Just acqired a pair of L212 speakers ... [Archive]

hjames

12-10-2016, 02:06 PM

I don't have them in hand yet, can't say if they are alnico or ferrite drivers ...but in a couple weeks I'll know.
They are supposed to come with a sub,but from all I have read, the subs were a bit fragile,
the energizer (amp section) had issues and the sub driver didn't have a lot of travel and could be bottomed too easily.
Or so people who have owned working ones have told me.
But a couple years ago Seawolf said some good things about the M&K volkswoofers, so I found and bought one back then.
I fell in love with the curved walnut box and bought one - and its a great sub on its own.
So, I'll probably use that with the L212s, if I don't use the L212s in my home theater system where I have a good sub already.
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JohnInICT

12-12-2016, 07:34 AM

I have a pair I'm currently going through. Put new surrounds on the mid-bass drivers and the sub. I believe the amp in the sub is a bit weak, so I am getting ready to look into that. I must say..they sound really good without the sub. I think you will be very happy with them. I currently have C-38's, 4410's and Lancer 99's..I think the 212's, when sorted out, could be my favorite. I have been searching for original grill cloth but haven't found any yet. I would like to find some and keep them as close to original appearing as possible.

Great find. I think you'll enjoy them.

hjames

12-16-2016, 08:40 PM

Box 1 and 2 of 5 arrived today - the seller pulled the upper tower sections off the bases and sent the bases in huge boxes.
They've arrive today and are in much better shape that I expected. It was twilight when I unpacked them and took pictures -
better pix during the day tomorrow, unless we get snow that cover the skylights and darkens the living room.
The bases do have some scratches, and a few veneer chips - and you can see a bashed in spot on the right one in the curved part - probably near the front.
But I figure they are rare and 40 years old - so I'm real happy so far!
An original L212 factory brochure will arrive soon, and the actual upper speaker parts will arrive after Christmas.
The mid-Bass surround kits are due tomorrow (Rick Cobb, of course)

There are no rubber (?) feet on the bases - not sure what they were supposed to have but I'll figure something out.
Very excited so far!

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Ed Zeppeli

12-16-2016, 09:12 PM

Congratulations!

Why such disparity in the shipments' arrival times?

Cheers,

Warren

DavidF

12-16-2016, 11:01 PM

I have never heard this model from JBL but I feel like I know it well. In the era of enclosures that were just a derivative of a shoe box set up on one end, these L212 enclosures were certainly striking in the visual sense. Even in the brochure they were a stand-out design. I always imagined that, set up in living room of the 70's, they would stand out above any else in the room. Even if you had no interest in audio, in the day.

Good luck and have fun with new-old JBLs, Heather.

hjames

12-17-2016, 05:19 AM

Congratulations!

Why such disparity in the shipments' arrival times?

Cheers,

Warren

The bases came in huge boxes Via FedEx, the tower cabinets are coming via UPS.
Not sure otherwise ...
Its hard to be patient - but I'll manage ...
Since I drifted from JBLs a few years back, I have gone through tall skinny slab speakers like the Transmission line designs of DCM TimeFrames
and the planar designs of Magnepans ... both have imaging out the yinyang!

To come back to JBL I wanted something different -
I don't have room (or money) for a Paragon - and most of the JBLs I've owned have been 70-80s era -
but these look like one of the more interesting "statement speakers" JBL ever made - and - they were affordable (always a concern!)

FWIW - and for future reference, as of today, the Service Manual (with bass module schematic) is still available on the Harman site at -
http://manuals.harman.com/JBL/HOM/Service%20Manual/L212%20sm.pdf

hjames

12-19-2016, 08:18 PM

The other box arrived today - with the upper 2 Towers - 78 lbs ...
I assembled them, pucolumns to check the drivers - rigged a temp jumper for those goofy JBL twist lock connectors up inside the column ...
and gave them a brief listen to be sure all drivers were working.
I knew the mid-bass surrounds were crumbling - I've already got replacements here from Rick Cobb (just need some time).
Sadly, both domes were pushed in on the 066 tweeters - I suspected they probably were, there were no clear pix of them -
but I spun the adjustment pots a few times and they mostly sound great - except for the woofer buzzing, of course!

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bldozier

12-21-2016, 10:08 AM

Im tickled we finally spoke. Thanks for all the information.

hjames

12-21-2016, 11:22 AM

So - yesterday morning I removed the 112A midbass drivers from the cabinets. After work I peeled off the "O-rings" that held the surrounds in place. I had already ordered and received the Surround kits from Rick Cobb, and have done many larger JBL surrounds in the past, so I figured it would be no big deal. I clean the bad surrounds and glue with MEK, which need LOTS of venting as its quite toxic stuff. I usually do the clean ups on our back porch, which is an open, screened in space. Its December, and its cold - about 30 degrees when I started to rub off the old surrounds, scrape the frames and wipe the surfaces thoroughly with MEK. Its messy, the MEK evaporates fast, and IT WAS COLD!

Once cleaned, I was eager to get back inside to do the glue work - no real fumes from that. I brought the "cores" in, popped them on my bench, and dropped the new surrounds in place just to confirm they were a good fit. I laid a clean bead of the glue on the inner edge of one of the new surrounds, slipped it around the cone, and pushed it against the back of the speaker cone. I went around it a couple of times to be sure it was fitted as the glue set up. Once that was done I started with the second speaker. But as I was working it around the cone I notice that moving the cone made a rustling sound. The Other One had NOT made any sounds and had floated free. This one rubbed and did not move freely. OMG - one driver is bad - and these drivers were rare when new and have been out of production for years! Parts have been NLA (No Longer Available) for years as well. Unobtainium!

Picture from yesterday, before I cleaned up the old surrounds -
amazing 8 inch Alnico drivers with 3 inch voice coils! Vintage JBL quality.

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Emma suggested i make a video to show the seller that there was a problem, so I grabbed the camera as she gently moved the speaker cones.
Pretty easy to hear the rub
https://www.youtube.com/watch?v=69_mDMH0gSI

The seller refunded some of my money so I could get the driver reconed - (actually, if I go that route, I'd get both of them reconed so they stay matched)
- but for now, I'm taking a couple days off for the holiday and will consider other possibilities. I did post a WTB ad in the marketplace, if anyone has a working spare 112A.

And - I dragged my vaccuum upstairs and tried to pull out the pushed in silver domes on the 066 tweeters - no success so far -
it's very stiff and feels more like a metal foil of some kind, instead of metallized silk as I expected.
But I'll haul the shop vac up in a couple days and try again. Maybe heat the domes up with a blow dryer (?) so they can pop free easier.

Krunchy

12-21-2016, 11:30 AM

Good luck with them Heather. I always liked those speakers (mainly for the aesthetics I admit), looking forward to your thoughts on their sound once you get them up & running.

SEAWOLF97

12-21-2016, 11:48 AM

And - I dragged my vaccuum upstairs and tried to pull out the pushed in silver domes on the 066 tweeters - no success so far -
it's very stiff and feels more like a metal foil of some kind, instead of metallized silk as I expected.
But I'll haul the shop vac up in a couple days and try again. Maybe heat the domes up with a blow dryer (?) so they can pop free easier.

http://www.audioheritage.org/vbulletin/showthread.php?29325-044Ti-questions-Help-needed&p=297332&viewfull=1#post297332

speakerdave

12-21-2016, 01:08 PM

The substrate is phenolic. The metallic finish was initially done by vapor deposition until the machine broke, thereafter brushed on. This from Giskard/Lancer/4313B ages ago, as I recall.

hjames

12-21-2016, 05:56 PM

For future reference - tho you can't find it via their "Support Pages" -

Harman Kardon still has the JBL L212 Service Manual online

http://manuals.harman.com/JBL/HOM/Service Manual/L212 sm.pdf (http://manuals.harman.com/JBL/HOM/Service%20Manual/L212%20sm.pdf)

And the JBL L212 Owner's manual is here -

http://manuals.harman.com/JBL/HOM/Owner's%20Manual/L212Instruction-om.pdf (http://manuals.harman.com/JBL/HOM/Owner's%20Manual/L212Instruction-om.pdf)

The crossover is here

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L212%20ts.pdf

(http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L212%20ts.pdf)

hjames

12-21-2016, 06:03 PM

http://www.audioheritage.org/vbulletin/showthread.php?29325-044Ti-questions-Help-needed&p=297332&viewfull=1#post297332 (http://www.audioheritage.org/vbulletin/showthread.php?29325-044Ti-questions-Help-needed&p=297332&viewfull=1#post297332)

Thanks so much, Tom - I'll have a go when I get some free time next week maybe!

Earl K

12-22-2016, 11:14 AM

Hi Heather,

I'm sorry to see that your purchase has turned into a "salvage project".

Here's a very important ( little ) thread (http://www.audioheritage.org/vbulletin/showthread.php?24917-4315s-midlows-travel&p=250162&highlight=underhung#post250162) to bookmark.

One wants to know the depth of the top-plate/gap ( .35" for this family of mid-rangers ) if ultimately, one is forced to rebuild the 112a ( using after-market parts ).

:)

rdgrimes

12-22-2016, 11:56 AM

Once cleaned, I was eager to get back inside to do the glue work - no real fumes from that. I brought the "cores" in, popped them on my bench, and dropped the new surrounds in place just to confirm they were a good fit. I laid a clean bead of the glue on the inner edge of one of the new surrounds, slipped it around the cone, and pushed it against the back of the speaker cone. I went around it a couple of times to be sure it was fitted as the glue set up. Once that was done I started with the second speaker. But as I was working it around the cone I notice that moving the cone made a rustling sound. The Other One had NOT made any sounds and had floated free. This one rubbed and did not move freely. OMG - one driver is bad - and these drivers were rare when new and have been out of production for years! Parts have been NLA (No Longer Available) for years as well. Unobtainium!

Honestly I don't think you've proven it needs a re-cone - yet. Until its properly centered and surround is secured, you can't be sure it has a rub. If the coil measures proper DCR you should play with this some more. There may just be some crud in the gap, or its just not centered right.

I'm just sayin', its not "bad" till you do some more due diligence.

hjames

12-22-2016, 12:08 PM

Subwoof and a couple others are leanin' towards crud in the gap - but with the holidays,
its going to be a few days at LEAST before I get a chance to pull it apart and check ...

And honestly, I've plans to xacto-slice and remove the center cap and clean whatever I can get to
before I take a shot at gluing the surround to the frame (already glued to the back of the cone).

speaker will wait ...

Christmas ... Holiday ... Sunday ...

4 day weekend ... Work Tu/We/Th ... then 4 day weekend again!

Good spirits ... Angels' Envy is great in Egg Nog ...
(we tried & thought it was better than that rum in eggnog).

Picture from last year - Doublewood Carribean Cask was a Christmas gift last year -
this year I asked for (and am hoping for) Monkey's Shoulder scotch.

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Honestly I don't think you've proven it needs a re-cone - yet. Until its properly centered and surround is secured, you can't be sure it has a rub. If the coil measures proper DCR you should play with this some more. There may just be some crud in the gap, or its just not centered right.

I'm just sayin', its not "bad" till you do some more due diligence.

grumpy

12-22-2016, 12:47 PM

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hope you get your wish! :)

:sleigh:

hjames

12-22-2016, 03:26 PM

That looks delicious! How do you like it?

They offered it up as 1 of 4 "expressions" to be sampled at the scotch tasting at the Highland festival in Richmond, VA on Oct 22 -
(a mix of three different Speyside Single Malts - Glenfiddich, Balvenie and Kininvie)
We found it real nice, which is why I asked for a bottle for Christmas (and my honey has hinted that - I asked, I got ...)
I'll know for sure on Christmas day ...

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hope you get your wish! :)
:sleigh:

grumpy

12-22-2016, 08:21 PM

Quite pleasant. 🐒🐒🐒

rdgrimes

12-22-2016, 09:37 PM

hjames

12-23-2016, 06:50 AM

You guys and your blended scotch don't know what you're doing.
Single Malt, try some 18 year old Glenfiddich. But if you're really serious go with the 21. Of course they also offer 40 and 50, but if you have to ask the price you can't afford it.

BTW, only Glenfiddich is audiophile scotch. It makes everything sound real good. ;)

Fixed that for ya! (added the smile)

Monkey shoulder is 3 "family" single malts blended together - and was tasty. It will be the only blend in our cabinet.

I think Scapa 16 is the oldest scotch we have - personally I prefer the Abelour A'bunadh for tasting ...
but the Balvenie Doublewoods are very nice too.
My wife bought a bottle of Tamdu - we enjoyed it and bought the last 4 on the shelf in the local ABC store -
the old bottle, before they closed down the distillery, sold it, and the new owner restarted it.
We drank one, have an open bottle and gave one away ... and one stashed for the future.

Lots of good scotch to enjoy - but I have cookie baking to do today - gotta scoot!

(Vintage toaster, vintage mixer, & "You Want it Darker" Playing on the vintage speakers - UREI809As)
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Afterwards - the results of a day of baking ...
Variations on Toll House cookies
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Shortbread cookies - tho the first tray got overcooked, the second is perfecto!

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grumpy

12-23-2016, 09:58 AM

Ha :) no scotch expert claim here. Was just funny I had some.
Hope to see a working pair of L212s reported here in the coming weeks! :)

Mr. Widget

12-23-2016, 07:53 PM

Hope to see a working pair of L212s reported here in the coming weeks! :):yes:

And hoping to have a few cookies... Heather's look good but unfortunately they are a continent too far. :( I'll have to find some locally. Luckily it is the right time of year.

Happy Holidays!

Widget

hjames

12-24-2016, 11:38 AM

I removed the 066 domed tweeters and since the household hoover didn't do it, I went out on the screened in back porch to try them with the shop vac.
I made an adapter out of PVC pipe to choke down the vacuum hose so it'd better fit over the domed area ...

So far I have avoiding physically put the vacuum tube directly on the dome to pull -
Surrounding it was enough for the first dome. As you can see, I did have success with one
- tho its got a faint dent remaining, I'd say this one is fantastic for 40 years old!
However, the second crushed dome is proving more stubborn, so after a cuppa coffee to warm up (its 42 degrees out back),
I'll head back and try some more ideas ...

My next thought is to take an 1800watt hair dryer and warm up the crushed dome.
My hope is that even with the heat sink of the rest of the driver, the warm dome may be more malleable and unkink.

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066 #2 is still smushed in ... more work needed -
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grumpy

12-24-2016, 02:28 PM

#1 came out amazingly well. Crossing fingers for the next one.
A 1/2" hole in the pvc might help you modulate the vacuum level better
e.g., with a finger... then use a good seal on the 066 face... blue tak or modeling clay(?)

Chas

12-24-2016, 02:44 PM

42 degrees? Must be a heat wave! :D
Looking good Heather. Good luck with the second one. Save the single malt for later....

Allanvh5150

12-24-2016, 03:45 PM

Take the diaphragm out and use your finger. It works well with all that style of driver.

Allan.

hjames

12-24-2016, 04:11 PM

Take the diaphragm out and use your finger. It works well with all that style of driver.

Allan.
I was hoping the vaccuum trick would work for both, but that's my next approach -
I peeled the gasket off and now have access to the allen screws - so next time I sit down to work on it,
I can open it up, remove the wires from the terminals move the diaphram and push out the dome from the inside ...
I'll document it with pix, as always.

I've got plans for a quiet Christmas eve with Emma, ham sandwiches and butternut squash soup,
eggnog and cookies and relax with a movie - and tomorrow is Christmas.

So ... this will keep for another day, but its nice to have the strategy mapped out for the next stage.

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rdgrimes

12-24-2016, 09:29 PM

Heat might cause aluminum to flake off the dome. So can vigorous vacuuming for that matter.

hjames

12-25-2016, 04:53 AM

Very interesting. Emma is doing her 6AM last minute fine tuning of today's sermon (her typical Sunday morning thing).
I could not sleep in like I usually do on Sunday, so I got up and made coffee, then hooked up the one working L212 speaker on the right channel,
left the Magnepan MGIIc connected on the left, and the M&K Volkswoofer still connected as a sub. All tied through the Jolida tube amp - and I started to play music.

The L212 is much more efficient than the Magnepan, so I am primarily hearing it ... getting to know its sound and range.
I started with S&G Sound of Silence, then some Garfunkle solo stuff (Mary was an Only Child, Bright Eyes and Wonderful World) -
then to Stephen Stills (Treetop Flyer - woah) - I let that play all the way through - very nice!

Cranked it a bit for Boston's More than a Feeling ... yeah!
Benedictus, by Strawbs - then Suzanne Ciani - Leonard Cohen was impressive as well
(various songs old and new - Dance me to the end of love - Cohen Live) But Leonard's bass on You Want it Darker was disturbing Emma, even behind closed doors (!)
I blame the Volkswoofer - so I switched to Beck - Sea Changes.

Not pushing to hard - the Jolida's only got 65w/ch or so ... and Emma is working behind closed office door - but -
I'm REALLY Impressed so far - can't wait to get the 2nd cabinet's drivers working ...!!

Merry Christmas to me!
And to all of you as well!!

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hjames

12-26-2016, 11:34 AM

Off work Day after Christmas - Had flapjacks and sausage ...watched the Doctor Who Christmas special we recorded last night, and - I took some time to fiddle with the other 066 Domed tweeter. I had a set of T handle jewelers screwdrivers and such - and one fit the allen screws holding the casing together. I removed the 3 allen screws and lifted the top off, revealing the diaphram and leads at each side. Mark which terminal/lead is Pos and which is neg (or as I did, which is blk and which is red)
Put a screwdriver on the philips head and turn slightly, then hold the screw head and spin the terminal off with your fingers. Gently lift the diaphram out of its depression -
careful with the voicecoil on the backside as you lift it from its gap in the magnet) Push the dented dome gently from underneath.
(mine still has a faint dimple that would not stay pushed out, but its much better than before!)

So - I reassembled the 066 driver. Fortunately the gasket was in good shape
(tho I read here years ago that you can cut a nice one out of a cereal box if its unobtainium, as this is)
I reinstalled it back into the cabinet, and taped up the leads for the missing midBass in that cabint, and hooked it up to the stereo.
Played a few track (Be Bop Deluxe, America, Sweet Honey in the Rock, Beach Boys) and determined the tweeter is well, and playing fine!
So, that task went pretty well!!

hjames

12-26-2016, 11:41 AM

5 out of 6 drivers now functional ...

So - on to the 112A midBass driver!
I took a sharp xacto knife and cut off the dome carefully - trying to be close to the original glue bead.
Not perfect, but not bad for a first time.Hopefully I can reglue the dome back on later.

Voicecoil is stamped Nov 9, 1977!
I can see the voicecoil is not centered.

But I wasn't expected a screen in there - so I'm not sure what to do next.

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Earl K

12-26-2016, 12:24 PM

Hi Heather,

Personally ( at this point for that 112a ), I'd un-glue the spider & lift the complete cone assembly out so that the gap can be checked for concentricy ( and the condition of the voice-coil inspected ).

If those are all good, obtain some appropriate shims & replace the cone assembly ( making sure to center the spider using the shims ).

You'll need glue & reconing advice ( for best practises ) from those in the know ( such as GordonW or Ken ).

:)

hjames

12-26-2016, 03:44 PM

Sounds like a job for oldmics (John) at Scavenger Sounds in Glen Burnie, MD ...
He's the local reconer guru to me ...

http://www.audioheritage.org/vbulletin/member.php?24-Oldmics

Hi Heather,

Personally ( at this point for that 112a ), I'd un-glue the spider & lift the complete cone assembly out so that the gap can be checked for concentricy ( and the condition of the voice-coil inspected ).

If those are all good, obtain some appropriate shims & replace the cone assembly ( making sure to center the spider using the shims ).

You'll need glue & reconing advice ( for best practises ) from those in the know ( such as GordonW or Ken ).

:)

rusty jefferson

12-26-2016, 06:54 PM

Sounds like a job for oldmics (John) at Scavenger Sounds in Glen Burnie, MD ...
He's the local reconer guru to me ...
Be sure you get to him in January as he usually closes shop for the month of February.:beach:

hjames

12-26-2016, 07:36 PM

Be sure you get to him in January as he usually closes shop for the month of February.:beach:

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.

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hjames

12-26-2016, 07:39 PM

Ha :) no scotch expert claim here. Was just funny I had some.
Hope to see a working pair of L212s reported here in the coming weeks! :)

By the way - Emma DID give me a bottle of Monkey Shoulder for Christmas -
and, with a few drops of water, its got fine medicinal properties .. ;)

Been too busy to have much more than a wee dram so far -
and tomorrow is a working day - but maybe Friday night!

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FYI - Monkey Shoulder is created from a mixture of single malt from Kininvie,
together with single malts from the Balvenie and Glenfiddich distilleries,
both of which are owned by William Grant & Sons.

Not your usual blended whisky.

hjames

12-28-2016, 07:29 PM

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!!)

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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.

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Mr. Widget

12-28-2016, 07:42 PM

6 out of 6 drivers working now!!Congratulations!!

Keep us posted.

Widget

rdgrimes

12-28-2016, 09:03 PM

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

Earl K

12-29-2016, 06:07 AM

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

12-29-2016, 06:29 AM

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

12-29-2016, 01:32 PM

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

hjames

12-29-2016, 07:25 PM

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!

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hsosdrum

12-30-2016, 01:24 PM

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

12-30-2016, 03:11 PM

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

12-30-2016, 03:56 PM

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

GeeDeeEmm

hjames

01-02-2017, 01:49 PM

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?

7528675287

hjames

01-02-2017, 01:54 PM

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!

7528875289

SEAWOLF97

01-02-2017, 05:28 PM

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

01-02-2017, 08:50 PM

BMWCCA

01-03-2017, 07:05 AM

^^^
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.
:D

SEAWOLF97

01-03-2017, 07:56 AM

Some speaker systems are actually designed to play low and don't "need" a sub.

The point that I was trying to make was .... the 250Ti's sound great w/o subs , I had the M&K setup so I could play or not by the single push of a button. Did a lot of comparing with it IN or OUT.

The sub DID add a little more , that I DID NOT know was missing.
Could I live w/o it ? sure , Was it essential ? No.

mine was not designed as a 2.1 and in brutal actuality , in that room the ESS bookshelves (w/ JBL 10in. powered sub) get more use. They have wider dispersion vs the beamey-ness of the JBL's. (and the two systems are orientated 90 degrees differently ie: different listening positions)

rdgrimes

01-03-2017, 09:06 AM

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

But my statement is still true: There's no such thing as a speaker system that doesn't benefit from a sub. It's got nothing to do with the capability of the speaker.

hjames

01-03-2017, 10:15 AM

No - please don't start such a contentious discussion on your Subwoofer beliefs
in the midst of this discussion on restoring a pair of L212 Speakers - its OFF TOPIC Here.

But my statement is still true: There's no such thing as a speaker system that doesn't benefit from a sub. It's got nothing to do with the capability of the speaker.

Fine - but please go argue it IN YOUR OWN THREAD ...
don't thread crap on this L212 thread to make a statement like that ...

hsosdrum

01-03-2017, 01:48 PM

SEAWOLF97

01-03-2017, 04:15 PM

I would try a mat of 1/8"-thick heavy felt, cut to the same shape and applied with thin double-stick tape.

I had 2 pairs of L40's . One pair had nothing, but the other had a cut piece of foam on the grilles underside. It looked like carpet padding. I'll try to find the pic .... ah, got it. :)

I recall it at 3/8 to 1/2 inch

JuniorJBL

01-03-2017, 07:31 PM

Those are very cool Heather!!

I like the felt idea too! It might be possible to use the double stick tape to put felt on the cabinet as well/instead for ease of application. (might not fall off as easy either)

Anyways, congrats on another Iconic JBL speaker! :)

hjames

01-04-2017, 11:19 AM

I would try a mat of 1/8"-thick heavy felt, cut to the same shape and applied with thin double-stick tape.

Thank you!
Currently, I am mostly listening to them, but when I do return to tweaking them,
that sounds like a good approach to doing so!

mech986

01-05-2017, 02:20 AM

Hi Heather, wonderful job of restoration and driver repairs.

Just for clarification on the below comments, which spider glue joint did you soak - the spider to frame (what I'm thinking) or spider to voice coil (not likely)?

Was the other option to lightly paint the spider corrugations (folds, which many times has a resin coating that gives it stiffness and shape) with MEK and let them resolidify in a new resting position?

Bart

"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."

hjames

01-05-2017, 03:01 AM

I used a capful of MEK and, with a Q-tip, I slowly spun the driver and applied MEK to the spider to frame junction.
Apparently, that softened that glue-bond enough that the spider could shift slightly.
I never lifted the spider from the frame, just wet it down.

The other option was to full dissemble the cone/spider assembly from the frame, clean the gap,
and then reglue the spider and surround into place. The risk there is damaging/tearing the spider in the process.

I figured I'd try the first process and hope, and I was lucky.

Hi Heather, wonderful job of restoration and driver repairs.

Just for clarification on the below comments, which spider glue joint did you soak - the spider to frame (what I'm thinking) or spider to voice coil (not likely)?

Was the other option to lightly paint the spider corrugations (folds, which many times has a resin coating that gives it stiffness and shape) with MEK and let them resolidify in a new resting position?

Bart

"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."