Post Number: 304
|Posted on Thursday, June 22, 2006 - 12:46 pm: |
One speaker in an SWR 4x10 is buzzing at the lower freqs. All connections are secure, no holes or other visible damage to speaker surface. This moronic question wouldn’t be my first: What should I look for next? I haven’t put a VOM to it – need to get one first.
Thanks in advance,
Post Number: 922
|Posted on Thursday, June 22, 2006 - 1:20 pm: |
Hope this isn't a moronic question, itself: Didja tighten the bolts holding the driver to the baffle? I went through diagnostic fits with a 15 once only to find that 3/4 of a turn on an adjustable wrench made all the necessary difference (In my defense, the speaker was not obviously loose.).
Post Number: 915
|Posted on Thursday, June 22, 2006 - 1:42 pm: |
I second Bill's suggestion; had the same problem with one of my cabs, though in my case 2 screws were completely missing; once I got some new screws and put them on the problem went away.
Post Number: 485
|Posted on Thursday, June 22, 2006 - 2:08 pm: |
The loose screws, boy that could be me, are a good bet. If the speaker is secure look inside to be sure a wire isn't rubbing on the cone. After this you could gently move the cone with your hand. If you feel any rubbing you might have a bad speaker and it is time to take it in and get it checked.
Post Number: 848
|Posted on Thursday, June 22, 2006 - 5:23 pm: |
Another way to check it: If you are so moved and pull the speaker out, either use the leads on the speaker, or round up a pair of small wires and connect it to a 9v battery: If it moves out and you DON'T hear that dragging/scraping awful-ness, the speaker's OK.
NOTE: In hopes of saving you one of my own "duhhh" moments: Be sure you make a diagram of WHICH wire goes back on WHICH speaker terminal!!
J o e y
Post Number: 923
|Posted on Friday, June 23, 2006 - 8:32 am: |
On Joey's cautionary note: I've gotten so bad in my old age that whenever I reinstall a speaker I fire up my rig (at low volume) before I put more than 2 screws - just to make sure I got the polarity right. As an unusually impatient character (can you spell ADD?), I used to rush through jobs. With time and experience, I learned I hate rework more than anything. So it seems I make fewer mistakes as I get older, but the time taken for preventive measures is a bitch...
Post Number: 306
|Posted on Friday, June 23, 2006 - 10:30 am: |
as it happens one of the mounting screws was loose, but wasn't the culprit when playing back. As a whim, I did gradually move the attenuator through it's range with the open E ringing, no luck, buzz is still there. Didn't have much time last night for Joey's suggestion, I've used that to check car speakers, it's a useful method, maybe tomorrow.
The way the interior of the cabinet is constructed it's difficult to see if anything is rubbing on the cone while in it's playing position. But it doesn't look like it, there's really not much in there to begin with.
I'll keep pluging away, thanks for the suggestions.
Post Number: 851
|Posted on Friday, June 23, 2006 - 6:41 pm: |
Bassman, you sound like a man who can appreciate my two favorite mantras about working on things:
"It was working 'till I fixed it"
and the ever popular
"It's a full-time job idiot-proofing myself!"
J o e y
Post Number: 1417
|Posted on Saturday, June 24, 2006 - 9:31 am: |
I've found my digital camera to be of great help when it comes to tinkering. Whether electronic or mechanical, before I take anything apart, I take a few pics with my digital camera so I have a clear and extremely accurate reference on how it goes back together. This has saved me a lot of time and aggravation.
Post Number: 49
|Posted on Saturday, June 24, 2006 - 6:08 pm: |
I like Bill's suggestion best. Look to the mounting hardware or to any local area wires or insulation rubbing on the cone. The best way to test for speaker polarity is with a smaller battery like a "C" or "D" cell. the + side should go to the red wire or terminal or tip of the speaker plug, and the - side to the black wire or terminal or sleeve of the speaker wire plug. with a slight touch the cone should move forward to show correct polarity. In your 4x10 cab, ALL spkers will move, and you should note that they ALL move in the same direction. As for the buzzing, sometimes this is an indication of the beginning of a blown speaker. A minor blow out occurs when the speaker is subjected to a large transient (ie: Slap / pop or surge) from the amplifier / bass that forces an overtravel on the speakercone. The coil can travel out of the magnetic gap and misalign on it's way back, scratching the voice coil wires. This buzzing can be an indication of that damage. If you notice that the buzzing gets worse, than that would be a cause of concern.