Mass Rings vs AquaPlas / Transients

[Earl K]

Hi All

This topic was hinted at recently in another thread so I thought I'd give it a bit of air-time .

I've been using le14a woofers ( or le14h ) in original S99 boxes biamped to whatever horn/driver combo grabs my interest ( usually 288-8K on a round horn - but today its 2440/2450SL ). Crossover point is 900 Hz. These small boxes ( virtual volume @ 1.6 cu ft ) give that woofer as much help in the mid as it's ever going to get. The last octave of info in the le14s is really quite dead ( like dead as in a door nail ) . Comparing to a 2235 on the other channel, its' pretty apparent that the huge amount of aquaplas coating in the le14 ( maybe 50 grams ) has smoothered the transients in the mid area. To my ears , the 2235 is able to deliver more life-like mids than a le14a .

As a result of this impression, I find it hard to believe that JBL used this exact cone assembly ( unaltered ) in the S9500 or M9500 series. My guess is the speaker would voice better with a 50/50 split between a mass ring and aquaplas treatment on the cone . (just my opnion)

I've been pursuing assembling a budget version of a S9500 since late fall. That's how I got to this conclusion. But, I found all is not lost for my project. I found putting a le10 in a smaller box sitting over top of the horn has restored the midrange transients. This 10" runs in parrallel with the le14 . They are very complementary to each other. Sensitivities match nicely and one fills in the others response weaknesses. Like the S9500 , this is not a bonafide D'Appolito setup ( the woofers are just too far apart to expect true midrange combining ) Still, works well with no apparent comb filtering . It is a a DIY nightmare when it comes to aligning the coils of the two speaker types because of the two different basket depths. A modular approach is the only way to go for alignment.

Anyone else have experiences of this nature ?

regards<. Earl K

[Rex Mills]

Earl
I have had a similar thing happen swapping out a pair of L-100 woofers (model# ?) into a L-166. The Lansaplas, Auqaplas, woofer had a slightly muddy, less resolving lower-mid than the mass ringed 166 woofer. Can't say if what I heard was the signature of the coating, different interaction with the xover in the 166 cabinet or any of the many variables that would come into play. Maybe others will chime in with thier experiences.

[Robh3606]

Interesting comments. My XPL-200 almosts use the 166 woofer. They came in 2 flavors one with the mass ring and one with the Lasaplas/white stuff on the backs of the cone. I use one of each so I have a coated cone on one side mass ring on the other. The XPL crossover is at 300hz. They sound the same to me so maybe the change is on the high end of the response. I sure would not want to take the LE-14a that high. Like you said one stiff heavy cone to move.

Rob

[NickH]

I figured I'd revive this thread since its pertinent to my question. If I recone a d130 with a 2235 cone kit but don't use a coating or a mass ring I'm guessing it won't perform well in the low frequency range? Is there a place where I can buy 2 mass rings? Also does anyone have a source for aquaplass?

thanks,
Nick

[Earl K]

Wow !! How quickly time passes .

I think I'll comment ( on my original comments ) a bit later when I can make the time to collect my thoughts .





PS : > Mass rings are shipped with each bona-fide JBL, C8R2235 recone kit ( fwiw ) .

> I know Mass Rings have been purchased separately ( within the last couple of years ) by a LHF member ( from a speaker reconing outfit within Florida / I need some time to track down the poster ) .

[pos]

eq will also do (for the better) :
http://www.audioheritage.org/vbulletin/showthread.php?27958-My-Mass-Rings-Arrived!&p=281472&viewfull=1#post281472

If I (...) don't use a coating or a mass ring I'm guessing it won't perform well in the low frequency range?

As can be seen in my simulation 2235 and 2234 (ie without massring) perform similarly in the low. The mass ring simply "kills" efficiency in the higher frequencies.

[4313B]

I still have quite a few of the mass rings left.

I've also aquaplased three pairs of 2235H cones instead of using the mass rings. I personally like the aquaplas better for VLF duty but it's alot of work. It takes eight to ten coats of the stuff with drying time between each coat. If you try and do it all at once you end up with a big soggy mess of what used to be a cone. The water content is quite high. I did the whole process in a room with a dehumidifier to help things along. It worked out very well.

There is nothing wrong with using a 2234H instead and applying EQ as desired/required. Don't be fooled about the group delay thing though, applying EQ adds group delay (for example, if I remember correctly the BX63 has something like 40ms of group delay added to whatever the driver/enclosure system has inherently). I'm not entirely convinced that we really care about group delay down that low although a really nice sealed box, non-equalized subwoofer (which happens to have minimal group delay) does sound very nice indeed.

Interestingly, other people seem to oscillate between these solutions too. JBL is currently working on a new version of the 1500AL with a very low Fs as opposed to simply adding EQ to the current crop of 1500AL models.

Obviously it is a vicious circle.

[4313B]

I figured I'd revive this thread since its pertinent to my question. If I recone a d130 with a 2235 cone kit but don't use a coating or a mass ring I'm guessing it won't perform well in the low frequency range? Is there a place where I can buy 2 mass rings? Also does anyone have a source for aquaplass?

I just re-read this. If you don't get that D130 recharged then the potential lack of flux density might make up for the lack of moving mass.

removing some of the low mid on the 2234 as I showed in my simulation will give exactly the same group delay/phase shift as a 2235.
By the way carefully equing the low end to mimic the 2235 will also give exactly the same phase shift as the original, as all this is minimum phase

Yeah, I guess I'd just be inclined to build the system around the efficiency of a 2234 and then add EQ on the bottom as desired. These days I consider the 2235H at 93 dB the absolute minimum for a high performance loudspeaker system. It's a personal thing.

[edgewound]

I figured I'd revive this thread since its pertinent to my question. If I recone a d130 with a 2235 cone kit but don't use a coating or a mass ring I'm guessing it won't perform well in the low frequency range? Is there a place where I can buy 2 mass rings? Also does anyone have a source for aquaplass?

thanks,
Nick

A D130F and 2235H frame are mechanically identical....and interchangeable.

An early D130 might have a narrow gap that won't fit a 2235 voice coil.

[NickH]

I think the frames are from the 70's

A D130F and 2235H frame are mechanically identical....and interchangeable.

An early D130 might have a narrow gap that won't fit a 2235 voice coil.

[edgewound]

I think the frames are from the 70's

As long as the gap specs at .057" you're good to go.

[John B]

OK, point out where my logic may be faulty but it seems to me that a speaker’s motor assembly doesn’t care when it’s pushing a certain amount of weight whether it’s a mass ring on mass spread out over the cone. The point of the cone attached to the voice coils will move the same. And the aquaplas is applied to stiffen the cone for more piston like action and reduced breakup. So an aquaplas coated woofer should sound better in the midrange than one with a mass ring. The “smothered transients” may actually be less distortion. Comparing the same woofer that is. A 2235 may sound better than a LE14 for reason unrelated to aquaplas.

The LE14 is crossed over at 800 Hz in the L220 and 240ti, both outstanding speakers. And used much higher in L55s, 99s and 101s.

[4313B]

"OK, point out where my logic may be faulty but it seems to me that a speaker’s motor assembly doesn’t care when it’s pushing a certain amount of weight whether it’s a mass ring on mass spread out over the cone."

The mass controlling ring shifts the center of mass of the cone closer to it's apex resulting in greater linearity and control.

"A 2235 may sound better than a LE14 for reason unrelated to aquaplas."

I don't think it does sound better. They each have their own unique sonic signature. I'm glad I don't have to choose one over the other. The bottom line is, one can't go wrong with any of these transducers unless they employ them improperly.



For those who care about such things... the current LE14H-1 cone assembly with dust cap weighs in at ~ 125 grams. The current 2234H cone assembly with dust cap weighs in at ~ 105 grams and the 2235H weighs in at ~ 140 grams. The suspension of the 2235H is quite robust and is capable of easily handling the MCR whereas the LE14H-1 is "close to the limit" and the addition of an MCR would overtax it's suspension.

"Comparing to a 2235 on the other channel, its' pretty apparent that the huge amount of aquaplas coating in the le14 ( maybe 50 grams ) has smoothered the transients in the mid area. To my ears , the 2235 is able to deliver more life-like mids than a le14a"

Yeah, I can see where you could come to that conclusion. I came to the same conclusion way back when I was building 2-way LE14A/LE20/LX8 and 2-way LE10A/LE20/LX11 systems.

The LE14H-1 has very smooth response extending up to ~ 2 kHz and then it tapers of quite nicely. The 2235H has very smooth response extending up to ~ 1 kHz and above that it gets a bit ragged. Response "peak" for the LE14H-1 occurs at ~ 600 Hz and for the 2235H at ~ 900 Hz.

[Tom Loizeaux]

Though the mass rings and AquaPlas coatings both add mass (weight) to thir cones, I suspect the AquaPlas coating damps much of the harmonics and upper frequencies that the cone would otherwise produce. The mass rings probably allow more higher frequencies to transmit to the cones while add mass to the entire cone/coil mechanism. This is one reason why the 2234 (2231/2235 without the mass ring) is popular in applications where more mids and a quicker low end are needed.

Tom

[4313B]

Interestingly the 10" transducers in the new SK2-1000 use a combination of a mass ring and aquaplas. I believe it is 10 grams of each. Neither by themselves (20 grams of aquaplas or 20 grams of mass ring) gave the desired performance...