DIY Sickness

[MrBoat]

This is probably old news to you regulars that have been around the DIY audio scene. I'm relatively new to it so these are surprises when I find them. Talk about dedication.
http://www.inlowsound.com/

 

[TLS Guy]

This is probably old news to you regulars that have been around the DIY audio scene. I'm relatively new to it so these are surprises when I find them. Talk about dedication.
http://www.inlowsound.com/

Paper mache loudspeaker horns have a long history going back to the dawn of audio.

This one from 1920

Paper mache has also long been favored by some in Lowther driver community.

Actually it is a good material for a horn.

This is what it is and how you make it.

Pretty simple and cheap.

 

[MrBoat]

Actually it is a good material for a horn.

This is what it is and how you make it.

Pretty simple and cheap.

I remember making things with paper Mache in school and at home as a boy.

We made a piñata out of it for my grandchildren's birthday party last year, using a balloon as a form.

It is interesting the lengths people will go to achieve these things. Those horns that man makes on that site are quite nice, as is the form he casts them on.

 

[Johnny2Bad]

Wood and metal is often the preferred material for construction of various objects, but it's not the only option. Paper Maché (or Papier-mâché) is a great material for creating moulds for glass or other composites, and in some cases can be the material itself for various projects. The process goes back to ancient times, ancient Greece at least.

I've also used modelling clay or other modelling compounds, and dental amalgam. There are thermoplastics in sheet form that can also be used, and there are the casting plastics and polyurethanes (which have the advantage of being capable of almost any density or durometer rating). And of course there are the Room Temperature Vulcanizing (RTV) rubbers and silicones, and wet-moulded leather.

At least as far back as the 1970's commercial loudspeaker manufacturers were "doping" paper and plastic cones with kraft glue (the kind that goes on white and dries clear).

In college we made papers from various plant straws, old cotton clothing, and similar materials. Currency is usually made with flax straws and cotton; it's very durable. I once bought a wallet made in Japan of some kind of paper, it lasted me many years and wore very well.

You can make almost anything of any reasonable size if you really want to, without the use of metals or wood. But if you think a paper maché loudspeaker horn is "out there", there are people who make DIY vacuum tubes, complete with blown glass envelopes.

 

[highfigh]

A local guy makes speaker horns from various species of wood, but they aren't made to sound great- just to look interesting.

http://www.designboom.com/design/fi...horn-speaker-new-york-design-week-05-27-2016/

 

[MrBoat]

I've done quite a bit of work with composite construction, even paper. Wood, foam, felt cores etc. Also hung and finished drywall for 20 years and can't even begin to count the things I fixed, faked or fabricated with quick-set (Durabond) mud and layers of joint tape.

Just kind of neat to see some of the tricky things people are into with the exposure the internet manages to bring.

 

[Doge]

Rather than start a new post....
I ordered my integrated tube amp Dec 6, 2018. I expect my replacement due this Friday. Best I can tell, transformer hum. I got to wondering - who/what company winds these things?

About 1982 I got into electromagnetic actuators - solenoids and stepper motors. I was formally educated in the EE physics but it became quite apparent, like most things, the real world and the maths were different (enough so experience mattered). In general, we got really good at guessing how things would work and after a few years, the calculators and most maths went away - we just guessed (and tested and tested....).

We were the state of the art at the time, and I am guessing, again, the state of the art now is still 1940s tech in transformer winding. The art makes the difference.

So where are the transformer artists?

 

[MrBoat]

Rather than start a new post....
I ordered my integrated tube amp Dec 6, 2018. I expect my replacement due this Friday. Best I can tell, transformer hum. I got to wondering - who/what company winds these things?

About 1982 I got into electromagnetic actuators - solenoids and stepper motors. I was formally educated in the EE physics but it became quite apparent, like most things, the real world and the maths were different (enough so experience mattered). In general, we got really good at guessing how things would work and after a few years, the calculators and most maths went away - we just guessed (and tested and tested....).

We were the state of the art at the time, and I am guessing, again, the state of the art now is still 1940s tech in transformer winding. The art makes the difference.

So where are the transformer artists?

Last winder of any kind I knew was an electric motor/armature tech from the old school. Lots of specialized tools, and an oven to bake the windings in. He would do transformers though, if they were vintage enough and could not somehow be cross referenced with current (NPI) offerings. He was absolutely brilliant though, and his works often exceeded the quality of the originals, just for the higher quality raw materials he believed in, over what had to be a career spanning 60+ years. I used to like to watch him work, and learned just enough about motor troubleshooting and such to be competent.

 

[Doge]

Last winder of any kind I knew was an electric motor/armature tech from the old school. Lots of specialized tools, and an oven to bake the windings in. He would do transformers though, if they were vintage enough and could not somehow be cross referenced with current (NPI) offerings. He was absolutely brilliant though, and his works often exceeded the quality of the originals, just for the higher quality raw materials he believed in, over what had to be a career spanning 60+ years. I used to like to watch him work, and learned just enough about motor troubleshooting and such to be competent.

Copper wire is coated. There are various materials. When you wind, you ideally want to layer so each wire lies between the layer below. But the coating deforms. So what was a tight wind, becomes soft after time. In a larger wires (low gage) the ratio of coating to copper is small. You can guide/place the wires where you want. But then the turns are fewer the resistance / and impedance is lower and these are not the best for transformers. In smaller wire, the coating is a bigger part, and it deforms. Some harder materials deform less, but craze/crack more. The better material cracks more easily. A polyimide coating looks best on paper as an insulator and it resits deformation. If the winding tension is too high you get crazing (cracks) more easily than other materials. Wire also varies in diameter so getting a machine to do it as well as an artist is hard. This stuff is all understood for decades, but actually getting it right is super hard. The oven part comes in with epoxy/or wet winding where you brush the wires as you wind and create a magnetic glob. Then you bake it. The idea is it will all be stable. After working with a hundred or so different designs and thousands of coils, I learned finding the artist is more important than finding the scientist.

To this day I believe the best coil artists live in SoCal (not born in SoCal). The niche is small and they are mostly doing the same aerospace stuff done decades ago, but better.

To what degree that matters in building amps, I really don't know. If it does matter, I think there is a lot of headroom for improvement.