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A question for you re-foaming gurus

SubLover said:
What is used to generate the tone? (I've heard of "tone generators" used for troubleshooting phone lines--is it something similar?)

Thanks.

SubLover
Click to expand...

I use a simple application I downloaded from the internet (don't have it on this computer, don't recall the name right now). You should be able go Google a free application. Hook your audio out from your computer into an amplifier. Hook the speaker being repaired to the amplifier output. Using the application, generate a 100hz tone and amplify it through the speaker. Turn up the volume so that you can hear the hum at about normal speaking levels (less if you are an infommercial advertiser). This will create a strong enough magnetic field to center the voice coil.

http://www.world-voices.com/software/nchtone.html

I have no affiliation with this application. I have not tested it either. This link is just an example of a free tone generator application.

Finally, as stated earlier and in my opinion as well, refoaming is a manual process. I have no experience using a voice coil shim, so I cannot comment on how that would work. I did work with my surrounds, baskets and cones for about an hour while the glue set, with the tone generator on, and have had had no issues with voice coil rub. So far, I have refoamed two paper cones and four poly cones this way.
 
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tensleep said:
I have no experience using a voice coil shim, so I cannot comment on how that would work. I did work with my surrounds, baskets and cones for about an hour while the glue set, with the tone generator on, and have had had no issues with voice coil rub. So far, I have refoamed two paper cones and four poly cones this way.
Click to expand...

I'd like to try using the tone method, I like the fact there's no removal of the dust cap. But....using the shim method one does get to inspect the voice coil close up and even visually see how well it's aligned. And, because of the shims I simply glued the surround to the basket, used several clamps and let it dry. That part is quicker by the sounds of it.
 
tensleep said:
I use a simple application I downloaded from the internet (don't have it on this computer, don't recall the name right now). You should be able go Google a free application. Hook your audio out from your computer into an amplifier. Hook the speaker being repaired to the amplifier output. Using the application, generate a 100hz tone and amplify it through the speaker. Turn up the volume so that you can hear the hum at about normal speaking levels (less if you are an infommercial advertiser). This will create a strong enough magnetic field to center the voice coil.

http://www.world-voices.com/software/nchtone.html

I have no affiliation with this application. I have not tested it either. This link is just an example of a free tone generator application.


Finally, as stated earlier and in my opinion as well, refoaming is a manual process. I have no experience using a voice coil shim, so I cannot comment on how that would work. I did work with my surrounds, baskets and cones for about an hour while the glue set, with the tone generator on, and have had had no issues with voice coil rub. So far, I have refoamed two paper cones and four poly cones this way.
Click to expand...

what a resourceful suggestion!..feeling a bit ignorant at not having thought if it myself, but, thats a feeling I'm growing accustomed to, as I read and benefit from the ideas and experiences of others here on AK..this place rocks:rockon:
 
pw5599 said:
I'd like to try using the tone method, I like the fact there's no removal of the dust cap. But....using the shim method one does get to inspect the voice coil close up and even visually see how well it's aligned. And, because of the shims I simply glued the surround to the basket, used several clamps and let it dry. That part is quicker by the sounds of it.
Click to expand...

I can certainly see the advantages to the shim method! On one of my JBL paper cones, my son had pushed in the dust cap so I had to cut it out and replace it. Also, all four of the dustcaps were loose on the poly cones - the original glue had crystalized, so I removed, cleaned and reglued them. Having the dustcaps off did provide a nice view of the voice coil and gap.
 
I did my first refoam "unprotected" with no shims, no sounds anything...they worked but I was told by a reputable speaker manufacturer that I should always shim. I started shimming and to be honest, cutting the dustcap, shimming and regluing when it's over might take 2 or 3 minutes out of my day, I have no problem with that, and with pushed in dustcaps, it's a good chance to get in there and pop them back out. I haven't had a problem yet, but neither have guys using other methods...I'm not really sure i've heard of a refoaming problem yet.

One notable expert here in Mass discourages self refoaming kits saying he can hear the voice coil rub that DIY's have done, and they can't hear it. I'm not sure if he's theatened by DIY's encroaching on his line of work, or if he's being honest but I certainly cannot hear any rubbing..maybe I'm deaf.
 
barredowl said:
Best thread on refoaming I have seen, thanks!

Bauhausler what is the most problematic in refoaming the LE-10s? I am thinking about refoaming my LE-14as in my JBL S99s and any advice you could offer would be much appreciated. I have refoamed smaller Avents and AR-5s and that was by feel and they came out fine, but I understand that the JBL with its narrower voice coil gap is quite a bit different and touchier than those speakers. If I do try it I'll get the kit with the 50 hz tone cd , anything else I should know?
Click to expand...

I recently refoamed a pair of LE10s. The worst part is trying to get the hard old foam off of the underside of the cone edge. I used a thin xacto blade and carefully sawed through it as close to the paper as I dared, then smoothed the bumps with a thin diamond file. It's essential to have a syringe to apply the glue. I use a large syringe from an inkjet refilling kit but you can buy glue syringes at a craft or hardware store.
It takes time and care. Prep is essential. Any bump or excess old glue will lift the new surround off and keep it from seating.

I recently used the shim method for the first time after refoaming more than 80 drivers 'freehand'. They were DQ20i drivers - effectively the same as a Large Advent Masonite woofer. I cut through the dustcaps except for a small tab to keep it attached for alignment. I used 4 stiff paper shims per VC. I flipped the cut off dustcap back down and ran a bead of glue over the cut. They aligned perfectly and the woofers test identically. I don't consider this step essential in all cases but I'l luse it in the future on some drivers.

Interestingly, this pair of drivers are going into a pair of speakers which had a woofer with a manufacturing defect. The original woofer was built with the cone tipped on the VC former. I've never seen this before. The cone is way off center at the edge. If this woofer was refoamed by eye to center the woofer edge on teh frame the VC would be cocked and would rub. This can possibly be remedied by refoaming it with the surround offset off center on teh frame. In this case, shimming would be essential to center the VC since the woofer rim is useless as a reference.
 
For JBL's you simply cannot beat Rick Cobb's kits. He includes a 30HZ tone cd to help you keep the VC centered while gluing the surround edge to the basket.

MEK, used sparingly around paper cones, (think it eats the poly ones) is what we all use to get the old foam off. There's tons' of threads on LHF with pics and tips. I could go on but have to run.
 
I recorded a 30hz tone from Adobe Audition to CD, but I have heard that the same can be done through Audacity. In any case I have done all my drivers, after about 10 with shims, with the tone and spring clamps.

It is a MUCH simpler, cleaner method and you know right away if you have VC rub. I can do a pair of drivers in less than an hour.

In fact I just did a set of drivers from a pair of EPI A70's this afternoon and I am listening to them right now.

I may also add that a heat gun helps with getting the glue to set. I recently switched over to Aleene's Tacky Glue and I like the way that sets up.
 
I need some speakers to do so I can try this method. Can we get someone to describe it in detail?

Yes, Audacity can generate a tone with your choice of frequency. Damn good free software that one is.

I tried Aleenes tacky and it sets up faster than the glue I got with a kit so you do have to be quicker when using it.
 
tensleep said:
I use a simple application I downloaded from the internet (don't have it on this computer, don't recall the name right now). You should be able go Google a free application. Hook your audio out from your computer into an amplifier. Hook the speaker being repaired to the amplifier output. Using the application, generate a 100hz tone and amplify it through the speaker. Turn up the volume so that you can hear the hum at about normal speaking levels (less if you are an infommercial advertiser). This will create a strong enough magnetic field to center the voice coil.

http://www.world-voices.com/software/nchtone.html

I have no affiliation with this application. I have not tested it either. This link is just an example of a free tone generator application.

Finally, as stated earlier and in my opinion as well, refoaming is a manual process. I have no experience using a voice coil shim, so I cannot comment on how that would work. I did work with my surrounds, baskets and cones for about an hour while the glue set, with the tone generator on, and have had had no issues with voice coil rub. So far, I have refoamed two paper cones and four poly cones this way.
Click to expand...

tensleep,

That is exactly what I was looking for! Thank you for your detailed explanation and link.

ATB,

SubLover
 
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