Designing Own Speaker Elements

Well, anyone who can recone speakers, has the potential to "make" their own speaker... to an extent. You're still limited to existing available magnet/basket assemblies, but pretty much, everything else is changable.

I've done some very basic mods, like mix-and-matching voice coils and cones... and it's interesting to see some of the UNINTENDED effects. Geometry can be a real bear, when you start mounting voice coils to cones to surrounds to baskets. But, if you're ever going to learn HOW this stuff works, this is part of that learning process, IME...

Regards,
Gordon.

For inspiration, check this: http://home5.inet.tele.dk/f-hammer/index.htm

SW, eg. FEMM http://mgc314.home.comcast.net/femmexample.htm

Magnets, Field-coil, Neodymium, Alnico.

hi

well heres a start :-

driver type :- Low frequency

cone type :- Re-inforced - Kevlar or Fibre glass / for tonal quality / composite fiber filling - with a heavy pulp beating and mixing process- - non press with non - hygroscopic pulp binders cone

surround - upon escursion limits - natural rubber - moulded - or foam - if intended for pro audio fabric surrounds - m roll or progressive m , or accordian or asymetrical

Spider :- large with deep corrugations - normal or progressive
( depending on limits ) , flexibility - medium , better if silcone doped - (helps cooling)

magnets :- wet pressed y 35 or above - for a linear (linear difficult to achive though) then good BH curve

Pole material :- low carbon cast steel - or forged from 1008 billets - then either the top layer machined off (peeled) or hydrogen annealed

Pole design - Field symmetry and vc inductance stabilisation - cooling design

Basket - pressure cast aluminum - moulded to your design / size of cone - surround clamping diameter etc.

voice coil - Hight temp Al / Cu Flat Wire - Spiral Edge Wound on Glass former (with high temp adhesives) - then slit - backed - ofc welded leads - solder tinned

Lead wire - paraffin doped high quality

Gold terminals

Rubitek Gaskets

High Quality High Temperature Adhesives -

Then a good test setup to evaluate the first prototype - measure vc temp - and power test - check distortions and evaluate to minimise or best eliminate all problems

Suranjan Das Gupta

Transducer Design Engineer

it isn't worth doing, bottom line.

1967cutlass said:

it isn't worth doing, bottom line.

Click to expand...

Most DIY isn't 'worth doing', but that's hardly the point.

Mr Evil said:

Most DIY isn't 'worth doing', but that's hardly the point.

Click to expand...

i disagree. you can make better loudspeakers for the $ than buying them. with making your own drivers thats nowhere near the case.

1967cutlass said:

i disagree. you can make better loudspeakers for the $ than buying them. with making your own drivers thats nowhere near the case.

Click to expand...

I disagree with that. Sure it's possible to make very fine DIY speakers, but for most people there is a limit because of the money needed for test equipment to squeeze that last bit of performance out. For instance an anechoic chamber is beyond the reach of most DIYers, but for commercial products the cost can be spread out. There are cases where it may be worth it monetarily, but that is not the only, or even most important reason for DIY.

Cone and surround have usually been optimized in commercial drivers, especially from the traditional European manufacturers (d-s-t, Seas, Audax,). There is little that can be gained from building something from scratch, with the exception maybe of a multilayered, sandwich carbon fibre cone, which may be just too expensive to manufacture for these makers. But still, expect to go through many iterations before it works well.

It might also be worthwile to optimize cones, i.e. cut edges off similar to what Vifa does, or put local edge reinforcement on the Seas alu cones.


The big field for improvement is motor design. Most motor designs on the market today were made before full FEM analysis was widely used. Even the Seas Excel motors leave the gap unshielded, and careful optimization may lower their distortion even more.

There are a couple of nice motor designs out there (Usher, Dayton RS, Adire), but all of these, IMHO, could do with optimization of their cones and surround (Dan will disagree with me there...).


Greetings,

Eric

hi

I am into pro - audio , hats off to the following including their application , usage - over all design to their selection of cone material for the type of driver

in the order i have been impressed by

1) Meyer sound 2) Peavey 3) JBL 4) RCF & EV

Suranjan

The best way to build your own loudspeaker is to contract it from an established manufacturer. That is by far the cheapest way. Here is the US, Eminence is a well known manufacturer who will OEM a driver for you. There is a minimum quantity, of course, but that is to be expected. You basically just supply your requirements, and they do the rest. The LAB12 horn driver is the result of one such collaboration. Many (if not most) Dayton drivers from Parts Express are also Eminence OEM supplied. Eminence has been OEMing drivers for decades, and they are used by a LOT of different companies.
Doing it all yourself, from scratch, is very impractical, and would be far more expensive than it is worth. If you already own the equipment to machine and/or cast the required assemblies, then it may be fun to play around with, but do not expect to save money in the exercise.

A manufacturer that I know of that produces customized drivers starting at a minimum quantity of 2:

http://www.audiotechnology.dk/iz.asp?id=4|a|119|||

A guy from a German loudspeaker manufacturer once told me that there was also a driver manufacturer in Germany manufacturing custom designs in small quantities but he was reluctant in telling who it is.

I don't think it is impossible to DIY drivers and it would be quite interesting as well. But I fear that I would get nowhere (much too bad time-cunsumption/success ratio) when attempting to do so.

Regards

Charles

1967cutlass said:

i disagree. you can make better loudspeakers for the $ than buying them. with making your own drivers thats nowhere near the case.

Click to expand...

that assumes the goal is only to save money.

I was really interested in designing my own speaker a while back. You should be able to pick up things like spiders, cones and surrounds etc. from reconing suppliers, but there's nothing to stop your experimenting by building your own from scratch. If you have acccess to a lathe then you can also try implementing your own motor designs.

This was my not so serious approach to learning about it:
http://www.vikash.info/audio/transducer_design/

Vikash, what technique did you use to wind your coils? Freehand? Or did you put your former onto some kind of axle?

Greetings,

Eric

Free hand.

Paper former put round a plastic lid to keep its shape and clamped while I manually do the painstaking winding. After winding it was brushed with varnish to keep it in place.


I began to make a DIY winding machine using a manual drill as the turning mechanism, but I'm yet to finish it.

hi

Basically lower the carbon percentage in steel - better the flux density and distribution + flow of magnetic lines ( one may say ) along the motor

in normal mild steel the carbon percentage is generally from
0.15 % to 0.25 % every country has its own standards 1008 is nothing but 0.08 % carbon in the steel 1006 0.06 % steel and so on - its very easy to find the corresponding material name standard in your countries if you have a material conversion chart

it will be available at your neighbourhood cnc lathe work - shop

ther best material then ideally would be 0 % carbon this is patented by an american (forgetting his name most probably Stan _ ) this is used as the core material of solenoids as this does not retain its magnetism at all - no memory effect you may say

i have not worked with this material therefore i do not know much about its machining properties etc

there is a lot about magnets and technology lot of books easily available at libraries

therefore regarding loudspeakers in brief :- there are two processes by which magnets are manufactured - wet & dry

wet process is better -

Dry process magnets are graded in a series called Y series - cheap magnets starts at about Y 25 - , Y 35 grade is quite good and comparable to a wet process magnet ( whose grading is different)

A smooth Bh curve is directly related to Frequency Responce to SPL - Plot

Add proper cooling and you will have a good driver

something like the difference between JBL 2242 to P - Audio 2242

oh by the way Vikash i hope you wore latex gloves as the salt and minearls in ones hand effects wire insulation within sometimes 1 year of winding

Suranjan Das Gupta

capslock said:

There are a couple of nice motor designs out there (Usher, Dayton RS, Adire), but all of these, IMHO, could do with optimization of their cones and surround (Dan will disagree with me there...).

Greetings,

Eric

Click to expand...

Actually, I agree with you about material science and cones and surrounds! That's what we're starting to look at now in ernest, like we did with motors and suspensions...

However, I'm firmly in the camp of "first do no harm"; using cones that have large breakup modes (some metal cones have narrow peaks that are more than 20 dB above the passband!) means not only a much more complex crossover, but issues with self-excitation.

It's more of an approach about accepting distortions below the threshold of audibility but at an overall higher level rather than pushing everything extremely low but allowing one or two peaks above the audibility floor.

I'll accept a dB of ripple over the passband if that's all I get; IMHO it's better than ruler flat up to a higher frequency where there's a couple of big 20+ dB spikes.

Dan Wiggins
Adire Audio

Suranjan,

0% is always a question of detection limit. Telar = Armco is probably the purest iron you can get in commercially viable quantities. It's typical carbon content is 0.003%, maximum 0.01%. Machining is easy if you consider that the material is pretty soft. Unfortunately, I have not yet found a dealer that carries small quantities. Remanence is low, by the way, but not zero. Here's the brochure:

http://www.remag.de/e1/e45/e721/e732/e734/e740/ARMCO-Broschre.pdf

St37-2 (1.0037), which is the standard colf forming steel here, seems to have a typical carbon content of 0.08%, with maximum values ever found in the 0.15% range, according to various source. One which I recall is:
www.metallograf.de


About insulated copper wire, the stuff we get here is insulated with a thin coating of PU. PU is the thoughest polymer coating I can think of, and I doubt that minearals will etch through the insulation.

Regards,

Eric