Ok I recently upgraded my bass amp from a ****** silvertone amp to an all peavey one. The head is no problem but the speaker cab (4x12) has one, the bottom two speakers hardly move, even at full voulme. At first i thought the speakers werent hooked up, but that wasnt the case, so i put in a heavier wire but still nothin. They still make sound but nothin compared to the top two speakers. if any one has an idea as to y this is happenin that would be great.
Not usually a crossover in a 4x12.
What cab is it?
Several things come to mind.
If there are two jacks, could this cab be a mono/stereo cab? That means plugging into the mono jacks gets all four speakers, but plugging into the stereo jack works only two of them.
Are all four speakers of the same type and same impedance? If the two speakers are odd, they might not be working for that reason. Someone may have replaced the original speakers with who knows what.
Are all four speakers wired in phase? That means do they all move the same direction together? Plug a cord into the jack, and touch a 9v battery to the other end of the plug. Touch the tip of the plug to one battery terminal, then lower the shaft of the plug dwon to touch the other terminal. This will make the speakers all move a little and make a thump or pop sound. WATCH THE CONES. They should all four move the same way. If one moves the opposite direction, it is wired backwards. Swap the two wires going to it.
While you are checking phase, make sure all four speakers are functioning. When music is playing, the air currents will make dead speakers move. The battery test will check a speaker for function. You can test individual speakers with the battery too.
If those two dead speakers are wired in series, if one of them is open, both of them will go silent. Use the battery to test each one.
Is the wiring correct? Especially with the common series/parallel wiring arrangements, the mess of wires can be confusing, and it may not be correct.
What cab is it?
Several things come to mind.
If there are two jacks, could this cab be a mono/stereo cab? That means plugging into the mono jacks gets all four speakers, but plugging into the stereo jack works only two of them.
Are all four speakers of the same type and same impedance? If the two speakers are odd, they might not be working for that reason. Someone may have replaced the original speakers with who knows what.
Are all four speakers wired in phase? That means do they all move the same direction together? Plug a cord into the jack, and touch a 9v battery to the other end of the plug. Touch the tip of the plug to one battery terminal, then lower the shaft of the plug dwon to touch the other terminal. This will make the speakers all move a little and make a thump or pop sound. WATCH THE CONES. They should all four move the same way. If one moves the opposite direction, it is wired backwards. Swap the two wires going to it.
While you are checking phase, make sure all four speakers are functioning. When music is playing, the air currents will make dead speakers move. The battery test will check a speaker for function. You can test individual speakers with the battery too.
If those two dead speakers are wired in series, if one of them is open, both of them will go silent. Use the battery to test each one.
Is the wiring correct? Especially with the common series/parallel wiring arrangements, the mess of wires can be confusing, and it may not be correct.
ok well i dont really know alot about the cab....all i know is that its a 4x12, made in 1982, all the speakers are the same make, im pretty sure there are all 16 ohms and there wired in parallel.
I tried the battery thingy and still that same thing happens, the top two are noticeably moving, while the bottom two (still makein a pop sound)are no movin. I also thought i might be hearing the other two but if you touch the bottom two you can feel movement.
I tried the battery thingy and still that same thing happens, the top two are noticeably moving, while the bottom two (still makein a pop sound)are no movin. I also thought i might be hearing the other two but if you touch the bottom two you can feel movement.
Well, the drivers are all in parallel. I would have expected two of them to be in parallel, and then those in series, or similar...The the impedence of all of them togehter is the same as one driver.
Does it say something like 8 Ohms or 4 ohms stamped somewhere on the magnet or frame on the drivers?(that's the iimpedence.)
If they are 8 ohm drivers the load on the amp is 2 ohms-pretty darned low.
If they are 4 ohm speakers then it is a load of one ohm reallly low...
BUT they still should move the same amount.
I also wonder if both input jacks really are are wired the same and as you show....
Anyway I'll wait for other's input, and if no one has a better idea I'll try to make a drawing on how I suspect they want to be hooked up.
EDIT:
I note in an earlier post that you said they were in parallel, and they are. Also 16 ohm speakers in parallel would end up as 4 ohms- that might be OK...Any reason you think they are 16 ohm?
MAybe you should try switching the 2 non-moving much drivers with the moving ones (electrically by just moving the wires is OK)- then see if the non moving start moving and the moving stop moving as much.
Does it say something like 8 Ohms or 4 ohms stamped somewhere on the magnet or frame on the drivers?(that's the iimpedence.)
If they are 8 ohm drivers the load on the amp is 2 ohms-pretty darned low.
If they are 4 ohm speakers then it is a load of one ohm reallly low...
BUT they still should move the same amount.
I also wonder if both input jacks really are are wired the same and as you show....
Anyway I'll wait for other's input, and if no one has a better idea I'll try to make a drawing on how I suspect they want to be hooked up.
EDIT:
I note in an earlier post that you said they were in parallel, and they are. Also 16 ohm speakers in parallel would end up as 4 ohms- that might be OK...Any reason you think they are 16 ohm?
MAybe you should try switching the 2 non-moving much drivers with the moving ones (electrically by just moving the wires is OK)- then see if the non moving start moving and the moving stop moving as much.
ok well i said i think the speakers are 16 ohms because i tested them with a really ghetto multimeter and it came out to around 18-20 ohms so i just assumed it was 16 ohms. I also rechecked the inputs and there are like i drew. Lastly i did also try swithing the speakers and the same thing happen, the top two move alot more than the bottom two
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.