K-140 Recone To What?

[billysbassplace]

I have a couple of K140 baskets. I may recone them for a DIY project. I would not be reconing these to be K140's anymore, since that's a bass speaker for a bass player. I want to change them to be for a stereo application.

Would they recone to 136a, 2231, or possibly 2235's. What is the correct JBL recone kit available? And what would this speaker now be considered, with a correct (not k140) 15" JBL recone kit?

Thanks for any help.
Bill

[Thom]

I find this confusing (this is additional question, not answer). I have always understood that 130 and 140 baskets were the same until recent reading has lead me to not be sure. (actually everything I have read was very positive but some was positive yes and some was positive no. I know you can have one coned as the other but is it?

[billysbassplace]

Thom, I'm not 100% sure either on the difference, with the techie stuff (gap, depth, etc). I know that the K140 should have copper material for the voice coil and the k130 should be made of an aluminum voice coil material. The K Series, pretty much replaced the d130f's & the D140f's for the musicians in the 70's. Now the question is, is there any physical difference in the magnet gaps, depths, etc. Hopefully one of the better techie's on the forum can shed some light.

Bill

[Zilch]

I believe K140 is on the list of cores reconable with 2235H kits.

Use "Search" to find it, as this has been discussed many times here....

[edgewound]

Would they recone to 136a, 2231, or possibly 2235's. What is the correct JBL recone kit available? And what would this speaker now be considered, with a correct (not k140) 15" JBL recone kit?

Thanks for any help.
Bill

Bill,

The K140 basket can accept an E140, E130, 2225, 2235 recone kit.

The specs then become whatever recone assembly is installed.

2235 is the best choice for hifi, with 2225 second...as 2225's were used in JBL Cinema systems

[Richard Long]

does anyone know how the tsp changes if you recone a k140 with an 2235 kit ?

[Earl K]

does anyone know how the tsp changes if you recone a k140 with an 2235 kit ?

An alnico magnet type speaker that has seen M.I. ( musicians ) or S.R. ( reinforcement ) duty , will no doubt suffer from some demagnetization .

How much actual loss of magnetic force is anybodies guess .

The TS parameters will be altered by these shifts of magnetic force, when measured with a coil in the gap ( is displayed as , "BL" in the TS parameters) .

Here are the resulting TS params. ( according to WinISD Pro auto calcs. ) with either 10% or 20% demagging occurring to the alnico magnet .

Pay attention to the box sizes ( & port tunings ) in these predictions .

What the software doesn't show is the real loss of midrange output when a magnet is patially discharged .

Personally, I think ( unless you get the K140s re-magged ) that putting a new ( & pricey ) 2235H recone kit into an old alnico beater, is a recipe for disappointment ( assuming, of course, that you originally liked JBL for its authoritative bass reproduction ) .



<> EarlK

[Allanvh5150]

Someone has done measurements with a 2235 cone in a 140 frame. I am pretty sure the specs are here somewhere. The 2235 cone in the 140 frame will give a pretty good result from memory. It will go pretty low but it wont be an exact 2235. However I am sure your friends wont be able to tell. Widget said to me a while back that it wont be a 2235 and it will always bug you.

Allan.

[Earl K]

Someone has done measurements with a 2235 cone in a 140 frame. I am pretty sure the specs are here somewhere. The 2235 cone in the 140 frame will give a pretty good result from memory. It will go pretty low but it wont be an exact 2235. However I am sure your friends wont be able to tell. Widget said to me a while back that it wont be a 2235 and it will always bug you.

Allan.

Perhaps you are referring to this :

Grumpy came by last night and brought over Woofer Tester-2 to see if the recharge on the 2205/2235s would sucessfully raise the BL factor. Two months ago we had performed two measurements on one of the three woofers and both tests came out between 17-18. (JBL spec for the AlNiCo woofer's BL is 21.)

All three woofers were purchased at the same time from the same ebay vendor in the same lot of the same origin as baskets in Nov 2005 and reconed/remagnetized by OCS in Dec 2005.

The tests showed that the recharge last Monday was a success. Two tests on one of the woofers (but not the woofer originally tested two months ago) both came up with the BL factor at 23.5. The Woofer Tester indicated that for all intents and purposes, these now spec out as true 2235s except that they have AlNiCo magnets.

- The above quote was taken from this thread !

- For what it's worth to this discussion, the final numbers that Grumpy & Todd measured ( after remagging ) are a bit too high ( BL = 23.5 vs @ 20.5 , for the stock, ferrite magnet 2235H ) .
- I don't know the reason for those ( measured ) high numbers .


<> EarlK

[grumpy]

FWIW, I don't expect that the wt2 numbers (or the operators ) are perfect, but the
measurements were performed several times (both before and after) to get a feel for
measurement consistency... in that, I think I can at least say that the re-mag was justified
on the frame/magnet that appeared to measure low.

As others have pointed out, it would be difficult to over magnetize a driver, so the indicated
readings from wt2 may indeed have been on the high side.

The other parameters measured were not using a test cabinet, but small-delta Fs shift
using additional mass, which for a few of the T/S parameters is a less accurate method.

I would be careful in relying on such measurements to 'prove' that a reconed Alnico
frame was an exact 2235H equivalent. That the wonky unit was surely much closer after
the re-mag, is all I would say, personally.

[edgewound]

FWIW, I don't expect that the wt2 numbers (or the operators ) are perfect, but the
measurements were performed several times (both before and after) to get a feel for
measurement consistency... in that, I think I can at least say that the re-mag was justified
on the frame/magnet that appeared to measure low.

As others have pointed out, it would be difficult to over magnetize a driver, so the indicated
readings from wt2 may indeed have been on the high side.

The other parameters measured were not using a test cabinet, but small-delta Fs shift
using additional mass, which for a few of the T/S parameters is a less accurate method.

I would be careful in relying on such measurements to 'prove' that a reconed Alnico
frame was an exact 2235H equivalent. That the wonky unit was surely much closer after
the re-mag, is all I would say, personally.

If you take a remagged K140 and recone it with a 2235 kit, it's functionally identical to reconing a 2231A with a 2235 kit.

Sometimes it's just not worth the anguish to be too anal about some of this stuff as it follows OEM protocol.

[grumpy]

Sure... I'd just rather folks not take any of my hobbyist/toy measurements
and make more out of them than they should. I trust your experience (quite
a bit) more.