#881695 - 12/12/00 08:55 PM
Speaker buzz
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ahanna@massed.net_dup2
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Registered: 01/01/01
Posts: 0
Loc: Shelburne Falls,MA,UNITED STAT...
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Question
I have a peavey 410tx bass cab. one of the speakers is buzzing at higher volumes.
How can I correct this? How can I tell if the speaker is bad?
Tony
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#881696 - 12/13/00 11:45 AM
Re: Speaker buzz
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breakway@bellatlantic.net
Senior Member
Registered: 06/25/00
Posts: 40
Loc: ,NJ,UNITED STATES
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Gently push the cone inwards, using eight fingers spaced equally around the cone. There should be no rubbing or scraping sounds. The buzzing you are hearing is from the voice coil hitting the pole piece of the magnet structure, as it moves in and out of the voice coil gap. Only remedy is to replace or re-cone.
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#881697 - 02/01/01 06:40 PM
Re: Speaker buzz
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MidiMagic
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Registered: 02/01/01
Posts: 17
Loc: Bloomington,IN,UNITED STATES
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More possibilities:
- The voice coil has overheated and a winding is loose.
- The speaker, or part of the cabinet, has worked loose and is vibrating.
- A nut has fallen off inside the cabinet and is stuck to the magnet on the cone side (cheapest speaker fix I ever found).
- Torn speaker.
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#881698 - 02/22/01 01:03 AM
Re: Speaker buzz
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zeokie
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Registered: 02/21/01
Posts: 2
Loc: ,,UNITED STATES
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Is it a buzz or a rattle?
A buzz sounds more like a wiring problem. Check the solders on the speaker in question.
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#881699 - 03/07/01 07:47 PM
Re: Speaker buzz
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MidiMagic
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Registered: 02/01/01
Posts: 17
Loc: Bloomington,IN,UNITED STATES
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Yeah! If it makes the sound when nobody is playing, you are getting hum into the speakers. That's something entirely different, and there is nothing wrong with the speaker itself. But the fact that only one of the speakers makes the noise made me think that this was not happening.
But if it is:
Start by turning inputs down one at a time. One of three things will happen.
1. The hum will disappear when one specific input is removed.
Check the wiring of this input. Turn off the mic or instrument, or turn it down. If it is a guitar, the pickup may be picking up stray hum. Another possibility is a ground loop. See below on that. A third possibility is running a long distance with unbalanced signal lines.
And look for a wall-wart power supply sitting right next to a DI box. This is a sneaky source of hum.
2. The hum will gradually diminish as you remove more inputs.
This is almost always caused by trying to run unbalanced signals over long distances. The cure is to change everything over to balanced line operation.
3. The hum persists.
Thin indicates that the trouble is in the amp, or is caused by a ground loop. To test for this, mute all of the inputs to the mixer, and then disconnect them one by one.
If the hum goes away when one particular input is disconnected, look for a ground loop or a bad cable.
If nothing gets rid of the hum, there is something wrong with the amp.
All about ground loops:
Ground loops are caused by more than one path connecting the grounds of two different pieces of equipment together. These paths include the shields of connecting cables, multiple cables between two devices, power line grounding plugs, metal chassis touching each other, and metal equipment racks. Here are some tips on how to banish ground loops:
1. NEVER NEVER NEVER disable the protective ground on your power plug. I know it seems the cheapest way to solve a grounding problem. It's also the cheapest way to risk your life. All it takes is one coke spilled down the air vents of your amp, and you could die quicker than the amp does. Ground loops should always be dealt with in the signal lines.
2. The most robust way to deal with ground loops is the signal isolation transformer. Radio Shack sells a pair of these for $15. No ground loop can get past these, and if the other ground paths are inadvertently disconnected (which causes BIG trouble with some other ground loop breaking methods), no big blast of hum occurs. The circuit continues to work properly no matter what happens elsewhere.
3. A DI box isolates the 1/4" side from the XLR side when the ground lift is activated.
4. Plug all of your equipment into one power strip, if you can do so without overloading circuitry. If you can't, use isolation transformers in cables that connect equipment pluggted into different supplies.
5. Group power cords coming from equipment mounted in a rack into a power strip mounted in that rack. This turns a bunch of haphazard grounds into one common ground.
6. Bundle power cords together.
7. Bundle signal cords connecting the same two pieces of equipment together (that's why stereo patch cords don't cause ground loop hum in home audio).
8. Go balanced line for any run over 3 feet long. Balanced lines are much less likely to cause grounding troubles, even if a ground loop is present. And the transformer used to balance the line can also isolate grounds.
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