Just acqired a pair of L212 speakers ...

[hjames]

Well, Subwoof had sent me some tips on 2 approaches to fix the midBass driver -
one of the worked and offset the voicecoil without deGluing the spider!

I didn't hear a rustle so I glued the surround to the frame, and an hour later I glued the dustcap back in place -
40 minutes later I reinstalled the speaker in the cabinet!

It played Very Fine ... Glues the original cap back over the cone (I had put 2 red marks to line up with the leads ...)
Its not as pretty as I might like, but - first time I cut a dust cap off!
6 out of 6 drivers working now!!

Played (Bowie) Blackstar and Lazarus, then some John Prine - then cranked a bit for Dance Along the Edge ...

I'll check with some intensity tomorrow - but - I think I'm done ...
at least until I rebuild the crossovers (some time NEXT year!!)

Thanks -
I called him Friday before Christmas and got his schedule -
I'll probably give him a call tomorrow and see if I can drive by this Friday -
talk to him and see what he can do ...

I'll pulled the screen loose that was under the dome, but I'm not really comfortable taking the spider loose myself.

Attachment 75193

[Mr. Widget]

6 out of 6 drivers working now!!

Congratulations!!

Keep us posted.


Widget

[rdgrimes]

Any working 112A is a "good" 112A.

[Earl K]

Well, Subwoof had sent me some tips on 2 approaches to fix the midBass driver -
one of the worked and offset the voicecoil without deGluing the spider!

I didn't hear a rustle so I glued the surround to the frame, and an hour later I glued the dustcap back in place -
40 minutes later I reinstalled the speaker in the cabinet!

It played Very Fine ... Glues the original cap back over the cone (I had put 2 red marks to line up with the leads ...)
Its not as pretty as I might like, but - first time I cut a dust cap off!
6 out of 6 drivers working now!!

Played (Bowie) Blackstar and Lazarus, then some John Prine - then cranked a bit for Dance Along the Edge ...

I'll check with some intensity tomorrow - but - I think I'm done ...
at least until I rebuild the crossovers (some time NEXT year!!)

Great Stuff Heather!

Perhaps for those here who don't visit AudioKarma you might explain the SubWoof tip that worked for you .

Thanks!

[hjames]

Great Stuff Heather!

Perhaps for those here who don't visit AudioKarma you might explain the SubWoof tip that worked for you .

Thanks!

I had already glued the surround to the back of the speaker cone, but not to the basket (frame)
when I realized one of the 2 midbass drivers had a rubbing sound as I moved it.

--> Note: MEK is VERY TOXIC so you need ventilation - Work OUTDOORS!! <---

Ok - subwoof is from here on LansingForums ...
I had asked his advice and he replied with the tip via email:

A:
Get some material that will act as a shim (HJ: I cut some strips longways from 3x5 file cards)
and get the coil centered and level position on the spider.( as seen from the side )

See if there are any "waves" or spider deformations.

If not, then with the speaker face up, soak the spider glue joint with mek (HJ: I wiped it with a wet Q-tip as I spun it on a tabletop) ... every hour or so for a good part of the day...let sit overnight and dry.

Remove shims and see if it's fixed. If it is now happily centered,
reinstall the shims as before and glue the foam.
===============================================

I did that, the next day I checked and it was silent moving up and down,
so I slipped the shims back into place and glued the surround to the basket.

He had also mentioned to note which side had the tight clearance - that Gravity may have had something to do with the coil shift, so when you reinstall the driver, rotate 180 degrees so the tight space is on the bottom (gravity can shift it downward over the next 20 years!) .

[grumpy]

"... always love it when a plan comes together"

[hjames]

And how! I'd never actually heard a pair before, but even using an M&K Volkwoofer to substitute as the active Subwoofer part,
these are some amazing speakers. Maybe I can get the Magnepans into the spare room and try these with no back-panel ...

Truly, thanks for all the help with these - direct, and indirect! I learned a lot digging through old posts from Giskard!

[hsosdrum]

I remember liking the L212 system when it first came out in the late-70s/early-80s. To my ears it was a departure (for the better) from what sounded to me as the distinctly nasally-sounding midrange of JBL's contemporary "box" speakers (L65, L300, etc.) — it was quite "open" sounding and it threw a pretty good soundstage. The 12" sub didn't have enough "oomph" for my taste, but then again, I've always favored 15" woofers (and currently, 18" subs).

I'll be curious to hear about the results of your dipolar experiment using them without rear panels (although you won't get any direct sound from the rears of the tweeters). The soundstage could be quite impressive.

[hjames]

Kudos to Greg Timbers for an amazing design ...


I have an M&K Volkswoofer doing the low-end part since these did not come with the B212 UltraBass unit ...
They are addictive - perhaps the favorite JBL speakers I have owned, so far ... and I had that custom L200 system for many years.
Still have them in front of the magnepans, got nowhere to put the mags for now ... -
but I have the L212 "towers" parallel to the back wall now, no toe in.

I've been home today, mostly I have been rolling through all different kinds of music - now "This Kind of Love" - George Micheal; before - A quiet Storm - Smokey Robinson; America - Simon & Garfunkel; The Valley of Strathmore - Silly Wizard; Mark Knopfler - Bang Like That, Far from the Clyde, & A Piper to the End; Diana Krall - a number of things; Madonna - Live 8 set; Some Phil Manzanera tracks, some old Roxy Music stuff ... all pretty amazing.

The combination is great - the Volkwoofer can go really low - even with Boz Scaggs Dig or the final Leonard Cohen album - You Want it Dark -
tho it did take a bit of fine tuning to dial it in just so - but not overpowering. All instruments are well defined and the soundstage IS quite good ...
They are just really pleasant to listen to - effortless I'd say.

I've got the tube amp at 9:00 (12:00 is pretty much full on, 3:00 can get harsh on some music), so its not over loud but is nicely room filling.
The amp is rated 65w/ch with a quad of 6550 Genalex Gold Lion tubes.

I remember liking the L212 system when it first came out in the late-70s/early-80s. To my ears it was a departure (for the better) from what sounded to me as the distinctly nasally-sounding midrange of JBL's contemporary "box" speakers (L65, L300, etc.) — it was quite "open" sounding and it threw a pretty good soundstage. The 12" sub didn't have enough "oomph" for my taste, but then again, I've always favored 15" woofers (and currently, 18" subs).

I'll be curious to hear about the results of your dipolar experiment using them without rear panels (although you won't get any direct sound from the rears of the tweeters). The soundstage could be quite impressive.

[gdmoore28]

Congrats, Heather! I always enjoy your posts here and on AK. Good going.

GeeDeeEmm

[hjames]

Like all foam on 40 year old JBL speakers, there was a layer of foam on the inside of the grills.
As expected, it was crumbling badly, so I removed it, measure it, and packed it away for use as a template later on.

It had a sticky layer that attached it to the grill cloth, but it's no longer sticky.
It was in the upper grill area where the mid and tweeter would reside.
I'd guess when new it was 3/16 to 1/4 thick,
and 10.5 x 14 would just do it - one per speaker, of course.

I presume it enhanced the imaging by separating the sound fileds to some degree,
and I presume it should probably be replaced. Any ideas?

[hjames]

Oh - I wanted to thank Seawolf for introducing me to the M&K Volkswoofer many years back.
It a gorgeous looking cabinet and is a very musical subwoofer (not all are)!
Worked well with the magnepans, and turns out to be a perfect replacement
for the B212 UltraBass module my system did not include.
Just bring it up slightly to fill in the bottom, be subtle ...
Its turned out to be one of the better buys I have made over the years!

[SEAWOLF97]

Oh - I wanted to thank Seawolf for introducing me to the M&K Volkswoofer many years back.

Have seen at least 2 other pairs of L212's configed that way. Great bass and the styling seems complementary also.

I own the original JBL UB212 UltraBass. It's OEM amp croaked and was replaced , then the replacement did also. The unit is in storage and had been replaced by another M&K and now a Velodyne servosub (didn't get the remote tho)

Heard a rumor that the UB212 was designed for the 250Ti's , but in production was replaced by the B460. I didn't think it was possible, but the 250's do benefit from a sub.

I actually have an M&K "Goliath" sub too. It's an UNpowered twin of the Volkswoofer. Was part of a sat/sub system. The sats were called "Davids" ... ie: David & Goliath

My Volkswoofer's amp was weak and so paired it with a NAD receiver whose FM died. Worked very well. Shook items on the other end of the house.

[rdgrimes]

^^^
All speakers benefit from using a sub regardless of their LF extension capability. Taxing a speaker with LF duty impacts what its able to do with mid and upper bass octaves and also robs power from your amp.

[BMWCCA]

^^^
All speakers benefit from using a sub regardless of their LF extension capability. Taxing a speaker with LF duty impacts what its able to do with mid and upper bass octaves and also robs power from your amp.

I understand what you're saying but not in the absolute . . . try telling that to the 4345 with an 18-inch woofer.