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View Full Version : 250Ti Maintenance Tips Needed



Steve K
04-23-2006, 12:48 AM
Hello all,

I've been really fortunate to have come across a pair of 250Ti's recently at an used audio shop about an hour drive away from where I live (see pix). Here in Japan it's a rare occasion to find these, as you all know that when it comes to JBL the Japanese think of those big studio monitors, the 43xx's and the 44xx's. So I drove up to the store this morning with a couple of my favorite CDs. The cabinets were in pretty good shape. The surrounds of the woofer had been replaced recently, but with stiffer foam material than on 'normal' JBL's. There were no dents, neither rips on any of the drivers either, but there were some discoloration of the center caps. The only flaw I could find was that the metal connectors, including the bars, on the fixed attenuators on the back had turned white from oxidization. Sound-wise, I found the 250Ti's to be very pleasant to listen to. The highs were very smooth, the mids very balanced and clear, but the bass lacked definition or wasn't as tight as the bass I'm accustomed to with the 4343s, although I shouldn't be comparing these two types as they were designed for different environments and purposes. Well, I loved them and got them! The price was also very appealing, too (you could say that for Japan these were being sold at a bargain!).
Anyways, would any 250Ti owners out there like to share their tips on how to go about improving/maintaining these speakers so that they will perform to their potential? Would appreciate any inputs. Thanks. :)

Steve K.

Earl K
04-23-2006, 10:07 AM
Hi

Nice investment !

- I'm not a 250 owner ( though I own many le14s ) . Hopefully others will chime in to answer your questions .


The surrounds of the woofer had been replaced recently, but with stiffer foam material than on 'normal' JBL's.

- That foam may just need to be "broken in". That'll eventually happen naturally (with some normal usage ) to any "new" compliance ( foam / hinge / suspension-system / etc. ) .


but the bass lacked definition or wasn't as tight as the bass I'm accustomed to with the 4343s, although I shouldn't be comparing these two types as they were designed for different environments and purposes.

- Were they on the same amplifier type ?
- I do find this statement a bit odd since the le14 speaker family is certainly more than able of creating "tight" bass . Perhaps you need to try a different room placement for these speakers. BTW; I usually think of "tight-foam" as actually adding lower midbass definition. Maybe a higher Fs has altered the overall system tuning into an area that is now "booming" ( & possibly exacerbated by room placement ).

- You need to get the Fs ( free air resonance ) of the woofers measured to make sure they're at least " ballpark " ( ballpark = 24 hz - 29 hz in my definition of the term ) .

:)

edgewound
04-23-2006, 01:16 PM
Keep those beautiful enclosures nourished with plenty of teak oil.:)

mike
04-23-2006, 04:29 PM
When the foam breaks in they should have bass that is at least as tight as your other JBL's. However it seems to take a really long time for that aftermarket foam to soften up. Also they are supposed to be placed away from walls and corners. Another factor that will greatly affect the bass is the amplifier that you use them with. I believe I see a Marantz 9 in the background of your photo.

Great purchase!
Mike

Steve K
04-23-2006, 05:37 PM
Thanks for your replies, Earl K, edgewound, & mike!

The picture is one that I copied from the shop's webpage listing, as I didn't bring my camera with me when I visited them for the test listening. In the actual session where I took about 10 CDs of various genres, jazz vocals, blues, pop orchestral, and rock (Doobie's Long Train Running, my personal favorite cut for testing guitar sounds), the shop had specially set up the 250Ti with McIntosh's C-1000 preamp connected to a Goldmund amplifier (not sure of power), as well as Goldmund's CD transport and D/A converter. That entire system probably was worth at least 5 times that of what I've got at home!
For the bass character, Earl K may be right about the placement. Due to room restrictions, I was seated only about 6 feet away from the pair which were only about 5 feet apart. The total listening area space was around 35 sq.ft, so that may have had something to do with it. At home I've got a little more breathing room which should help.
And on the 'tight' foam surrounds, so you don't believe I should have them re-surround with softer material, because the foams on my other JBLs would easily be pushed in with only a slight nudge of the finger.
Edgewound, I'll be sure to look for some teak oil. Thanks.:)
Mike, this shop specializes in 'recycled' audio, and had loads of high-end electronics. Wish you all could see them!:bouncy:
At $1,630 (at today's yen/dollar exchange rate), I just coudn't pass up on these beauties, right? They'll be delivered in the first week of May, and I'll be sure to post some pictures and listening impressions then.

Steve K

Earl K
04-23-2006, 06:48 PM
And on the 'tight' foam surrounds, so you don't believe I should have them re-surround with softer material, because the foams on my other JBLs would easily be pushed in with only a slight nudge of the finger.

Steve, I'm left-handed, definately have at least a mild case of ADD, I'm dyslexic and at 52 years old, I'm having more "seniors' moments" than I want to admit ( must be the fact that I lived "on the road" for too long. ) All my life I've been accused of being a "literalist" / but it's my way of dealing with the "cards" that I've been dealt. So ;

- Without a ? - mark in the above quoted statement / I really can't know what you mean .

- If you were asking , "Do I think you should refoam your refoams with softer foam" ? Then the answer is no . Not until you have run at least a basic Fs test of the existing woofers . Plus , I would give them ( the existing refoams ) some time to break in before considering any other options .

:)

mike
04-23-2006, 06:51 PM
I don't think you can get softer aftermarket foam for the LE14 woofers and I don't think JBL offers a recone kit either. If your brave you can soften them up by carefully applying WD40 to the foam with a Qtip. It does soften the foam and bring down the resonance. I don't know what it does to the life expectancy of the foam though. Once the oil absorbs into the foam the surround looks pretty original and feels dry to the touch. Of course be careful not to let it absorb into the cone. There is no theory behind this just experimentation, but it works.

Once you get used to the 250Ti's you'll never want to part with them.

Mike

Steve K
04-23-2006, 10:09 PM
Earl K - sorry for the confusion, but you got it right. I was posing a question. So I'll stick with the current foams then. Thanks for the advice!

Mike - Afraid I'm not that brave. :p You can still get a recone from Harman Japan, but the prices are %#*@!!!!:biting:

One more thing, what can I do with the oxidized attenuators?

JuniorJBL
04-24-2006, 08:20 AM
I would polish them on a bench grinder with a polishing wheel. As for the surrounds when I did mine they were very stiff as well but I did not notice a lack of definition. I did notice a lack of bass for about a week but then all was better. A friend of mine has his set up in a pretty small room and they are about 6 feet apart and you sit on a couch about 6 feet away and his sound pretty good. Mine are in a bit bigger room with speakers about 7' apart and about 9' back from the speakers. As Earl said the LE14 line of transducers are some of the best sounding drivers I have ever heard. Not to mention their versatility.;)

I bought mine used as well and when I did some looking into them I found that all of my by-pass caps where toast. (mine where L250's not Ti's) That's when I decided to change mine to Ti's. There are quite a few threads about 250's here on the forum and more about their crossovers. There are most certainly some mods you can do to improve their sound over and beyond how good they sound from the factory!!

Read here.
http://www.audioheritage.org/vbulletin/showthread.php?t=289