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Old 2nd September 2012, 11:30 AM   #41
tvrgeek is offline tvrgeek  United States
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Originally Posted by hajj View Post
I personally cold not pick up the ringing at 4khz

And I was just as surprised as you are by the length of the cone ringing, seemed weird to me too, that's also why I'm waiting for someone to validate the measurements.
Length of cone ringing means lack of dampening. It is the difference between plucking a string and plucking it with your finger resting on it. All materials have points of resonance. The more spread out they are, the better. The idea of adding a massive low durometer material is to dampening the resonance, like your finger on the string. The idea of the pattern spaced dots is to break up single frequency resonances to many so each is not as significant.

Look on the "what's the attraction" thread. The 125 rings like a freeking bell. Others may not, but a 10dB resonance peak at 7K does not sound like an extended top end to me. It sounds like a cheap desktop radio and I would be concerned with the IM it is causing in the most sensitive ranges.

With some doping (I used artist gesso which is actually kind of a glue) I was able to help it quite a bit. I am looking forward to hearing a set done by Planet10 to see if I am anywhere near his mark. I doubt it as he has a lot of experience with this.

It seems the 125 is at just the wrong size for the cone material. Just larger and just smaller seem to be far better. You can even see that in their published charts. The very best treatment I can think of for this driver is a steep crossover. It is one of the flattest mid-ranges I have seen. LR-4 @ 2K seemed to be fine. When pushed to 3K, I had to add a notch at 7K to keep the main resonance more than 12 dB down. As I found tweeters that are happy at 2K, and mid-woofers happy at 2K, I don't need the complication of a mid-range.

So, why do manufactures insist on using highly resonant cones? Yes, they have a very good reason. They are more rigid and within their useable range, that means lower distortion. The paper in the 125 is very stiff. Low distortion, but breakup issues. It is much like many of the metal cones in that respect. Being paper, it is easy to modify into a "bonded cellulose fiber composite" and achieve results that are outside of the OEM's product price point.
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Old 2nd September 2012, 11:35 AM   #42
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and the mica (talc powder) added to poly drivers are starting to sound really nice also.


Norman
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Old 2nd September 2012, 11:45 AM   #43
ODougbo is offline ODougbo  United States
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I would have to agree with Tvr here, might add that it is pretty good speaker, but it's going to need help, cone treatment, filter. The driver cost is nice, the savings can be used for fine tuning (once we figure out what that is).

Btw, It does take about 200 hours to break them in.

Also, agree with earlier post, small changes make noticeable differences.

Last edited by ODougbo; 2nd September 2012 at 11:54 AM.
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Old 2nd September 2012, 03:57 PM   #44
tvrgeek is offline tvrgeek  United States
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Originally Posted by norman bates View Post
and the mica (talc powder) added to poly drivers are starting to sound really nice also.


Norman
My Kef Q1's are mica filled I think. They still sound like poly though. I am being rough on them, but I do remember they were only about $300 a pair and I bought them off e-bay for a lot less. For my ears, I still keep falling back on paper. I just love the Seas reed paper mid-bass I used in my last build. Easy to use. No filtering, no muss, and works in half a cubic foot. The ScanSpeaks and Ushers need bigger boxes. Someday when I save up for it, I want to try the Seas mag cone mid-bass. I am no longer anti-metal as I have learned a lot about using them, just still pro-paper. I'll have to wait to hear a poly cone that does not sound like mush. My biases change as fast as they can be proven wrong. If you know of a filled poly that is nice and tight, let me know.
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Old 2nd September 2012, 05:55 PM   #45
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I think the main reason paper is so popular, is the immense variation in composition that is possible. Some kapok, cotton even, wool. composites are most definitely that way, and paper is probably the most versatile.

I used to have a penchant for modern composites, which has faded thankfully. Random fibrous composites containing both natural and synthetic fibres are most interesting to me.

Unfortunately, the immense scope for differing stiffness, hardness, and weight is a double edged sword.

you never quite know what your getting with paper, until you hear it

Since my 1st ever pair of DIYs I havent used paper. I changed from the paper Audax I was using, to the HDA version. I was blown away by the detail I just couldnt hear through the (mild and smooth) breakup of the paper cone. But at least it was smooth.

Harder paper would perhaps reveal more detail (I hate the word too), but introduce a more resonant nature to the material.

I am still wary of metal cones, but I own some, and they are by far the best speakers Ive ever had/heard. It is frustrating that the resultant crossover (if used) requires more work. The Seas Mg cone breakups are just crazy, and even the small FR drivers like Mark audio A6, fountek etc need some crossover work IMHO.

Id get the paper A6P, but again, paper as a medium is just sooo damned variable.

So now Ive bought some more paper cones, albeit because they were cheap. despite this theyre very dead, damped paper. Less detail than the AL cones I use, but I may finally get to go minimalist with the crossovers/EQ.

(I know this is in fullrange, but I think that there is probably more variabilty in paper types, hardness etc than in multiway drivers. Its probably MORE relevant in a FR driver)

To use the awful word:detail yet again, I would say Ive also never heard a poly cone that I liked. They seem to be similar to paper (perhaps more humidity stable?), but less detail than paper. I cant imagine id like a polycone FR driver at all, but perhaps thats shortsighted of me.

very fine fibrous composites using paper, and polyfibres could be good. I have no idea if there are any such drivers out there.

If I got the chance to make my own paper cone maybe id use:

fibrous Nylon
fibrous glass (again though, glass is pretty variable)
fibrous polypropylene
kevlar
Carbon fibre
wood fibre
cotton
wool
hemp
paraffin wax

maybe itd work, maybe its be a mess

maybe id even try a fine (2000 TPI) weave of a metallic alloy. That might be interesting.

Right im off to win the lotto, and set up my laboratory

Oh yes.......the real point of posting

Ive always found that judicious use of PVA wood glue (the stuff thats 'stronger than the wood itself') has merit in taming some nasty breakups. Ive never tried dots, and I dont believe NABL is really anything you couldnt experiment with at home. A ring of PVA or helical spokes (like the slits on revelators) would probably serve to do a similar thing to dots. Might even be worth trying rubber solution glue, but itd look awful no doubt
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Last edited by mondogenerator; 2nd September 2012 at 06:09 PM.
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Old 2nd September 2012, 09:12 PM   #46
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Well I looked at the graph and I see a rise starting a 6 khz and topping off at 7 khz and going back down at 8 khz. If I am reading and seeing this right. I would and I really try never to go this way to crossover the ff125wk at 5 khz and then cross a tweeter in at 4.5 khz if I am doing this right? I have not done a crossover in years so if I am wrong please bear with me. This is what I would do a 6 or 12 DB crossover and the peakness is solved. Jm
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Old 3rd September 2012, 07:42 AM   #47
hajj is offline hajj  Lebanon
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Quote:
Originally Posted by natural sound View Post
Well I looked at the graph and I see a rise starting a 6 khz and topping off at 7 khz and going back down at 8 khz. If I am reading and seeing this right. I would and I really try never to go this way to crossover the ff125wk at 5 khz and then cross a tweeter in at 4.5 khz if I am doing this right? I have not done a crossover in years so if I am wrong please bear with me. This is what I would do a 6 or 12 DB crossover and the peakness is solved. Jm
Well, after listening extensively to the FF125WK's over the weekend, I can safely say that these don't need any tweeter help (at least to my ear), and the peak at 7khz (6,7khz actually) becomes much less objectionable once you apply the zig 2-way glue to the back of the surround and listen a bit off-axis (5-10 degrees)

Regards

Nick
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Old 3rd September 2012, 10:13 AM   #48
tvrgeek is offline tvrgeek  United States
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Originally Posted by natural sound View Post
Well I looked at the graph and I see a rise starting a 6 khz and topping off at 7 khz and going back down at 8 khz. If I am reading and seeing this right. I would and I really try never to go this way to crossover the ff125wk at 5 khz and then cross a tweeter in at 4.5 khz if I am doing this right? I have not done a crossover in years so if I am wrong please bear with me. This is what I would do a 6 or 12 DB crossover and the peakness is solved. Jm
Look at the SCALE of the graph. It is not slight!
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Old 3rd September 2012, 10:37 AM   #49
tvrgeek is offline tvrgeek  United States
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Nick, you actually put the glue on the surround itself, not on the cone where the surround attaches?

We want a cone that is stiff to get low distortion, very light to get some HF without a wizzer, and breakup modes above the audible range. I don't know of that material. Beryllium is probably a good material, but it is horrible to manufacture and is rather toxic, let alone very expensive. Cone shape can do a lot for spreading out resonances, but usually means less stiffness. (See the early RCA papers)

It all sort of comes back to a driver being suitable for about a decade range. That of course kind of kills the full range concept unless it is for a phone ( 300 to 3300 Hz)

The Walsh driver could be argued to be a full range very steep cone that decoupled regions of the cone to work semi-independently. Ohm is still out there selling direct.
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Old 3rd September 2012, 10:53 AM   #50
hajj is offline hajj  Lebanon
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Originally Posted by tvrgeek View Post
Nick, you actually put the glue on the surround itself, not on the cone where the surround attaches?
The latter
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