| Author |
Topic: Speaker distortion |
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 12 May 2009 2:11 pm |
|
When I set up my rig yesterday after a weekend gig, I noticed a distortion from my speakers when I play the pitch A 440 (E9th sixth string with the B pedal down, etc.). This is a one-year old pair of 50 watt Weber 1250fs in a 135 Watt SF Twin Reverb. My first thought was that, as one might have expected, despite Ted Weber's assurances, My 135 watt amp had blown one of the underpowered speakers. (In Mr. Weber's defense, I described my playing situation to him and assured him neither of my bands play at excessive volume. If it was too loud for the speakers, that's on me.)
When I pulled off the speakers I could find no rips or tears in the cones. However(!), I did discover that the two upper baffle screws (that attach the baffle to the ribs in the cabinet) were a little loose, as were a few of the nuts that attach the speakers to the screws in the baffle. Is it possible that the distortion I was hearing was some sort of sympathetic vibration at A440 and not a speaker issue at all? Alternately, is it possible the distortion is, in fact, in the speaker but not the cone?
I know: I could test this by simply tightening everything up and trying it again. But thought I'd get some advice before taking that step.
Thanks.
Dan
_________________
Durham, NH
dbmCk mUSIC |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 12 May 2009 2:20 pm
|
|
| Quote: |
| Is it possible that the distortion I was hearing was some sort of sympathetic vibration at A440 and not a speaker issue at all? |
Absolutely. I'm not saying that you've found the culprit but this is very common. I was certain I had a bad speaker and was about to make an ass of myself to the guy I bought it from but one last check found a slightly loose piece of hardware on the cabinet.
There are other things like cone cry that can cause extraneous noises including frequency-specific off-sounds but for sure you want rule out the simple mechanical stuff before going any farther. |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 12 May 2009 2:25 pm
|
|
Thanks Jon.
What is "cone cry"? I'm imagining its the edge of the cone rubbing against the frame of the speaker.
Dan |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 12 May 2009 2:50 pm
|
|
Here is Weber's description:
| Quote: |
Cone Cry, Ghost Notes, Edge Yowl
Context: I replaced that speaker because it had too much cone cry.
Description: As the speaker cone is vibrated by the voice coil, it can generate frequencies of its own that may be strong enough to be audible along with the intended note or signal from the musical instrument. These notes or tones may or may not be harmonically related to the intended note, and in some cases may be either higher or lower in frequency than the intended note. This usually means that the voice coil is driving the cone so hard that it is overcoming any damping and is essentially out of control. Sometimes manufacturers use huge magnets and loose spiders so they can win the 'sensitivity ratings' contest, but the result is a system that is difficult to control. Edge yowl is the term used to describe sounds that occur when the surround resonates, imparts energy back into the cone, and generates tones and notes that may or may not be harmonically related to the intended note. |
Doping is what is usually indicated---the application of 'dope' to the cone--to tame the vibrations and remedy cone cry. But I am just spouting stuff I've read. I am over my head here. |
|
|
|
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
Posted 12 May 2009 3:16 pm
|
|
| First, you should determine if the distortion is, in fact, coming from the speakers. Distortion can come from anywhere in the sound chain, but it's almost always heard as coming from the speaker. Of course, checking for loose hardware is one of the first things you should do whenever you're confronted with "noises". Tighten the speaker mounting nuts with just your thumb and finger using a nut driver (spin-tite). Then, anchor the nuts in place with some clear fingernail polish or coil dope. Speakers are sometimes ruined because someone overtightened the mountings, and warped the frame (which causes the voice coil to rub the magnet). |
|
|
|
Dan Beller-McKenna
From:
Durham, New Hampshire, USA
|
Posted 12 May 2009 3:22 pm
|
|
Okay,
I reinstalled everything nice and tight and the distortion is gone.
I did, however, give the screw nuts a couple of twists with a pair of pliers. Donny are you suggesting this is too much; just "finger" tight? I don't have a nut driver (but suspect I'm about to be advised I should).
Thanks for your help guys.
Dan |
|
|
|
Bill A. Moore
From:
Silver City, New Mexico, USA
|
Posted 12 May 2009 3:37 pm
|
|
| I have read that Mr Dumble filled his wonderful amplifiers with goop, not only to disguise his circuitry, but to ward off any component vibrations that may cause noise. True? |
|
|
|
