is the woofer repairable?

smarvelous · #1 11-21-2011, 01:05 PM

This 12" neo woofer developed a problem soon after buying it. GK has offered to replace it (no complaints there) but is out of stock until January. I'm just wondering if I could resolve it myself...

The issue: low volume but nasty sounding distortion in the high mid frequency range (kind of like a bad distortion pedal, but again very quiet, kind overlaid over the otherwise good signal). I noticed that when I touch the bottom edge of the cone, it goes away but when I touch the top edge of the cone it gets worse. I even made a video (listen with headphones as the distortion is pretty subtle)

Speaker problem documented - YouTube

Any speaker experts out there who can diagnose the issue? I will probably just wait for the replacement speaker, but I'm pretty curious. And maybe I could fix it?

BassmanPaul · #2 11-21-2011, 01:11 PM

Sounds to me to be more likely crossover distortion from your amp. If you have eliminated the amp then check the driver for something touching the cone like possibly the tinsel leads.

smarvelous · #3 11-21-2011, 01:21 PM

do you mean the crossover in the speaker cab? I'm pretty sure my amp (and bass guitar) is fine because it sound perfect with my other cab.

I suppose I could wire the speaker directly to my amp (take the cab crossover out of the equation) but I kind of thought the fact that touching the cone makes it go away or come back was a smoking gun that there was something wrong with the driver itself.

dmusic148 · #4 11-21-2011, 01:24 PM

Place your fingertips around the dome, and push in gently. Listen carefully for a scratching sound. Do it again while applying pressure in the upper right 'makes it worse' area. If you hear a scratching sound, the speaker is said to be 'blown.' The voicecoil has overheated and distorted, and is now rubbing on the magnet. The only way to repair this is to re-cone.

craig.p · #5 11-21-2011, 01:32 PM

Pull the speaker and check to see if the wires from the amp are touching the back of the cone. When you put the speaker back, rotate it 90 degrees (if the wire length will allow that, without the wires resting on the back of the cone), then VERY LIGHTLY snug up all the screws, then gradually tighten in a star pattern just like lug nuts on a car wheel so the frame gets evenly torqued to the baffle board. See if that helps any.

By any chance were you playing this amp pretty loud just before this happened? Reason I ask is that you might have a burned voice coil. They can go out of round when they hit a super high temp. This causes scraping inside the magnet gap, which can be made better or worse by pressing at different cone locations, just like you did in your video.

EDIT: Beat me to it, dmusic, lol.

babebambi · #6 11-21-2011, 01:32 PM

Quote:

Originally Posted by BassmanPaul

Sounds to me to be more likely crossover distortion from your amp. If you have eliminated the amp then check the driver for something touching the cone like possibly the tinsel leads.

Tinsel leads like Paul said.

BassmanPaul · #7 11-21-2011, 01:34 PM

If the amp sounds fine with the other cabinet then pull the speaker and lok it over carefully for anything touching the cone. Check the cabinet lining isn't touching it either.

What amp do you have and what is your other cabinet? How are you using them.

smarvelous · #8 11-21-2011, 02:46 PM

Thanks for all the replies. I did pull the driver, all the cables were neatly tied in there, nothing was close to touching the driver. I don't see anything unusual. I didn't do anything out of the ordinary, I just played it at a low volume out of the box and noticed the distortion soon after (I'm guessing it was there from the get go). Pressing the cone or the edges does not make any noticable rubbing sound by itself. It's looking like I may need to just wait for the new driver. I'll muck around with it somemore tonight. Thanks for everyone's input!

will33 · #9 11-21-2011, 02:52 PM

Maybe a seem that isn't glued good, either where cone meets surround or dustcap.