Building a Speaker

[Prairie Dawg]

So no books on mining ore aye?

Speaking of smithying, at one stage I was dead set on becoming a blacksmith. I even knew the last blacksmith in the town where I grew up as a kid, and when I was a kid I used to hang around the forge and learn by watching. He told me he did his apprenticeship in the big foundries in the UK where they had huge mechanical drop-forges for making components for steam locomotives. I was intrigued by how he could take a length of iron and melt it and pelt it into all sorts of shapes. He used to make everything under the sun from iron. He even tried to teach me to shoe horses as the first part of learning, but as a kid I lacked the strength to keep a firm grip of the hooves, as I tried in vain to tack the shoes on. I eventually admitted to myself that it'd be no good as a career for me because I was too tall and a large part of his trade was back-breaking farrier work. Such are the decisions we make.

that's kinda interesting. Did you know that during the war there was only one forge in Britain (Vickers) capable of banging out raw crankshaft forgings for Rolls Merlin engines? So I've been told.

That's right folks-one well placed thousand pound bomb and a determined flight crew coulda changed the entire course of history if the squareheads in the luftwaffe had but known this information.

Yeah yeah, I know.

[tedmich]

compared to blowing your own vacuum tubes, this is quite reasonable!

Best to tear apart a cheap 12" and try to reproduce parts...the VC wire can be 30AWG or smaller copper, flat wound copper, copper clad aluminum etc. and they use enough to get the right resistance: ~ 50-70ft of 30AWG = 5-7 ohms. its wound around a paper, aluminum or kapton bobbin.

Some use hemp, paper, aluminum, fiberglass, kevlar, CF, polypropylene, talc filled plastic or even papyrus (seriously!) for cones. Surround is either butyl rubber, paper, fabric or a magical urethane foam which oxidizes and dissolves in a few short years. Magnets are usually ferrite ceramic or rare earth (Nd)

Baskets are typically stamped steel, cast AL, or thermoplastic.

If you roll your own, I can almost guarantee it will sound completely unique!

[sean k]

I've never thought about makin speakers but after making a spreaker grill for an amp it did cross my mind to build, well, have produced, speaker grills. I had a grill I cut out of wood a few years ago which was a kind of Deco design and I dug it out and realised the wood would be to brittle for the job so after looking about I found a big old boil up pot with the bottom dished in so I decided to use that to cut an alumnium grill from.

After about 10 minutes cutting the jigsaw started juddering from the build up on the blade so I had to take it out and use a really sharp carbon steel knofe to cut the stuff off. It took me about an hour to get this thing cut out then I spent about 1/2 an hour hammering it to deepen the dish. Now I'll go out and file it for about an hour to get it kinda nice and rounded...

Handmade I couldn't retail something like that for less than 200 bucks but if I take it to the aluminium casting shop down the road I could get them for about 20 bucks each. Now that has possibilities... limited at best but there are possibilities.

Some guy also asked about buying my stuff and I said it was too expensive and kinda silly to buy my handmade stuff when the same or better, in doing the job, could be bought for a fraction of the cost.

I think you have to isolate one part of a specific process that you might actually be good at and then find a way to have what you do replicated and then use that revenue to do more of the stuff that'll never pay but gives you a really good inside line to the stuff you're really interested in.

There maybe an opening in changing out ceramic speaker magnets with Alnico ones and in the interim, given you could smelt it up and cast it and magnetise it, selling slugs and bars to pickup winders... theres the odd cobalt dump on the edges of steelmill towns. I heard talk of there being one in the town I was born in and it was making all the men somewhat sick.

But who knows, maybe you were born to make speakers and you'll land a job with experts in no time at all. Follow your nose and if it finds your luck then your nose was indeed pointing in the right direction.

[J M Fahey]

Hi tedmich.
Quite close, eh?
0.20mm (#32 AWG) high temperature (Class F) enameled round copper wire , 90 turns wound on a 2" heavy paper former, 2 layers, giving somewhat over 6 ohms dcr were my staple handmade voice coils for years.
They were very good, warm, fat, although they lacked some attack compared to C12Ns and G12Ms, the main competitors I had to match on stage.

[tedmich]

Hi tedmich.
Quite close, eh?
0.20mm (#32 AWG) high temperature (Class F) enameled round copper wire , 90 turns wound on a 2" heavy paper former, 2 layers, giving somewhat over 6 ohms dcr were my staple handmade voice coils for years.
They were very good, warm, fat, although they lacked some attack compared to C12Ns and G12Ms, the main competitors I had to match on stage.

it can get pretty fancy although the basic loudspeaker design hasn't changed much

check the flat Cu wire wound internally to a Nomex bobbin:

from Po Yun Enterprises Tw

[J M Fahey]

Loudspeaker mechanics themselves, at least on guitar and bass units, remain basically the same.
The advances are shown in *manufacturing* technology, such as improved adhesives, better enamels and base materials, lighter and stronger magnets, and "improved" cone materials, although I'm not yet sold on hemp cones.
A quite popular voice coil supplier here in Argentina swears by his "sandwich" voice coils: one internal layer of copper, mid layer nomex base material, external layer of copper wire.
They *do* sound good, but I still prefer to wind my own the old way: paper, nomex, kapton or aluminum former, and two layer copper winding, always round wire.
The custom made flatwire edgewounds are bought from a friend, who mastered the technology long ago.

[Richard]

Seems like the easiest route would be to find examples of production speakers that you like, figure out what you like about them and see if a speaker reconer or maybe someone like Weber could duplicate or combine those features in one speaker. It seems like you have a cone, a basket (probably interchangeable at the same diameter), surround, spider, and motor assembly (magnet structure and voice coil). I bet a lot of these parts can be mix/matched, and probably cover as much range as a single person could possibly be capable of building. When you consider the leaning curve, cost of setting up to manufacture a very small batch, etc., you would probably come out ahead this way, especially if you could sell the production speakers and recoup some money.

[Alan0354]

Ha ha, I won't touch building speaker with a 10' pole. This sounds much harder than building a transformer(which I won't touch either) and need more equipments.