9 Volt Speaker Re-Foam

Me Tarzan

Me Tarzan

EARTH
I have done refoam with shims but never with a signal or 9V that I keep hearing mention of. I have watched 10 videos showing how to push or pull the coil with a 9V but none of them mention alignment. I looked through the reference threads. Basically what I want to know is if it will harm the driver in any way to leave the 9V juice to it for a minute or two. Glue, pull in with 9V, align, clothespin, remove battery. Am I way off?
 
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Okay thanks. From what I can find the battery doesn't do anything I can't do with my fingers. Was just led to believe the battery method was the accurate way to go...
 
MMMMM may want to think about lowering the voltage down to a D or anything less. Depending on the wooer voice coil windings it may wel be fine- but if it is minimal or has a weak spot you could toast it, IE burn it out! It is nothing more than a long coil of wire wrapped tightly around a former. Once it get overheated the coating on the wire burns off and it shorts together. Music allow the voice coil to heat up and cool down depending on the volume level- putting a battery on with no interuption could be whack! Get a test tone CD from the free sites and use that to be safe.
DC
 
Or use a 30hz test tone, push method etc... Everyone has their own way of doing re foams. In my experience alignment is not an issue when using a test tone while refoaming. I have done 20-30 sets all various brands with 0 issues.
 
IMO, the D cell helps to center the voice coil/magnet end of the speaker. It's also my opinion that rapidly connecting and disconnecting the battery while the glue is still wet can help center the foam surround end of the speaker. That's my theory, anyway. I haven't done a ton of speakers, but I have done 6 or 8 pairs without shims and have never had a vc rub. I have even been known to hook a speaker to low level music output as soon as I have the gluing done, the theory being the LIGHT vibrations of low level music will cause the cone to center itself before the glue grabs.

If I'm way off base with these suggestions, someone please feel free to correct me.
 
Thanks for replies. I tried the battery (D) and didn't get much help out of it. Also hooked up to a little music and static on a couple. Nothing seems to be rubbing. Guess I am a go by the feel kind of guy. I felt like I needed to learn the secret handshake before the magical battery alignment knowledge would be bestowed upon me. Maybe I am 2nd Degree now, only 31 more degrees to go... Tubal Cain.

Hey Greg (Ghog) if you are wondering it isn't the Toby's I am working on. I just put a little glue over that tear and all is well. I really like them a lot. Thanks again.
 
Me Tarzan said:
I have done refoam with shims but never with a signal or 9V that I keep hearing mention of. I have watched 10 videos showing how to push or pull the coil with a 9V but none of them mention alignment. I looked through the reference threads. Basically what I want to know is if it will harm the driver in any way to leave the 9V juice to it for a minute or two. Glue, pull in with 9V, align, clothespin, remove battery. Am I way off?
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I've always been leery for the reasons noted (overheating windings).

However, this might be useful for front mounted surrounds, and for applying down force for rear mounted.

I would think cycling the battery would be useful when attaching to the frame, maybe even reversing polarity alternately.

I would think amperage would be more a concern than voltage.
 
Yeah, I was kinda' wonderin'. Glad the Toby's are suitable. I still feel bad about that "little hole" being a tear instead. I shoulda' looked before I spoke. Did you not ever hear from the mfr?
BTW, had another one of those weird loads Monday, and Tuesday it was just laid flat on the trailer, and was just over 14ft wide and they sent me without an escort. I'm thinking of letting my hair grow out so I can pull it out!
 
Ghog said:
Yeah, I was kinda' wonderin'. Glad the Toby's are suitable. I still feel bad about that "little hole" being a tear instead. I shoulda' looked before I spoke. Did you not ever hear from the mfr?
BTW, had another one of those weird loads Monday, and Tuesday it was just laid flat on the trailer, and was just over 14ft wide and they sent me without an escort. I'm thinking of letting my hair grow out so I can pull it out!
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No I never heard back and didn't get an answer the 2 times I called. The hole/tear is not a concern to me. I plan on keeping them and I hear no degradation in the sound. I am not huge on jazz, but it sure sounds sweet through those things. Sure seems like an awkward cargo to have no escort. You better plan ahead on the hair pulling out thing, might take you a while. :D
 
Not just awkward, but illegal. Technically the pc was 13' 11", but is actually wider if not perfectly place on the trailer(they weren't), and chains add another inch on each side. Escort required by law at 14'.
Not gonna hijack the thread. Glad the Tobys sound good. Maybe I should have kept them, but I really want to try building something one of these days. I'm just happy knowing they went to someone who will appreciate them. It was a pleasure meeting you, even if it was a brief meeting and in a truck stop parking lot.
Gimme a shout if you ever get down this way.
 
I used to use a Heathkit function generator hooked up to a small NAD integrated amp (3020 or 3155) amp to power the driver. Now I've downloaded a function generator/test tone app to my iPhone and use that to drive the amp into the driver.

Nice part is I can easily vary the frequency with a nice digital readout, plus I can set the output to a fixed out on the iphone, then vary the signal power to the driver through the amp's volume control.

When you do this, the voice coil is nicely centered by the magnetic signal flow in the voice coil. With the surround already glued to the cone (back or front), its then easy to temporarily clamp down two opposing sides, then two more (or thirds if you like) while the tone if running. After clamping, test again to be sure you're centered - I've found I need to hold the driver in free air so that table vibration and resonance doesn't cover up any distortion or noise. I use medium to large binder clips or alligator type clothes pins.

Once you're satisfied you're centered, then take off one clamp and glue a section of surround to the frame. Once that's done, reclamp with 1-3 clamps, test again and adjust the position of the surround (usually not needed), then move around the driver till all sections are glued and reclamped. All along the way, the testing has confirmed at each step I'm still centered at any frequency I use.

BTW, if using binder clips, they are strong, so you might consider putting a sliver of thick card stock under it to spread out the force, otherwise you can get some dents in the outer frame part of the surround. If you're putting on a gasket on top of that part, may not be needed from a cosmetic standpoint.

I like this method because I'm concerned that trying to glue without clamping may angle the voice coil and you would't know it just by feel with some wider gaps.

As for playing signal while the glue is wet and that centering the surround, I would have to think the glue has to be quite fresh and wet to be able to move any bit laterally, otherwise once it gets tacky, only finger pushing and pulling is going to effectively move the outer surround edge on the frame IMO.
 
I've re-foamed over 100,000 sets of speakers using a very low-level music signal and have had no problems whatsoever.
 
Works out to about 27 years at ten per day, seven days a week. Longer if you take Christmas Day off. :D
 
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