Page 6 of 6 FirstFirst ... 456
Results 76 to 85 of 85

Thread: DIY 4344 MKII using Beyma TPL-150

  1. #76
    Senior Member grumpy's Avatar
    Join Date
    Oct 2003
    Location
    SoCal
    Posts
    5,469
    Another alternative in an adjacent/current thread:

    http://www.audioheritage.org/vbullet...l=1#post430265

  2. #77
    On Holidays Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,382
    Quote Originally Posted by Drummerboy2 View Post
    I'm planning on replacing the diaphragms in my JBL 2420s this weekend and wanted to know what is the proper procedure for doing this. I have never done this before on a CD and don't want to make a mistake and cause them to accidentally rub.

    Anyone here have any suggestions on how to do this?

    I have brand new Radian 16 ohm diaphragms.

    Im still looking for some foam for the back cap. Kendrick had some but we're really expensive for the two.

    Thanks.
    If you have no experience then get a professional technician to do it like our Edgewound at Upland loudspeaker repairs. It’s not as simple as it might seem and to do the job properly requires cleaning out the magnetic gap and careful centering of the diaphragm with test equipment.

    The Radian diaphragms are designed to be a drop in replacement for the Jbl diaphragms. The motional impedance curve a similar so it should work in with the crossover okay. There may be some response variations however so expect to hear some subtle differences.

    On my do to list is to measure a radian diaphragm and work out any crossover tweaks required for the popular legacy systems.

    https://m.facebook.com/UplandLoudspeaker/about

    http://www.audioheritage.org/vbullet...ression-Driver

  3. #78
    Member
    Join Date
    Jul 2015
    Location
    San Diego, CA
    Posts
    54
    Quote Originally Posted by Ian Mackenzie View Post
    If you have no experience then get a professional technician to do it like our Edgewound at Upland loudspeaker repairs. Its not as simple as it might seem and to do the job properly requires cleaning out the magnetic gap and careful centering of the diaphragm with test equipment.

    The Radian diaphragms are designed to be a drop in replacement for the Jbl diaphragms. The motional impedance curve a similar so it should work in with the crossover okay. There may be some response variations however so expect to hear some subtle differences.

    On my do to list is to measure a radian diaphragm and work out any crossover tweaks required for the popular legacy systems.

    https://m.facebook.com/UplandLoudspeaker/about

    http://www.audioheritage.org/vbullet...ression-Driver
    Seems like I will just need some masking tape to clean out the gap where the voice coil goes in and a Oscillator for a curtain frequency to make sure there is no buzzing? correct? If there is buzzing just slightly tap on the diaphragm surround mount til buzzing stops? Correct?

  4. #79
    On Holidays Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,382
    You need a reasonable signal voltage which l dont recall off hand and sweep oscillator and a power amp. Ideally an oscilloscope to evaluate the sine wave. Also ear muffs.

    One slip of the screw driver and its game over.

    If l were you l would ask Edgewound to do it.

  5. #80
    Senior Member grumpy's Avatar
    Join Date
    Oct 2003
    Location
    SoCal
    Posts
    5,469
    IF dead set on DIY, here's some old man ranting for you:

    You may also need to open up the holes slightly on the diaphragm 'frame' and/or put a -slight- bevel/relief on the outside of the frame where it meets the top plate... to allow for more -minor- adjustments (ONLY if needed).

    Tech Manual calls for 2.83v input 550-1.2KHz, but is slim on details like... is that RMS, peak, peak-to-peak and with the driver 'loaded' (horn attached) or hanging in the breeze (on the low end of the frequency range in particular). I'd keep it below 2v p-p regardless, working your way up from much less.

    Do you have a way to measure this? A -normal- Digital voltmeter will not likely give you a good reading at higher audio frequencies (often calibrated for 60Hz). An oscilloscope would be good...using it properly, better. Along with hearing protection (as has been noted), and tolerant family/neighbors.

    Hearing the distortion of a voice-coil barely touching does take some experience (other times it's quite obvious). Then there's the phase plug to diaphragm spacing... probably other things I'm not thinking of.

    All that said, sometimes you get lucky (or are ok with it being non-optimum). Have a way to measure on-horn frequency response later?

    Mostly, if the process does not go so well and something is damaged, you have ZERO remedy, but maybe gained some experience.

    It may sound like I'm leaning toward a recommendation of leaving it to the pros (as most should)... but if you have the time, interest, and can afford to make a few mistakes, have at it!

    (is there an emoji for getting off of a soapbox?)

  6. #81
    Member
    Join Date
    Jul 2015
    Location
    San Diego, CA
    Posts
    54
    Quote Originally Posted by Ian Mackenzie View Post
    You need a reasonable signal voltage which l dont recall off hand and sweep oscillator and a power amp. Ideally an oscilloscope to evaluate the sine wave. Also ear muffs.

    One slip of the screw driver and its game over.

    If l were you l would ask Edgewound to do it.
    I will talk with Ken when I pick up my 2245H that he is doing.

    thanks

  7. #82
    Member
    Join Date
    Jul 2015
    Location
    San Diego, CA
    Posts
    54
    Quote Originally Posted by grumpy View Post
    IF dead set on DIY, here's some old man ranting for you:

    You may also need to open up the holes slightly on the diaphragm 'frame' and/or put a -slight- bevel/relief on the outside of the frame where it meets the top plate... to allow for more -minor- adjustments (ONLY if needed).

    Tech Manual calls for 2.83v input 550-1.2KHz, but is slim on details like... is that RMS, peak, peak-to-peak and with the driver 'loaded' (horn attached) or hanging in the breeze (on the low end of the frequency range in particular). I'd keep it below 2v p-p regardless, working your way up from much less.

    Do you have a way to measure this? A -normal- Digital voltmeter will not likely give you a good reading at higher audio frequencies (often calibrated for 60Hz). An oscilloscope would be good...using it properly, better. Along with hearing protection (as has been noted), and tolerant family/neighbors.

    Hearing the distortion of a voice-coil barely touching does take some experience (other times it's quite obvious). Then there's the phase plug to diaphragm spacing... probably other things I'm not thinking of.

    All that said, sometimes you get lucky (or are ok with it being non-optimum). Have a way to measure on-horn frequency response later?

    Mostly, if the process does not go so well and something is damaged, you have ZERO remedy, but maybe gained some experience.

    It may sound like I'm leaning toward a recommendation of leaving it to the pros (as most should)... but if you have the time, interest, and can afford to make a few mistakes, have at it!

    (is there an emoji for getting off of a soapbox?)
    I have all the test equipment to do it but I will talk with Ken about these when I pick up my 2245Hs he is doing.

  8. #83
    On Holidays Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,382
    Good plan

  9. #84
    Senior Member grumpy's Avatar
    Join Date
    Oct 2003
    Location
    SoCal
    Posts
    5,469
    Ken's a good guy. Hope it all comes together.

  10. #85
    On Holidays Ian Mackenzie's Avatar
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,382
    Absolutely

    The whole job is only as good as your drivers so its worth getting them right.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. 4344 mkII DIY help
    By laszlo in forum Lansing Product DIY Forum
    Replies: 97
    Last Post: 03-01-2017, 04:04 PM
  2. unpaired JBL 4344 MKII
    By unlimitedquest in forum Lansing Product General Information
    Replies: 14
    Last Post: 10-15-2012, 02:57 AM
  3. 4344 mkII
    By Turnitup in forum Lansing Product General Information
    Replies: 4
    Last Post: 07-23-2006, 06:57 AM
  4. 4344 MKII MF Caps
    By jim henderson in forum Lansing Product Technical Help
    Replies: 27
    Last Post: 10-28-2003, 10:19 AM

Posting Permissions

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