DML500's manufactured under the Tectonic Audio Labs brand, used a cast-aluminum "hold down" tab on the carbon fiber transducer. These tabs had a tendency to crack and break off over time, resulting in the loudspeaker emitting a dependent buzzing sound. This occurred generally in the 250-500hz range. 

FlatPanel Audio manufactures an updated CNC-aluminun anodized tab, that is available for purchase as a retrofit, if your panels have cracked tabs.

The kit includes 4 tabs plus 8 replacement countersunk hex-drive screws. Replacement is described below.

IMPORTANT NOTES BEFORE BEGINNING - PLEASE READ:

  1. This process takes patience - the screws that attach the original tabs have been installed with Loctite - and with the small 2.5mm hex head, the head can strip easily. If this happens, you can choose to drill out the head of the screw, or in some cases, the tab - being brittle - can be "broken" in place, allowing the screw to be removed with vice grips. Take care when drilling to prevent any grindings to slip past the edge of the carbon fiber, and end up inside the exciters (use a vacuum while drilling if necessary.)
  2. Once the screws are removed, the tab itself may be tightly installed into the basket and seem difficult to remove. If so, use a small screwdriver and insert through one of the screw holes in the tab, and attempt to press the screwdriver tip between the bottom of the tab and the aluminum frame in which it is mounted. This can cause the old tab to lift, or to break free. Please take care not to damage the carbon fiber.
  3. You will be removing the front cover off of the DML500 exposing the carbon fiber diaphragm. Please be aware that the edges of the carbon fiber are very sharp, and contain glass fibers. Please use extreme caution.
  4. Please keep track of all screws - allowing a screw to slip down past the edge of the carbon fiber can cause the screw to stick magnetically to the exciters, which if unnoticed could cause a new unwanted sound.

TOOLS & CONSUMABLES NEEDED:

  • Loctite "Blue" (or equivalent
  • One tab kit from FlatPanel Audio (per DML500.)
  • Drill and small bits (in case the old screws have to be drilled out
  • Vacuum (in case of drilling)
  • 2mm hex key or Allen drive socket
  • 2.5mm hex key or Allen Drive socket
  • 5mm hex key or Allen drive socket
  • Rubbing alcohol

Please use only high quality, new Allen/hex wrenches, especially on the 2.5mm size. Loose or worn out Allen wrenches can strip the heads very easily (due to the Loctite used during original installation.)

Removing the Front Cover and Grille

  1. If you can access all of the 5mm hex bolts around the rear perimeter of the DML500 without removing the panel from it's mounting, you may be able to service the panels in place. The front grille and frame are removed from the front.
  2. Start by using a 2mm hex key/Allen to remove the small countersunk screw on the left side of the front of the panel - on the grille - it’s the only screw in the front grille, off to one side.
  3. Now remove all of the perimeter bolts around the back of the panel all around the edge using the 5mm Allen wrench. Please note where the screws came from, there are several different lengths used at various locations.
  4. The front grille and frame should be able to be removed now, it might need a slight pry to get it started - but then it should come free. You can pry with a blunt plastic tool where the grab handles are at the rear.

Removing the Old Tabs

  1. With the grille off, you can now remove the 4 tabs with two screws each. VERY IMPORTANT: Please remove the Allen bolts with a “snap” counter-clockwise turn, not a constant pressure turn - the "impact" of the snap movement will help overcome the Loctite before the hex head has a chance to strip. The heads can easily strip under constant torque pressure. If stripping occurs, please see note above about drilling out the tab screws
  2. Once the screws are removed, you can pull the tabs out. They may need a slight pry to come out of the aluminum frame. If any of them are stuck hard, try prying them up through the srew hole - inserting the screwdriver through the screw hole and attempting to get in between the tab mount, and the speaker basket.
  3. Pull the tabs carefully away from the carbon fiber, being careful not to damage the Caron fiber edge and cause delamination of the carbon fiber panel. On some models, the tabs are attached to the carbon fiber with foam and adhesive. Prying the tab away will break the foam, and will leave some residue on the carbon fiber -see next step
  4. With the tabs removed, remove any foam and adhesive from the panel with a rolling motion using your finger. If you have some rubbing alcohol, clean the area where the adhesive was

Installing The New Tabs

  1. If you have some rubbing alcohol, clean the area where the tab foam contacts the carbon fiber (so that the new adhesive will take hold.)
  2. IMPORTANT: Remove the paper from both the top and the bottom of each tab's foam strip to expose the adhesive on both sides - and install each tab in its location.
  3. Install using the new screws provided in your kit, and apply a tiny bit of blue Loctite to the screw before installing. Gently tighten to avoid striping the head.

Please pause to make sure you have removed the tape backing from both sides of the tab prior to install - if the tape backing is left sandwiched between the carbon fiber and the tab, undesired noise can be created.

Reinstalling the front cover and grille.

  1. Now re-install the grille and frame - taking care to place the screws back in the same locations as they were removed - as some are specific lengths.
  2. Tighten snug, but not overnight - the bolts are steel, and the frame is aluminum so the frame can be stripped if overtightened.



- end of instruction -