PDA

View Full Version : Mass Rings vs AquaPlas / Transients



Earl K
04-26-2003, 05:58 PM
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
04-26-2003, 08:25 PM
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
04-26-2003, 08:46 PM
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:)

John B
05-03-2003, 05:33 PM
OK, point out where my logic may be faulty but it seems to me that a speakerís motor assembly doesnít care when itís pushing a certain amount of weight whether itís 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 ďsmothered transientsĒ 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
05-03-2003, 10:08 PM
"OK, point out where my logic may be faulty but it seems to me that a speakerís motor assembly doesnít care when itís pushing a certain amount of weight whether itís 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
05-04-2003, 05:27 AM
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
09-07-2004, 08:02 AM
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...

Earl K
09-08-2004, 06:37 AM
Hi Giskard

That''s interesting info. Though without actually hearing a 251J ??, I don't know what JBL is trying to voice/match that driver up to . Does the 1500al/fe share this type of split weighting ?

<> Earl K

4313B
09-08-2004, 07:00 AM
Hi Earl :)

The system was designed as the center channel for a pair of K2-S9800's. It goes behind a perf screen.

I do not believe the 1500AL/1500FE/1500SUB use mass rings at all.

Earl K
09-08-2004, 07:46 AM
Hi :)


It goes behind a perf screen.

Oh yea, I forgot about perf screens . That'll surely change things .


I do not believe the 1500AL/1500FE/1500SUB use mass rings at all.

Hmm,, I have some ME150(s) that I've been auditioning for a few months - it wouldn't surprise me if they were also 100% aquaplas-weighted. I find them a real nice project woofer when used no higher than 800 hz . When setup in vertical pairs, they do benefit from pole-splitting in the low-pass network ( passive and/or active ). This helps begin to level things out after @ 400hz . ( Mr. G.Ts' passive networks are a very fine roadmap for the practical implementation of this type of approach for filtering . ;) )

<> Earl K

Earl K
05-13-2010, 05:40 AM
Okay Now,

It's a 7 year old thread , but what the heck ( I feel this is the appropriate place for my question :p )

4313B,

Could you please share your observations of the sonics of aquaplased 2235H woofs ( where you aquaplased their cones instead of employing the usual 35 gram mass ring ) ?

If you were to do the experiment again, would you feel it's worth trying a mass adding approach using some of each type ?
ie ; ( 1/2 mass-ring & 1/2 aquaplas )

<> cheers Earl K

4313B
05-13-2010, 08:55 AM
Hi Earl,

If I had to do it over again I would compare the mass ring 2235H with the aquaplas 2235H above 290 Hz. The original motivation for doing the aquaplas instead of the mass ring was to see if there was any way to increase xMech. There isn't. The aquaplas does stiffen up the cone quite nicely though and should change the upper response negating its use in something like a stock L300 or 4430. I prefer the aquaplased version for subwoofer use or in a JBL 4-way.

Earl K
05-13-2010, 09:01 AM
Ahhh, Okay,

Thanks !

badman
05-13-2010, 09:11 AM
It's all about how, how much, and what you're starting with. A mass ring will indeed affect highs differently/less. If you're using it purely as a subwoofer I think I'd prefer a heavier overall cone to push breakup higher in frequency. For trying to extend the bottom end when using a wider bandwidth, where you need non-piston behavior to extend the FR, the mass ring is likely a better solution.

Different combinations thereof would suit different apps better. I used heavy coating on my 122As to make them more useful as sub drivers. I used woodglue and shellac-base primer. They now are high Qts (.7) low Fs monsters, only useful as subs.

robertbartsch
05-19-2010, 05:45 PM
The Le14 is the worst woofer I have owned. ..way over rated IMO.

JeffW
05-19-2010, 06:01 PM
The Le14 is the worst woofer I have owned. ..way over rated IMO.

Them idiots at JBL shoulda consulted you before slapping it into the 1400 Array, I reckon.

4313B
05-20-2010, 08:03 AM
The Le14 is the worst woofer I have owned. ..way over rated IMO.User error.

NickH
04-25-2012, 08:10 PM
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
04-26-2012, 05:48 AM
Wow !! How quickly time passes . :crying:

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
04-26-2012, 07:01 AM
eq will also do (for the better) :
http://www.audioheritage.org/vbulletin/showthread.php?27958-My-Mass-Rings-Arrived!&p=281472&viewfull=1#post281472


(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
04-26-2012, 07:24 AM
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. :rotfl:

pos
04-26-2012, 08:00 AM
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

4313B
04-26-2012, 08:15 AM
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 phaseYeah, 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.

NickH
04-26-2012, 08:16 AM
Thanks for the info. You answered my question. Except where can one aquire aquaplas?



Thanks,
Nick

4313B
04-26-2012, 08:34 AM
Thanks for the info. You answered my question. Except where can one aquire aquaplas?I received my supply directly from JBL. They have to buy it in 55 gallon drums which means someone had to walk out to a drum and ladle it out into a container for me. Since JBL moved everything to Harman Audio de Mexico that just isn't going to happen anymore. I don't have enough left to give out. I sent containers of the stuff to Germany and Japan and that was the end of it.

RobH3606 might know of a way to get some derivative of it. The JBL stuff is unique but a derivative should work.

HCSGuy
04-26-2012, 08:35 AM
NikH,
I will let one of the tech's on the forum chime in on why this won't work - but am I correct that you are intending to put a 2235 recone kit into a D130 frame? I think you're done right there - get a proper frame. I don't know what the VC gap or cone depth is on either one, but even if you can get it to fit, you'll run out of XMax really quick in the D130's pot. Besides, for what a recone kit costs, you should be able to get a complete 2235 driver with predictable specs and sound quality instead of a frankenwoofer. I will be happy to redact this if one of the techs on the forum feels otherwise:)

4313B
04-26-2012, 08:40 AM
Good point. subwoof or edgewound might be able to remember if a D130 core is valid. I can't remember anymore and can't look it up right now. And it's posted in the forum somewhere I'm sure.

edgewound
04-26-2012, 09:00 AM
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
04-26-2012, 10:18 AM
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
04-26-2012, 12:40 PM
I think the frames are from the 70's

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

subwoof
04-27-2012, 07:43 PM
Some of the early 130's and derivatives with the narrow gap can be ID'd by the gold anodize in the part of the top plate that is exposed - but this is NOT a hard fast rule.

Early frames did not have the recess grooved for the mounting rubber gasket ( and the posts were mounted on a rib not a tab ) - I suggest you do NOT use them. they require a 14.25 cutout which is too close to the bolt circle...grrr...

And yes - the kit will bottom out in the alnico musical series pots ( D/K ) but the early pro alnico ( 2230/31/etc ) will work. at that age they should be remagged too.

of course to keep it interesting the K140 frame was used for the 135/136 alnicos in the L series with a different sticker....:)


sub