I'm swapping out some old and tired VCs from a pair of Auxax TW034s. Both the new dome assemblies buzz when swept with a sine wave @ 2.83V. The old ones worked ok before, except for showing signs of old age, so i thought it would be business as usual replacing them. Of course I cleaned and inspected the VC gaps a few times, checked the drive amp for distortion, tried rotating and clocking the VCs 180 deg.... nothing fixed it. I got excited when I did find a tiny string of glue on the inside edge of one VC and removed it, but it didn't fix the issue. I also tried opening up the dowel holes a tiny bit for some wiggle room, but it doesn't appear to matter. Starting to think the VCs are out of spec and I may have older magnet assys that are a little different - they came from JBLs, but clearly were marked as TW034XO. I've repaired 100s of tweeters before and never had this problem. Oh well...
Anyone else have this type of issue before with the TW034?
Anyone else have this type of issue before with the TW034?
Afaik they are supposed to be direct replacement but who knows what’s happened over the 30+ years since JBL made the SVA’s
Have you put the calipers to work, new diaphragm vs old?
Have you put the calipers to work, new diaphragm vs old?
They measure identical in ID and winding thickness with a few thousand variation in thickness. I'll post a few pics when I can.
Wonder if there were different VC made for Nexo and JBL ?
Where di you purchased the new ones ?
Edit : the second ref I know TW034X0P47N has just a different coating, so VC are the same in the offical parts catalog.
Where di you purchased the new ones ?
Edit : the second ref I know TW034X0P47N has just a different coating, so VC are the same in the offical parts catalog.
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look at this with google translate : http://cyrille.pinton.free.fr/electroac/experiences/tw034x0p47n/tw034x0p47n.html
@diyiggy - Hmmmm.... that link is a bit revealing and may have answered the riddle. My old VCs are 2.5mm winding width.
" The air gap of the old version is thinner ~0.75mm, against ~1mm.
The coil is shorter on the new version: 2mm against 2.5mm "
Upon further investigation, there are 2 versions of TW034X0 used by JBL. New version is P47N, but there is another version in between it and the old HD13D34H. Audax states the VC is interchangeable, but i believe an unfavorable stack up of tolerances make compatability uncertain. Problem is I went through the hassle of drilling the pole pieces on these motor assemblies, so they may be useless with the new version VCs.
" The air gap of the old version is thinner ~0.75mm, against ~1mm.
The coil is shorter on the new version: 2mm against 2.5mm "
Upon further investigation, there are 2 versions of TW034X0 used by JBL. New version is P47N, but there is another version in between it and the old HD13D34H. Audax states the VC is interchangeable, but i believe an unfavorable stack up of tolerances make compatability uncertain. Problem is I went through the hassle of drilling the pole pieces on these motor assemblies, so they may be useless with the new version VCs.
