PDA

View Full Version : LE14A magnet type



Donald
10-23-2004, 09:46 PM
If my late 70's L222 LE14A are alnico, should I see about getting them re-gaussed? If I still can?

Bass response has changed. For lack of a better description, they can't take it. It is almost like the magnet is weak and lets the voice coil push/pull to an extreme point. They were re-foamed by OC Speaker 2 years ago. As were the PR15c.

Another question. Based on a pic I sent to him of the PR BEFORE I sent it for new foam, Steve G says they are missing the tuning discs. I just pulled one out of the cab. There are no extra discs mounted. To determine how much weight to use requires knowing the cube of the box. Since the L222 cross-section is a trapezoid the area is h/2 (b1 + b2). H = 13", b1 = 18" and b2 = 12". I calc 192 sq inches. The height of the bass box is 32.5". Times the area gives 6337.5 cubic inches. Divided by 1728 cubic inches in a cubic foot I get 3.66 cubic feet for the L222 bass box. Using the latest chart posted by Giskard (and rounding to 4 cubic feet, I should have 3 20g discs mounted.

Am I off base here? I assume a 60g metal disc would also work?

Zilch
10-25-2004, 04:42 PM
PR15C:

Donald
10-25-2004, 07:13 PM
The same but different. :-)

Zilch
10-25-2004, 08:33 PM
Allegedly, factory tuning of L222 vs. L220 was done with the PR damping discs. I don't know which was intended to have fewer.

BUT, we now have two example L222's with no discs. I doubt that anybody "messed" with mine. They just cranked them until they smoked.

Early "assembled" Olympus came with instructions for tuning to taste by changing the number of discs. Perhaps the info is in the library here....

4313B
10-26-2004, 04:36 AM
Some distant memory tells me the L222 didn't have any discs.
I know the L220 had the discs, I just can't remember how many.

Steve Gonzales
10-26-2004, 01:27 PM
I am very puzzled at by this!, Don's L222's have LE14a's and a PR15 and no disc's and Giskard has some with LE14-H's(?), yet both are tuned without disc's!. We know that the internal volume is the same in both the 220 and 222 so why did JBL tune a L220 that had the LE14A with 2 100gram metal discs and then use the exact same drivers/internal vol and tune the early 222 with no discs at all?. All I can say is that Don seemed to like the performance of my 220's and 222's when he visited and they are both tuned with 2 100 gram metal discs. I removed the discs to hear what difference it made and the LACK of weighs caused both the LE14A and H's to flop around and bottom out. I wonder if this is what is happening to Don? I would make some weights out of metal and mock-up several values. The fiber discs are 20grams and the metal 100grams. I know with absolute certainty that the L220 was tuned with 2 metal discs as I have 2 pairs of them and they were untouched and also have a friend in Mich. who has L220's with LE14A's that are tuned with 2 metal discs. So Don, what you have is really an L220 set-up. I hope this helps you out.

4313B
10-26-2004, 01:35 PM
Just to clear things up a little bit here. The L220 and L222 used the LE14A. The L220A and L222A used the LE14H when JBL moved from AlNiCo to SFG Ferrite in 1979-80.

I know for a fact the L222 was tuned higher to yield greater thump. I just can't remember the exact disc arrangement. Like I've posted before, two metal discs seem awfully heavy for the PR15C but that doesn't mean JBL didn't use them.

4313B
10-26-2004, 01:46 PM
Ok, I'm wrong.

No discs would tune the ~ 4.2 cubic foot volume (system losses) to ~ 40 Hz and the two metal discs would tune the ~ 4.2 cu ft volume to ~ 26 Hz which sounds right.

Zilch
10-26-2004, 02:32 PM
This disc-ussion is starting to make sense, now.

From the revised 1973 version of "Installation and Use of JBL Passive Radiators:"

"The tuning instructions should be used as a guide for best overall performance. However, you can experiment if you wish and use the number of discs which gives best performance in your particular installation ... using fewer discs will give stronger mid-bass at the expense of the very lowest tones."

SOOOO, if you want "punchier" bass (L222), remove discs. If you want "extended" bass (L220), add a cuppla fender washers.

I know some folks consider PR's to be crap, and the forum has probably debated them exhaustively. But from this discussion, they appear to have considerable utility as tools in the tuning arsenal here.

Altec literature had something to say about them, as well. Maybe I should pay more attention.... :rolleyes:

4313B
10-26-2004, 03:04 PM
"I know some folks consider PR's to be crap, and the forum has probably debated them exhaustively."

I thought they were quite neat in the Lancer 44 and Lancer 77. That's pretty much where my interest in them for personal use ends.

Steve Gonzales
10-26-2004, 03:24 PM
wow, I just cannot imagine what would make someone say that a passive is crap? I get such a wonderful, punchy low end respone that I am sold out to the idea. I have heard L300's and they don't seem to have much of an advantage if any over the LE14/PR15 set up in my L222/220's. opinions are like as*holes, everyone has one and most of them stink but I consider the 136A to be the best LF driver JBL made for use in a fullrange system but again I don't feel like like I am missing anything, if at all. I know the 2245 and 2235's are excellent too but I'll stick with the 136A. I realize room gain has alot to do with low end response and if anything my small room suffers from cancellation, but I can shake the house if I want to with the clean musical low end I get from this combination.

Donald
10-26-2004, 08:23 PM
Well, the PR conversation is going well. :)

What about getting my LE14A de-re-gaussed? Does JBL still do it?

Mr. Widget
10-26-2004, 08:33 PM
Yes.

I would go to Orange County Speaker. They charge $25 per woofer. They will do it while you wait.

http://www.speakerrepair.com/

Widget

4313B
10-27-2004, 05:03 AM
"wow, I just cannot imagine what would make someone say that a passive is crap?"

I've heard a few people refer to them as crap, among other things. :p Who cares?

"I have heard L300's and they don't seem to have much of an advantage if any over the LE14/PR15 set up in my L222/220's."

The 136/2231 was a bit more efficient, could handle a bit more power from a mechanical perspective, and could move a bit more air than the LE14. It was the right choice for the 43xx Studio Monitors although the LE14 was generally considered to be the more "accurate" transducer.

"I consider the 136A to be the best LF driver JBL made for use in a fullrange system but again I don't feel like like I am missing anything, if at all."

Ok. I personally think it's great you like the L220's and L222's. :yes:

"I know the 2245 and 2235's are excellent too but I'll stick with the 136A."

Tough to do since the C8R2231 recone kit for the 136/2231 was discontinued and replaced by the C8R2235 many, many years ago.

Steve Gonzales
10-27-2004, 07:27 AM
I am still amazed at the wealth of info here. I have a friend in NY that has 4 original 136A's, I better snap up a pair. I want Don to let us know how the re-gauss goes.

Donald
10-27-2004, 07:50 PM
Well, L300 arrived. They kick butt! I still need a more powerful amp. :-)

I have no ear memory so I will set up the L222 and L300 to my McIntosh Loudspeaker Switching Console so I can do quick A-B comparisons. If I can get all my sig speakers into the same room I will do A-B-C-D-E-F-G tests. :)

4313B
10-27-2004, 07:54 PM
Originally posted by Donald
Well, L300 arrived.Sweet! :)

Donald
10-27-2004, 08:35 PM
Based on what I have seen on eBay, I got a great deal. $2300 shipping included!

Steve Gonzales
10-27-2004, 09:04 PM
you lucky so and so!, maybe you will like the LE85/H92 set up enough to treat your L222's to some. Ditch the cone!!!, A pair of L300's sold for 3800 then the next 2500 so it appears you got them on the low end of the scale. They are priceless. What other speaker aside from some 43xx's , of ANY brand can compete with the L300 ? Godda get me some N333's and see how they compare to the stock L222 X-overs. I doubt i'll ever own some L300's so thats what I have will have to do, poor me :(. . I am very happy for you Don.

Mr. Widget
10-27-2004, 10:38 PM
Originally posted by Steve Gonzales
What other speaker aside from some 43xx's , of ANY brand can compete with the L300 ?

I certainly join you in congratulating Don, however I do think you may be over stating it a bit. ;)

Widget

John
10-28-2004, 01:59 AM
Last i heard that deal did not go down,and if you watch things a little longer than just at the compleation of the auction you will notice that alot of those auctions that seem to go thru the roof never get compleated by the two parties.:rolleyes:

Steve Gonzales
10-28-2004, 07:28 AM
I forgot to mention that the pair that sold for $2,500 a few weeks ago were sold by my friend in NY and that deal did go thru. The shipping added about $300.00 to the total so I think you did fine at a $2300.00 total price

paragon
10-28-2004, 09:19 AM
Congratulations Don,

Yourè lucky..
Two ore three years ago an old man sold his L 300 pair
for very low money (650 US Dollar) but i was to late.:banghead:
He bought a pair of "Wilson watt puppy.." or so.
Both 2235 were new reconed !! by Harman Deutschland.
What a shame !!

Eckhard

Donald
10-28-2004, 08:48 PM
Well, I won an auction for a Carver Model PM 1.5 Magnetic Field Professional Power Amp. 450w/ch into 8 ohms.

If this ain't enough power I am joining a convent!!

Steve Gonzales
10-28-2004, 11:14 PM
If that doesn't do the trick, try a Yamaha M80, M85 or MX1000. Lots of amp for a reasonable price, very clean class A power and LOTS of headroom. My brother has some Silver Sevens t's and although they are powerful, I like the big old Yamaha's. I'm sure you will get a TON of skeptics on this choice but I would ask them if they LIVED with them to form their opinion or just dismiss it because of something else.

Donald
11-05-2004, 06:22 PM
Won a Carver M-500t. I don't like the sound when played loud on the L300. In talking with the seller, it turns out he worked for JBL for 20 some years. Name is Dean Rivera.

Since some of the problem is present with all the amps, he suggested I pull the woofers and check the spiders.

Donald
11-05-2004, 07:02 PM
Well, not sure if I have a problem. The 136A bottoms out when driven around 1-3 Hz at a voltage of 11 vac. Don't know if my DVM accurately reads AC at that low freq range.

The surround is not 100% glued on. It appears a bead of glue circles the cone but it is not wide enough to hold down the whole width of the foam.

Comments?

Robh3606
11-05-2004, 07:41 PM
Could be the foam is buzzing against the cone. So these were a refoam??? Can you get in there with a soft brush and finish the glue joint so the entire surround is glued to the cone?? That's what I would do or have the seller do it or go back to the place that did the refoam and hit them over the head for doing a half ass job.

Rob:)

slxrti
11-06-2004, 11:11 PM
In a 5 cubic foot box's. the 136 does not compare to a 2235 in deep bass
production.

How do I know??, I tried, it using a rane xover for both

slxrti

Steve Gonzales
11-08-2004, 10:17 AM
half that quote is mine and I don't EVEN understand what it has to do with this part of the discussion:confused: