The post was edited to add that line. It is indeed not well understood. Again, the visuals in audio can be compelling to some.
Possibly, although according to the log about six hours before your post, so in fairness it appears to have been there some little time.
Indeed, but assumptuons can work both ways, and since adding even minor amounts of mass at specific points, and in specific forms on a substate can and will affect its resonant profile to some extent (wideband drive units producing the majority of their BW through controlled TL modes) I for one don't find it especially difficult to believe that it may in some cases produce an audible difference.
Re the Tang Band unit's unusual central structure, I don't have one to hand, but I suspect it may be being viewed here from a slightly erroneous angle. Based on fallible memory (and pictures) under the copper structure it has a flat metallic cap bonded to the VC which if so will act as an HF subemitter (i.e. a tweeter.). Under those conditions the outer copper cage structure will serve as much as a means of altering the dispersion of said and its frequency response, which is likely of more functional significance than its effects on the transverse wave across & through the cone itself -if that were the case something rather less elaborate would serve equally well. Whether it works any better than a simple bonded metallic cap is another matter. Possibly, since these TB units don't have the flattest cone profiles under the sun, and also use a fairly large roll surround.
Indeed, but assumptuons can work both ways, and since adding even minor amounts of mass at specific points, and in specific forms on a substate can and will affect its resonant profile to some extent (wideband drive units producing the majority of their BW through controlled TL modes) I for one don't find it especially difficult to believe that it may in some cases produce an audible difference.
Re the Tang Band unit's unusual central structure, I don't have one to hand, but I suspect it may be being viewed here from a slightly erroneous angle. Based on fallible memory (and pictures) under the copper structure it has a flat metallic cap bonded to the VC which if so will act as an HF subemitter (i.e. a tweeter.). Under those conditions the outer copper cage structure will serve as much as a means of altering the dispersion of said and its frequency response, which is likely of more functional significance than its effects on the transverse wave across & through the cone itself -if that were the case something rather less elaborate would serve equally well. Whether it works any better than a simple bonded metallic cap is another matter. Possibly, since these TB units don't have the flattest cone profiles under the sun, and also use a fairly large roll surround.
Hi Guys,
First off, I don't want to hijack the phase plug topic, so I will respond to the question about 'the physics' in this more general post and leave you to search elsewhere to satisfy - or more likely not satisfy - your curiosity. Also I'm not the least bit interested in convincing doubters that some unpredictable treatment is real/effective/desireable. Pursue your hobby/passion as you see fit.
That said, materials science in loudspeakers is really interesting. Clearly, cones and dust caps have energy applied at one margin, and transduction is affected and limited by the material properties. I was interested to encounter an acoustic finite element modeling program for the kinds of radial deformation that one would expect:
https://www.loudsoft.com/finecone/
Pretty cool to play with the variables and see what might happen! Perhaps more to the point is a proper live demonstration of the kinds of deformation possible in operation. A limited (non-musical) example is here:
In addition to driver surface material, one would also expect the quality of the driver motor to be a factor in generating 'real world' radial deformation. I only mess with very efficient drivers. Eliminating the distortion of the piston surface (if that indeed is happening) typically subtracts sources of sound. Some might like that, some might not. Because of the vast variation in musical recording and mastering techniques, the missing distortion may not always be as obvious as it can be in a live performance in clean stereo. In those recordings, the source is the entire room or hall or whatever.
The cancelation ring method uses hydrophilic adhesives - PVC glue and acrylic model paint. The Elmer's glue only goes on the apices of center domes for mass. Acrylic paint is used for the cancellation ring patterns of 1° by 2° rectangles separated by 1°. The method, called "EnABL" was developed on paper cones, where cellulose fibers can wick the paint into the surface. This would seem to produce an obvious local stiffening of the substrate without adding significant mass. I've also tried it on aluminum, where it can't significantly penetrate and seems less effective (note 3 rings on photo above), resin treated fabric, and varnish-sealed paper. Familiar to most readers will be the drivers treated by Dave at Planet 10. He treats both cellulose and metal cones plus dust caps. Can paint dots really cancel surface waves on drivers? I'd love to see the laser interferometry. They certainly DO NOT enhance the appearance! 🙂
The Lowther drivers for which I made the dust caps have an overlapping radial lap joint from the voice coil former to the surround or to the free edge of the whizzer. What a bad idea! If that localized mass doesn't also create non-radial surface distortion, I'd be shocked. I wound up iteratively adding more than the usual number of cancellation rings plus back-side latex to get them sounding transparent. I don't recommend them.
Why bother with all this? When you get everything sorted out, you no longer hear 'the speakers'! They seem to disappear, and you hear the space in which the recording was made. Plus, turn it up as much as you like, it won't get "loud". That's it in a nutshell - now back to the question of phase plugs.
Best regards,
Frank
First off, I don't want to hijack the phase plug topic, so I will respond to the question about 'the physics' in this more general post and leave you to search elsewhere to satisfy - or more likely not satisfy - your curiosity. Also I'm not the least bit interested in convincing doubters that some unpredictable treatment is real/effective/desireable. Pursue your hobby/passion as you see fit.
That said, materials science in loudspeakers is really interesting. Clearly, cones and dust caps have energy applied at one margin, and transduction is affected and limited by the material properties. I was interested to encounter an acoustic finite element modeling program for the kinds of radial deformation that one would expect:
https://www.loudsoft.com/finecone/
Pretty cool to play with the variables and see what might happen! Perhaps more to the point is a proper live demonstration of the kinds of deformation possible in operation. A limited (non-musical) example is here:
In addition to driver surface material, one would also expect the quality of the driver motor to be a factor in generating 'real world' radial deformation. I only mess with very efficient drivers. Eliminating the distortion of the piston surface (if that indeed is happening) typically subtracts sources of sound. Some might like that, some might not. Because of the vast variation in musical recording and mastering techniques, the missing distortion may not always be as obvious as it can be in a live performance in clean stereo. In those recordings, the source is the entire room or hall or whatever.
The cancelation ring method uses hydrophilic adhesives - PVC glue and acrylic model paint. The Elmer's glue only goes on the apices of center domes for mass. Acrylic paint is used for the cancellation ring patterns of 1° by 2° rectangles separated by 1°. The method, called "EnABL" was developed on paper cones, where cellulose fibers can wick the paint into the surface. This would seem to produce an obvious local stiffening of the substrate without adding significant mass. I've also tried it on aluminum, where it can't significantly penetrate and seems less effective (note 3 rings on photo above), resin treated fabric, and varnish-sealed paper. Familiar to most readers will be the drivers treated by Dave at Planet 10. He treats both cellulose and metal cones plus dust caps. Can paint dots really cancel surface waves on drivers? I'd love to see the laser interferometry. They certainly DO NOT enhance the appearance! 🙂
The Lowther drivers for which I made the dust caps have an overlapping radial lap joint from the voice coil former to the surround or to the free edge of the whizzer. What a bad idea! If that localized mass doesn't also create non-radial surface distortion, I'd be shocked. I wound up iteratively adding more than the usual number of cancellation rings plus back-side latex to get them sounding transparent. I don't recommend them.
Why bother with all this? When you get everything sorted out, you no longer hear 'the speakers'! They seem to disappear, and you hear the space in which the recording was made. Plus, turn it up as much as you like, it won't get "loud". That's it in a nutshell - now back to the question of phase plugs.
Best regards,
Frank
In fairness (having zero axe to grind on the subject) I would gently suggest that 'certainly DO NOT enchance the appearance' is a matter of opinion rather than fact. I personally find Emilia Clarke rather attractive for example, but this is not universally held. 😉
EnABL is a somewhat open topic, in that in its original form, it was relatively generic with a fixed relative location for the block rings. It subsequently developed however, where the location of the blocks was determined by empirical testing of the cone modes, irrespective of material. YMMV as always of course, but I can certainly vouch for the quality of Dave's work, when he was still actively involved in modifying drivers.
EnABL is a somewhat open topic, in that in its original form, it was relatively generic with a fixed relative location for the block rings. It subsequently developed however, where the location of the blocks was determined by empirical testing of the cone modes, irrespective of material. YMMV as always of course, but I can certainly vouch for the quality of Dave's work, when he was still actively involved in modifying drivers.
Regarding dustcap resonances, here is an interesting trick I discovered with electrical tape:
https://www.diyaudio.com/community/threads/dust-cap-damping-with-caterpillar-tape-hump.355080/
https://www.diyaudio.com/community/threads/dust-cap-damping-with-caterpillar-tape-hump.355080/
In the past I also have used electrical tape to model - though not at the creative level of the hump! 👍
Attachments
I've approached the topic several times reading the patent and some topics here, and it's certainly fascinating, but I haven't yet found something clear to me to start, or a speaker cheap enough to be wasted.
It resembles an ancient lost technology leaked through a dream.
Yes, I've tried small shapes of tape on different parts of speaker cones and there is usually very little effect unless you cover a large part of the cone. You need something of comparable stiffness to the cone itself but with a high tan delta or damping factor. Or in some cases just something heavy that can shift a bending mode. You may have gotten better results using much larger pieces of tape.
In that sense EnABL is somewhat benign in that it doesn't seem to affect the measured speaker behavior much. So it's less risky to try than say cutting slits in the cone or heaping on the mod podge.
In that sense EnABL is somewhat benign in that it doesn't seem to affect the measured speaker behavior much. So it's less risky to try than say cutting slits in the cone or heaping on the mod podge.
Yeah, those little pieces of tape were just to understand what was going on - whether pure mass was the solution or whether cancellation was also in order. Both were appropriate, and the final result was very well behaved.
I agree with this. "Extra" rings of cancellation blocks really seem benign. For that reason, I wouldn't hesitate to treat decent drivers. When you're done, why regret that you didn't start with something that has a motor that's as good as you've made the cone? You could do Fostex or MarkAudio drivers placing the blocks where you see them on Dave's examples (at Planet 10) and be golden. Though, learning to tap is part of the game... Whizzer cones are a notch up the scale of difficulty, and beware that crossovers might need adjustment on multi-driver systems. My first attempt was on JBL LE-8TH's - somewhat legendary - and I went ahead knowing that if I blew it I could get them re-coned. When they were done - wow! Regrettably, the surrounds rotted after OEM parts were gone...
I would only add, for now on this topic diversion, that EnABL is like a final 'polish' that is not subtle, but it doesn't make up for other deficiencies. So I always leave the speaker cones for last when I'm working on a system.
Cheers,
Frank
If there is merit in the cone treatment, the claimed improvement should be measurable whether the motor is of good quality or not. That said, I believe the GRS 4FR-8 is a sleeper and deserves much more prominence in the DIY community than it currently has. I prefer it over any of the dozen or so Fostex, Tangband or Faital Pro drivers I've owned over the years in terms of both quality and value. I've read claims that it is superior to the Pioneer A11EC80-02F driver it was modelled after.
Yes, of course. Some folks have shown differences at the edges of waterfall plots, and that's fine but not the whole story by any means. Every driver is different, and while human acoustic perception can be way more sophisticated than a waterfall plot, not everyone hears nor listens alike. Its YMMV to the max! 😉
The cone and dust cap look like decent candidates for EnABL and the fun of playing with them is yours for the taking! 👍 I've never tried any driver with a Qts above 0.5, so no idea what to expect with something whose Qts is 0.98.
Ahh, yes - the sheet I looked at had Qes/Qts switched. As you consider the options, you might have a better chance of a satisfactory result because you are familiar with the basic driver and it's best applications. All the fundamental principles of speaker building still apply. Of course a search is in order to see if others have tried EnABL on your driver as well... Enjoy!