Are these speakers worth refurbing?

[Kaiman]

Mothman, how come you chose electrolytics instead of MKPs?

[hornucopia]

Hmm.....maybe I should look inside my Leak Sandwiches.......15 ohm versions.

I'm sure, like many oldies, a re-cap might add some sparkle.

[Mothman]

Mothman, how come you chose electrolytics instead of MKPs?

I went for replacement electrolytics rather than polypropylenes beacause this was to be my first stab at DIY elecetronics and as space was restriced on the boards I wanted to keep things as simple as possible. However had I known that I would end up having to pay someone else to do the work then I would have got the bigger polyprop caps and let them figure out how to fit them on the board, but hey thats life

[Kaiman]

Making new boards is very easy and dirt cheap. Any electronics technician should be able to make such a simple board in a jiffy. I think I shall have a new one made, larger and with better layout. As far as I can see the coils are cored, right? I wonder if it would be worth it to replace them with air ones.

[Reid Malenfant]

As far as I can see the coils are cored, right? I wonder if it would be worth it to replace them with air ones.

Only if the air cored inductors have the same DC resistance as the originals, which means they'll likely be quite large & expensive

If the DC resistance is different then the filter characteristics will change.

[Kaiman]

I know. They are not that expensive, unless one considers $15 expensive. One could also buy enamelled wire in bulk and wind them themselves, provided there is access to measuring equipment. Once correct values are reached, they can be doused in resin and baked to a crispy golden brown. As a matter of fact, one need not even use a circuit board; there are various ways to hardwire a simple circuit and stuff it in a spare plastic box with some fiberglass to keep everything snug.

[nat8808]

RIGHT!!!!!

Robin Marshall (later of Epos fame) designed these and worked bloody damned hard on the crossover to get it right with the drivers, which were very good at the time. ...


For those of you that don't know, the MLS4 was a goodie, cost around half the price of the likes of Spendor BC1's/KEF 104ab's/Rogers Export, yet sounded very nearly as good and were recommended in HiFi Choice. These are very well worth updating and restoring and I remember them (and the baby MLS1) with great affection These days, they'd sell for well over a grand the pair.

Out of interest, do you know much about the ML5s, two bass units and maybe a stepped baffle for the tweeter? Might have a friend with some doing nothing - can't remember..

[nat8808]

I went for replacement electrolytics rather than polypropylenes beacause this was to be my first stab at DIY elecetronics and as space was restriced on the boards I wanted to keep things as simple as possible. However had I known that I would end up having to pay someone else to do the work then I would have got the bigger polyprop caps and let them figure out how to fit them on the board, but hey thats life

You just poke the correct legs into the holes with the caps at a distance that means you can fit them all in! That's it...

Arrange them how you want, marking the lengths of leg you need and before you solder them in place, just cut up the internal ink holding part of a used biro and slip the tubes you've made over the legs so they never touch the legs of others..

To be honest, I'd have thought electrolytics were harder or at least no easier to use.

[Mothman]

You just poke the correct legs into the holes with the caps at a distance that means you can fit them all in! That's it...

Arrange them how you want, marking the lengths of leg you need and before you solder them in place, just cut up the internal ink holding part of a used biro and slip the tubes you've made over the legs so they never touch the legs of others..

To be honest, I'd have thought electrolytics were harder or at least no easier to use.

Unfortunately Nat I have absolutely no experience in DIY electronics, I am sure if I had your knowledge I would have done things differently.

[Welder]

What a shame.

There are some ways to deal with difficult hardwired large component soldering.

For two or more lead joins the leads can be twisted together tightly and then soldered. This helps when you find that you cant hold everything in place as you apply solder and heat.

One way to deal with large diameter multi strand wire such as the leads from the drive units to the crossover board is to use good quality Lucar connectors; the type with a ring with a hole in.
Screw the Lucar connector to the board through the ring and then gently open up the part that takes the wire so the drive to board wire along with the last component lead just slides in. Give it a squeeze with a pair of pliers and then by heating the whole assembly let solder run into the joint.
Large capacitors can be held in place using fine cable ties. Just need to drill small holes either side of the cap to thread the cable ties through. I prefer this to using glue.

A bit late now.