Page 2 of 2 FirstFirst 12
Results 16 to 28 of 28

Thread: Noise in 2235H

  1. #16
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Hey, Guido...

    Yea, I know. The "futtering" you describe is perfect for the sound I get on poorly aligned cones - but only when slightly mis-aligned. It can be very subtle, but needs be gone.

    I wonder if covering the "vent" is merely reducing the cone movement, and reducing the "fluttering"... ?

    Still "sounds" to me like one of those reconed K140's ain't quite right. And anyway, if the K140's are same vintage, and a pair - shouldn't they be the same?

    If you can hear it, and it's mechanical (and not sound...), I'd say it ain't right.

    Oh well...
    Last edited by boputnam; 07-10-2003 at 01:06 PM.
    bo

    "Indeed, not!!"

  2. #17
    Senior Member GordonW's Avatar
    Join Date
    May 2003
    Location
    Marietta/Moultrie GA USA
    Posts
    1,455
    Man, I'm in total agreement with JBLDog and Bo here. A partially demagnetized motor wouldn't do ANYTHING to cause a noise like that... especially if its occuring at relatively moderate power levels.

    All the effect demagnetization will generally have is to make the speaker:

    -less efficient (less motor strength)
    -higher Q (lower, albeit boomier bass in box)
    -less top-end (weaker motor, less acceleration, hence slower movement giving less upper-end response).

    None of these things should make the speaker do something non-linear like rubbing, ticking or chafing sounds...

    Regards,
    Gordon.

  3. #18
    Senior Member MikeM's Avatar
    Join Date
    Apr 2003
    Location
    Las Vegas NV
    Posts
    208

    Re: Noise in 2235H

    Originally posted by Guido
    Today I got my K140 reconed as 2235H. I started to break them in and one work perfect.
    Unfortunately the other one makes some clicking noise. Its not loud and not really clicking. It's like fluttering with something touching the cone. Checked the wires, ok.
    It seems to come out of the dust cap inside the voice coil. When I'm moving the cone there is no sound or scratching.

    What the h... this could be?

    Thanks for help
    Sounds like a warped voice coil/cone kit. Also the magnet might be out of alignment. I bet its a bad cone kit. Take that driver back to them and have them replace the kit. Jbl will send them a new kit free. sometimes reconers try to spray a formulation on the voice coil former that will shrink it a bit so be careful and mark the old cone with something. Good luck. When they go playing around with swapping cones and frames thats asking for trouble. I bet that frame is out.
    Last edited by MikeM; 07-11-2003 at 07:11 PM.
    Von Schweikert VR-8
    Canary Ref. 1 300B monoblocks. 300Bx16

  4. #19
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Great points, Mike.

    Hey - if we can offer any help with your "Avatar", drop a pm - those 4350's (??) look worth seeing!
    bo

    "Indeed, not!!"

  5. #20
    Senior Member MikeM's Avatar
    Join Date
    Apr 2003
    Location
    Las Vegas NV
    Posts
    208

    avitar

    Originally posted by boputnam
    Great points, Mike.

    Hey - if we can offer any help with your "Avatar", drop a pm - those 4350's (??) look worth se

    eing!
    No the picture is in color thats as large as the system will accept. i shrunk it with "Paint". need to convert to BW. yep those are my 4350's.
    Von Schweikert VR-8
    Canary Ref. 1 300B monoblocks. 300Bx16

  6. #21
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Hey, Mike...

    Go back to "Paint", open up the original pic, and save it as ".GIF", and say "yes" to the "Loss of color information OK?" dialogue box.

    Then, if the file is still too large, use the "Image" / "stretch/skew" choice, and slowly, repeatedly step the image down (both horizontal and vertical IDENTICALLY% each time), and save each iteration, until the file size is acceptible.

    Your ending Avatar will be substantially improved.

    I have done my editing in a mediocre photo editing package, and get there by "resizing" the .jpb until right-sized (ie.e, small enough). Do not be discouraged if the image you see is kinda blocky (those are pixels) - at the reduced size of the Avatar, the blockiness blurs to resolution...

    Maybe others out here have different ideas to offer Lordy knows, there could be a bit more clues (like maximum file size!!) on the Avatar "Help".
    Last edited by boputnam; 07-12-2003 at 07:23 AM.
    bo

    "Indeed, not!!"

  7. #22
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Hey, Mike...

    I've been testing doing an Avatar in "Paint" - it ain't easy because the image must be BOTH

    <= 150x150 pixels
    <= 20 kBytes

    If you want, reply to this Post with a .jpg attachment of your photo reduced to <= 160,000 bytes. I'll snag it from your Post, and see if I can get an Avatar done for you. If so, I'll Post it and you can snag it from my Post.

    Alternatively, email the original to: [email protected] and I'll make a stab at it.
    Last edited by boputnam; 07-12-2003 at 09:31 AM.
    bo

    "Indeed, not!!"

  8. #23
    Webmaster Don McRitchie's Avatar
    Join Date
    Apr 2003
    Location
    Winnipeg, Canada
    Posts
    1,753
    it ain't easy because the image must be BOTH
    <= 150x150 pixels
    <= 20 kBytes
    This is actually not hard to do. Just make sure that you are saving the picture in a "jpg" format and not a "gif" or "bmp". Jpg's are a compressed file format while gifs and bmps are uncompressed. My avatar is close to the maximum pixel size yet is only 3 kBytes.
    Regards

    Don McRitchie

  9. #24
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Don...

    You are right - I toyed around with this over the weekend, and found that what you now post is right-on.

    I had tried the .GIF for reduced file size, but the results were not good. I then copied Tom's Avatar (being simply one of the cleanest and with best definition), and studying it, found his was a .jpg and only 4 kBytes, but the pixels were within the guidelines. Ah HA!

    So, I next tackled the 150x150 pixel limit alone, without concerning myself of kBytes. I went back into Paint and just kept "Image, Stretch/Skew"ing, reducing by identical % both the vertical and horizontal, and got both below 150, and produced a desireable result.

    All this and Transducers, too!
    bo

    "Indeed, not!!"

  10. #25
    Senior Member Guido's Avatar
    Join Date
    Apr 2003
    Location
    Germany
    Posts
    2,503
    Today I did check the speaker in the cabinet. There was no fluttering except below approx. 28 Hz. But I think this is normal as the cab is tuned to 30 Hz and below the tuning frequency the woofer start to flutter. So the fluttering noise has gone when the speaker is mounted inside cab. Strange
    Anyway, at the moment I’m searching for a magnetizer who is able to regauss such a big speaker. I think it could only be an advantage as I do not know what they did with my speakers before. Of course I will keep you informed.
    I think demagnetising is not such a common task.

  11. #26
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    There was no fluttering except below approx. 28 Hz. But I think this is normal as the cab is tuned to 30 Hz and below the tuning frequency the woofer start to flutter. So the fluttering noise has gone when the speaker is mounted inside cab. Strange
    IMHO, greatest cone excursion will occur at low frequencies and when not mounted in a cabinet. When sitting on a bench, there is no air pressure resisting cone motion, and so is therefore the best for testing. And that is why the testing of woofers is so important at low Hz, and why one must be careful to avoid damage from excessive excursion on the bench.

    It may be that the affects of your voice coil mis-alignment (if that in fact is what the issue is) is most (only...?) pronounced at the extremes of cone motion.

    I don't think magnetization of the basket, or whatever you seek will resolve this low Hz "fluttering".
    bo

    "Indeed, not!!"

  12. #27
    rehkop
    Guest
    The problem could be caused by the lose 50 gr massring, which normally is glued inside the voice-coil with the 2235h. Cut off the dustcap and have a look. Use epoxy to reglue it.

    Peter

  13. #28
    Senior Member Guido's Avatar
    Join Date
    Apr 2003
    Location
    Germany
    Posts
    2,503
    Thanks Peter,

    but the massring is fixed!

    It is demag or missalignment.

    I will have regaussed it within the next weeks. If this is not working I will have them reconed from the JBL Shop.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Is this an original 2235H cone?
    By Guido in forum Lansing Product Technical Help
    Replies: 31
    Last Post: 09-10-2003, 06:39 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •