Tannoy CPA 12 Cabinets

Discussion in 'DIY Discussion' started by Dev, Feb 20, 2011.

  1. Dev

    Dev Moderator

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    As luck would have it we measured the "faulty" unit. I wish we'd had measured them both. It would've confirmed if there was a problem with the right speaker.
    Yes, to me it sounded like the bass cone had blown but I'll try SQ and Cooky's suggestion. I'll post pictures in case they can see anything odd.
     
    Dev, May 10, 2011
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  2. Dev

    RobHolt Moderator

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    Hmm, very hard to blow that pro driver on a 30w gainclone. Might be worth a quick test for dc though.
     
    RobHolt, May 10, 2011
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  3. Dev

    nando nando

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    rob, if DC was present then when dev swaped channels it would affect the other drive unit?
     
    nando, May 10, 2011
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  4. Dev

    TonyL Club Krautrock Plinque

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    Hi Dev, how do you attach that foam stuff to the cab? I'm thinking of doing my Tannoys as the cabs are pretty ropey inside at present.

    Tony.
     
    TonyL, May 10, 2011
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  5. Dev

    Dev Moderator

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    The dark foam bought from Wilmslow had adhesive already applied, so I just peeled off the paper and applied it. For the lighter (and cheaper) foam I used spray on Evostick. Spray both surfaces, wait a few minutes until the adhesive is semi dry and then stick the foam on.
     
    Dev, May 10, 2011
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  6. Dev

    cooky1257

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    FWIW,
    I had an HF with a weird notch around 2.5k so uninstalled cleaned out old ferrofluid/gap recharged, reinstall dias-very easy self centering assembly, jobs a good'un back on spec.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
    cooky1257, Jun 2, 2011
    #86
  7. Dev

    felix part-time Horta

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    OK, picking this up very late - what is the heatsinking like on the gainclone, Dev? They do seem to be inordinantly sensitive to cooling - because the current/power protection onboard (esp ones with National's 'SPike' circuitry) is horribly, horribly sensitive to both load curent (like deep bass, even into 8R) and temperature.



    (I tried these things up to c. a decade ago and always went back to discrete amps. When my 'latest and greatest' got blown into the weeds by a 20yr old, unserviced Quad 4-5-2, I gave them up. There have actually been very few new IC power amps since then...)
     
    felix, Jun 2, 2011
    #87
  8. Dev

    Dev Moderator

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    Frank, thanks for the pictures. That HF unit looks so familiar:). I've seen the official frequency response for a 3134 and it isn't as bad as the driver Simon measured, so I suspect you're correct and it needs some work. It may be beyond my ability though, so rather than risk damaging it even more I've decided to have it checked. It probably isn't worth repairing though and if the quote is excessive I may decide to have a go.

    Martin, my Gainclone doesn't run hot at all. The heatsink is the whole chassis:). The noise was there with Rogue as well, so I think it is definitely the driver.
     
    Dev, Jun 2, 2011
    #88
  9. Dev

    Tenson Moderator

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    Martin, what area did you prefer the Quad in? The gainclone I have running here seems very good in all areas. The only point I could find a lower distortion amp is at the 10KHz+ range, but it is still better than many. Having said that, you know well I have found it sensitive to implement well, but then I guess discrete amps one might build oneself would be too.
     
    Tenson, Jun 3, 2011
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  10. Dev

    Dev Moderator

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    Frank, this HF driver looks identical to the one used in 3134 and 3158. Are you familiar with 3158s? If so, what are differences between 3158 and 3134s? They look identical to me except for the gold surround at the front.
     
    Dev, Jun 3, 2011
    #90
  11. Dev

    cooky1257

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    cooky1257, Jun 3, 2011
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  12. Dev

    Dev Moderator

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    Thanks Frank.

    I ended up taking the drivers to Lockwood in the end. They found that the bass cone had become slightly detached from the spider and glued it. They also said that someone had previously tried to bodge it, judging by the excessive amount of glue on it. They suspect the bass cone has a slight tear, covered by glue. The permanent repair is to re-cone it at a cost of £140 (GULP). Hopefully the temp repair will last a while.

    I wonder if the 3518 will work with the sealed boxes and the crossover from the CPA12? I was offered reconditioned drivers for £250 each. They looked good as new.
     
    Dev, Jun 8, 2011
    #92
  13. Dev

    cooky1257

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    I'd find out if the LF re-cone kit is the same.
    Ah, it isn't, the 3518 kit is no longer available.
    So Lockwood found no issue with the tweeter?

    F
     
    Last edited by a moderator: Jun 8, 2011
    cooky1257, Jun 8, 2011
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  14. Dev

    Dev Moderator

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    They only tested it with a signal generator, and thought it was OK. Not a comprehensive test. However, it's possible that if LF is showing signs of abuse the HF probably suffered as well. I think the re-cone cost (£140) is high compared to the 3158 (£250), which were in excellent condition. Sorry Frank, 3518 was a typo, I meant 3158s, 12" DC used in the Edinburgh. The Edinburgh was 200L distributed port cabinet, so 125-140L sealed box may not be a good match.
     
    Dev, Jun 8, 2011
    #94
  15. Dev

    cooky1257

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    I guessed it was a typo, the correct 3158 re-cone kits are still unavailable lol (this lack of recone kits is what put me off some TAD bass drivers recently).
    They dont look like they'd work in any case do they?.
    On the CPA12's, £140 is a bit steep-the kits are only about £80 and the process is really easy if you take your time.
     
    cooky1257, Jun 8, 2011
    #95
  16. Dev

    Dev Moderator

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    Sucks :(


    I've never done this sort of thing and would be afraid of screwing it up and wasting £80 and ending up paying another £140 to have it done. I'm hoping the temp repair will last a while. Then I'll look at alternatives. Perhaps buy another pair of CPA12s and hope they are in better shape:).
     
    Dev, Jun 8, 2011
    #96
  17. Dev

    cooky1257

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    I reconed one of my 3833's a few weeks ago.
    With not too much work you could alter those cabs to take the 15" drivers.
    The DMT 15 is 150L with 2 ports. I'm thinking of selling off the DC drivers from my 215's @ £325 each if you are interested.

    F
     
    Last edited by a moderator: Jun 9, 2011
    cooky1257, Jun 9, 2011
    #97
  18. Dev

    Dev Moderator

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    I thought you sold your 215s?

    Good idea, I'd love to try a pair of proper size DC:). However I don't think the front baffle of my cabs is wide enough. How wide does the opening for the driver need to be?
     
    Dev, Jun 9, 2011
    #98
  19. Dev

    cooky1257

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    Hi,

    As 215's cabs they're just too big for all but the most enthusiastic(and probably single:)).
    So I'm going to just sell the drivers-I'm getting a lot of domestic pressure-she has been very patient with me tbh.
    The opening has to be 345mm dia, a proper router with a deep plunge depth would be needed, a bit of trimming the rear driver/brace area and any screws from baffle to bracing may need taking out but from the pics it looks viable.

    F
     
    cooky1257, Jun 9, 2011
    #99
  20. Dev

    Dev Moderator

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    Frank, the front baffle is 360mm. The driver will be wider than that, so 15" DC (385mm) will need to be another project I'm afraid:).
     
    Dev, Jun 10, 2011
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