Leslie,

Exquisite, I think is the correct word!

I'd like to find a pair of CX100's, but so far I've not been successful in Israel. Shipping and duties from outside make importing quite uneconomical.

Menahem

Jeff:

Absolutely gorgeous, great job! I keep an eye out for these but so far have only managed to score the one pair of CX50's in white. Grills are fine, but I had to refoam and need to do the stripes.

The bare aluminum looks great, did you spray it with clear coat or anything?

Thank you Jeff. I left the aluminium bare as it is. Tried to spray it with clear coating but that became messy and looked unnatural.

Same for the stripes. Next time I'm gonna spray the stripes with clear coating.

yachadm:

Leslie,

Exquisite, I think is the correct word!

I'd like to find a pair of CX100's, but so far I've not been successful in Israel. Shipping and duties from outside make importing quite uneconomical.

Menahem

Great to hear from you Menahem and thanks. I have been admiring your work for a long time but unfortanetely I'm not able to mingle in these kind of discussions. Out of my knowledge

I have 7 pairs of CX100's and about 8 pairs of CX50's collected and refurbished over the last 2 years. Now it's time to sell and/or exchange them. Pitty you're import fees/taxes are high.

Got my BM 4000 yesterday checked and its working, will open for cleaning and checking for parts, will buy caps and lamps from Martin

Thread here

I do about 1 set a year Leslie. My most recent pickup was a white set of CX-100. te cabinets are fine and the drivers are still intact but definatly in need of refoam. The pricing here is a real crap shoot.

the best deals are always for the black pairs. In my case with both set I have refurbed I stripped off all the black paint in sanded polished the aluminum back.

the whites I intend to keep white.

Leslie:

I left the aluminium bare as it is. Tried to spray it with clear coating but that became messy and looked unnatural.

The problem is, if you leave the aluminum bare it will not continue to look good...you'll need to 'harden' the surface (as B&O does).
Well -you can not do it as they do in the factory But -the solution for amateurs is...sodium hydroxide.

I once bought a set of badly damaged alu C 30's with lots of scratches. I sanded the surfaces and afterwards i gave it some "Caustic Soda" dissolved in water (Sodium hydroxide) to harden the surface. It looks very close to the original finish. I think it's better than some clear lacquer.

Steffen:

Leslie:

I left the aluminium bare as it is. Tried to spray it with clear coating but that became messy and looked unnatural.

 

The problem is, if you leave the aluminum bare it will not continue to look good...you'll need to 'harden' the surface (as B&O does).
Well -you can not do it as they do in the factory But -the solution for amateurs is...sodium hydroxide.

I once bought a set of badly damaged alu C 30's with lots of scratches. I sanded the surfaces and afterwards i gave it some "Caustic Soda" dissolved in water (Sodium hydroxide) to harden the surface. It looks very close to the original finish. I think it's better than some clear lacquer.

Thanks Steffen for the tip. I have made some alum. base (feet) for my Beovox replica's and polished them about 3 months ago and they still look great. Also for my Grundig tweeters which you can see on the background. They look fantastic...

Steffen:

But -the solution for amateurs is...sodium hydroxide.

Steffen, does the polished aluminium stays bling bling when I use this caustic soda stuff. What's your exeperience? Never knew you have this soda in almost each household.

Leslie:

Steffen:

But -the solution for amateurs is...sodium hydroxide.

Steffen, does the polished aluminium stays bling bling when I use this caustic soda stuff. What's your exeperience? Never knew you have this soda in almost each household.

And how do you mix it ?

Søren Mexico:

Leslie:

Steffen:

But -the solution for amateurs is...sodium hydroxide.

Steffen, does the polished aluminium stays bling bling when I use this caustic soda stuff. What's your exeperience? Never knew you have this soda in almost each household.

And how do you mix it ?

 

And how long does it has to stay in? Seen some videos on youtube what you can do with it.

My experience is, that "raw" aluminum is very sensitive to fingerprints etc.

When you use sodium-hydroxide it will not stay bling-bling (if you by this mean "shiny"). The surface becomes a little more "white" - like the brushed aluminum surfaces on the "old" B&O -like the Beocenter 9000 and BeoSystem 5500 etc.
When I sanded my speakers they became more shiny than the original finish - after the sodium-hydroxide they look more like the original.

I once made a new alu-plate for the dust-cover of a Beogram 5500. I bought a thin alu-plate, sanded it and put it in a sodium-hydroxide solution for just a few minutes.
Actually - I don't have an excact recipe...I just pour some water in a tub and then I put some caustic soda in, and then it must be stirred (not shaken) - till it's dissolved.

In case of the speakers, I dipped a cloth in the solution and gently rubbed the surface for a few minutes, untill it looked right.
BE CAREFULL - use rubber gloves and eye protection! 
Finally you rinse with water and wipe the surface with a piece of dry cloth. Voila!

I've seen some of the videos on YouTube - Don't try this at home, kids

When anodizing aluminum, the only time you use caustic soda is when you have old pieces already anodized, you use the caustic soda to strip the surface down to raw alu, thereafter you anodize. What you get after inmersing in caustic soda is raw alu which wil oxidize, starting immediatly with contact to air, the oxide will give a "whiter" look and the oxide will also, to some grade, seal the surface, but any liquid like coke or beer will penetrate the surface and accelerate the oxidation and give a "whiter" area, and after years the aluminum, like iron, will disappear and all what's left is the oxide. The surface can be protected to some grade with wachs, Pledge or some oil, but it will continue oxiding.

Anodizing closes all pores in the material and hardens the surface, making it withstand all not acid liquids and to some grade scratch resistant.

Sorry Steffen, when I read your reply, it triggered something I learned long time ago and I had to do some homework.

What B&O do with aluminum is something amazing and is known throughout the world as one of the best, they are now experimenting with a way to make a totally white (without dyes) aluminum   

Thank you both for explaining, very interesting to read. With "bling bling" I mean shiny, that's right! I think I leave it that way and I don't mind the finger prints as long as I can wipe it off. It's like an Iphone

Leslie:

Thank you both for explaining, very interesting to read. With "bling bling" I mean shiny, that's right! I think I leave it that way and I don't mind the finger prints as long as I can wipe it off. It's like an Iphone

I have made good results with marine grade poly urethane varnish, it more stable in color (cheap ones gets yellow), but you dont find it in spray cans, so you will have to use a spray gun, just before spaying, a light polish and wipe of with acetone, spray 2-3 layers, polish before each layer, use cotton gloves to handle.

Thank you for your explanation, Søren.
However - I have to tell that I learned this (sodium hydroxide thing) when I was a teenager, following a electronics course. (As you say -the oxidation protects the surface).
Here I build my first amplifier -japanese style -with an aluminum frontplate and lots of knobs and buttons.
I sanded an aluminum plate and treated the surface as mentioned earlier in this thread. I still have it -and the aluminum still looks good. 
Now -many years later - neither the oxidation, nor the aluminum is gone

I must add...I have not tried to pour beer or cola over it

Steffen, As Einstein truly remarked "All is relative", so is time, in 100 years your alu is gone, but so will your Jap. amp. be.

Take a look at how Leslie do his refurb, perfect until the last detail, he will not be happy with "only" caustic soda treatment.

And I will try caustic soda on a pair of items, just to see how it comes out, also over time.

At the moment I'm working hard on my siesta, after that I have to open my BM 2400 again, it came back with the old failure, changing channels by itself, and after doing that for one or 2 hours  it turned of.

Søren Mexico:

and after doing that for one or 2 hours it turned of.

You just let your BeoMaster do what it wants?

BM2400: "Well, it doesn't seem like anything good is on, I think I'll just go to sleep." (Click)

Just got done with my calculus home work, now going to try and make some progress on my headphone amp pcbs.

Sanded an awfull painted set of CX50 in high gloss black and sprayed in matt black. As finishing touch, I dusted with metalic flakes. As an experiment I recloth the speakergrills.  I have an extra grill set with new reproduction black cloth.

What do you think of the cloth in black&silver? 

Restored my Grundig tweeters from which I have made the aluminium base and connected this pair with the bassbox to my Beocenter BC9000. Great sound!

Leslie,

Those. Are. Stunning!!

They are Evan, to be honest, I like them more than the Beovox 2500

[View:http://www.youtube.com/user/MastroVintage?feature=mhee#p/u/0/NodHzm_KMuo:560:315]

Just done!!!!!!!!!!!!