L112 Strategy?

[Chip-HP]

Several weeks ago, I bought four sets of speakers at an estate sale … including a pair of L112s which I knew nothing about at the time. Had I examined them more closely (they were sitting on top of a bookshelf) before I committed to buy them, I probably would not have bought them. The woofers need refoaming (there is no foam around either cone) and there are four 9/64” mounting bracket holes in 3 sides of the cabinets (top, bottom and one side) of each speaker … 12 holes per speaker.

The cone of one woofer is cock-eyed with the highest edge sticking up almost 3/4” above the metal edge of the basket … not surprisingly this cone does not move (I applied very gentle downward pressure around the dust cap). After reading several posts here, I bought a multi-meter to check the continuity … this speaker reads 6.0.

The cone of the other woofer sits down evenly in the basket … with its edge even with or just below the metal edge of the basket … the cone moves without any noticeably noise … and the continuity reads 6.2.

As you may have already figured out … I am a novice at this. Based on my limited knowledge, I am guessing that the “cockeyed woofer” probably has some serious ills … while the other woofer may just need refoaming.

My initial plan (before closer examination) to refoam the woofers … plug the holes in the cabinets … and end up with a nice sounding pair of JBL speakers for an all in cost of around $150.

Given what I think I know now, it appears that the “cock-eyed woofer” … at a minimum … needs reconing … which I understand runs $200 to $250 … in that case; I would have $320 to $370 invested in a pair of L112s with flawed cabinets.

I am guessing that I could part the speakers out … and get my $70 back.

Based on the information provided … I would welcome any input and/or recommendations.

[grumpy]

It's possible (I think) that the voice coil is not sitting in the gap of your non-moving-cone
128H... worth checking. Parting out may still be your best bet (did I just say that?)
-grumpy

[Chip-HP]

It's possible (I think) that the voice coil is not sitting in the gap of your non-moving-cone
128H... worth checking. ...

How do I check it? ... and get back in the gap? ... if that's the case ...

[grumpy]

How do I check it? ... and get back in the gap? ... if that's the case ...

First, understand that this driver is probably toast and will require reconing.
That frees you up to try several things I can think of:

See if you can pull the cone up slightly or if it's stuck... the voice coil former
could be mishapen or distorted. If the cone magically plops back into place
and doesn't rub and you really need to postpone a recone for fiscal reasons,
a refoam -might- be possible (certainly not guaranteed as the spider
might be tweaked to one side).

If no go, you could carefully cut out the center dome to visually inspect
what's going on (educational, if nothing else... and no worse off as a new
dome can be glued on). As it is, the driver is essentially worth the value
of a core frame anyway. Maybe look for a used single 128H and set this
one aside.

Others might chime in, or may ask why I'm suggesting anything other than
an immediate recone ;). Just thinking out loud what I might do before
handing it over to the professionals.

-grumpy

[Chip-HP]

First, understand that this driver is probably toast and will require reconing.

That frees you up to try several things I can think of:

See if you can pull the cone up slightly or if it's stuck... the voice coil former could be mishapen or distorted. If the cone magically plops back into place and doesn't rub and you really need to postpone a recone for fiscal reasons, a refoam -might- be possible (certainly not guaranteed as the spider might be tweaked to one side).

The cone will lift up ... it makes a scraping noise ... but it doesn't plop back into its normal position ...


If no go, you could carefully cut out the center dome to visually inspect what's going on (educational, if nothing else... and no worse off as a new dome can be glued on). As it is, the driver is essentially worth the value of a core frame anyway. Maybe look for a used single 128H and set this one aside.

I may cut the dome off ... to look inside for the education ... when you say core frame ... is that the same as the metal basket? ... what's a single core frame worth? ... a range? ...


Maybe look for a used single 128H ...

Are there any compatibility issues (with the existing good (?) 128H driver) if I buy a used 128H from another source (i.e. eBay)?

Thanks for your interest ... I really appreciate it :) ...

FWIW, I can afford to have it reconed ... but would that likely solve all the potential problems? ... and does it make sense to invest $350 in a pair of speakers that still have blemishes on the cabinets (which are in very good condition ... except for the drill holes) ...

Another consideration ... is that I have more good sounding speakers than I can listen to ... so I am reluctant to sink $350 in to a pair of speakers that I may not even like ... and might not be able to get my money back if I wanted to sell them ...

[macaroonie]

and punt them to someone on this forum who has the know how and inclination to put them to rights. I'm sure there are many impoverished but keen members who would welcome the kick start that that would give to their JBL career a sit were. :applaud:

[grumpy]

... when you say core frame ... is that the same as the metal basket? ... what's a single core frame worth? ... a range? ...


yeah.. mag + frame. frame value is market driven ... maybe $20-$50?



Are there any compatibility issues (with the existing good (?) 128H driver) if I buy a used 128H from another source (i.e. eBay)?


No. If you mean will they match -exactly- in response, cone color, etc..., then of course there
will be differences ... ranging from audible (worn out) and mis-colored to a best case of
trivial differences. Seems there was a black-face version (IIRC)... you'd want to check.



FWIW, I can afford to have it reconed ... but would that likely solve all the potential problems?


Dunno... have you listened to them without the bad woofer connected to see if there
might be other issues (such as worn/scratchy L-pads, burnt mid/tweet drivers, ...) ?



... and does it make sense to invest $350 in a pair of speakers that still have blemishes on the cabinets (which are in very good condition ... except for the drill holes) ...


Totally your call. If you can get the woofers fixed or replaced reasonably, then it
might be worth it to you. Do you have the grill frames? Condition?
I have a pair and like what they can do... you may not. Would be hard pressed to
find a current pair of $350 speakers that would compare well (IMO).



Another consideration ... is that I have more good sounding speakers than I can listen to ... so I am reluctant to sink $350 in to a pair of speakers that I may not even like ... and might not be able to get my money back if I wanted to sell them ...

I would be reluctant to do so too. What speakers do you have that you like the
sound of in your listening space (for reference)?

-grumpy

[Chip-HP]

... have you listened to them without the bad woofer connected to see if there might be other issues (such as worn/scratchy L-pads, burnt mid/tweet drivers, ...) ?

Have not ...


... Do you have the grill frames? Condition?

Yes ... they are in excellent condition ...


... What speakers do you have that you like the sound of in your listening space (for reference)?

My main speakers are Pioneer HPM-100s ... but I am listening to rock 'n roll music most of the time ... I have JBL L36s ... and 4311Bs ... two pairs of Herseys (1967 and 1983) ... Ohm Walsh 2s ... Altecs (the ones with the granite-like tops ... forgot the model name) that I also listen to ... another pair of Klipschs (3246) ... JBL L56s ... and 150As (need refoaming) ... that I haven't hooked up yet ...

I took the "cock-eyed" 128H woofer to a local JBL service center (Freeman-Tuell) this morning ... he confirmed that it needs reconing ($220 incl ST) ... and told me that reconing should correct any other problems ...

I have come up with a plan ... the woofers (128H) in the L150As need refoaming ... I am going to have them refoamed by Freeman-Tuell ($50 each) ... and then put them in the L112s to see how like the sound before I decide what to do with the L112s ... the radiators in L150As also need refoaming ... but I think that I can do them ... with one of Rick Cobbs kits ...

Thanks again :) ... grumpy ... for your input ...

[trueview]

I have come up with a plan ... the woofers (128H) in the L150As need refoaming ... I am going to have them refoamed by Freeman-Tuell ($50 each) ... and then put them in the L112s to see how like the sound before I decide what to do with the L112s ... the radiators in L150As also need refoaming ... but I think that I can do them ... with one of Rick Cobbs kits ...

Thanks again :) ... grumpy ... for your input ...


I too am a novice but was successful refoaming some 122a's...just go for it, It hink it cost me abot $20 for the pair...:D

[grumpy]

...
I have come up with a plan ... the woofers (128H) in the L150As need refoaming ... I am going to have them refoamed by Freeman-Tuell ($50 each) ... and then put them in the L112s to see how like the sound before I decide what to do with the L112s ...


Sounds like a reasonable plan to me :) I'm guessing you'll like them.
-grumpy

[majick47]

Chip re your L112 cabinets with holes drilled in them but otherwise in nice shape consider them to be JBLs with some history/character. I have a few pairs of JBLs (4301b/L200b) that were formerly used in a recording studio, movie theater and club and with either wood filler or mounting bolts they look very respectable and I'm proud to say they have a "pro" history.

[majick47]

Chip re your L112 cabinets with holes drilled in them consider these to be JBLs with some history/character. I have a few pairs of JBLs (4301b/L200b) that were formerly used in a recording studio, movie theater and club and with either wood filler or mounting bolts they look very respectable and I'm proud to say they have a "pro" history.

[Chip-HP]

Chip re your L112 cabinets with holes drilled in them but otherwise in nice shape consider them to be JBLs with some history/character. I have a few pairs of JBLs (4301b/L200b) that were formerly used in a recording studio, movie theater and club and with either wood filler or mounting bolts they look very respectable and I'm proud to say they have a "pro" history.

Thanks for your input ... the holes don't bother me (a friend ... with woodworking skills ... has offered to plug them for me) ... but they would probably decrease the resale value (which I like to keep in mind ... especially when I am considering investing another $250 to $300) ... I should have the refoamed 128Hs from the L150As back next week ... I will install them in the L112s and listen to them for a month or so before making a decision on whether or not to recone the "broken" 128H ...

[Chip-HP]

Got the refoamed 128Hs from the L150As back today ... installed them in the L112s ... and put a homemade comp from The Complete Motown Singles 1966 on the Sony SACD player ... and wow! ...

[briang]

Got the refoamed 128Hs from the L150As back today ... installed them in the L112s ... and put a homemade comp from The Complete Motown Singles 1966 on the Sony SACD player ... and wow! ...
:) so you like them then? ;)