Re-Coning the mighty Cerwin-Vega! Stroker 18, Stroker 15, & Stroker 12 - TCCoA Forums

 
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post #1 of 25 (permalink) Old 02-04-2011, 09:28 PM Thread Starter
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Re-Coning the mighty Cerwin-Vega! Stroker 18, Stroker 15, & Stroker 12

Here's what I'm starting off with--just the empty basket




Things needed:



First step is to use the masking tape to clean the inside of the voice coil gap both on the pole-piece side and the top-plate side:



Once all particles have been fished-out with the masking tape, cover up the entire gap with tape to prevent any further debris from falling in:



Next is to scrape off the remnants of the old spider off the frame:



The hardened glue seemed to come off easier by smacking the scraper radially-inwards:



As you can see, there was a very good reason the magnetic cap was taped sealed, you get lots of debris from the hardened epoxy cracking off:



Next, cleaned the spider mounting flange with some 120-grit sandpaper to get rid the last of the epoxy and also roughen up the surface:



Next I proceeded to scrape off the old gasket:



Since the adhesive that is used on the gasket is different (non-hardening), it wasn't coming off cleanly with the scraper, so I just propane'd it off outside:



Now with the frame nice and clean, it was time to start the actual re-coning process. These parts are from www.legacysoundservice.com. Cone, voice coil, dual spiders, heavy-gauge tinsel lead, thick cryanocrylate voice coil adhesive, cryanocrylate accelerator, and strips of index cards that I cut up :



First step is to measure the top-plate thickness:



Then measured the voice coil length:



To set the voice coil in the magnetic gap, one must calculate the "overhang". Normally you take the length of the voice coil, subtract the top-plate thickness, and the remaining length is cut in half to determine the length of coil above the top plate. Since in this design, the coil length is equal (for all practical purposes) to the top-plate height, there are to be no coil windings above the top-plate.


To do this coil setting, I first slipped on the lower spider from the bottom-up, all the way up to the top of the voice coil former. The index cards you saw in the pic with the rest of the materials get cut up into strips and are to "lock" the coil in place, both centered in the gap AND at the proper height:



I needed to use double-strips, spaced 90° apart, to perform the dual-purpose of centering the coil and physically locking it at the proper height. Here you can peek at the coil windings just barely visible (because the camera is at an angle):



With the coil locked in place, I rotated the spider back and forth as I slowly slid it down the former so as to set the outer edge flat on the frame in a neutral position. With the spider in the proper location, I applied the adhesive to bond the coil former to the lower spider:



With just a small bead of adhesive, I applied a couple quick sprays of accelerator to set the adhesive. It's best to apply adhesive in small beads to avoid it running. Then removed it from the motor structure, turned it upside-down, and did the under-side of the spider-coil joint:



Then I applied another thicker bead of adhesive to the top joint (and accelerator):



Then slid the cone over the former, but not all the way to the bottom where the lower spider met the former. It went down only to the point where the surround just barely met the frame, so as to keep the cone in a neutral position (the index card strips are not doubled-up here since the coil height is now already set by the spider, they are only used for centering:



As a result, there was a gap between this cone (which is an RCF driver cone) and the lower spider. Adhesive applied at the outer cone-former joint:



Now that the lower-spider/former/cone were effectively a single piece, I decided to weigh the whole thing to compare it to the original moving assembly from my other Stroker, since I could tell the cone was thinner. Here is the original assembly:



Here is the new assembly with the top-spider just placed on the cone:



Since the new assembly was significantly lighter due to the cone, I decided to even things up a bit with this (more info later):



Now I set the assembly in place with adhesive on the underside of the lower-spider and quickly inserted 4 index card strips to center the coil once again (this is tricky because the adhesive started to set rather quickly so the centering must be done at once). Then applied a heavy bead on top of the outer edge of the lower spider:



Once the lower spider outer-edge sets after spraying accelerator on it, I drilled 4 small holes to route the tinsel lead through the cone, used my butane soldering iron to solder the voice coil wires to the tinsel leads, and routed them to the terminals, and heat-shrunk the tab at the push-terminal:



It's pretty much done. There's a couple extra steps for this speaker, but for most speakers, it's the bulk of the work. All that is left is to lift up the edge of the surround to apply adhesive, as well as applying adhesive on top of the surround to set the cardboard gasket. I used the same adhesive, but in restrospect I should have used perhaps a rubber-cement because at this point, the heater from the central air unit had come on and it started to set rather quickly (without accelerator) due to the warm air. I used my other Stroker on top of the gasket to apply pressure:



As for what I did with the JB Weld, I "brushed" it on the underside of the cone to give it some strength, since there would be no weight penalty compared to the original assembly. The reason for this is because the 18" models were particularly susceptible to cone-damage due to flexing at the outer edge near the surround because of the extremely strong motor structure:



I weighed it before I set it all in place, and it ended up around 230-235 grams.




EDIT: A couple more pics and things to look out for.

On the second Stroker 18 that I'm reconing, I opted for some rubber cement for the purpose of adhering the surround edge to the frame and the cardboard gasket on top of the surround. An issue I ran into with the first one I believed was caused by a mistake of mine when setting the surround/gasket with that fast-drying cryanocrylate adhesive--the gasket didn't quite set right, and here's why:

Seems that the included gasket was made for a speaker with a slightly larger frame, and you can see, if you fit the two edges of one gasket piece in place, the difference in radius of curvature between the frame and the gasket becomes apparent.




I shaved some material off the edges of two of the gaskets in my first recone to try and make sure all the bolt holes lined up, and it worked but this time around I went an extra step on ALL 4 gasket pieces:



With that, the edges fit in much better, and the different curvature was dealt with more appropriately with a cheap plastic clamp set from Lowes, as not everyone will have an extra identical speaker to place atop the one being reconed to provide pressure for the adhesive to set:



I also made sure the cone was in the correct position by using my phone and a "leveler" app:



And there you have it. Clamped the top-spider in the mounting ring, installed the center pole w/ lower washer, and glued the top-spider to the cone at the outer edge (with adhesive on the underside), applied accelerator, and there it is:





Last edited by guitar maestro; 02-13-2011 at 07:06 PM.
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post #2 of 25 (permalink) Old 02-05-2011, 01:04 AM
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Nice writeup, GM!

Those are going to sound great; what kind of cabinet do they go in?

I don't even have anything to drive that with, lol.

My Gallien-Krueger is barely able to drive a 12...

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post #3 of 25 (permalink) Old 02-05-2011, 09:22 AM
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Quote:
Originally Posted by Grog6 View Post
Nice writeup, GM!

Those are going to sound great; what kind of cabinet do they go in?

I don't even have anything to drive that with, lol.

My Gallien-Krueger is barely able to drive a 12...
+1 Very good write-up. I have a Yorkie (Yorkville) 15 here right now that needs repair; I just never done it before so it's one of the many projects around here that hasn't been completed. I'm a bit skeptical on the JB-Weld, but if you've done it before and it lasts and doesn't give you any audible penalties, nice job!

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post #4 of 25 (permalink) Old 02-05-2011, 10:12 AM Thread Starter
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Originally Posted by Grog6 View Post
Nice writeup, GM!

Those are going to sound great; what kind of cabinet do they go in?

I don't even have anything to drive that with, lol.

My Gallien-Krueger is barely able to drive a 12...
Not sure what kind of cabinet because these two I'm going to give to my Pops. They were supposed to be a Xmas present, but the recones didn't arrive til mid-january due to the coils needing to be custom-made (they are not shelved at LSS). I have a third 18D2 that I bought for myself already reconed from Ebay, but it was not reconed properly (the guy lowered the cone all the way down to the spider, consequently the surround ended up sloped downward towards the center, thus the whole assembly was offset inwards). We might just do some simple ported boxes, but will probably end up doing some front-loaded-horns since I know he's always had a thing for them. Maybe even some tapped horns.

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+1 Very good write-up. I have a Yorkie (Yorkville) 15 here right now that needs repair; I just never done it before so it's one of the many projects around here that hasn't been completed. I'm a bit skeptical on the JB-Weld, but if you've done it before and it lasts and doesn't give you any audible penalties, nice job!
The JB Weld will last, I have no doubt of that, lol. As for audible penalties, I don't feel it will be any more detrimental than a heavier cone assembly to start with. Granted it may cause some weird standing waves or whatever within the cone, but these things won't be driven above 100Hz, so mid-bass be damned! lol
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post #5 of 25 (permalink) Old 02-05-2011, 12:45 PM
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I have a third 18D2 that I bought for myself already reconed from Ebay, but it was not reconed properly (the guy lowered the cone all the way down to the spider, consequently the surround ended up sloped downward towards the center, thus the whole assembly was offset inwards)...


... Granted it may cause some weird standing waves or whatever within the cone, but these things won't be driven above 100Hz, so mid-bass be damned! lol
The ebay speaker; I hate it when people don't take the time to do stuff right. Once the glue goes on, it's not changing easily... it's much harder to redo something than to do it right the first time. If I didn't know what I was doing, I'd throw the parts in the box, and sell it complete to someone who does.

JB weld is pretty rigid; for a 15, none of the frequencies of interest is smaller than the cone, so it should be as rigid as possible. Everything else that comes off the speaker acoustically is noise, (over the third harmonic, that is). Third harmonic on 100Hz is about 3 & 2/3 feet... bit bigger than the cone. (lambda(wavelength)=speed (1100fps)/frequency(300Hz))

I would still measure the parameters of the speaker; to see how much everything has changed. The AC impedance will be different, at least. I've never had two voice coils be the same. You can measure everything with a true rms meter or a scope, and of course you need a good sine wave generator.

If you measure the whole box, you'll be amazed at the holes in your upper hearing range, lol. It's weird seeing a signal on a scope, and not being able to hear it.

And yeah; cars and guitars, they are bad for your hearing, if you haven't noticed.


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post #6 of 25 (permalink) Old 02-05-2011, 01:07 PM
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Damn! You have mad skills in everything. I am a little perturbed by the idea of replacing just the foam on a speaker, let alone the spider and cone! I am thinking of getting ahold of some 12w6s that may need some work (foam, maybe voice coil too). Is this something a moron such as myself can tackle? What can you do when the voice coils short out? Thanks

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post #7 of 25 (permalink) Old 02-05-2011, 03:35 PM
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The JB Weld will last, I have no doubt of that, lol. As for audible penalties, I don't feel it will be any more detrimental than a heavier cone assembly to start with. Granted it may cause some weird standing waves or whatever within the cone, but these things won't be driven above 100Hz, so mid-bass be damned! lol
A slightly heavier cone just needs a good amp with a high damping factor, IMHO. I have had amps with a damping factor of 100 and with 1000, and when it comes to subs, you can definately hear the difference at high volumes.

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post #8 of 25 (permalink) Old 02-05-2011, 04:11 PM Thread Starter
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Quote:
Originally Posted by Grog6 View Post
The ebay speaker; I hate it when people don't take the time to do stuff right. Once the glue goes on, it's not changing easily... it's much harder to redo something than to do it right the first time. If I didn't know what I was doing, I'd throw the parts in the box, and sell it complete to someone who does.

JB weld is pretty rigid; for a 15, none of the frequencies of interest is smaller than the cone, so it should be as rigid as possible. Everything else that comes off the speaker acoustically is noise, (over the third harmonic, that is). Third harmonic on 100Hz is about 3 & 2/3 feet... bit bigger than the cone. (lambda(wavelength)=speed (1100fps)/frequency(300Hz))

I would still measure the parameters of the speaker; to see how much everything has changed. The AC impedance will be different, at least. I've never had two voice coils be the same. You can measure everything with a true rms meter or a scope, and of course you need a good sine wave generator.

If you measure the whole box, you'll be amazed at the holes in your upper hearing range, lol. It's weird seeing a signal on a scope, and not being able to hear it.

And yeah; cars and guitars, they are bad for your hearing, if you haven't noticed.

As far as the Ebay 18D2, he made a few critical mistakes. The first being that he slipped the lower spider from the top->down on the coil former, and I can see why he did this--its much easier due to the way the rolls on the spider are formed with the very first "lip":




so what he did was this:



when he should have done it like in these next two pics:




You can see it in this pic where the first spider roll is inverted downward:



In that last pic you can see how he pushed the cone all the way down on the former until it met the lower spider. This offset everything because the replacement cone is not as tall (due to original cones now being obsolete):



He also tried to use the same hardening adhesive in the valleys of the surround, which ended up causing a crackling noise because it ended up splitting, mostly on the underside):



As far as parameters, I have the Woofer Tester 3 from Parts Express, so measuring parameters once I break it in will be a cinch. I'm gonna try and get a hold of a kit minus the voice coil. I feel I can salvage the dual-2 ohm coil from the Ebay 18 by just cutting away all the soft-parts from it and grinding off the adhesive. I'll have to see what LSS says about that.

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Damn! You have mad skills in everything. I am a little perturbed by the idea of replacing just the foam on a speaker, let alone the spider and cone! I am thinking of getting ahold of some 12w6s that may need some work (foam, maybe voice coil too). Is this something a moron such as myself can tackle? What can you do when the voice coils short out? Thanks
nothing much you can do, as you can't un-wind them and wind new coils yourself--this needs to be precisely done. As far as doing it yourself, just look at the pics I posted. If they look difficult to follow, its best you leave it up to someone with a bit more confidence.

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I figured those coils wern't readily available..How much did those coils run you?..Are those 2.5" voice coils?..They look kinda small..Was this your first Re-cone?..If so..Well Done!..



Rayo...
The re-cones come in a kit, as pictured above in the 1st post, for $79 I think it was. The coils are 3" diameter in all three Stroker models. Yup, first re-cone ever for me.

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A slightly heavier cone just needs a good amp with a high damping factor, IMHO. I have had amps with a damping factor of 100 and with 1000, and when it comes to subs, you can definately hear the difference at high volumes.
Very true. I have heard this difference as well. Luckily the motor on these speakers is very powerful, with the electrical damping Qes being 0.20-0.26 on the 12s, 15s, and 18s that I have. So they should be able to b*&%$-slap the cones around quite easily.
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post #9 of 25 (permalink) Old 02-05-2011, 07:42 PM Thread Starter
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Nice..That's not a bad price ..Were they nice enough to include the CA glue and rubber adhesive?..3"? Sweeeet!..Are those 4 layer voice coils?


Rayo..
Nah, no glue is included. I had to buy the glue and accelerator. They do include the tinsel lead. You can get a better idea of what all is included by clicking on the link for LSS . And yes they are all 4 layer coils.
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post #10 of 25 (permalink) Old 02-13-2011, 07:09 PM Thread Starter
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Added a couple more pics where I dealt with a gasket fitment issue.
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post #11 of 25 (permalink) Old 04-10-2011, 04:49 PM Thread Starter
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Update on the 2nd recone. Things went astray because I didn't notice this:

The top-plate is shifted from it's proper location on the frame:



This caused a slight, but noticeable rubbing noise as the voice coil moved outwards only.

Here you can see how one side of the top-plate is flush with the frame, and the other isn't:



Not only that, there is a small gap between the top-plate and the frame itself on one area which throws everything off:



I was able to move the bottom plate a bit after loosening the three hex bolts, and this helped a tiny bit. Then I noticed that if I pressed on the lower spider along a certain portion of the circumference out the outer edge, it silenced it quite a bit, probably because it caused a rocking-motion that causes the coil to shift just the needed amount to clear the pole piece on the outward stroke. So a bit of rubber cement on the outer spider roll to stiffen it up a bit, and its 95% gone, but I'm still not happy.


Last edited by guitar maestro; 04-10-2011 at 04:58 PM.
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post #12 of 25 (permalink) Old 04-19-2011, 08:00 PM Thread Starter
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Another update for all the CV fans out there, LOL.

The third stroker 18, which I affectionately dubbed "my ebay stroker", just wasn't gonna cut it for me with how bad the seller reconed it (see post #9 above). So yesterday I did this to it (which brought a tear to my eye because that dual-2ohm coil was brand new):




Why not just live with it you may ask? Because due to my 2nd recone incident, I took a good close look at the motor. Sure enough, look at the shifted top-plate:






I was able to quiet down the second reconed stroker18 quite a bit, but it just isn't as clean-sounding as the first one that came out immaculate. So since I caught the shifted-motor early, I'm gonna tear it completely down before I get the extra recone kit for it. More pics to come.
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post #13 of 25 (permalink) Old 05-08-2011, 02:41 PM Thread Starter
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good news, salvaged the new 2-ohm coil from the Ebay Stroker18. Just fired up the air compressor, took a die grinder with a standard grinding stone and about 30 min of very slow, careful grinding, and its almost like new with the exception of the shorter wires:




So now that I know it can be done quite easily, I'm going to take out the dual-4 ohm coil from my second recone and do the same, and then try to get two sets of cones/spiders to do it right this time.


And here is the motor removed from the basket in order to clean that adhesive off and properly center it on the frame







This is turning out to be a lot of work lol.

Last edited by guitar maestro; 05-08-2011 at 11:13 PM.
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post #14 of 25 (permalink) Old 12-10-2011, 07:43 PM Thread Starter
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Alrighty, here we go. Recone kits are in from Speaker Exchange. Overall, they are very good quality, just like the ones I got from Legacy.

First off, comparison of voice coils:

Stroker 18 D4 coil, 69g (LSS)


Stroker 18 D2 coil, 84.5g (LSS)


Stroker 12 D4 coil, 67.3g (LSS)


Stroker 12/15 D2 coil, 83.7g (SpEx)


Stroker 12 Cone/surround, 65g (LSS)


Same cone, but on more precise scale, 64.8g


Stroker 12 Cone/surround, 30g (SpEx)


Same cone, but on more precise scale, 30.3g


Stroker 15 Cone/surround, 90g (SpEx)


Stroker 18 Cone/surround/D4 coil/dual spiders (LSS & SpEx parts), 195g




Thoughts about Speaker Exchange parts:

Stroker 18:
  • Cone: Looks to be identical to LSS cone (ligher/thinner/less stiff than OEM)
  • Spiders: Look to be identical to LSS spiders, very rigid like OEM
  • Gaskets: N/A (will purchase a set or two soon, forgot to add in order)
  • Coil: N/A (not ordered, likely identical to LSS coils)
  • Tinsel lead: 0.060" diameter


Stroker 15:
  • Cone: Looks to be identical to OEM cone (don't have another to compare, but very thick/heavy/stiff)
  • Spiders: Look to be identical to LSS spiders, very rigid like OEM
  • Gaskets: rubitex cork, same as OEM style
  • Coil: D2 on Kapton former, not metal former like OEM, but same former as LSS coils.
  • Tinsel lead: 0.060" diameter

Stroker 12:
  • Cone: ligher/thinner/less stiff than OEM (LSS supposedly had the last remaining original Stroker12 cones--very thick/heavy/stiff)
  • Spiders: Look to be identical to LSS spiders, very rigid like OEM
  • Gaskets: rubitex cork, same as OEM style
  • Coil: D2 on Kapton former, not metal former like OEM, but same former as LSS coils.
  • Tinsel lead: 0.060" diameter


More reconing action coming soon!.....................

Last edited by guitar maestro; 12-10-2011 at 07:53 PM.
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post #15 of 25 (permalink) Old 03-03-2012, 12:06 AM
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That is dam impressive work you've done. Always loved the Strokers. I'm a DD guy now.

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post #16 of 25 (permalink) Old 03-04-2012, 09:43 AM Thread Starter
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Quote:
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I thought this would make a good addition to this thread..



Rayo..
Yup, I have that cutaway pic somewhere on my hard drive as well. That one is of a stroker15; the stroker 12 has smaller spiders (6.5") and the stroker 18 has a thicker top plate (1").

I just finished cleaning off a stroker 15 basket as well as a stroker 12 that I am gonna recone and lets just say that who ever was in charge of quality control at Cerwin Vega when Strokers were still being made didn't take their job very seriously. More pics coming soon.....


just found this pic, Rayo:




the actual cut-up Stroker

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post #17 of 25 (permalink) Old 04-08-2012, 10:36 PM Thread Starter
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..and now for your viewing enjoyment, a recone of a Stroker 15D2.

First I detached the basket from the motor due to my previous experience with misaligned baskets. Here you can see a huge freakin gap between the top plate and the basked (likely caused by improper tightening of the hex nuts from the other side of the basket, under the spider):



So, I really went back to the production line and took everything apart and make sure the gap was [as] perfectly radially equidistant from the pole piece. Here I cleaned off the old adhesive from the motor:


I reattached the motor to the basket using this adhesive:


Those bolts in the previous pic are not the original black-oxide button head hex bolts. I replaced them with 316 stainless steel bolts. Bolts are 1/4-20 threads, 2.5" long, #12 flat washer.



Now on to the rest. Here I measured the length of windings above the top plate with a digital dial caliper:


With a 1" long coil, and a 0.5" thick top plate, there should be 0.25" of windings above the top plate. I opted for ~0.27 (0.020" more) because being the expert that I am :ugeek: , I know that suspensions sag inward just a tiny bit once the entire moving assembly goes in and also with age as the suspension softens up.


Once the spider goes on the former, it's no longer easy to view the windings, so I used a marker to mark the inside of the former. Unlike the Stroker 18 where the top of the coil is flush with the top plate, the Stroker 15's coil isn't as easily "eyeballed" from under the spider due to the angle of line of sight:



Now the lower spider can be slid onto the former from the underside, and the coil is lined up to the top plate with the markings on the inside in order to apply CA glue and accelerator to the top of the triple-joint:


Then, removed to apply CA glue to the underside of the triple-joint. (I don't know why, but this black CA glue turns whiteish after it hardens from the accelerator. None the less I know it works because it hardens like a mo-fo.)


The Stroker15 cone from Speaker Exchange had to be trimmed to "shorten" it up a bit because the glue on the topside of the triple-joint was taking up some real estate where the cone needed to slide over (which made the surround not touch the flange), and also to increase the coil opening so as to not force it onto the former and collapse it since it is made of Kapton.


Gluing the outside of the triple-joint:


Here the cone is centered using the plastic shims before the glue is applied between the cone and the former:


Another look after the glue is applied. Centering of the coil is of paramount importance due to the extremely tight gap (even more so with D2 coils vs D4 or S4 coils).


One thing I didn't get a shot of was laying a bead of CA glue on the spider mounting flange nor the dual beads of contact cement adhesive on the surround flange (this gets the most even spread of adhesive under the surround). I'll get a pic of this next time I recone my other Stroker 15, as this is very important; if the adhesive doesn't spread out properly towards the inner circumference of the surround flange, it will literally flap up and down a tiny bit and this can and is audible (ask me how I know, lol). The important thing to remember while the glue under the spider and under the surround is tacking up is to leave the shims in between the coil and pole piece to keep everything aligned, super important!!

Next, soldered the lead wires to 0.081" thick tinsel leads, and dabbed some adhesive on them so they don't vibrate on the cone:


Drilled a couple small holes lined up with the push-terminals on the basket, and attached the tinsel leads to the tabs:


Here you can see where I also opted to replace the stock hardware with SS counterparts. Screws are 316 SS 10-32 x 0.5" long, set screw on the side is same spec, 10-32 x 0.5" long.


(NO PIC): Don't tighten the screws on the top spider clamp yet! Leave just a tad loose, so you can slip the top spider assembly over the center post. This lets you line up the top spider much, much better to the cone because the 3-hole setup on the top spider (2 screws and center post) have A LOT of slack, its easy to tighten up and think it is centered when really it's not. Once it's on the center post, but just resting on the cone, then tighten up the two scews to clamp up the top spider.

Make sure the angled "lip" at the outer edge of the top spider is not angled too much, otherwise it won't contact the cone as it should. Bend as needed. Apply CA glue to the underside, slide down the center post, and rotate a few inches. Then remove to apply another bead to the underside of the top spider before setting it into place permanently. Offset the spider inwards just a quarter of an inch or so, so the lip on the outside of the top spider adheres to the cone properly, and tighten up the set screw to hold it there for a few minutes while the CA glue hardens after applying accelerator.

Then release the set screw, remove it, add the most important part: the shiny gold emblem! LOL.









Coming next, reconeing a Stroker 12D2!

Any questions?
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post #18 of 25 (permalink) Old 04-08-2012, 11:44 PM Thread Starter
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Quote:
Originally Posted by Rayo View Post
Your attention to detail is impeccable..

This is how they should have been built to begin with..With Precision like you've shown us..

After looking at a couple of your Stroker rebuilds..

I'm wondering exactly what kind of QC they had...Back when they were building these at the factory..


Did you use Speaker exchange parts exclusively on this build?..

Hopefully you upgraded to Dave's Tinsel Wire & CA Glue..


Piecing together a Recone like this...Is not for the squeamish or a beginner!

Big Thumbs Up!

By the way...Nice Glue Joints!



Rayo..
Yea Sp. Ex. parts, but even then their coils are identical (even markings) that I got from L.S.S; they probably got their coils from the same supplier, seeing as how there are probably only two or three here in the cont. US.

I did use Dave's black CA glue, but I used my leftover accelerator from L.S.S./Parts Express. Probably why it discolored upon curing. No biggie, I used it previously on another speaker and it hardens as good as anything out there. I did use clear CA glue on the top spider however so it won't seep through the threads of the spider lip; would have looked ugly, lol.

Now the tinsel wire is another deal. At 0.100" thick, no way Dave's was going to be able to go through the stock stroker solder tabs. I'll save it for later; I had about 1.5ft of 0.081" tinsel left over anyways.
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post #19 of 25 (permalink) Old 04-09-2012, 03:19 AM
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I have some old subs Id like to recone is it worth it to experiment and recone them. THey arent blown but the cones rubber ring is toasted. Any ideas on what to do with them if I wanted to learn to recone on them? They are kickers with dual voice coils 12" vr's.

Not to ramble on your thread but I think many want to ask about sub rebuild advice and get some good tech discussion if thats ok by you.

Spinning pies like wheels.

DD driving my 20 year old project

Now with new ball joints...again
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post #20 of 25 (permalink) Old 04-09-2012, 09:14 AM Thread Starter
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Quote:
Originally Posted by Splattered View Post
I have some old subs Id like to recone is it worth it to experiment and recone them. THey arent blown but the cones rubber ring is toasted. Any ideas on what to do with them if I wanted to learn to recone on them? They are kickers with dual voice coils 12" vr's.

Not to ramble on your thread but I think many want to ask about sub rebuild advice and get some good tech discussion if thats ok by you.
No, problem, man. Do those have a dustcap, or are they those 1-piece cone things?
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post #21 of 25 (permalink) Old 04-09-2012, 04:33 PM Thread Starter
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If that is the case, then yea it's not worth it to try to even re-edge them because without centering the coil while the surround is setting up, you run a HUGE risk of voice coil rub. At which point, you'd have to throw them out anyways.
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Almost forgot to do this to the 1st Stroker18 that I reconed. Surround damping (latex glue is all it is):




Last edited by guitar maestro; 04-15-2012 at 09:21 PM.
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post #23 of 25 (permalink) Old 05-01-2012, 07:40 PM Thread Starter
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For the final chapter of this story (for now at least), reconing a Stroker 12

Lets start with the speaker I picked not because the coil was blown, but because the suspension was very worn. Slicing the surround:



Slicing the spider:



One good thing about the aftermarket coils, they are a full 1" long, versus the stock ones that I've seen some variability. Here is the stock coil:



Good thing I took it apart, the adhesive at the triple joint (on the underside) had pretty much given out, as it was already separating from the spider:



If you're lucky, the spider remnant will come off cleanly by yanking it off with pliers:



So close to getting it all in one piece!:



Remove the center post:



Cleaning out debris from the motor structure with compressed air:



Cleaning particles in the magnetic gap with tape (both inner and outer circumference, super important!!:



all taped up and ready for more prep work:



Lifting off the surround/gasket remnant with a chisel:



Luckily it came off all together by just rolling off with pliers:



My best friend that I've made when it comes to removing old glue/adhesive:



I'm using the thin 3/8" wheel:



Once all that crap is off, clean off the spider flange with acetone:



...as well as the surround flange:



prepping the tinsel lead tabs:



heating up the tab with a soldering iron to remove the old lead:



nice clean solder tabs:



removing the nuts that hold the magnet structure to the basket (7/16" socket IIRC):


since this speaker didn't have a mis-aligned magnet structure, I simply flipped it upside down because the motor although not bolted to the basket anymore, it was still glued to the basket so no worries about shifting, in order to remove the stock hex button-head bolts (4mm):



these bolts hold the bottom plate/magnet ring tight to the top plate, but they release quite easily:



putting in new stainless steel hex cap bolts and #12 flat washers (3/16" hex IIRC):



all buttoned up:



Now I will admit, at this point I switched to another empty Stroker12 basket because I had forgotten that the coil I was gonna use was a dual-4, and the basket only had one set of terminals, so I needed a basket that was originally a DVC style.

Now, the replacement cone from Speaker Exchange has to be trimmed to accommodate the voice coil since it is a general-purpose replacement cone (closest one to the original). Using a marker, I scribed a line where I needed to trim the neck:



carefully trimming the neck:



making sure the cone neck slips over the coil former:



Now, if you read my previous posts, you will recall that this replacement cone is very close visually to the original, but it is around half the weight. So, I ordered an extra cone to "double them up":



Using the first trimmed cone as a template, I trimmed the second cone. There was still a small lip that I needed to trim afterwards:


cutting off the surround of the "backing cone":



time to resin them together. Had a bunch, so figured might was well use it:



slathered it on, but being careful to not get it on the underside of the surround:



this was the dry-fit before, but essentially it is how it ended up after the resin hardened up. MUCH stiffer, and probably just a few grams heavier than the original:



setting up the coil height. Stock spec calls for 0.25" of windings above the top plate, but I opt'ed for 0.27 to account for suspension sag that naturally occurs with age:



once the shims are in place between the former and the pole piece, I marked the inside of the former with the marker, this way when the spider is in place, I can still verify the coil is in the proper location without having any visible windings at all:



dry-fitting the spider on the former, double-checking the coil height markings:



removed it carefully and flipped it over and glue'd the spider with CA and accelerator:



put the coil/spider assembly back in, shimmed it, and set the cone down for another dry-fit:



gotta make sure the surround is nice and flat on the flange:

Last edited by guitar maestro; 05-01-2012 at 07:48 PM.
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with shims in place to keep everything centered (very important!!!), I glued the cone partly to the former, because I wanted to fill in some gaps from the other side to prevent any CA glue from seeping through and getting all over the spider. This normally doesn't happen, but I didn't have steady hands that day:



this extender tip came in very handy:



...as you can see, its a tight fit, but I like to glue both sides, (where as stock it is only on the underside of the spider, and above the cone):



then I glued the rest of the former to the cone after the underside was glued:



at this point, gotta make sure the voice coil leads are lined up to the correct location on the frame:



this is what the glue beads look like on the spider flange and the surround flange. Spider glue is CA, and surround glue is Gorilla Wood Glue:



setting the whole cone/coil/spider assembly down and shimming it IMMEDIATELY to keep everything centered. Once shimmed, I layed down some more gorilla wood glue on the top side of the surround to lay the gaskets down and clamp them to the frame. Also, the holes for the tinsel leads were drilled:



tinsel leads being soldered to the coil lead wires:



lead wires all soldered up and with a dab of GOOP to prevent them from flexing and breaking:



I forgot to put heat-shrink tubing until it was too late. Oh well, no biggie. I can probably slice them up and they will still adhere.



set the top spider in the clamp with new stainless steel screws, slid it over the post to make sure the spider was centered on the cone, and glued it in place with clear CA and accelerator with the clamp about 1/4" down on the post to make sure there was good contact. The rest is just replacing the set screw that holds the spider clamp to the post, which also got replaced with a stainless steel part. Once the glue sets up, just gotta make sure it's level, and add the gold emblem, and voila!






Ready to pound and disturb the peace for another 50 years as Cerwin-Vega's were meant to!
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many might be wondering, "why bother with such old subwoofers, when there are tons of new ones that handle more power, etc, etc". Well this is one of the reaons why. This is the projected frequency response level (SPL) of one of these bad boys in an massive FIFTEEN cubic foot horn-loaded enclosure I plan to build for outdoor use.

Pay close attention to the vertical scale in the first pic



For those with bad eyesight, that's 100 dB of SPL in 2pi space (sitting on the ground with no other nearby boundaries), from about 35-150Hz, with only 1 watt input! Most modern 12" subwoofers will barely get you 90 dB from typical enclosures (hint: you need 10x the power to go up 10 dB). You can also see how the excursion is minimized (dips) in the second graph in many places, something no other type of enclosure can do. This reduced excursion drastically reduces distortion for a very natural, clean sounding bass. All because of that super-tight magnetic gap that the coil sits in, that is able to be used due to the extra stabilizing feature of that extra top-spider. Without the extra stabilizing the top spider provides, the coil would rock around at the end, scraping in all sorts of spots (most manufacturers usually combat this by making the gap extra wide, but this loses valuable magnetic flux as 2nd-order quadratic.

Most modern speakers cannot get the level of magnetic force that this speaker has from a single 1" magnet ring, and would fall flat on their face when trying to move a 17-foot long column of air in a tight folded horn configuration, regardless of how much power they can handle. Funny thing is, to make this kind of response possible, the space in the horn column that the cone fires into has to be very small compared to the cone area, resulting in what is known as, yep you guessed it: high compression ratio. Interesting how Mother Nature is pointing me in the same direction, both with speakers, and with my car.

Last edited by guitar maestro; 05-01-2012 at 08:19 PM.
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