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DIY SBL Gaskets

Discussion in 'reference' started by dubblebubble, Mar 19, 2017.

  1. dubblebubble

    dubblebubble pfm Member

    Can anyone share the inner and outer dimensions of an SBL gasket?
     
  2. Central Audio

    Central Audio Trade Central Audio

    17 cm x 14
    13.5 cm x 11
     
  3. dubblebubble

    dubblebubble pfm Member

    Many thanks
     
  4. Naimngame

    Naimngame pfm Member

    I'm curious...
    Are you going to make your own?
    The kits are unjustifiably expense for what they are.
    I know my seals are broken yet they still sound good to me so I've been wary of risking outlay of about £120 when I might make matters worse breaking seals completely to start again.
    I'd be interested to hear your progress and whether it was worth the move.
    Cheers,
    Mark
     
  5. madmike

    madmike pfm Member

    Pictures too please...would like to see where no man dare go...
     
  6. peterm

    peterm pfm Member

    The gasket kits are indeed unjustifiably expensive, see my post about sbl Mk1 phase plugs for the name of the firm I bought a sheet of self adhesive (one side only) neoprene foam from. 5mm thick, 500mm x 1000mm for £13 and free delivery I reckon that's about 18 gaskets worth! I suspect it's the same stuff that Naim used, and the scrap pieces from the hole in the middle of the gaskets look suspiciously like the foam rubber bonded to the aluminium plates that they used for their "dampers" - waste not want not!
     
  7. Whaleblue

    Whaleblue Box-swapper extraordinaire

    I believe the exact correct thickness is 6mm, though I imagine with the silocone sealant added it can't really matter. At least that's what Mark is using. :)

    Let us know how it goes Mark!
     
  8. dubblebubble

    dubblebubble pfm Member

    Thanks Ian! The SBLs had broken seals and, to my pleasant surprise, washing up liquid had been used prior to sealing them. The silicone came away relatively easily from the middle box (a bit of gentle application from the edge of a new Stanley blade removed the remainder). The 'gasket' was made of strips of self adhesive neoprene tape arranged on each side of the lower box opening. I pulled these off and used furniture polish to soften and remove the remnants of adhesive.

    A few sheets of neoprene had been included in the sale. I measured the opening in the lower box, measured and cut a square that was 20mm bigger than the opening. I cut the internal edges of the sheet to make a gasket that sat over the opening. A smear of washing up liquid and a steady 5-6mm bead of clear B&Q silicone was applied, the mid box was lowered into position. Once the sealant has set (24 hours) the speakers can be moved around with care. Kneel before them, lean the side of your head against the lower box, get your hands in a good position under the bottom of the steel frame, then move a bit at a time to the side, forwards and backwards. Make sure the spikes are level. Play some music....

    After a lot of experimentation I have found the best position for them and everything has come together nicely: smooth, but detailed treble and a solid tuneful bass.

    However, I've realised after looking at the Tom Tom website that the gaskets are rectangular. Hence the question asked above. I'll cut the new gaskets and fit them tomorrow, with pics at each stage.

    Remember, the £120 is plus VAT, that is £144 for two pieces of cut neoprene, a small tube of silicone, eight pieces of 0.28mm aluminium sheet and sixteen staples (that you will probably never use!)

    Here's a few links:

    Neoprene: http://m.ebay.co.uk/itm/121215824485

    Aluminium sheet:
    http://m.ebay.co.uk/itm/272029424701

    Silicone:
    http://www.diy.com/departments/diall-sanitary-transparent-sealant-310-ml/268959_BQ.prd

    Veneer pins:
    http://www.diy.com/departments/avf-veneer-pin-dia12-l20mm-125g-pack-of-611/250510_BQ.prd

    For around £20 you can treat your SBLs to a new gasket and sealant (and have many more applications left over)... £144? I don't think so.
     
  9. Whaleblue

    Whaleblue Box-swapper extraordinaire

    I'll always have a soft spot for SBLs. Those are as nice a pair as we'll see, I believe. :)

    Post some pics when you're ready!
     
  10. dubblebubble

    dubblebubble pfm Member

    I've overstated the gasket kit price. It's £130.66 including delivery....still expensive though?
     
  11. Naimngame

    Naimngame pfm Member

    Haha glad to see I'm not alone MadMike
     
  12. timH

    timH Senior Moment Member

    I've just done this on my SBLs. Used an A4 sheet of 4mm neoprene (I originally bought 6mm but found it to be too thick). The A4 sheet was about £3 on EBay and did two gaskets. You're right the bathroom seal can take up any thickness.
    I thought mine were sounding quite good but I wanted to move them and I thought I'd set them up properly. When I took them apart I found that the self adhesive on the originals was perished so they weren't making a proper seal. Key thing is to clean all of that off.
    Now it's all done I can honestly say they're sounding the best they ever have. Anyone who says SBLs don't do bass is just wrong ;)
     
  13. Naimngame

    Naimngame pfm Member

    This has been a great thread.
    It's persuaded me to have a go at resealing my sbls and the links make it reassuring to know I'd be purchasing the right kit.
    Good to hear experiences of others too
     
  14. timH

    timH Senior Moment Member

  15. dubblebubble

    dubblebubble pfm Member

    Here's where I started, with a ruler, a sharp knife and a steady hand...

    [​IMG]

    [​IMG]

    [​IMG]
     
  16. dubblebubble

    dubblebubble pfm Member

    Next up, separating the seal...
    A long, thin blunt tool is required.
    I used an icing spatula that did the job remarkably well.

    [​IMG]

    Aim for the top of the gasket, not the bottom of the mid box. It will slide between the silicone and gasket, if washing up liquid has been used (always use washing up liquid!). Work it horizontally back and forth, the seal will start to part. Move to another side and repeat. The box will lift away once the front and sides have been separated. Remove the old gasket and use a liberal amount of furniture polish to soften the adhesive and good old elbow grease to remove it. Once all traces of old adhesive are removed you can put the new gasket in place.

    [​IMG]
     
  17. dubblebubble

    dubblebubble pfm Member

    The mid box is where the most care must be taken.
    Peel away the old silicone.

    [​IMG]

    Check the pads, mine were pierced through and into the wood.

    [​IMG]

    They all had to be removed. Use a pointed blade to gently work under the staples and use pliers to pull them out.

    [​IMG]

    Fill the holes with woodfiller (I found some Ronseal General Purpose Woodfiller in the garage) the holes are tiny, just push it in and wipe off the excess.

    [​IMG]
     
  18. dubblebubble

    dubblebubble pfm Member

    The aluminium pads have double sided tape to hold then in place, but to be sure, I used 15mm nails (the cabinet is 20mm thick).

    [​IMG]

    the mid box now needs to be carefully lined up above the bottom box and allow the pads to rest on the spikes. There will be a >2mm gap between the bottom of the mid box and the gasket. This is essential as the spikes support the mid box and the silicone is only "squashed" to make a seal between the gasket and mid box. I now understand that this has a profound effect on the quality and depth of the bass. I did read a quote, attributed to Julian Vereker, that setup of the pads and spikes is the most important part of the process. Once the pads are pierced the mid box will sit too low and the silicone/gasket becomes a support. I think this then absorbs some of the bass energy leading to "bass light" comments. A dimple to seat the spike is sufficient. If you look at the picture above of the old silicone I removed, the silicone is about 1mm thick and has flowed over the edges of the gasket. With the new pads in place the silicone is 2mm thick and sits neatly within the gasket.
     
  19. dubblebubble

    dubblebubble pfm Member

    Before you get your gun ready and put a steady 5-6mm bead of silicone around the gasket, make sure you put a THIN layer of washing up liquid on the gasket and around the bottom of the mid box. This will save much stress in the future...

    [​IMG]

    Carefully lower the top box onto the spikes and dimples in the pads. Give the top of the box one firm tap and that's it. Now get down on your knees, with a torch, and admire the uniform seal you have made!

    [​IMG]

    [​IMG]

    I knew that one day I would use my old LPs again... :)

    [​IMG]

    Almost there...

    [​IMG]

    And finally, grilles on...

    [​IMG]

    That's it, make yourself a cuppa and get ready to do it all again!

    My room is far from perfect (don't mention the radiator:D), but right now the SBLs are rocking...
     
  20. dubblebubble

    dubblebubble pfm Member

    Another bit of housekeeping I did before re-sealing:

    The wool in the lower box will have settled over time. Get your hand in and underneath it to gently lift and separate, so that it sits about 75 mm below the top plate.

    Something I noticed, but neglected to take a photo of :mad:, was the Hornslet label inside the lower box. It had serial number 00048 on it. These are a late (2001) pair and I was wondering if this serial number reflected the total number of cabinets made by Hornslet or those in Beech (I know of 4 including this pair)?
     

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