Renovating old Loudspeakers

[Steveshj]

Hi,

I have a pair of old but much loved loudspeakers from around 1990, made by a British company called TDL which unfortunately no longer exists. I have owned them for around 12 years now and have decided to upgrade them (since a new pair of equivalent spec speakers would run out at >5k). I am sorting out the electronics side, but need some advice on the wood finish.

Considering their age they are in generally good condition, apart from the tops, which are patchy, scratched and in one case chipped. I'm not exactly sure what the finish is, European walnut was a common finish at the time these were made.

I am looking for advice on how to deal with the tops. The redeeming point is the veneer is quite thick, over 1mm by the look of the damaged area. Do I sand back and match the veneer with a suitable stain or should I try to recover the existing finish. I have limited experience with veneers, should I try to patch the damaged area or fill with a repair putty?

Lots of questions, I need some good advice.

Cheers

Steve

 

[MrTeroo]

Don't know about the chip but I have restored many pairs of speakers with Howard's Restor A Finish



https://www.google.co.uk/search?biw...akers&oq=howard's+restor+a+finish+speakers&gs

 

[thick_mike]

Cherry is a popular veneer for speakers, could be that?

It depends on how fussy you are about your speakers. If you refinish them so the colour is even, you might not notice the dent so much. Otherwise, I think it might be difficult to match filler or replacement veneer. You will need to do some filler colour tests if you go that route.

I used black marker pen on my old Kefs, but then they were black ash!

 

[ED65]

Do I sand back and match the veneer with a suitable stain or should I try to recover the existing finish.

Sanding off old finish is best avoided if possible.

Good news is you may not need to go back to bare wood for most of this. There's a simple test which gives a good preview of how the finish will respond to 'reviving' (repair or touch up) and that's to wet a fingertip with spit, or water if you prefer, and rub it over the damage in a few areas. If the damage essentially vanishes in all cases it indicates the finish is a good candidate for repair.

There's no need to use commercial finish restorer for this type of thing if the results of the test are favourable, any oil-based finish can do what's needed and they'll be far far cheaper. This is a simple wipe-on/wipe-off process and sometimes a single application will give a decent cosmetic repair although you'll want to take it further if you want them to look very good.

There is a school of thought that finish should be removed rather than made good and there are a few things to recommend this approach. If you decide you do need to get back to bare wood I think scraping is your best option. It's both the fastest and cheapest method, by a substantial margin. There is some potential for damage to the piece (all stripping comes with this risk) but it's not difficult to learn how to scrape effectively and even a first-timer can get acceptable results if they're careful and get some guidance from some online guides.

I have limited experience with veneers, should I try to patch the damaged area or fill with a repair putty?

The chip is the hardest thing to fix here, but at least it's small and not right in the middle of a surface. Ideal spot for it if you had to pick one!

An invisible repair is difficult to impossible without patching in matching fresh veneer and getting something that matches in grain, colour and thickness might prove very difficult. There isn't by any chance a spot on the speakers where you could steal some matching veneer without it being noticeable?

 

[RobinBHM]

It looks like teak to me

 

[dynax]

or give them a new custom look, mirror window film on some acrylic sheet, then use some aluminium angle sprayed with a black/chrome combo to cover the joins, or just give them them the black/chrome look instead,

 

[custard]

It's a banker's bet that the original finish was sprayed lacquer, it's a commercially manufactured item so why would it be anything else? Furthermore, sprayed lacquer normally has a life expectancy of 20-30 years, so that fits. And when lacquer fails it looks just like your photos, scabby patches where the finish flakes and lifts off. It's also consistent that it's the top surface that is in the worst condition, moisture from the air has condensed out on the top and permeated underneath the lacquer, accelerating the degradation.

It'll strip off in a jiffy, I'd use a card scraper but if you haven't used one before then try 120 grit abrasive paper followed by 180 and 240 grit. In order to avoid dubbing over the edges use a hard, flat sanding block (not a cork block, it's too soft) with the abrasive paper very tightly wrapped around (personally I'd use self adhesive abrasive attached to a scrap of melamine, but for a small job like this you can get away with something more conveniently to hand). Do the top first and then stop and review, you'll find it much easier to identify the wood species at this stage. You may even decide not to refinish the sides and front, or to just do the top and sides. So do just the top and then pause.

It would help narrow down the wood species if I knew more about the cabinet construction. Specifically what is the substrate below the show veneer? It's difficult to tell from that blurry photo, is it chipboard, MDF, plywood, or something else? I've got a faint memory that marine ply was often used for speaker cabs, and it certainly looks like the rotary cut, 1mm thick, Iroko, Sapele or Gaboon veneers that you associate with good quality marine ply. But before you start patching you want to reflect on your level of skill and your access to matching timbers. In practical terms you may be better of building up a patch using coloured hard waxes.

The best repair waxes are the Konig hard waxes, dig around and you'll find lots more about Konig on the web,

https://www.youtube.com/watch?v=BzwgCmA3R6M

If even that seems a bit tricky then maybe think about Morrells soft waxes.

The basic approach with all waxes (and their predecessor, shellac sticks) is to fill the void with a shade that matches the wood background, then fill in grain lines with darker shades. It's not hard and if you mess it up you can remove it and start again. The benefit of Konig is the hardness of the wax, and ease of then matching surrounding finishes and adjusting gloss/matt levels.

If you're going to patch then it's best to match grain lines, so you need a fair bit of donor timber to search through. I draw the major grain lines on some tracing paper then move this around the donor board to find a good grain match. You'll also need the tools and ability to take out a clean 1.5mm deep recess for the patch, and cut the curved sided patch so it matches exactly.

If you're not confident that you have the necessary skills for patching then stick to wax, otherwise you'll just make a pig's ear out of it that will look far worse than it does now.

 

[bugbear]

I found a website talking about these speakers;

http://www.imf-electronics.com/Home/tdl/studio-4

The PDF brochure says they were made in Walnut with brown grille or Black Ash with black grille.

BugBear

 

[dynax]

have a look at this thread, post1166612.html#p1166612

 

[Steveshj]

Thanks for the replies lads, very interesting.

Hi Bugbear, I also downloaded the pdf from the IMF website, the sole source of my information regarding likely finishes.

The Restor a Finish looks most promising as it requires the least skill (which suits me), I’ll see if I can get hold of some.

However, I have a few oils and waxes lying around which I will test out on small areas sometime this week.

As for the veneer damage, there is plenty of spare veneer. Whilst I was poking about inside the cabinets to get the crossovers out, I was amazed to find that the cabinet is veneered on the inside as well.

I should be able to cut a piece from the area adjacent to the terminal port.

I’m still trying to get my head around Dynaxs’ suggestion, however, I’m 100% sure I’ll never be able to “sell” this to the wife!!

I’ll post when I’ve tested some of these ideas out.

Thanks

Steve

 

[bugbear]

As for the veneer damage, there is plenty of spare veneer. Whilst I was poking about inside the cabinets to get the crossovers out, I was amazed to find that the cabinet is veneered on the inside as well.

I should be able to cut a piece from the area adjacent to the terminal port.

That's not so surprising - it was done for balance; if the outside veneer were rare or expensive, or hard to work (e.g. Walnut burr) the balancing inside veneer might have been something commoner/cheaper.
http://www.joewoodworker.com/veneering/ ... veneer.htm

Do I take it you're planning to replace the Electrolytic caps on the X-over?

BugBear

 

[Eric The Viking]

A couple of those look like back-to-back electrolytics - horrid!

I redid some Monitor Audio crossovers years ago using polyester instead of those things: it vastly improved matters, not least because the caps frequency response was much better, as well as being an accurate capacitance value and stable. The most obvious improvement acoustically was to the stereo imaging.

It was a bit of a challenge fitting all the caps on the board, but worth the effort.

E.

[edit] I think all the blue ones are back-to-backs, actually. Hard to tell from the picture though.[/]

 

[Sheffield Tony]

Oooh. Transmission line speakers. I remember looking desirously at a pair of those when I was going through a HiFi phase. Well worth the bother.

 

[Steveshj]

Hi,

Whilst getting away from the topic, yes, crossovers already out and away for "re-capping" all I will do myself is replace the internal wiring and connectors and do the cabinet work

I first heard a pair of IMF transmission line speakers at a hi fi show when I was a lad (1970s), I was hooked. Many years later when I saw a pair for sale I had to get them.

One of the reasons I am a bit cautious about the finish, I want them to sound and look brilliant.

I'll post my progress.

Cheers

Steve