JVC PC-5 speaker surround replacement ?

[Beosystem10]

i just love them....arguably jvc's finest moment

No argument from me! I just found my PC-5 after a search that saw me buying several dozen lesser boxes along the way! Then I found this old thread. My foam and glue are on the way and I can't wait to get sticky with it.

The surrounds were definitely held in by clips, not screws, though screws are used in the PC-11 speaker enclosures for this purpose. Getting the rubber feet out to reach the clips that have to be pressed inwards was difficult to do without some improvisation; I whittled down the sharp end of one half of a sprung clothes peg, milled a slot up its centre and rounded off the ends of the peg to fit along the sides of the rubber foot, then pulled up on the other end of the modified peg for leverage and out popped the feet without leaving any marks on the surrounding plastic. The feet did stretch slightly but were reuseable and will be easier to replace next time I want to take the drivers out.
Why would I want to do that? Well, the Sansui drivers that I fitted in there as a temporary measure sound so good that I can quite happily live with them so refoaming isn't the urgent task I'd thought it might be.

 

[Beosystem10]

Fresh post rather than an edit here as I have speaker-related stuff to say..

I just bagged some (JVC oddly enough) car speakers which measure 5.2 Ohms in a DC resistance test, so in other words, pretty much 6 Ohms in impedance, like the originals! They have the slim basket edges so will drop straight into the PC-5's cabinets and they're 2-way, coaxial ones with the JVC brand name on the tweeter surround.

Anyroadup; I bought four as the seller wasn't selling by the pair so if any other PC-5 owner here fancies trying a pair of these, all I'm after is covering my costs for half of the total, which is a straight £10. UK members welcome to collect, otherwise I'll need time to get the cost of sending these things. They should be with me midweek.

 

[Beosystem10]

So I eventually bought the speaker foam surrounds from Queensland Speaker Repairs in Australia as they were cheaper than anything I found in the UK. Half as much in fact, and that included the excellent and speedy shipping from the maker to me.
Today, finding myself with a free moment or three during a period of not staring at the bowels of the M70 project as I'd begun seeing M70s in my nightmares, I opened the Australian parcel and got in about at the job. If I'd realised that refoaming speakers was this easy, I'd have bought the foam for my classic Hacker speakers' Elac Oval (14"x8") woofers while I was ordering but they can wait just now. I didn't take photies during the removal of the original foam surrounds as they were mostly dust and getting their traces off the JVC cones was easy, though getting the shims and the spacers off the baskets was a bit trickier as they didn't make those with future repair in mind but the pics show one before and one after so you'll see that those shims came off after a good scraping with my profile gauge which was chosen because following the exact shape of things is its job. After that, the remaining glue was lifted with a scoosh of switch spray and then the metalwork was all treated with a spirit wipe to ensure that it would take the fresh glue - two tubes of which came supplied with the kit.
In the after pics, the white traces are PVA that oozed slightly when I clamped the surround to the underside of the cone but that'll clear as it dries and the coverage is actually very even and after fitting the shim, then the surround to the basket, followed with the spacer, the voice coil doesn't rub at any point when pushed by hand, which suggests that the job's a good 'un. I checked the DCR of the finished one just to make certain that no lacquer had come off when the cone was unsupported and it read as it had before so that one will work, just the other to do but that should be easier again so I have no concerns about the PC-5 soon sounding exactly as it should once more.

So now the only other job I need to do, and this can happen once I know that both speakers are working as they should, is to find the best way to make the cones white again.

Has anyone used white ordinary, household distemper on speaker cones? It's a slightly shiny, vinyl silk one that I have left after doing my bathroom ceilings with it and I figure that by diluting to the point where it's mostly water and putting up very fine coats with only a can of propellant to provide the pressure rather than my airbrush compressor, the coat that goes on should be virtually mist by the time it lands, meaning that the pigment will stick but there'll be so little water hitting the job that the paper shouldn't soak through and stiffness will be unaffected. Of course this won't affect the sound, but I just want the speakers looking as good as the rest of the JVC does and that means making them white.

 

[jimmyjimmy19702010]

Great work John! Queensland Speaker repairs are located the next suburb over from me!
It will be great, even just on a psychological level, to have the original JVC speakers back in place.
I remember when I had my TRK-9300 speakers reformed - it was so great to hear them sing again.

Keep up the good work,

James....

 

[Beosystem10]

James, the job is now completed and the speakers replaced whence they came.
Although the glue was dry long before I'd expected it to be, I wasn't going to wreck my work by cranking the beast before at least eight hours had passed so I fitted some fresh D cells into the battery tubes (the output is reduced when running from battery..) and gently brought the volume slider to the first notch on its scale with some gentle MOR tunes playing from a GD King & PV Airey jazz/blues tape that's at least as old as the PC-5 herself.
Wooooaaaahhh! This thing is so sweet with those factory drive units back where they belong. No need for co-axial tweeters and bright blue, metallic cones here, this is a very, very tuneful old thing that - in typical JVC fashion - plays even old, type 1 prerecorded tapes with a quality that makes these tapes sound as though they were new. I did risk pushing the loudness button once, after I'd reduced the bass level on the pot and turned down the volume, and although these speakers should be treated gently for a while, the potential is obvious and the sound precise, clean and very, very strong even at that low setting.

I can't wait to give her a bit more throttle tomorrow when the JVC and I will be heading south to give a certain other Northern forum member a taste of why he needs to add at least one multi-section box to his fleet!

Big thanks are due to the guys at Queensland Speaker Repairs, thanks to whose clearly marked diagrams on their site - to show every dimension needed when selecting the surrounds for the job - this classic piece of kit is singing as sweetly as she would have done when new. The parcel took only six days to get here from Aus, they're great people to deal with and as I said already; their price was lower than any price for a similar product from within the UK and none of the UK suppliers listed a kit that came with the correct glue (loads of the stuff, I have one unused tube left and there's still a little in the one tube I opened), some big cotton buds to help with getting the glue in under the cone in the awkward bits where the leads run behind it and into the coil, a comprehensive set of instructions how to go about the repair and plenty of packing to make sure that my bits arrived safely.
As for whitening the cones, that'll have to wait. I can see this box being on constant cassette duty for the foreseeable future!

Both cones finished:

The way that the surrounds fit to the underside of these cones:

And the speakers back where they belong, I'll whiten them some day, honestly, I will:

 

[Northerner]

Nice work John, looking forward to hearing how they sound,..not sure you'll persuade me to move away from one piece boxes but we'll see

 

[Beosystem10]

Indeed we will. Let battle commence tomorrow, 2pm. May the best, the loudest, the hardest thumping or - if these criteria defeat my little JVC - the heaviest in terms of weight win!

 

[-GZ-]

Bleach those cones!

 

[Beosystem10]

I suspect that bleach would kill them as it would remove the starch from the paper, making them floppy. But at some future time I may try the left over distemper, which can be fired at them from my airbrush and won't soften them.
The pictures make them look even less white than they are as the lighting is all from tungsten filament lamps but yeah, some day soon..

 

[superlew]

If I'd realised that refoaming speakers was this easy...

Shhh...That's proprietary information.

They're even easier when the foam is adhered from the front...But no one needs to know that.

 

[Northerner]

We'll I can vouch for John's speaker refoaming skills...this JVC sounds bloody good

 

[Beosystem10]

We'll I can vouch for John's speaker refoaming skills...this JVC sounds bloody good

Thanks man, yes, it would seem that the glue held up just fine and I was pleasantly surprised by how incredibly solid the bass is with these original and correct speakers back where they belong.
Having blasted the bass with the PC-5 for quite some time today, I decided that the repairs must have held so I whipped the drivers out to check thoroughly and yes, they're still intact. Phew! I've just been giving the thing another workout with some of the dub versions of my favourite Horace Andy and Dennis Brown tunes and this time, I placed the machine on the coffee table in my living room and didn't turn the bass down at all. Then, having been satisfied with the bass set flat, I turned the bass knob round to about 3/4 of its travel and had the thing playing clean and distortion free with the volume at over 75% of its travel. The air coming from those reflex ports was most welcome as the temperature is still over 70F even now (11:15pm) and I don't have a fan in the house, which I think is my best excuse ever for making lots of noise.

To anyone else who has speakers that are in need of this work I say do it! All you need is a steady(ish) hand, a good supplier for the foam kit (Queensland Speaker Repairs will ship their products all over the world and I can recommend them without hesitation), a decent amount of overhead lighting in your work area and a telephone with a handsfree facility so that you can work and talk to callers at the same time!

 

[oldskool69]

I refoamed my PC-5 speakers. (I've refoamed all of my speakers that needed them.) And it is best with it's original full range drivers. Nothing like it. Maybe I'll take mine down for a listen.

 

[Michiel]

Yeah, I also refoamed my pc5s. It sounds much better with the original full range drivers. Did you glue the foams direct on the metal basket? There suppose to be an extra ring, but I see you removed it?

 

[Beosystem10]

Yeah, I also refoamed my pc5s. It sounds much better with the original full range drivers. Did you glue the foams direct on the metal basket? There suppose to be an extra ring, but I see you removed it?

Fear not, I did the job properly. I removed the old cardboard bits so that I could clean all traces of the glue from the baskets, they were covered in bits of glue and the dusty remains of the old foam so the new surrounds wouldn't have had flat surfaces to stick to, hence my removing those. I didn't take a picture of the new ones going on but they are in there.
Quite why they're there I don't know as they were and are only =/<0.011" thick.

 

[Michiel]

Fear not, I did the job properly. I removed the old cardboard bits so that I could clean all traces of the glue from the baskets, they were covered in bits of glue and the dusty remains of the old foam so the new surrounds wouldn't have had flat surfaces to stick to, hence my removing those. I didn't take a picture of the new ones going on but they are in there.
Quite why they're there I don't know as they were and are only =/<0.011" thick.

They were exactly 1 mm thick. Dunno how much inch that is lol I made some myself too. Without the ring the foam outer diameter would not get enough support on the metal frame. I put some pics of it on the other site I really love these boxes

http://www.stereo2go.com/topic/jvc-pc-5-refoam

 

[Beosystem10]

1mm is about 0.040" so almost four times thicker than the ones I took off mine. My replacements were made from something as close as possible to the original thickness; an empty Cornflakes packet!

I just looked at your S2G thread and couldn't see the rings going back on (the ones on top of the edges of the foam surrounds that are a tight fit between the frets and the baskets when you tighten the screws after replacing the speakers). When I put mine all back together, the frets wouldn't have reached the screw holes if the shims had been any thicker than the eleven thou' ones I made and used. I assume that they were put back on there.

 

[Michiel]

Find it strange that your rings were much thinner! It's not my first set of pc5 speakers I did, and the ring between the foam and metal frame is always exact 1 mm thick. It endures quite a lot of mechanical strength when the cones are pumping. But if it works with a cornflakes packet, than that's great lol. Just don't use the box in your bathroom or other moistly environment I guess

Do you mean the ring that sits on top of the outer foam and that's being pressed down by the the speaker grill? Had no problem mounting these rings. Nice and tight, no resonance at all. I used the original rings and setup. No glue needed etc.