Hemp Cones and SQ?

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sreten

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Joined 2003
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mayhem13

Member
Joined 2008
Funny you should mention the WgMM, i built a pair with the RLY version sealed in 30L and i'm very happy with them. We're in the proccess of setting up a dedicated HT and i was hoping to build something new for behind the At screen. Something a bit more Dynamic. I see alot of interest in Pro drivers these days and thought i might give one a try. May go the route of the Nathan, but where's the fun in that?
 
planet10

planet10

frugal-phile™
Joined 2001
planet10-hifi.com
Paid Member
mayhem13 said:
Any thoughts or adjectives to describe the performance of Hemp as a cone material? Muddling over a high sensitivity 2way for HT and thought this driver http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=290-516&ctab=9#Tabs might be a good choice crossed to a 1" compression driver at 1.5khz. Any thoughts ?
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<rant>
As far as hemp goes for a speaker cone, one should give it no more status than any other paper cone material ... why?

1/ there are literally an almost unlimited number of receipes for paper that have sufficient material from a plant with the name hemp in it, for the marketing department to call it hemp.

2/ there are over a dozen different plants with common names having the term hemp in them. Only 1 of those is "true" hemp or fibre from cannabis plants. For instance the preferred receipe for "hemp" cones in the tone tubby patent application, uses manila hemp. Manilla is a close relative to the banana plant, and no relation to cannabis. It should be noted that when this question is raised wrt the hemptone drivers (including the Omegas) no one is willing (or doesn't know -- the response from Louis himeself) to give a straight answer.

These plants all got the "hemp" added to their names because, when the US Government made cannabis hemp illegal, they needed a way to indicate substitutes as hemp was widely used in a hige number of applications (to the point where the ban on c hemp was lifted for the WW II effort)

3/ even if the cone has true hemp in it, things like the paper receipe (including fiber length, and how they were processed), the cone profile & construction, any coatings, the glue bonds, and surrounds, and how synergistic the cone is with the rest of the speaker all play significant roles.

4/ That said, c hemp (as with any of the pretenders -- they did earn the suffix because of similar properties) have the potential to make VERY good paper. But a single ingredient in the paper, with no context, tells you very little about the loudspeaker
</rant>

A musical instrument loudspeaker, in general, has to be carefully considered for repurposing for hifi -- the design goals are not the same. At least it is not a guitar speaker.

dave
 
Patrick Bateman

Patrick Bateman

Member
Joined 2006
sreten said:
Hi,

Very likely you would be better off with this :
http://www.zaphaudio.com/Waveguidetmm.html

If you have speaker modelling skills you could try to use the Seas
reed cone drivers (above designed before they were released.)

:)/sreten.


http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spkrbldg/DesigningXO.htm

http://www.zaphaudio.com/
http://www.rjbaudio.com/projects.html
http://www.geocities.com/woove99/Spkrbldg/
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I'd love to hear this. The mains in my system use a waveguide, and I'm curious to hear what a "conventional" dome sounds like on one. A few years back I heard a speaker with a conventional dome in a waveguide, and it couldn't hold a candle to my speakers, but it also used a diffraction horn (which is bad.)

The zaph design has a much better waveguide profile.
 
S

sreten

R.I.P.
Joined 2003
mayhem13 said:


Just how audible will it be? I see another at 1.2khz but less pronounced.

Ok, what's Magic Dope? I don't want any of what you've been peddling to ARod.
Don't plan on going to the Yankees anytime soon!
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Hi,

You tell me ? and the writing speed of the eminence graph ....

There is no magic in audio, dope may improve matters or make it
worse, what is most highly unlikely is that it "fixes" any problems.

IMO : After BSC'ing the driver, speaker senstivity will not be much
better than Zaphs design, if you use an innapropriate treble horn
for domestic use (longish throw) you will get your self into a real
pickle, and nowhere near as good as Zaphs design.

No BSC is always more "dynamic", peruse : http://www.pispeakers.com/

:)/sreten.
 
S

speakerdoctor

R.I.P.
Joined 2006
classicloudspeakerservices.com
Hemp cone drivers began their life with guitar speakers. The infamous "tonetubby" was the first and it garnered many testimonials from famous guitar gods. Guitarists are extrememly particular about how their instrument sounds and apparantly the tonetubby found the right 'formula' they liked.

Now, the idea has begun to spread to the hi-fi market. Just be aware this is another new cone material following the almost endless list of others to try on the consumer.

IMO, you should be careful here in picking a hemp cone based driver for home hi-fi. Stereo reproduction is supposed to be as neutural as possible and not add an colorations to the music being reproduced. In the case of a hemp based driver, there may be some risk in doing just that. Not having been down that road personally, I can't say for sure if they will.

.
 
J

John_E_Janowitz

Member
Joined 2004
aespeakers.com
sreten said:
There is a definite cone resonance issue at 400Hz, see impedance.
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This is actually a spider resonance. We see this in most all drivers to some magnitude at some frequency. It is very difficult to correct by damping. You need to examine the spider with a stroboscope or even a cheap timing light set correctly to the 400hz frequency. Then you can get an idea of what is happening and how to correct it.

speakerdoctor said:
IMO, you should be careful here in picking a hemp cone based driver for home hi-fi. Stereo reproduction is supposed to be as neutural as possible and not add an colorations to the music being reproduced. In the case of a hemp based driver, there may be some risk in doing just that. Not having been down that road personally, I can't say for sure if they will.
Click to expand...

I also haven't quite understood why so many people want to use drivers like the tone tubby in open baffle and hifi applications. If you look at a guitar speaker it has it's own characteristic sound due to intentional cone breakup. This is what give it "scream" or "growl" or makes it sound "orange" or "purple" to guitar players. These breakups are typically 10-20dB in magnitude. They have wildly varying inductance to give intentional distortion and have very poor power handling. Putting that kind of a driver in a high end system is not a recipe for accurate reproduction.

John
 
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