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Remaking Isobarik cabinets

Discussion in 'd.i.y.' started by PatrickM, Jul 3, 2006.

  1. PatrickM

    PatrickM New Member

    Hi I am a new member and I have a question regarding the possibility of remaking Isobariks. I have two pairs of Isobariks, one mid 80's which are in good nick, which I promise never to harm. The other pair are early 80's and the cabinets have started to come apart badly at the rear. The cabinets are very sunbleached and the labels on the rear are bubbled, to the extent that the serial numbers have dissapeared. The top plate bearing the Linn logo has also warped from sun exposure. I just purchased these for a very reasonable price with the intention of having some fun with them. The electronics seem OK and they don't sound significantly worse than my good pair.

    The options that I think I have are to either attempt to remake cabinets to the same specs as the orriginals, or to make a new design that maintains the same enclosure volumes but perhaps takes the semi-omni attributres further - or conversly does away with them altogether. I imagine that I could turn the bass driver on its end much like a Keltic and achieve a narrower, taller, more appealing speaker that sounds much like the orriginal.


    I realise that such suggestions may cause sharp intakes of breath amongst some, but I also assume that some Brik owners might be interested to hear or see the progress with such a design.

    So I am seeking any suggestions or information that may help. I would be very greatful to hear from anyone who has tried a similar thing or taken apart an Isobarik before . If there is interest I will document my progress or faliure and make it available on the web.

    Warm regards,

    Patrick
     
  2. RichardH

    RichardH Bodging pleb

    If you've not seen it, there's a mass of Isobarik info in the FAQ section - may be worth dredging through!
     
  3. SteveC

    SteveC Satisficing

    Personally I would think about regluing the places where it has separated and use several sash cramps to tighten up the whole thing while setting. The label-veneer could be peeled off and re-stuck with a big weight on top. The faded veneer could be sanded down, re-stained etc. Or simplest would be to make a big black sock out of speaker-grille material and clothe it. Just MHO
     
  4. James

    James Lord of the Erg\o/s

    Hi Patrick, and welcome to PFM.

    If you are certain you want to remake the 'Brik, here are a few thoughts to help you on your way.

    (1) The spatial orientation of the drivers work in concert with the crossover network. If you change the location of the external drivers or their orientation, then your 'Brik will not sound like a 'Brik.

    (2) The baffle of the loudspeaker has a direct influence on the radiation pattern, and hence the power-response of the drivers. A narrower cabinet might be more visually appealing, but it will also raise the frequency at which baffle diffraction and radiation losses start to happen. This will undoubtedly change the sonic signature of the 'Briks to the extent they won't sound like 'Briks.

    (3) As the above two points show, the best option - unless you want to reinvent the 'Brik with a new crossover network design - is to replicate it physically. I believe the cabinet is made of heavy chipboard (but I could be wrong). You might do better with a high-grade birch plywood of similar thickness. It is imperative that the remade cabinet is completely air-tight, which is easier said than done. Don't forget that the midrange units require their own isobarically separate chambers of the same volume.

    (4) A distinct advantage can be had if you housed the crossover network externally. If I were to remake a pair of 'Briks, I'd be inclined to use a trio of 4-pole Neutrik connectors for each cabinet, one each for each pair of drivers. This will enable you to use split external XOs or go active easily in the future.

    James
     
  5. PatrickM

    PatrickM New Member

    Thanks guys for your replies. I have had a good read through the Isobaik threads and there is allot of good information there. I could not find any that related to a complete remake of the cabinets so I may be on my own here.

    My concern with re-gluing and clamping the existing cabinets, is that once a glue join has failed it really needs to be taken back to raw timber if it is to form a proper bond. The only glues that you can re-glue over are animal hide glues used in instrument building. The only way to do this properly is to take the cabinets apart completely. I think it’s most likely that they will sustain a bit of damage in the process, which makes me think that it may be best to plan for a re-build.

    The other advantage to taking them apart completely is that I can then replace the caps in the crossover, or go active etc

    I had not considered how much impact a narrower baffle would have on the overall sound, but I would be interested to try and see.

    Obviously if all else fails I will simply remake the cabinets. I live in Australia and I have access to some very beautiful and dense, but I think I will try the Birch ply option first. Not sure at which point density or mass becomes a liability rather than an asset.

    Thank you for your advice.

    regards,

    Patrick
     
  6. PatrickM

    PatrickM New Member

    Thanks guys for your replies. I have had a good read through the Isobaik threads and there is allot of good information there. I could not find any that related to a complete remake of the cabinets so I may be on my own here.

    My concern with re-gluing and clamping the existing cabinets, is that once a glue join has failed it really needs to be taken back to raw timber if it is to form a proper bond. The only glues that you can re-glue over are animal hide glues used in instrument building. The only way to do this properly is to take the cabinets apart completely. I think it’s most likely that they will sustain a bit of damage in the process, which makes me think that it may be best to plan for a re-build.

    The other advantage to taking them apart completely is that I can then replace the caps in the crossover, or go active etc

    I had not considered how much impact a narrower baffle would have on the overall sound, but I would be interested to try and see.

    Obviously if all else fails I will simply remake the cabinets. I live in Australia and I have access to some very beautiful and dense, but I think I will try the Birch ply option first. Not sure at which point density or mass becomes a liability rather than an asset.

    Thank you for your advice.

    regards,

    Patrick
     
  7. SteveC

    SteveC Satisficing

    Patrick, you missed out a word there. As far as I can make out, it was either "trees" or "bed-partners" ;)
     
  8. PatrickM

    PatrickM New Member

    That would have been blondes - possibly norwegian ones:)

    but having posted the same reply twice I am not in any position to make blonde jokes.
     
  9. RichShortland

    RichShortland pfm Member

    Patrick,
    as a fellow 'Brik owner I'd be very interested in how you get on - I don't think I'd ever modify the pair I have but if I came across some with damaged enclosures I'd be very tempted to have a go as you described.
    I wouldn't be too concerned about changing the shape - they are probably going to sound 'different' to Briks no matter what you do, but that's not to say they would be worse!
    Good luck - please keep us posted on what you decide.
    Rich
     
  10. Mick Seymour

    Mick Seymour Member

    :)

    I always fancied buying a scruffy pair to take them apart, carefully detailing the design, but since moving to Spain even a reasonable pair are hard to come by within delivery distance.

    If you do it, I'd love to see the drawings/photos and would gladly add them to the faq.

    Mick

    And no, I'm not taking mine apart for anyone!
     

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