[BCDrums]

A friend asked for my help on this. He needs to replace a woofer in
his 30-year-old JBL Century speaker. I think the woofer is a JBL 123-
A. I have seen them used on EBay, but am hoping to find a source for a
new driver.

Has anyone got an idea on this?

Thanks!
BC

[Michael L. Squires]

In article . com,
BCDrums wrote:
A friend asked for my help on this. He needs to replace a woofer in
his 30-year-old JBL Century speaker. I think the woofer is a JBL 123-
A. I have seen them used on EBay, but am hoping to find a source for a
new driver.

Has anyone got an idea on this?

Thanks!
BC


I'd look into getting the driver reconed; the D123A was not made by anyone
other than JBL as far as I know.

You can call JBL tech support and ask about reconing.

Mike Squires

[Michael L. Squires]

In article ,
François Yves Le Gal wrote:
On 16 Apr 2007 06:19:57 -0700, "BCDrums" wrote:

Has anyone got an idea on this?

Finding a new woofer is nearly impossible. You can either get a used one or
have the original one reconed using JBL parts - quite an expensive option.


The L100's have a cult following so I expect that reconing would be
cost-effective. It can't be more than I paid for an LE15A reconing ($140).

Mike Squires

[jakdedert]

Michael L. Squires wrote:
In article ,
François Yves Le Gal wrote:
On 16 Apr 2007 06:19:57 -0700, "BCDrums" wrote:

Has anyone got an idea on this?
Finding a new woofer is nearly impossible. You can either get a used one or
have the original one reconed using JBL parts - quite an expensive option.


The L100's have a cult following so I expect that reconing would be
cost-effective. It can't be more than I paid for an LE15A reconing ($140).

Mike Squires

I saw a pair sitting out in the weather at an low-rent apartment house.
I tried to get the resident to find out to whom they belonged, with
the intent of buying/restoring. IIRC, when I checked eBay prices it
seemed less than a profitable venture (complete sets going for little
money), so never pursued it further. Had they been very expensive I
would have.

Perhaps something has changed in the last couple of years since then,
but it seemed like components were pretty readily/economically available
at the time.

jak

BCDrums wrote:

A friend asked for my help on this. He needs to replace a woofer in
his 30-year-old JBL Century speaker. I think the woofer is a JBL 123-
A. I have seen them used on EBay, but am hoping to find a source for a
new driver.

Has anyone got an idea on this?

Why does he need to replace the woofer? If the surround has rotted away
(as is usually the case with foam surrounds of that vintage) and the voice
coil is intact, then the speaker can be refoamed without throwing away
the entire unit.


Francois.

[jakdedert]

(null) wrote:
BCDrums wrote:
A friend asked for my help on this. He needs to replace a woofer in
his 30-year-old JBL Century speaker. I think the woofer is a JBL 123-
A. I have seen them used on EBay, but am hoping to find a source for a
new driver.

Has anyone got an idea on this?

Why does he need to replace the woofer? If the surround has rotted away
(as is usually the case with foam surrounds of that vintage) and the voice
coil is intact, then the speaker can be refoamed without throwing away
the entire unit.


Francois.


A note of caution: the OP's friend needs to be very sure that he did not
stress the driver as the foam was deteriorating (does a JBL 123a even
have foam surrounds?). I purchased a set of vintage EPI's which looked
good in every way, aside from seriously rotten foam surrounds. I
purchased a kit and did the replacement myself...looked great, VC was
nicely centered and they sounded great....for about a week.

I started noticing distortion in one woofer. Upon manually depressing
the cone, the driver would cut out completely, indicating an
intermittent in the conductor leading to the coil. I haven't examined
it closely, but I suspect the former owner simply played the speakers
until they sounded so bad he couldn't stand it. In the process, I'm
pretty sure that somewhere between the terminal and the voice coil the
wire got overstressed.

I might get lucky and find a visible, repairable break, but I'm not
holding my breath.

The moral is: only refoam woofers which have been *verifiably* not
subjected to over-excursion--ie NOT played with bad surrounds. A
complete recone is the only sure route to woofer salvation.

Also, if you are treating one woofer--reconed or refoamed--do both. If
one failed from age or abuse, the other is likely to be on it's way out
as well. In any case, there will undoubtedly some slight change in the
sound of the driver, and you obviously want both sides to sound alike.

Good luck.

jak

[jakdedert]

François Yves Le Gal wrote:
On Tue, 17 Apr 2007 01:03:29 -0500, jakdedert
wrote:

does a JBL 123a even have foam surrounds?

Nope, all the 123's had pleated surrounds. If I remember correctly, the
first JBL 12" woofer with a foam surround was the 126.



That's what I thought. I was picturing it in my head and didn't
remember any foam on there. I've got the Japanese knockoff Centuries:
the Pioneer HPM-100 (also pleated). I've had them for nearly 20 years
and wouldn't trade them for the JBL's unless someone offered me some
serious....

Nope--wouldn't trade them at all. I'm fond of saying that if I could
have any set of speakers I wanted for a thousand bucks or less,
that...well, I already have them.

jak

[Arny Krueger]

"jakdedert" wrote in message
...
François Yves Le Gal wrote:
On Tue, 17 Apr 2007 01:03:29 -0500, jakdedert
wrote:

does a JBL 123a even have foam surrounds?

Nope, all the 123's had pleated surrounds. If I remember correctly, the
first JBL 12" woofer with a foam surround was the 126.



That's what I thought. I was picturing it in my head and didn't remember
any foam on there. I've got the Japanese knockoff Centuries: the Pioneer
HPM-100 (also pleated). I've had them for nearly 20 years and wouldn't
trade them for the JBL's unless someone offered me some serious....

No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.

[BCDrums]

Thanks for the replies. I am impressed that there is so much knowledge
aobut these old speakers.

As I said, these are not my speakers, but they belong to a friend. He
has decided to take his bad woofer to a JBL service center for
diagnosis and repair. If he's lucky, it's jus the surrounds.

Thanks again!
BC

[jakdedert]

Arny Krueger wrote:
"jakdedert" wrote in message
...
François Yves Le Gal wrote:
On Tue, 17 Apr 2007 01:03:29 -0500, jakdedert
wrote:

does a JBL 123a even have foam surrounds?
Nope, all the 123's had pleated surrounds. If I remember correctly, the
first JBL 12" woofer with a foam surround was the 126.



That's what I thought. I was picturing it in my head and didn't remember
any foam on there. I've got the Japanese knockoff Centuries: the Pioneer
HPM-100 (also pleated). I've had them for nearly 20 years and wouldn't
trade them for the JBL's unless someone offered me some serious....

No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.



I wonder, then, why--when Pioneer hired away Bart Locanthi, JBL's vice
president of engineering, with the specific intent of building a better
speaker (the HPM-100 being the result)--he designed them.

If you're an AES member, you can download the development paper on the
tweeter design--authored by Locanthi and the Japanese designers with
whom he he worked--he http://www.aes.org/e-lib/browse.cfm?elib=3052
The abstract reads:
"Development of a Loudspeaker System with Omni-Directional Horn Loaded
High Polymer Tweeter
The design and performance of a unique four way loudspeaker system using
an omni-directional horn-loaded high-polymer tweeter is presented. The
tweeter has good transient response and dispersion. The system has a
wide frequency range (25 Hz to 20 kHz) smooth frequency response and
high power handling capability (250 W).
Preprint Number: 1302 Convention: 58 (October 1977)
Authors: Locanthi, Bart; Maekawa, Koji; Sugano, Katsukuni; Fukura,
Hideto; Koyano, Shinji"

Of course, you don't need to listen to him. Listen to the speakers,
both of which he designed...side by side.

I have. Have you?

Granted, the HPM line went downhill pretty fast after the initial
offerings; but the 100's--the flagship--were and are superb. That's not
to knock the Centuries, by any means. They're a great speaker system.
I'd be proud to own a set, but the HPM's are a refinement of those,
created by the same designer. I 'have' a set of those, which is why I
have no desire to acquire the JBL's.

jak

[Arny Krueger]

"jakdedert" wrote in message
...
Arny Krueger wrote:
"jakdedert" wrote in message
...
François Yves Le Gal wrote:
On Tue, 17 Apr 2007 01:03:29 -0500, jakdedert
wrote:

does a JBL 123a even have foam surrounds?
Nope, all the 123's had pleated surrounds. If I remember correctly, the
first JBL 12" woofer with a foam surround was the 126.



That's what I thought. I was picturing it in my head and didn't
remember any foam on there. I've got the Japanese knockoff Centuries:
the Pioneer HPM-100 (also pleated). I've had them for nearly 20 years
and wouldn't trade them for the JBL's unless someone offered me some
serious....

No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.

I wonder, then, why--when Pioneer hired away Bart Locanthi, JBL's vice
president of engineering, with the specific intent of building a better
speaker (the HPM-100 being the result)--he designed them.

You are pursuing a different issue than the one I raised.

I never said that the HPM100 isn't a fine speaker. I once heard it and it
seemed OK. It was long ago and the circumstances weren't definitive.

If you're an AES member, you can download the development paper on the
tweeter design--authored by Locanthi and the Japanese designers with whom
he he worked--he http://www.aes.org/e-lib/browse.cfm?elib=3052 The
abstract reads:
"Development of a Loudspeaker System with Omni-Directional Horn Loaded
High Polymer Tweeter
The design and performance of a unique four way loudspeaker system using
an omni-directional horn-loaded high-polymer tweeter is presented. The
tweeter has good transient response and dispersion. The system has a wide
frequency range (25 Hz to 20 kHz) smooth frequency response and high power
handling capability (250 W).
Preprint Number: 1302 Convention: 58 (October 1977)
Authors: Locanthi, Bart; Maekawa, Koji; Sugano, Katsukuni; Fukura,
Hideto; Koyano, Shinji"

Being an AES member doesn't keep the paper from costing money. Why should I
spend my good money in support of someone who doesn't want to respond to the
issue I raised?


Of course, you don't need to listen to him. Listen to the speakers, both
of which he designed...side by side.

I have. Have you?

Not side-by-side, as there were no dual Pioneer/JBL dealerships in my area
in the day of.

Granted, the HPM line went downhill pretty fast after the initial
offerings; but the 100's--the flagship--were and are superb. That's not
to knock the Centuries, by any means. They're a great speaker system. I'd
be proud to own a set, but the HPM's are a refinement of those, created by
the same designer. I 'have' a set of those, which is why I have no desire
to acquire the JBL's.

You see to be very defenseive about this issue. So much so that you've
pretty missed the small point I tried to raise.

[GregS]

In article , jakdedert wrote:
Arny Krueger wrote:
"jakdedert" wrote in message
...
François Yves Le Gal wrote:
On Tue, 17 Apr 2007 01:03:29 -0500, jakdedert
wrote:

does a JBL 123a even have foam surrounds?
Nope, all the 123's had pleated surrounds. If I remember correctly, the
first JBL 12" woofer with a foam surround was the 126.



That's what I thought. I was picturing it in my head and didn't remember
any foam on there. I've got the Japanese knockoff Centuries: the Pioneer
HPM-100 (also pleated). I've had them for nearly 20 years and wouldn't
trade them for the JBL's unless someone offered me some serious....

No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.



I wonder, then, why--when Pioneer hired away Bart Locanthi, JBL's vice

I don't remember too much, but a friend had them when we listened to disco.
My cheap 30 watt marantz with the capacitor outputs, seemed to make
the bass boom a lot more than my friends receiver. I forget what receiver he
had, and the reason I had my amp connected. I didn't like the added bass.

greg

[jakdedert]

Arny Krueger wrote:
snip

That's what I thought. I was picturing it in my head and didn't
remember any foam on there. I've got the Japanese knockoff Centuries:
the Pioneer HPM-100 (also pleated). I've had them for nearly 20 years
and wouldn't trade them for the JBL's unless someone offered me some
serious....
No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.
snip
to acquire the JBL's.

You see to be very defenseive about this issue. So much so that you've
pretty missed the small point I tried to raise.

Your 'point' as I read it seemed to somehow deal with the HPM 'tweeter
thingies'. That's a point? You want to restate it somehow that doesn't
make you sound like a complete idiot?

jak

[Arny Krueger]

"jakdedert" wrote in message
. ..
Arny Krueger wrote:
snip

That's what I thought. I was picturing it in my head and didn't
remember any foam on there. I've got the Japanese knockoff Centuries:
the Pioneer HPM-100 (also pleated). I've had them for nearly 20 years
and wouldn't trade them for the JBL's unless someone offered me some
serious....

No way are those high polymer neo-tweeter thingies comparable to JBL's
cone/dome.

You see to be very defensive about this issue. So much so that you've
pretty missed the small point I tried to raise.

Your 'point' as I read it seemed to somehow deal with the HPM 'tweeter
thingies'. That's a point?

Wow, what a great example of poor reading comprehension!

You want to restate it somehow that doesn't make you sound like a complete
idiot?

Doctor, cure thyself.

[Jerry G.]

Contact JBL directly. I am sure that they can supply you a replacement.
There are also companies that do speaker re-building.

--

Jerry G.


"BCDrums" wrote in message
ups.com...
A friend asked for my help on this. He needs to replace a woofer in
his 30-year-old JBL Century speaker. I think the woofer is a JBL 123-
A. I have seen them used on EBay, but am hoping to find a source for a
new driver.

Has anyone got an idea on this?

Thanks!
BC