JBL L150A?

[Chip-HP]

I recently acquired a pair of L150As ... based on a cursory inspection, I thought they each had two 12" woofers (all 4 of which need refoaming) and wondered why the cones were different colors ... but then I found this old thread ... which leads me to believe the "woofer" with the black cone is a passive radiator instead of a woofer ...

Is my conclusion correct? (I have never heard of a passive radiator ... while my interest level is high ... my techical knowledge is limited ) ...

If so, does one refoam a PR the same way as a woofer? ... using the same material? ...

[4313B]

Is my conclusion correct?

If so, does one refoam a PR the same way as a woofer? ... using the same material? ...

Yes, yes and yes.

[Chip-HP]

Yes, yes and yes.

Thanks ... that was quick ...

[johnaec]

If you get them refoamed, be sure they mount the new surrounds to the *back* of the cones, like the originals. Many take the easy way out and mount them to the fronts when refoaming, but this pretty much destroys any future value...

John

[Chip-HP]

If you get them refoamed, be sure they mount the new surrounds to the *back* of the cones, like the originals. Many take the easy way out and mount them to the fronts when refoaming, but this pretty much destroys any future value...

Thanks ... I had seen that somewhere else ... I am considering refoaming them myself using one of Rick Cobb's kits (I assume that he will sell extra surrounds ... I will need 4) since it will cost me $200 ($50 each) locally to have it done professionally ...

[BMWCCA]

Thanks ... I had seen that somewhere else ... I am considering refoaming them myself using one of Rick Cobb's kits (I assume that he will sell extra surrounds ... I will need 4) since it will cost me $200 ($50 each) locally to have it done professionally ...

Do the passive radiators first, for practice, since there's not really a critical alignment involved as there is with the 128Hs. I'm sitting here contemplating the same project with enough of Rick's kits to do the L150As and a pair of L112s. Rick will ask you for the diameter of the cone on your 128Hs to make sure he's sending you the right surround. There is apparently some variance in different years. Or else he does that just to make you feel good!

[Chip-HP]

Do the passive radiators first, for practice, since there's not really a critical alignment involved as there is with the 128Hs. I'm sitting here contemplating the same project with enough of Rick's kits to do the L150As and a pair of L112s. Rick will ask you for the diameter of the cone on your 128Hs to make sure he's sending you the right surround. There is apparently some variance in different years. Or else he does that just to make you feel good!

Good suggestion ... what a co-inkey-dink ... I picked up a pair of L112s (that need refoaming) with the L150As ... did you have to buy 3 kits? ... or can you buy 1 kit and 2 additional pairs of surrounds? ...

[grumpy]

If you get them refoamed, be sure they mount the new surrounds to the *back* of the cones, like the originals. Many take the easy way out and mount them to the fronts when refoaming, but this pretty much destroys any future value...

John

Hi John,

While I certainly agree that this common shortcut is not in the best interest
of the customer, and also agree that the collector value may be reduced
somewhat, I think putting forth the statement that refoaming on the front
"destroys any future value" is a bit over the top... especially in regard to a
passive radiator or a 128H (I have both, one set I did properly and one set
OCS did improperly a number of years ago ... in this particular case, I
can hear no difference, for whatever that's worth). I know the concerns,
aesthetic and technical/performance, have been discussed here already.

Does an improper re-foam bother me and is it an eyesore for the
perfectionist? Sure... a bit. Might that affect the value somewhat?
In some cases, significantly... in others, not so much.

I'd hate to see someone fret over a set they already own, or dump them,
thinking them worthless. People read this, ah, stuff.

-grumpy

[johnaec]

I'd hate to see someone fret over a set they already own, or dump them,
thinking them worthless. People read this, ah, stuff.

-grumpy

You're right - it's been said that there isn't much sonic difference. I was just trying to give a heads-up in advance, rather than having the OP discover it after the fact.

And I admit - I was lucky with the first refoams I had done - they were done correctly. But until I found this website, I probably would have never known the difference if they weren't...

John

[GordonW]

There is some sonic difference between foam on the front, and foam on the back, due to the off-set of the coil in the gap (pushed rearward when the foam is improperly mounted to the front). It is small, but it does exist.

And since there IS a difference (and a negative one at that), the foam SHOULD NOT be put on the front. That's logic good enough for me; I flatly will NOT do the work this way. If someone wants those surrounds mounted to the front of a 128H or PR300, they need to take it to somebody else besides me...

Regards,
Gordon.

[grumpy]

sound advice -grumpy

[BMWCCA]

Good suggestion ... what a co-inkey-dink ... I picked up a pair of L112s (that need refoaming) with the L150As ... did you have to buy 3 kits? ... or can you buy 1 kit and 2 additional pairs of surrounds? ...

Rick will sell you six surrounds with the rest of one basic kit for less than buying three kits. He does sell one kit for the L150 with four surrounds anyway, and he just added two more for me. He says there's enough glue to do six in the main kit and you certainly don't need more than one CD. I've also been told the glue smells and acts a lot like normal old Elmer's, but I've not confirmed that. Anyone else have any favorite glue for the job?

[doyall]

Anyone else have any favorite glue for the job?

Anything but a Methyl Ethyl Ketone (MEK) based glue. It was not nearly viscous enough and actually distorted the foam.

[bigyank]

i have purchased surround kits from Rick and his kits include what I feel is the "correct" glue. Correct for me to do the surrounds myself with a nice working period. Never had to rush and did the job correctly the first time.



Yank