how to look inside speakers

[B3ta]

Hello,
Recently I bought 4 speakers, 2 JVC's and bonus of 2 no brand ones for $150CAD. I was looking for the JVC's and the seller told me, if you take the JVCs you have to take the other two---so, I tried them, and the sound was just amazing, probably the best speakers in all my life and believe me, I grow up with an amazing nakamishi system. Took all of them and didn't even say a word about the quality of the speakers.

So now, I'm very curious about the speakers, the screen doesn't come out and no hole on the back whatsoever.

Anyone here with any ideais on how to check the brand and hmos of the speakers inside???

NOTE: these speakers are pretty heavy for their size.

I'm posting some pictures...

Cheers
T

 

[djnagle]

Any speakers I've seen where the back does not come off, the grill does come off. Did you try prying the grills off? Use a small screwdriver and something to protect the edge.

 

[djnagle]

By the look of the backs they may be DIY speakers with treasures inside.

 

[RTally]

If the grill is set flush or below the frame, NEVER pry them off. It is too easy to scratch and dent the wood unless you take precautions. I cringe every time I come across a speaker where some used a putty knife or screwdriver to pry the grills out.

An easy way to remove grills, whether nailed or glued in place, is to get a small wood screw and screw it into the grill frame near a corner. Go in about 1/8 to 1/4" inch, leaving the head exposed. You may want to use a pick or brad to spread the fabric so it is not damaged by the screw. Once the screw is in place, Use pliers to pull the screw, and the grill, away from the baffle. Slow, steady force works best. Once the grill rises above the face of the speaker, slide a credit card or plastic putty knife between the speaker and the grill as you work the grill away from the frame.

Another technique I use, particularly when the grill is easier to pull off, is to use a dental pic to go through the cloth and under an edge of the opening for a driver. This technique should not be used if the grill does not easily release. If the pic slips, it will tear the grill cloth.

i just removed the grills from an AR2ax that were glued to the baffle. After I got one corner lifted, I used a yardstick pushed between the baffle and the grill to break the glue bond. Gotta stay clear of the drivers when doing this. A metal yardstick works well, as does a hammer to pound it through the glue if it gets tough going.

 

[B3ta]

Hello everyone, Thank you so much for the replies.
These speakers are really something. A friend was at my place last night and we played some tunes, he was impressed with the quality and transparency of the sound.
I live in a loft style, 1000sq single room with exposed wood, the sound just travels all around in an unique way!!!!

I'll play around this weekend and see if I can pull the screens without damaging, and then, I can find out what speakers are inside. YAY!!!


cheers
T

 

[maxhifi]

What do you see, if you shine a bright flashlight through the grill cloth, in a dark room? Sometimes I can get a good look through grill cloth doing that, holding the lens of the flashlight right up to the woofer and tweeter openings.

 

[B3ta]

What do you see, if you shine a bright flashlight through the grill cloth, in a dark room? Sometimes I can get a good look through grill cloth doing that, holding the lens of the flashlight right up to the woofer and tweeter openings.

Tweeter and midrange have a shiny silver ring around the dust cap. But, I have to check it better on the dark like you said.

 

[sax6]

Get them opened, I can't hardly wait !

 

[B3ta]

So, I did what maxhifi told me to---and, turns out that,

01 - these speakers don't have a visible vent hole,
02 - these speakers have two twitters and one mid-range and of-course the woofer.
03 - the woofer surround is intermittent, it isn't 360 degrees continuous.
04 - the screen is attached to a wooden piece of about 1/2 inch thick that seems to be pressed in on the top of where the speakers are mounted.
05 - never seen nothing like this before and, I'm afraid of playing with it.

conclusions,

06 - I can't pry open the screen, is too much inside the frame and more likely glued down on a step flange kinda thing.
07 - more likely there is a vent hole between the plate where the speakers are mounted and the 1/2 inch screen plate
08 - speaker box might be filled with foam, making impossible to drill a hole from the back and probe it with a snack camera.

steps,

09 - thinking on cutting a corner of the box with a very thin blade to see how the screen seats and go from there. I can always glue that same corner back.
10 - other way is what RTally advice, putting not one wood screw but 4 or 6 all around and then, pry it up evenly.

I did take some pictures of what I saw with a flash light on the dark.

M aybe some of you guys can help me out with ideas???

 

[RTally]

If the woofer surround is not completely around the cone, then it is likely a foam surround that has partially disintegrated. It will need to be refoamed. Do not play the speakers until you refoam the woofers.

If the grill cloth has a tight weave, you could try pounding in small nails in the corners instead of using screws. There would be less chance of damage if the weave is tight. Once the nails are in the grill frame (assuming it is not plastic), pull the nails, and the grills, out.

 

[faber12]

#2 for sure. I would not go cutting on it just yet. The woofers surround needs replaced, sounds like it has a gap in it where it has deteriotated.

Edit: RTally beat me on that last bit.

 

[B3ta]

Hello!
Weave is very tight, the screen plate sounds like wood---for the outside design, the type of wood and the "weave", these speakers look like late 70's early 80's materials.

Even better idea, I can use those spiral shaped nails for wood and use one of those set-up tools to pull pins out---I have one that i need to probably machine an adapter to grab the nails head...

Thanks RTally!!!

if they need refoaming, right now, the sound out of them is just amazing!!!!
I'm just using the JVC's SK-101 that are brand new, made in Japan.

I'll keep you in the loop indeed...

cheers

If the woofer surround is not completely around the cone, then it is likely a foam surround that has partially disintegrated. It will need to be refoamed. Do not play the speakers until you refoam the woofers.

If the grill cloth has a tight weave, you could try pounding in small nails in the corners instead of using screws. There would be less chance of damage if the weave is tight. Once the nails are in the grill frame (assuming it is not plastic), pull the nails, and the grills, out.

 

[B3ta]

Thanks for your reply, I did a numeric re-organization of my previous notes,
#2 is #09 now.

cheers

#2 for sure. I would not go cutting on it just yet. The woofers surround needs replaced, sounds like it has a gap in it where it has deteriotated.

Edit: RTally beat me on that last bit.

 

[RTally]

If the woofers need refoaming, be very careful about playing them. If the surrounds let the cone get off center you can damage the voice coil. That is not an easy fix. I would never play a speaker that requires refoaming except at a low level for a very short time to verify that the drivers work.

 

[B3ta]

question---if I pull out the screens---should I wear a breathing mask as a PPE? I never did nothing like this. You are talking about foaming, woofers surround deteriorating.

Never really understood that, my first nakamishi system, the speakers had a layer of cork inside and that's it, no foam, I still have those speakers and I have my 1988 Technics made in Japan in perfect working conditions.


okay!
tomorrow is a big day!
I'm excited!!

If the woofers need refoaming, be very careful about playing them. If the surrounds let the cone get off center you can damage the voice coil. That is not an easy fix. I would never play a speaker that requires refoaming except at a low level for a very short time to verify that the drivers work.

 

[faber12]

There should not be a health hazard, we are more worried about damage to the woofers.

 

[B3ta]

the screws don't work, the screen moves up a little which is a good signal but need higher grab than just the screws... Look images below---I'm heading to the hardware store to buy thinner wood screws. I'll get it open!!!

 

[B3ta]

Hello everyone!!!

first of all, thank you so much for sticking with me. I did open the box and feel that I can do a better job putting the screen back on, instead of nails I can actually put exposed screws---this way I can open it again in the future.

These are Coral made in Japan, never heard about the brand and don't know how good they are?, I contacted the previous owner and he believe these speakers are from the 70's

conclusions
11 - everything seems to be in a good conditions except the woofers
12 - the woofers surround needs replacement
13 - dust cap needs to be re glue

questions
14 - what would be the price for these speakers once the surrounds are fixed?
15 - where should I buy the surrounds from? I don't care about the price
16 - what is the best glue for this job
17 - should I replace the inside white foam?
18 - should I fix anything?
19 - should I inspect anything?

cheers
T

 

[galactus2]

This website https://www.simplyspeakers.com should be able to help you out with foam kits for those woofers. Just guessing by your pics that they're 8" woofers? Whether they're 8" or something close to that size, that site is likely to have a kit that fits.

Good luck, and keep us all posted.

 

[hugo454]

Coral speakers are well liked.You did good, a refoam kit and you'll be in business.