ebay recone kit, 2234/2235, aquaplas, cone weight

[patallen]

Hi, recently i bought some 2225 baskets in the hope to recone them, using some 2235 recone kits. ive read tons of threads about this and all the controversy about those kits that will never be like the oem one, bla bla blaoem 2235 kit is nla for decades so there isnt many options.there is a lot of comments in thoses threads about the final weight of the cones and most seem to be off.as mentioned in thoses threads there is a defenitive missing 20g from the recone kits, both from SS and "speaker guy" from ebay. ive weighted a old oem, marked 2225h cone to be 95g, the ebay cone is 105g, both confirmed by dry weight and once assembled into the frame using DATS. my attemp is to build 2234 since i dont have mass ring.2234 effective moving mass is stated at 120g from public specs so i need 15g more to "comply" with that spec.my only guess is that the 2234/2235 cones where heavier/thicker to start with when JBL made them. Fs recone kit is 30hz from now, from a new assembly, untrained stiff cone. i guess FS will drop a bit once break in.since its a test/experiment, whould adding Aquaplas to the back of the cone be a sacrilege to add up some of the missing weight ?15 doesnt seem to be much to reach.thanks.

[turnitdown]

Did you weigh just the cone or all moving mass?

[patallen]

i should have been more precise..i weighted the whole moving mass, not just the cone.i doubt that a empty cone would weight 95-105geither.DATS measurement is spot on with the static balance weight2225 is 100g, dats says 102g.ebay kit 105g dats says 103ggive or take 5g. my balance is not an nasa equipmentso from jbl spec the ebay kit, as metioned in many other very old threads, is missing 20g dead on.

[Earl K]

@patallen,

It's appreciated that you attempt proper punctuation ( by including commas, periods, etc. ) in your sentence structures .
( Capitals, at the beginning of each sentence would help others plow through the crowded text ).

Also, your ( or anyones ) paragraphs would be more readable if you change your personal settings to what's shown in my last picture.

FYI,

DATs ( and similar ) will return MMS weights that aren't accurate if the additional weights used are insufficient and out of a certain range.

I believe the most accurate MMS reading is obtained by adding weight that's about equal to the static weight of the complete assembly ( iow, something like 100 grams in this particular case ).

The range of errors obtained from using too little added weight is tabled somewhere out-there on the net ( though I don't have an immediate URL to give you for reference purposes ).

A couple of days back I posted the Static weight of a NIB 2235H recone kit ( this static 137gram weight which included the mass-ring is about equal to a given MMD weight >> but not the MMS weight, which also includes an air-load component ).
- A common "air-load" for a 15" woofer is @ 17-18 grams ( this number includes more than just the weight of air within the Vd of that cone ).

Frankly, if your new aftermarket 2234H kits weigh in at @ 105 grams on a kitchen scale then I would say your are good-to-go without adding any extra weight ( since the @ 18 gram "air-load" will make up the rest of the missing weight of your recone kit ).

OTOH, if you were to add aquaplas weight, I would start by copying what JBL did with the 2216nd-1 ( adding some weight on the back , in a single @ 2-3"wide band located a couple of inches away from the cone//surround joint ( see the following pics ).

[turnitdown]

I just bought a pair of cone kits for 2234s and had the mass rings in my possession. The weight of the cones with all parts (surround, dust cap, etc.) weighed 102 grams. With the 35 gram mass ring (for 2235s) the total weight was 137 grams. Spot on for either 2234 or 2235.

[Earl K]

I just bought a pair of cone kits for 2234s and had the mass rings in my possession. The weight of the cones with all parts (surround, dust cap, etc.) weighed 102 grams. With the 35 gram mass ring (for 2235s) the total weight was 137 grams. Spot on for either 2234 or 2235.

Thanks for that! Denny

[RMC]

patallen,

The mass issue with DATS has been with us for a while now. A way to bypass the problem and getting an idea is to do your usual routine in DATS, BUT SKIP the weight step causing causing the hurdle, or pain in the butt. Take note of the other parameter values you measured.

Then using the Win ISD (linearteam.org) speaker software latest edition (2016) input the DATS parameters you got from the latter program for the driver involved (except for the weight thing). Once you're done to input this data in ISD then click the AUTO CALCULATE feature at the bottom of the parameters box. You'll see the mass number sought.

WIN ISD calculates the mass number you were missing based on the other parameter numbers you entered. The reason you can do that is some parameters are interrelated. Plus knowing a few of them the software can calculate the value for other(s). The mathematical formula for each TS is already programmed in ISD, doing the long calculation work for you. Don't be surprised if some original numbers change a little it happens, though major changes might be cause for concern (user error, number supplied way off, etc)

Hope the above will help getting where you want.

Richard

[patallen]

I just bought a pair of cone kits for 2234s and had the mass rings in my possession. The weight of the cones with all parts (surround, dust cap, etc.) weighed 102 grams. With the 35 gram mass ring (for 2235s) the total weight was 137 grams. Spot on for either 2234 or 2235.

how do you know its spot on ? are they eom JBL recone kits or aftermarket kits?

[patallen]

ok lets ignore the presence of DATS on the planet since its seems to confuse everyone. i should just put it into the trash apparently.

i use a kitchen scale.
my old oem 2225h cone assembly (all moving mass) measure the same as my 2235h ebay recone kit, at 105g.

JBL specs calls for effective moving mass of:
105g for the 2225h
120g for the 2234h

where does the extra 15g comes from ?

to me it feels that the ebay recone kit is just a 2225 cone kit but with a foam suspension. otherwise there is a missing weight somewhere.

AND to add confusion to the equation, after sever break in period, the ebay recone kit still doesnt go down to 30hz Fs. it went from 33 to 30. i doubt that if i abuse it to death it will come down to the jbl advertised 22hz.
feel free to throw me rocks as it seems common practice on this forum.

[Earl K]

ok lets ignore the presence of DATS on the planet since its seems to confuse everyone. i should just put it into the trash apparently.

i use a kitchen scale.
my old oem 2225h cone assembly (all moving mass) measure the same as my 2235h ebay recone kit, at 105g.

JBL specs calls for effective moving mass of:
105g for the 2225h
120g for the 2234h

where does the extra 15g comes from ?

to me it feels that the ebay recone kit is just a 2225 cone kit but with a foam suspension. otherwise there is a missing weight somewhere.

AND to add confusion to the equation, after sever break in period, the ebay recone kit still doesnt go down to 30hz Fs. it went from 33 to 30. i doubt that if i abuse it to death it will come down to the jbl advertised 22hz.
feel free to throw me rocks as it seems common practice on this forum.

Thanks for implementing my suggestion to make your posts more readable.

Now to your first question:

With the static weight of your eBay cone kit being around 105 grams, the missing weight comes from the "airload" that will be anywhere from @ 16 - 20 grams ( dependent on various numbers related to the suspensions compliance ).
- Add that airload number to your own numbers and one gets an MMS for the 2234H that's correct.

If one studies the following link ( from the LoudSpeaker Database ) one can build up an understanding of "airload" by comparing the differential seen between the MMD & MMS numbers ( for various 15" woofers that I've preselected ).

PreSelected 15" Woofers at the LoudSpeaker Database for study


At the following link is an overly simple formula for deriving "AirLoad" from a manufacturers published MMS figures.
- Unfortunately the numbers derived are a few grams short due to the formula not fully taking into account the compliance of the kits suspension ( which the hidden formulas over at LoadSpeaker data base obviously do )
A Simplistic Formula for deriving "AirLoad" from a published MMS figure



Your comment of: "i doubt that if i abuse it to death it will come down to the jbl advertised 22hz."

That's a little bit more concerning.
- I'm guessing that the maker of your aftermarket kit is using a spider that is one category too stiff.

Still, 30hz is a pretty good number to start off with. The Fs of Altec 416 woofers are mid to high 20's ( for some reference ).

[patallen]

Thanks for implementing my suggestion to make your posts more readable.

Now to your first question:

With the static weight of your eBay cone kit being around 105 grams, the missing weight comes from the "airload" that will be anywhere from @ 16 - 20 grams ( dependent on various numbers related to the suspensions compliance ).
- Add that airload number to your own numbers and one gets an MMS for the 2234H that's correct.

If one studies the following link ( from the LoudSpeaker Database ) one can build up an understanding of "airload" by comparing the differential seen between the MMD & MMS numbers ( for various 15" woofers that I've preselected ).

PreSelected 15" Woofers at the LoudSpeaker Database for study


At the following link is an overly simple formula for deriving "AirLoad" from a manufacturers published MMS figures.
- Unfortunately the numbers derived are a few grams short due to the formula not fully taking into account the compliance of the kits suspension ( which the hidden formulas over at LoadSpeaker data base obviously do )
A Simplistic Formula for deriving "AirLoad" from a published MMS figure



Your comment of: "i doubt that if i abuse it to death it will come down to the jbl advertised 22hz."

That's a little bit more concerning.
- I'm guessing that the maker of your aftermarket kit is using a spider that is one category too stiff.

Still, 30hz is a pretty good number to start off with. The Fs of Altec 416 woofers are mid to high 20's ( for some reference ).

you dont get my point, that still dont explain why both cone assembly, 2225H (oem) and 2235H (ebay, without mass ring) weights BOTH on my kitchen scale 105G while the ending results should be, per JBL spec, effective moving mass is 105G for the 2225H and 120G for the 2234H. they both have the same mass of air to move, unless one is use in space.

[Earl K]

you dont get my point, that still dont explain why both cone assembly, 2225H (oem) and 2235H (ebay, without mass ring) weights BOTH on my kitchen scale 105G while the ending results should be, per JBL spec, effective moving mass is 105G for the 2225H and 120G for the 2234H. they both have the same mass of air to move, unless one is use in space.

One needs to entertain the possibility that JBL's TS numbers for the 2225H have always been wrong ( within their official documentation ).

After-all, JBL's numbers have proven to be wrong previously on a couple of 15" models ( including in the "easy-to-disprove" case of the 2234 >> where JBL stated an obviously too-low MMS, instead of the now accepted @120-122 gram ).

I have an early 1990's 2225H that needs a recone // perhaps when the weather permits I'll carefully remove the kit using strong Solvents ( so as to preserve intact, all parts of the suspension ).

Who knows, maybe that kit will also weigh-in at around 105grams on my kitchen scale ( though according to all other information it's MMD ought to be a smidge less than 90grams ).

It has a cone# of 52254 ( printed in white ). JBL had a few different numbers for their 2225 cones over the years >> what does yours have ??

[patallen]

here is a picture of the old dead 2225h, suspension surround has detached from the cone and killed the voice coil (sad)
pn look like it is J583-506158.
i have other 2225h (6) in working orders and measured mms with my dats with all weights combinations possible (i use 100g for test weight) is around 105g too.

[Ian Mackenzie]

No horse in this race but if in fact the cone mass was high then the real fs would be lower.
However, if the compliance is firmer this will make the fs higher.

As Richard suggested if you pop in the known TL and mechanical parameters you are getting the formula behind these online calculations will tell you ? This is because all the parameters have to fit!

Ian

https://speakerboxlite.com/?from-app=1

[turnitdown]

how do you know its spot on ? are they eom JBL recone kits or aftermarket kits?

I weighed all the parts on a nice little kitchen scale I have. I also have DATS but didn't even consider it because the moving mass is the weight of all the moving parts. What better way to find out than a scale that measures grams to 2 decimal points? The shortest distance between two point and all...