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Thread: Opinions wanted: 240Ti vs L-150A

  1. #91
    RIP 2021 SEAWOLF97's Avatar
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    Quote Originally Posted by Dagfinn View Post
    *Sigh*. If you look closely at the pics of the tweeter, there's a small black dot in the middle of the dent in the first picture. My friend in France recieved it like that, yet in the pics posted by the seller it was undented. The black dot is a tiny needle hole . It looks punctured on purpose. I didn't catch it until today, my eyesight is less than perfect.

    But, what will the hole do, you think?
    somebody in the other 044ti rescue thread had recommended try to pull out a dome dent with a needle, much as you described.

    Since it's already there, your options are limited.

    IF it bothers you or causes problems, guess you could fill it .... silicon ?
    Some kind of happiness is measured out in miles

  2. #92
    Senior Member grumpy's Avatar
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    Personally, i’d leave the hole alone and not worry about it.
    re alignment, if the adhesive is now completely ineffective, you could try thin, double sided tape... A sweep test will bring out any buzzes. I’d just visually center it and test. It sounds like you’re experiencing more back pressure from the foam than I would expect (not having the factory foam is why I suggested trimming it a bit more; the compression doesn’t need to be more than a mm or two as the dome excursion is very small).

  3. #93
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    Ok, I see. As you say, it's already there so... Guess I'll ignore it for now and proceed. I should be able to generate a sweep test, hopefully that will tell me something. It's a backup, but I still hope it's working ok. I've found that vintage gear often needs some investment in time or parts, or both. And some self education, so thanks for your guidance and input .

    This guy is fixing a 2412h driver, https://youtu.be/YNaTzoI-i7M
    The 2412h uses a foam plug see 2:42-3:12. I wonder what they do to replace them? 2412h seems like a more current product?
    And, they have "direct copy of 035Tia" which has "Foam plug behind dome to reduce unwanted ringing and resonance" https://www.simplyspeakers.com/repla...-t-035tia.html

    I sent them a request, maybe it could be possible to get plugs from them...

  4. #94
    Senior Member grumpy's Avatar
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    There was someone selling an equivalent item (as stated by the seller) on ebay at one time (?) or perhaps contact member Edgewound for one of his.

    Quote Originally Posted by Dagfinn View Post
    Ok, I see. As you say, it's already there so... Guess I'll ignore it for now and proceed. I should be able to generate a sweep test, hopefully that will tell me something. It's a backup, but I still hope it's working ok. I've found that vintage gear often needs some investment in time or parts, or both. And some self education, so thanks for your guidance and input .

    This guy is fixing a 2412h driver, https://youtu.be/YNaTzoI-i7M
    The 2412h uses a foam plug see 2:42-3:12. I wonder what they do to replace them? 2412h seems like a more current product?
    And, they have "direct copy of 035Tia" which has "Foam plug behind dome to reduce unwanted ringing and resonance" https://www.simplyspeakers.com/repla...-t-035tia.html

    I sent them a request, maybe it could be possible to get plugs from them...

  5. #95
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    I'm a little fuzzy on what you're looking to repair.

    The 035Ti was first produced without a piercing. The 035Ti was then revised, with a piercing in the dome like your photo, but the P/N was unchanged. My 4312As first came with the un-pierced domes, later while still in Germany they were changed to the later pierced-dome 035Tis, an upgrade. I can't recall what it was that JBL found that was solved by the small piercing.

    All of my D8R035Tia kits have the piercing. I haven't looked closely at the 044, but it wouldn't surprise me to find that at least one revision of it also has the piercing. I have no spare D8R044 kits so the only ones I have I'd have to peer through the screen, and with my aging eyes that's a challenge in itself. I tried a few minutes ago to look through the screens but can't tell.

    The only way I can see currently to get a good matched pair of 044s is by buying a pair of used 1.8Tis, throwing away the cabinets (and probably the woofers), they often sell for less than the value of the tweeters. I would prefer to buy a pair, especially used or aftermarket, as matching tweeters (and mids) are extremely important to your imaging. When I bought my 240Tis (used) I couldn't find a pair of new JBL diaphragm kits to hoard, so I bought a nice pair of 1.8Ti speakers instead, ... as spare tweeters (kept the 1.8s, they are nice office speakers).

    Regarding the damping foam (not "dampening"): The original and the 035Tia series kits include one open-cell foam pellet, which goes on top. Adhesive-backed / self-stick. It also includes a small, harder black pellet of a high-density foam rubber, self-stick, which is to be stuck down to the pole-piece first. The larger/softer piece then sticks over it and forms a dome shape to match the inside of the Titanium dome. I did measure the two pellets in a kit once, posted on AK some years ago, not sure if I still have those dimensions. The larger foam was the same density material that is used by Simply Speakers as the diffraction ring for the L100A speakers and is what I've used. The small pellet can be cut from rubber, I used gasket material. That small pellet was not designed to compress, just a "dead" piece of material that forms the dome in the larger pellet.

    Incidentally, when I opened my last 035Tia kit a year or two ago, the larger foam pellet had started to disintegrate, was becoming unstable and had turned from resilient foam to fragile, and was only useful for dimensions and I had to make new damping foam for it. Being that mine were fairly late production and stored inside in air-conditioning and out of sunlight, I am confident that you won't find any around with good foam.
    - Jeff

  6. #96
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    Colleagues,
    Ken does use a "spot" of glue on the pole piece to hold the foam in place.
    Edge wound does great work, he did some 2214's for me a few years ago. I;m going to attempt doing a plugendectomy (which looks like it's 3/4 inch dia. and 1/2 inch thick) on my 035's I have 4 of them that need help.

    So thanks Wolf for the foam link.

    Oh yes a note of caution to those who haven't worked on 035's before; Ive ruined 2 of them by not taking adequate caution. So be careful and take your time.

    Ed
    KEEP ON LISTENING!

  7. #97
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    This is the complete D8R035TIA kit, note the small pellet (die-cut but not pressed out of the square piece yet) next to the larger low-density open-cell pellet.
    Attached Images Attached Images  
    - Jeff

  8. #98
    Senior Member macaroonie's Avatar
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    Having worked in manufacturing this looks like a bodge to me. It's not uncommon in the world of hi fi , a couple of reviews flag up an issue and you do have to go back and make a fix , if you can.
    You can see it all over turntables if you have a keen eye and look under the hood.

    I have a pair of 044Ti that have not been opened from new , in all likelyhood the foam will be mush. I'm motivated to get my hands on some magic dust plus add a felt domed backer on the pole piece ( not in contact with the dome )
    This FWIW is straight from the compression driver world where the foam in the back cup is replaced with felt and some dia's of course have the magic dust.

    I'll report back when I get round to it.

    Here's a bodge if thre ever was one. This is the sub chassis from an Ariston RD11 circa 77/78.
    The original chassis was the shape of the pressed part below the obviously added on part got added and spot welded on. This was not the original design.
    Total bodge to effect a change that circumstances deemed necessary.
    Happens all the time.

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  9. #99
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    OK .... a trick I forgot

    .
    On the first 044Ti , I did the 8 screwdriver blades under the "plinth" to
    remove operation and waited an hour for it to "pop".

    On the second one I did, got a little smarter. Took about 2 minutes.

    took the pocketknife ... laid it against THE TOP at a 90 degree angle.
    Then pulled the blade back so that the tip was about a half inch from the dome.

    took some tape and attached to the blade at the edge of the plinth as a depth marker guide.

    put the blade tween the plinth & magnet up to the blade tape marker and just ran the blade around 360 ... came right off safely.
    Some kind of happiness is measured out in miles

  10. #100
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    Quote Originally Posted by SaturationPt View Post
    I'm a little fuzzy on what you're looking to repair.

    The 035Ti was first produced without a piercing.
    I'm trying to fix some 044Ti's with powderized damping plugs. The 044Ti wasn't pierced originally, so I'd be hesitant to pierce it, myself. I was hoping a 035Tia foam plug could maybe be compatible, but the shop didn't sell foam plugs separate. I think everyone is punching their own. I have ordered some more foam, actually maybe the same diffraction ring you mention !

    Ken mentions using acetone to loosen the glue, but I'll certainly go slow and easy on the next tweeter. Knife tip method may be worth trying too, thanks for that tip Seawolf.

    Mac, I'm eagerly awaiting your magic dust results ! If there was a box of JBL-aquaplas available, I'd go for it, for sure. The foam plug is bound to degrade over time, not a perfect solution from the start, and maybe even creating its own problems when degrading and maybe filling the gap for the diaprahagm. The Thorens foam I have was an afterthought, to cancel resonances from footsteps in the spring suspension .

    Curiously, another set of 240Tis have shown up locally, twice the price of mine, yet strangely attractive... .

  11. #101
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    Quote Originally Posted by macaroonie View Post
    Here's a bodge if thre ever was one. This is the sub chassis from an Ariston RD11 circa 77/78.
    The original chassis was the shape of the pressed part below the obviously added on part got added and spot welded on. This was not the original design.
    Total bodge to effect a change that circumstances deemed necessary.
    Happens all the time.

    Name:  ariston chassis bodge.jpeg
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    Interesting to see this sub chassis, I have a Heybrook TT2 which is very much the same design principle, yet solved slightly differently.
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    New temporary armboard, different arm coming in a while.

  12. #102
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    Absolutely no reason to pierce a diaphragm that isn't pierced Dagfinn.

    As mentioned, I don't know that the 044 is pierced by JBL, I am more thinking that someone installed an 035Tia dome somehow. The 044 is a slightly different tweeter and might have a different venting scheme.

    As far as adding mass to the dome with aquaplas or other, I'd consider that experimental on the 044, if it works that is great, but I would leave it to those among us who can actually measure the results and that isn't me. It might change the response of the 044 tweeter in ways other than just damping a resonance.

    It has always been interesting to me that JBL discontinued the embossing on the dome when they designed the 052, how I'd like to be able to understand what changed and why. Of course the next version the 053 had no embossing either, and included the coated dome, but again it was a complete redesign, not just added coating.

    Also as someone mentioned below, JBL does only offer a complete tweeter, there is no 053 repair kit at this point, and it is designed to be used with a waveguide (I am not aware of any application with the 053Ti that has a flat face).
    - Jeff

  13. #103
    Senior Member macaroonie's Avatar
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    Quote Originally Posted by Dagfinn View Post
    Interesting to see this sub chassis, I have a Heybrook TT2 which is very much the same design principle, yet solved slightly differently.
    New temporary armboard, different arm coming in a while.
    I only came across the insides of thTT2 a couple of times. Well made priduct with a few new ideas in it.
    I lived and worked in the maelstrom of the Scottish turntable industry.
    Ariston , Linn , STD , Systemdek , Fons etc. They are all of a type ( and hype )

  14. #104
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    When Giskard rebuilt some 44tis I would guess over 10 years ago he coated the inside with Aquaplaus without me asking , said it should be done, charged me 10 bucks extra I think for 2 he did maybe each..

    I said thank you as I paid him.
    Changing to Legacy Audio and started with a Silver Screen HD for my center between the 250TIs

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