Dual Stereo Integrity HT15" DIY Thread

Discussion in 'DIY Speaker & Subwoofer Building' started by MartinGR, Feb 27, 2014.

  1. MartinGR

    MartinGR
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    I suppose this is the start of a DIY thread, so get ready for lots of questions:thumbsup:

    Thanks to 3Hz I have two drivers on their way. Im planning a DIY using these two SI HT 15" dual 4ohm subs wired to 2ohm each and one ran off each channel of a Cerwin Vega CV amp.

    Are the figures quoted on the Cerwin Vega website RMS? i.e. 2x900W RMS @ 2ohm for the CV1800, and 2x1400W RMS @ 2ohm for the CV2800?

    Ive modelled a 75L sealed box (one driver per box) in Win ISD, and with 900W (CV1800 amp) it hits xmax at 14Hz, but with the 1400W amp (CV2800) it will hit xmax at 32Hz, so the question is, am I better off going with the smaller Cerwin Vega CV1800 amp as a better match for these drivers?
     
  2. MemX

    MemX
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    If you reduce the box size it will increase the power needed to get to XMax at 32Hz (or any given value) which should mean that the XMax points drops lower.

    It may get a bit 'boomy' in a smaller box, though?

    I would be tempted by the CV1800 and run it in 2Ohm stereo for 900w per driver in the 75L box, just for safety. I think the XMech is about low-30s mm - what Hz do you reach that sort of excursion with this configuration? (XMax is pretty much the limit of 'clean' and linear output but you are technically safe up to XMech.)

    System roll-off should reduce output down low, and there is not that much content going that low and really loud, so you should be fine...
     
  3. MartinGR

    MartinGR
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    Thanks MemX:smashin:

    I don't think I want to go any smaller than a 75L box. Ive had another look at Win ISD, and with the CV1800 (2ohm stereo 900w per driver) cone excursion is 27.5mm @ 5Hz.
     
  4. scottthehat

    scottthehat
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    if you stick it in a 75l cab it will take 800w rms to hit its xmax at 10hz, my advice dont worry just get and cv2800 and you will have loads of headroom.

    xmax is 22.5mm and xmech is 40mm i believe.
     
  5. MartinGR

    MartinGR
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    How are you finding sound quality from your CV 2800 scottthehat? Have you done a fan mod?
     
  6. scottthehat

    scottthehat
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    finding it very very good, (in my op a step up from the nu3000 in everyway) I have done the fan mod. mine has 2x 80mm fans at back and 2x 60mm at front.
     
  7. MemX

    MemX
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    Good stuff, the CVs are -3dB at 5Hz, IIRC, so I don't think the drivers would receive the full 900w by that point anyway, if I understand it correctly. (??)


    Headroom is good, yes :)

    XMech was tested to be about 35mm inward by Josh Ricci on data-bass, IIRC, so I've designed mind round that!
     
  8. scottthehat

    scottthehat
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    That's interesting on the x mech because no the site they state 43mm

    Stereo Integrity | HT Subwoofers
     
  9. MartinGR

    MartinGR
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    Looks like im swayed more towards the CV2800 now, as you say headroom is good:)
     
  10. scottthehat

    scottthehat
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    Headroom is good it always the amp to run easier and if you have any eq that will use some.
     
  11. MemX

    MemX
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    They do indeed!

    Check out the link to the DB forum at the bottom of that page, though:
    Data-Bass

    and

    :)
     
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  12. MartinGR

    MartinGR
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    Drivers arrived yesterday, and order has been placed for the Cerwin Vega CV2800 amp. Things are starting to progress nicely with the DIY:clap:
     
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  13. MartinGR

    MartinGR
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    Now the build is complete, its about time I updated this thread:smashin:

    Subs arrived:
    IMG_0891.JPG

    ..... then the boxes arrived from Gordy:
    IMG_0892.JPG

    .....and this lot arrived from CPC:
    IMG_0894.JPG

    The CV2800 arrived and the first job was to upgrade the Jamicon fans to Papst 8414ngl's (which are literally silent) using the factory spec terminals which were ordered from CPC:
    IMG_0844.JPG IMG_0858.JPG IMG_0864.JPG IMG_0866.JPG IMG_0884.JPG IMG_0886.JPG
     
  14. MartinGR

    MartinGR
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    IMG_0887.JPG IMG_0888.JPG IMG_0889.JPG

    Mat black vinyl was placed over the front rack mounting lugs to make the holes less obvious:
    IMG_0868.JPG IMG_0870.JPG IMG_0872.JPG

    The amp mods were now complete, so I moved onto the boxes themselves. Although Gordy builds an excellent sturdy box to any spec you want, people have complained about being able to get a good finish on them, particularly when using a gloss black finish. To get over this I had the sides and top of the boxes laminated with 6mm MDF, which was glued with mitred edges, so that there are no screw holes or joins on the flat surfaces to try and hide. The boxes were then covered in 4 coats of PVA to seal them, with sanding between each coat:
    IMG_0988.JPG IMG_0989.JPG IMG_0990.JPG IMG_0991.JPG
     
  15. MartinGR

    MartinGR
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    Boxes all sealed, sanded and ready to go to the bodyshop for paint:
    IMG_0992.JPG IMG_0993.JPG

    The boxes are being built as downward firing, so feet were needed to give the required clearance from the floor to avoid the 'choke' effect. 85mm timber cube feet were sourced from a furniture supplier, and these were wrapped in walnut vinyl to tie-in with the Dali's and other furniture in the living room:
    IMG_1092.JPG

    ......the finished article:
    IMG_1095.JPG

    ....and now all eight complete:
    IMG_1093.JPG
     
  16. MartinGR

    MartinGR
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    Next up was to make all the cables and terminals, which involved soldering all ends, heat shrinking and sealing the cables to ensure there was no air leakage through the cables themselves as they pass through the boxes. Attention to detail is what this build is all about!!!:
    IMG_1128.JPG
    IMG_1127.JPG IMG_1096.JPG

    IMG_1129.JPG

    The boxes were sealed on the internal corners prior to being insulated. This probably wasn't necessary, but I wanted to ensure minimal air leakage:
    IMG_1146.JPG


    The feet were attached using M10 bolts, and silicone sealed on the inside. 10mm foam underlay was glued to all internal faces and gasket tape applied to the sub mounting flange (these boxes are damned air tight!!:
    IMG_1159.JPG

    Plenty of low modulus silicone was applied where the cable passes through the boxes to the banana plug terminal plate to ensure an air tight seal: IMG_1160.JPG

    3lb of polyfill was then placed into each box: IMG_1161.JPG
     
  17. MartinGR

    MartinGR
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    The subs were bi-wired, resistances checked and then prepared for dropping into the boxes:
    IMG_1164.JPG
    IMG_1165.JPG

    Sub completely mounted using black allen bolts and T-nuts:
    IMG_1162.JPG
     
  18. MartinGR

    MartinGR
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    And now for some finished article pictures:
    IMG_1166.JPG
    IMG_1167.JPG IMG_1168.JPG IMG_1169.JPG IMG_1170.JPG IMG_1171.JPG IMG_1172.JPG IMG_1177.JPG IMG_1178.JPG
     
  19. MartinGR

    MartinGR
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    To say im impressed is an understatement, they sound absolutely awesome and the finish is unreal:thumbsup:. A huge huge thanks to the folks on this forum, if it wasn't for a certain few individuals this build would never have happened and id have been content with my BK XXLS400;).
     
  20. gav21041981

    gav21041981
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    Awesome build. Just shows what can be acheived
     
  21. kbfern

    kbfern
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    What a lovely job you have made of these Martin you should be proud of yourself at the standard of finish & detail you have achieved.What has been the final cost? whatever it was you could not have bought a pro made sub for anywhere near what you have paid which gives a huge amount of self satisfaction and knowing it's all your own work.:thumbsup:
     
  22. 3Hz

    3Hz
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    Wow Martin, they look fantastic! With that much attention to detail I should have got you to build mine! :D

    Good to hear you're enjoying them.
     
  23. The Liberator

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    Great job :thumbsup:, very nice set up, like the 6mm MDF idea to get a perfect finish.
     
  24. MartinGR

    MartinGR
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    Thanks Gav
     
  25. MartinGR

    MartinGR
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    Thanks for the kind comments. The total cost came in at just under £1500, but like you say, commercial subs at this level would be considerably more.
     
  26. kbfern

    kbfern
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    You would be lucky to get 1 sub for £1500 of this caliber let alone 2 so very well done.
     
  27. MartinGR

    MartinGR
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    Thanks very much Tim. I'm holding you the most responsible for all the hard work and expense I've had to endure, as if it wasn't for your group buy, I wouldn't have done it:smashin:. It was all worth it though, and I definitely owe you a pint if you ever local:thumbsup:
     
  28. MartinGR

    MartinGR
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    Thanks, the MDF laminate worked out excellent and there's no risk of any filler sinking and lines/holes becoming visible.
     
  29. 3Hz

    3Hz
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    I thought you were bored and needed some excitement in life so I had to... :D

    My pleasure Martin. Well done on such a fantastic build. :clap:
     
  30. MemX

    MemX
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    Nice job!! :thumbsup:

    Great finish on those and they fit right in - I love the little feet, they give them 'character', like they're going to waddle over and try to sit on your lap like a pet at any moment :laugh: (It is early, I've not yet had caffeine, bear with my strange thought processes... lol)

    May I ask what spec the amp fans are? (cfm, dB, etc) I've got my CV5000 in the same room at the moment and my background noise level with it on is something like 50dB... :laugh: It's driving me nuts! I'm going to put it in a cupboard and run cables through the wall lol
     

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