Grenadeslio
Lunatic Member
Very minimalistic crossover, woofer looks to be running full range, I'm guessing these are home made.
how to look inside speakers
- Thread starter B3ta
- Start date
Quite a few Coral fans around here, and the time and money invested in refoaming the woofers will be well-spent, As far as a loose dust cap...it would need to be removed anyway to center the voice coil during the refoam process and is easily reglued to the cone. Might as well check the capacitor values and replace them while you have them open. Have fun...and there's plenty of videos out there taking you step by step through the refoam process.
RTally
Speaker addict
As for reinstalling the grill, I suggest using velcro in the corners. If you want to get fancy, you can use magnets. Velcro is simple and readily available. I also like pull tabs. I glue a fold of color matched, cloth ribbon to the bottom of the grill so that I have something to grab and pull when I want to remove the grills.
RTally
Speaker addict
Good catch! I missed that. I bet the Coral speaker cabinet was made the same way as my Goodmans: totally sealed and never intended to be serviced. I had to cut the rear panel out and reinstall by building a lip the back panel could rest against.
For these speakers, when the baffle is reinstalled it must be air tight. So OPs idea of using screws makes the most sense. I would also use a gasket for the baffle to sit against. For my Goodmans, I ran a bead of RTV and let it cure. Screwing the back panel compressed the cured RTV and sealed the box.
B3ta
New Member
Thanks guys, much appreciated!!!
Yes, the grill cloth is actually directly covering and attached to the baffle. No actual, separate, removable grill. The grill cloth was somehow glued, easy to come out leaving a white residue on the baffle. I have to remove the screen cloth in a few places because during the pull up, I damaged the baffle with the screws, so have to fix it and maybe apply some wood glue on the damage holes.
Yes, these are sealed with no vent port, never seen nothing like it before. I'm thinking on getting some fancy screws with a 1/2 inch washer kinda thing, all black. The 1/2 inch washer area is enough to press the baffle down, Thinking on 6 screws.
Good idea on the gasket RTally, need to make something at work and glue it down to the step box. Have to research what is the best material to make a gasket in this particular case.
question---
Any suggestions on the type of material to make a gasket?
imral3, check images below, they used just a piece of insulation, right on size, when I touched it, it started to release a lot of microfibers in the air. I wonder if this type of insulation is actually safe to breath?
question---
should I replace this insulation with something else? or just leave it untouched
I've been thinking that now the speakers are open, I should sand the outside box and varnish them, they will be like new and with a vintage look.
Yes, the grill cloth is actually directly covering and attached to the baffle. No actual, separate, removable grill. The grill cloth was somehow glued, easy to come out leaving a white residue on the baffle. I have to remove the screen cloth in a few places because during the pull up, I damaged the baffle with the screws, so have to fix it and maybe apply some wood glue on the damage holes.
Yes, these are sealed with no vent port, never seen nothing like it before. I'm thinking on getting some fancy screws with a 1/2 inch washer kinda thing, all black. The 1/2 inch washer area is enough to press the baffle down, Thinking on 6 screws.
Good idea on the gasket RTally, need to make something at work and glue it down to the step box. Have to research what is the best material to make a gasket in this particular case.
question---
Any suggestions on the type of material to make a gasket?
imral3, check images below, they used just a piece of insulation, right on size, when I touched it, it started to release a lot of microfibers in the air. I wonder if this type of insulation is actually safe to breath?
question---
should I replace this insulation with something else? or just leave it untouched
I've been thinking that now the speakers are open, I should sand the outside box and varnish them, they will be like new and with a vintage look.
sax6
Loudness always ON
Get to it... Audio vintage passion IS, from my point of view, spending time upgrading speaker cabinets
imral3
Enjoy the musics!!
With grill cloth wrapped around baffle, as already done, you may not get an airtight seal. This also is dependent upon the cabinet makers accuracy in construction. On the other hand, the grill fabric itself may act as gasket helping with sealing the baffle to the cabinet. How was the baffle secured to the box? Nails or screws?
70's Rockfan
Rough N Ready
I have bought many foam kits from these guys.
I have been very happy with their products.
https://www.springfieldspeakerrepair.com/Default.asp
I have been very happy with their products.
https://www.springfieldspeakerrepair.com/Default.asp
SoCal Sam
Lunatic Member
Mystery speakers are part of the fun. If the cabinet is heavy, then the speaker gets a closer look. Rap your knuckles on the side of the cabinet and listen for resonance. If it sounds like a ripe melon, that is secondary resonance which means poorly damped and sh*tty sound. No effort in the cabinet usually means poor quality drivers. If the knuckle rap sounds like solid wood, the cabinet is well made and could have better drivers inside.
B3ta
New Member
acording to the https://www.simplyspeakers.com there is no need to center the voice coil during the refoam. Should I really do it the proper way and emove the dustt capt?
and, also, is there any technique of removing the dust cap and putting it back on?
I thought we would need to cut it and place a new one?
the dust cap need to be re-glued in one section only.
cheers
T
and, also, is there any technique of removing the dust cap and putting it back on?
I thought we would need to cut it and place a new one?
the dust cap need to be re-glued in one section only.
cheers
T
B3ta
New Member
with 10 nails all around, it was sealed ended, the baffle with the cloth around the edges have a tight fit into the flange. I believe that now after all this years me removing the baffle I would need to place a gastek layer between the flange and baffle. Just a small layer of let's say 2 MM thick and 8 screws instead of 10 nails.
B3ta
New Member
Regluing the dust cap is pretty easy...Ailene's "Tacky Glue" (available at JoAnn Fabrics and many other places like WalMart) does a good job. Many refoam kits also include a replacement dust cap which makes the process even easier. Tacky Glue once again. As far as centering the voice coil, in my opinion it's a wise move. Again, many refoam kits include thin plastic shims to do this. Just insert 3 of them equally spaced between the voice coil and the magnet pole piece and leave them in place until the glue attaching the new foam to the cone and basket is cured. Or...one flashlight battery connected to the driver terminals will center the coil nicely.
RTally
Speaker addict
There is always a need to center the voice coil while refoaming. There are several techniques:
1) Remove the dust cap and use shims to center VC. Glue dust cap when finished. Time consuming and extra work. This is not really "the proper way." It is just what was first used and some prefer it.
2) Use a 30 to 50 Hz tone to magnetically center the VC during refoaming. A phone app can provide the signal to a receiver/amp connected to the driver. Simple and non-invasive.
3) Manually push in the cone to ensure no VC rub. Works well for drivers with a large gap. Centering the VC is dependent upon your skill level and how quickly the glue sets up. I do not recommend this method for neophytes.
I usually do 2 to magnetically center and and then do 3 to verify I did a good job.
This video illustrates method 2)
This video illustrates method 3)
B3ta
New Member
These are good information, I'm onto it, ordering the foaming kit... just have to figure out exactly dimensions which I'm a little confused how to check it...
These woofers have two sets of numbers, 137 7426 and 5812517, can't find much when browsing them, is there any data base of coral speaker somewhere online? I don't even know if they are still in business still.
These woofers have two sets of numbers, 137 7426 and 5812517, can't find much when browsing them, is there any data base of coral speaker somewhere online? I don't even know if they are still in business still.
There is always a need to center the voice coil while refoaming. There are several techniques:
1) Remove the dust cap and use shims to center VC. Glue dust cap when finished. Time consuming and extra work. This is not really "the proper way." It is just what was first used and some prefer it.
2) Use a 30 to 50 Hz tone to magnetically center the VC during refoaming. A phone app can provide the signal to a receiver/amp connected to the driver. Simple and non-invasive.
3) Manually push in the cone to ensure no VC rub. Works well for drivers with a large gap. Centering the VC is dependent upon your skill level and how quickly the glue sets up. I do not recommend this method for neophytes.
I usually do 2 to magnetically center and and then do 3 to verify I did a good job.
This video illustrates method 2)
This video illustrates method 3)
VC drivers are easy to refoam, and the guy doing it has done it many times, so, of course, it looks easy.
