Tube Amp Archive

I recently started using a 12" hellatone a25 alnico speaker, and the tone is very good, but it seems to be producing a secondary note on top of every note being played. Its lower and pitch, and is present with literally every note that can be played with the guitar. its definitely the speaker, is ive tried it with 2 different amps with 3 different cabs. Im going to email the guys at avatar speakers and see if they have any suggestions, but i figured i'd ask here as well. Is there anything i can do to fix this ghost note?
Thank you!
-josh

Sounds like voice coil is rubbing. You can confirm by pressing carefully on the cone with both hands. You should be able to work it in and out without making any noise at all. In other words, the cone should move freely and silently.

I was literally JUST about to start a thread on 'Cone cry' based on a relatively similar issue. At loud volumes there seems to be a second note that sounds kind of like Ring Modulation type distortion over the notes. Is this cone cry or something else.
Weber speakers claim to have better tolerances to avoid voice coil rubs, but who knows, anything can happen, and I think they use the tighter tolerances to get a tighter gap.


OP, is there any info on how those speakers are 'doped'?
I think my webers have relatively light doping, which is why I believe my issue might be cone cry.

JD0x0- i couldnt locate anything about their doping methods on the avatar website, but i did shoot them off an email seeing if they had any suggestions for this problem.

Xtian- i pulled the speaker, and while lightly pressing on the cone, i can definitely hear it rubbing. It only makes sound while pressing in two areas; they are located directly across from eachother, and one is significantly louder than the other. To me that makes it seem like it's only rubbing in the one place, and pressing the opposite area causes the same place to rub. Is there anything i can do for this?

I'm not a speaker repairman. I only know, if it rubs, it's fuxx0red.

JoshBernstein wrote:JD0x0- i couldnt locate anything about their doping methods on the avatar website, but i did shoot them off an email seeing if they had any suggestions for this problem.

Xtian- i pulled the speaker, and while lightly pressing on the cone, i can definitely hear it rubbing. It only makes sound while pressing in two areas; they are located directly across from eachother, and one is significantly louder than the other. To me that makes it seem like it's only rubbing in the one place, and pressing the opposite area causes the same place to rub. Is there anything i can do for this?

Just to add a fine point to this: It is important to apply equal pressure to as much of the cone as you can. Generally, this means using the tips of the thumbs and middle fingers, spaced equidistantly from one another, and placed symmetrically about the center of the cone. Applying more pressure at one point than another will likely result in cone rub.

I tried again, doing my best to apply equal pressure around the cone, and i can sill feel/hear it rubbing. The speaker is still under warranty, and i only used it for a few hours trying to figure out where the noise was coming from. So ill see what they say, and if they wont agree to fix it, is there anything i can do besides get it reconed? It would be a pretty big bummer, since it wasnt working correctly right out of the box.

If I am not mistaken, xtian has some experience with speaker voice coil rub repair - I am pretty sure there is a thread here about his project.

JazzGuitarGimp wrote:If I am not mistaken, xtian has some experience with speaker voice coil rub repair - I am pretty sure there is a thread here about his project.

Not me. I have found a good speaker repair guy near Sacramento: http://www.nealspeakerrepair.com

Just received an email from dave at avatar speakers, saying that this problem usually happens when the voice coil heats up and deforms. I told him about how i'd been using the speaker, and how it was rubbing right out of the box. Turns out the speaker was still under warranty and he will be shipping me a new one tomorrow.
Thank you for the help, and if i ever run into this problem in the future, ill know how to diagnose it.
Thanks again
-josh

xtian wrote:

JazzGuitarGimp wrote:If I am not mistaken, xtian has some experience with speaker voice coil rub repair - I am pretty sure there is a thread here about his project.

Not me. I have found a good speaker repair guy near Sacramento: http://www.nealspeakerrepair.com

Oops, Sorry Aaron.

sometimes you can cut off the dust cap puts a shim in the gap then wet with acetone around it .then lett it sit over night with the shim Its worked for me a couple times

I'm going to assume Avatar doesn't want the bad one back. It is just extra postage for them and something they have to discard. If it rubs, they can't sell it, even for junk. OTOH, you can try what cbass says and then you'll have an extra. It's a good deal all around.

Here's the rules. If the sound is lower in pitch than the note you are playing, and typically static (same pitch, more like a bark), then this is a bad voice coil.

Cone cry is something else entirely. Cone cry happens at the forward edge of the cone, in the last 1" or so. What you hear is the result of the magnet pushing the cone forward (positive polarity, full excursion) and the cone surround resisting the excursion. There is a ripple that happens on the cone in this 1" area as the two elements fight each other. It goes without saying that cone cry occurs at higher power levels and not at lower levels..

To explain the idea of doping being able to reign in cone cry, it is because the doping is typically placed in this 1" area. It dampens the ripple.