Repairs to colour and paper

[Moondog55]

I have a pair of Magnavox 8FR's I am going to be using in a open baffle project as a gift for family friends
The paper is very (VERY) thin and used to be bright Burgundy red in colour, I would like to return the drivers to the original colour but without spoiling the sound.
I was thinking of using a thin wash of PVA adhesive mixed with wood stain.
Query?? will this work, is there a better way to do it?? If I am not extra careful with the added mass and stiffness will I spoil / ruin the driver??
I need to be very careful around the edge as this unit has no seperate surround, just pleats in the paper of the cone

[Moondog55]

Whoops ; it looks like I forgot some High school chemistry.
PVA on paper is fine; no problem; but the woodstain I used is ALCOHOL based.
What happens when you mix an alcohol with an acid??? ALDEHYDE.
The cones have a nice red colour but are now covered with a sticky layer that isn't hardening.
If the mix doen't harden I've lost a dollar and learned a lesson.
Any one else here made this same or similar goof??

[Moondog55]

Let others learn from my mistake, I've ruined them, the speakers are now quite sibilant and muddy.
Still the boxes will be usable, I'll just make a new baffle front and replace tha stupid DIN speaker input

[rcavictim]

Gotta hate it when that happens.

Food coloring dye available at a grocery store. Red is one of the bright colors available. That is water based. Should be able to be applied directly in solution to the paper cone mixed with some alcohol which will then evaporate.

Clear water would dissolve the dye but it causes grain damage to paper fibers, just as it does to a bare, smooth sanded wood surface. The cones would be compromised in a bad way.

I have treated paper cone drivers with shellac diluted with alcohol with good success rather than use PVA, so I know the alcohol bath of the paper cone is fairly safe.

Best to test your dye solution on a piece of printer paper and let dry. See what if any sheet deformation occurs once allowed to dry naturally.

If you insist on a PVA treatment the food coloring may be suitable as a dye. I do know that painter's (artist) acrylic paint (in the toothpast type tube) mixes fine with PVA. I used black once to restore the color on some faded Goodmans 12" cones. I did not use a PVA treatment. I forget what I dilluted the paint with. It may have been a very tiny mix of shellac with alcohol, or just plain alcohol. The speakers were not compromised performance wise. They are very, very good efficient drivers IMO for low power SET. 20Hz to about 5 or 6 Khz. I use them in large front loaded horns with a helper HF horn in a 2-way, 1st order passive crossover.

[Moondog55]

I had used PVA on other occasions with success, I'll know next time.
I used "Feast & Watson" wood stain which has an alcohol solvent, easily diluted with either methanol or ethanol.
I don't think I would have tried the PVA if I hadn't got the drivers so cheap.
I once used acrylic paint with added talc to play around with some ultra cheap chinese woofers, that worked surprisingly well; it must be that the paper used in the 50's has no additives.

[Moondog55]

Luckily I bought a replacement on Ebay.
See the post in Full-range forum

http://www.diyaudio.com/forums/forum...?s=&forumid=51

Anybody know anything about Kaltro brand drivers??

[Moondog55]

Please don't laugh too loud, I was picking them up to throw in the bin and held the drivers up to the light "just in case" all the warping in the cone seems to have flattened out and the doping has hardened.
Sometimes; often; ( I wish I'd paid more attention in school) I don't know how or why, but while no way as smooth in the highs the drivers will be usable.
Not perfect but usable in the party speaker sense and anything has to be better than the plastic Akai boxes my friends are using for music at the moment.

So it's a return to plan "A" and a medium size open baffle with a couple of cheap 10 or 12 inch woofers to boost the bass.

This means I get to keep the "KALTRO " full range for myself, another project to keep me off the streets and out of the pubs.

[Nordic]

I wonder how it will react to danish oil... I once left a paper kitchen wipe I used to oil a piece of wood lieing around for a few days.... I was very impressed with how it seemed to strenghten and slightly harden the paper...

[Moondog55]

Doesn't danish oil have a wax component?? I have noticed a similar effect on the rags I use for polishing furniture I just can't see me putting that much pressure on a driver cone so I imagine you'd need some sort of solvent that evaporates.
Interesting that this appears to be a surface treatment, the pigment did not penetrate to the rear of the driver, the back side is still dark but no darker than before

[Moondog55]

OK trial baffle started.
"Gainphile" thanks for the coments on the cheap Jaycar 10 inch woofers, I'm using them in this speaker.

http://www.flickr.com/photos/2551065...=1220516408546

Trial baffle is made from 22mm bead board, stiffer than cardboard but not as easy to cut.

The Magnavox full range is predominate at the moment first order om the woofers 3mH on a nominal 4Ohm load and second on the full-range