sense I guess if you wanted to run a full stack with 2 8 Ohm cabs to a 16 Ohm head. They could have just 2 16 Ohm cabs on a 16 Ohm head as well.
I just called a local tech guy and he is going to rewire it back to original. Just so happens he has the same cab from another guy with a blown speaker so he can just copy it.
Thanks a heap!