Manufacturing a paper cone

[SunRa]

Hello Chris,

you've mentioned that Mr. Teramoto is making the paper cones in-house for the Feastrex drivers.

Could you please (if possible and if permited) describe a little the process of manufacturing these cones?

Thank you!

[cdwitmer]

I really know very little about how the cones themselves are made. The ribs and so forth are pressed into the paper before it is folded upon itself and glued. I'm sure he uses various presses and jigs to hold things together while the glue is setting.

And then the voice coil former!

That is very special and important to the sound, I'm sure. But again, I know very little of the details about how they are made.

And the various resins, etc. applied to the cone are a complete mystery to me, although I am sure they have a major impact on the sound.

Maybe Clark Blumenstein can give you some more information . . .

-- Chris

[SunRa]

Hello Chris,

Thank you for your reply. I am sure there are lot's of practical details and little "trade secrets" regarding these cones and the entire voice-coil assembly but it's not my intention to go into these details.

However carefully looking at various pictures on the net and also thank to your posts in various threads I've answered some of my questions.

For example I've observed that the cones in the feastrex are actualy of conical form and not curvilinear or some other curveture. I think this makes them easier to manufacture and also doesn't require molding.

I find this an important aspect in speaker design as i thought for some time that extended frequency is a result of the cone profile. However I learned that actualy the high magnetic flux and stability in the gap actually gives the extended high frequency in a cone.

There are some widerange speakers like the supravox 2000, that have a different cone profile. These drivers extend in frequency without the help of a whizzer cone. Am I right if assuming that the cone profile helps only in controling the breakup and is just helping the driver to extend in frequency by controling the non-pistonic behaviour of the cone?

[cdwitmer]

I'm not sure about your closing question . . . you are probably already my equal if not my superior as regards your knowledge in this area. I think cone shape plays a role both in frequency response characteristics and control of cone breakup modes; however, the materials and other physical characteristics of the driver also all come into play organically so I don't want to be too dogmatic about the role of the cone shape.

My feeling is that, all other things equal, a curvilinear cone shape is probably preferable to straight; however, the other factors are never truly equal . . . how you use the combination of factors to achieve the total end result is all that counts, in the end.

-- Chris

[auplater]

Here's a paper speaker cone pushing 70 + years in exceptional condition, save a little dried out glue (which has been repaired... from a Philco 37-116 set I'm restpring...




Wonder what pulp additives were used for this?

John L.

[SunRa]

Hello John,

These are nice looking considering their age. Is the bottom part of the cone part of the spider system? Or the ribs and the different material are for cone reinforcement only? I can't figure it out from these angles.

[SunRa]

There are 4 main cone vendors in the US. Rapid Die and Molding Company (RDM), Hawley Products, Nuway Speaker, and Loudspeaker Components LLC. They each comprise about 25% of the market. Most large companies in the pro audio industry end up splitting up their business equally among two or more of these companies. One product line from Emenince may go to RDM, another line to Loudspeaker Components. The reason being, it makes things more competitive between the vendors to do things quickly and correctly. Also it develops a good relationship with multiple vendors who could quickly pick up if one vendor had issues. http://www.rdmco.com/ http://www.hawleyproducts.com/ http://loudspeakercomponents.com/ http://www.nuway-speaker.com/ Outside the US there are tons of companies who do paper cones. One main difference between US paper and Chinese paper is the difference in starch. We use corn starch for paper in the US and China uses rice starch. The corn starch creates much stronger paper. Here is a good link to an old page talking about a few cone/surround materials: http://web.archive.org/web/20031011....com/indext.htm John

Mr. Janowitz,

I think I didn't thank you for these references you've posted. I apologise for that. There are much appreciated, thank you!

I would like to point out to a very interesting site (with some good material and links) : S.M. Audio Engineering