Twin SI HT18 been built

Discussion in 'DIY Speaker & Subwoofer Building' started by bmkev, Apr 25, 2016.

  1. bmkev

    bmkev
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    Hi guys

    About a week ago I purchased and already home built sub. This is a single cabinet, twin SI 18 build complete with an Inuke 6000DSP. I lost my set up mike so I’ve been listening so far with no EQ and its already blown me away.

    What I’m asking is if someone could model this for me so I know what sort of response I can expect. The cabinet is 600x800x800 with a middle internal divide and driver mounted in each end sealed.

    Cheers in advance if anyone can help.
     
  2. MemX

    MemX
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    Piiiiiiiiiiiiiiiiics :p



    As it's a sealed sub (IIRC?) it should roll off about 12db/octave, although mine seems to be a lot steeper when I measure it!

    That said, they still sound great and integrate nicely, so I'd just be happy with what you have until you can pick up a mic and perhaps a miniDSP if you want to boost the lower end :)
     
  3. bmkev

    bmkev
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    Cheers for the response buddy [emoji106][emoji106]
    I've ordered a new Mike and just waiting for it to arrive. I'll get my head around some measurements when it arrives and will be sure to post results.

    ImageUploadedByAVForums1461695567.832344.jpg

    Here's a small pic of it currently. I'm just blown away by the sound [emoji51][emoji51]
     
  4. MemX

    MemX
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    Nice! :)

    There are many haters of DIY subs, but once you've experienced the quality/value it can be hard to justify the cost of 'big name' kit :)


    Just looking at the measurements...

    600w x 800t x 800d = roughly 24" wide x 32" tall x 32" deep.

    Internal depth will likely be external depth minus 2" each end for a double-layer baffle, and minus 1" for the internal dividing 'wall', taking it down to 27" internal depth.

    Likewise, external width and height measurements likely need 1" at each end taken off to get to internal measurement.

    I would therefore guesstimate that each internal section is 13.5" deep, 22" wide, 30" tall.

    30*22*13.5 = 8910 cubic inches.

    8910 cubic inches / (12*12*12) = 5.15 cubic feet.

    Take off perhaps 0.5 cubic foot for the volume of the driver itself, internal bracing and stuffing, and knock off a bit more because my inches are rounded up from the exact mm conversion, and you're around 4.5 cubic feet internal space for each driver, which is seemingly pretty much the usual internal volume for sealed SI HT18 subs :)


    I don't know how your drivers are wired - they could be:

    - 2Ohms (if dual 4Ohm voice coils wired in parallel),
    - 8Ohms (if dual 4Ohm voice coils wired in series),
    - 1Ohm (if dual 2Ohm voicecoils wired in parallel) or
    - 4Ohm (if dual 2Ohm voicecoils wired in series).

    IIRC the 6000 won't run in 2Ohms (as it is effectively two bridged 3000s, which only bridge down to 4Ohm) and it definitely won't run at 1Ohm :laugh: so it's likely to be wired either as the second or fourth options on that list.

    Can you check with the seller as to how it's wired up? (If they know?)


    The 6000 is running in stereo (because it can't be bridged) but I can't remember how much power they put out...

    IIRC they will do (a true, measured) 1700wRMS at 4Ohm and about half that at 8Ohm.

    If they are wired up at 8Ohm each then that will mean each are getting about 850wRMS maximum, which IIRC is well under their safe power and excursion limits in that box size.

    If you can find my DIY thread, you will see mine are in similar internal space but are on an amp which should be able to give them c.1250wRMS each, and that shouldn't bottom them out, according to the modelling graphs.


    Giving them either amount of power for too long, though, such as feeding them full-power sine-waves for any period of time, might mean you cook the voicecoils :eek: but on film and normal music content (so no 'Bass I Love You' on repeat ;) ) and at the likely levels you'll be listening to them, they should be just fine to crank them up and enjoy them without worry :)
     
  5. jk330ci

    jk330ci
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    Nice sub, may I ask where and how much you paid?
    I have two si 18 drivers which I've had sat in the boxes for nearly a year, will be looking to get them up and running in the next couple of months lol.
     
  6. bmkev

    bmkev
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    Memx

    Many thanks for the in depth reply mate [emoji106][emoji106]
    You've got them to a tee and they are running at 4ohm.

    I would never ever buy a shop sub ever again after this experience [emoji3][emoji3] and I've had 2no mono pluses in the past.

    What's the lowest you recorded on your setup? If you don't mind me asking?

    Kev
     
  7. bmkev

    bmkev
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    Mate

    There's 2no 600mm square empty cabs in the for sale section that used to house these drivers. Only £100, I may have them but feel free to jump in as its not yet a deffo.

    As for the price,,,,,, what would you suggest a good price would have been?? [emoji6][emoji6]

    Kev
     
  8. MemX

    MemX
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    I have run some REW sweeps while playing with it and have seen the cones move at 4Hz :cool:, but I've still not done a proper measuring session so I can wire in the MiniDSP I bought over a year ago :laugh: lol

    (I can feel @mattkhan shaking his head at my lack of graphs ;) )

    In theory, if Room Gain is kind and I actually get them EQd with a suitable amount of bottom-end boost, I should be good for movie Reference level output down to single digit Hz IIRC...


    Ooh, but re: the power to yours - are the two drivers wired together and running on just one channel of the 6000? If they are then that would seem to make sense power-wise, but if each driver has one channel of the 6000, that could be a risk unless you set maximum output levels on the amp!
     
  9. markymiles

    markymiles
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    Were you after something like the attached?

    This is just using the standard parameters, giving the drivers 2000W total which will keep them under xmax until 6hz.

    Summary plenty of output :smashin:
     

    Attached Files:

  10. markymiles

    markymiles
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    Hold your head in shame :p
     
  11. MemX

    MemX
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    +1 to getting those cabs - they will be the quickest and easiest way to get up and running @jk330ci! I've seen them in the flesh and they will look good in your room ;)

    Don't think about it, just get them bought!!
     
  12. neo_2009

    neo_2009
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    Yes, there must be hard to realize that their micro 12" audiophile sub (with XPTO RCA and power cable), that cost them more than 2000€, is easily outperformed by this big box with a colorful amplifier :rotfl::devil:
     
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  13. MemX

    MemX
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    Once I've finally EQ'd mine I need to get some of you people round to audition them before I have to move out and most probably back to my mother's house for a (very long...) while to save up a deposit for somewhere proper to live :laugh: lol
     
  14. bmkev

    bmkev
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    Memx

    Again many thanks for the info,
    Regarding the power, I've not even scratched the surface when pushing them although that's not to say one day I won't [emoji16][emoji16]
    Do you think I'd be better off reconfiguring to 8ohms?? Or, what's a safe power limit to adjust the 6000 to?
    I don't want to run both drivers from one channel.

    Marky

    Cheers mate, that's the sort of thing I were looking [emoji106][emoji106]

    Neo

    I'm not slagging commercial subs at all, I've owned 2 mono pluses and they were fantastic [emoji106][emoji106]
    Let's just say, I'd never now go back though,,,,,,,

    Kev
     
  15. MemX

    MemX
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    Just to confirm, each driver has a connector in the side of the box, and each connector is currently connected to a channel of the two-channel 6000?

    I'm not that up on the iNuke amps - there is a way that you can limit the power using the DSP in the amp, to protect over-driving it with too much power, so it could be worth checking with the seller if he set it up to do that already.

    It not, personally I'd be tempted to set one up, just in case! 1250w RMS on mine shoudn't be able to bottom them out all the way down to single digits, but thermal damage is a different matter, so perhaps you could just run them near their rated power of 600w RMS. After all, doubling the power is only +3dB, and I don't think you will be short of output, even with the rated power! :)

    Others may have a view on this and chime in soon hopefully :)

    If it was me, with my drivers, I'd perhaps run 1000w a side.


    Alternatively, if you don't want to mess around with the DSP, re-wiring the drivers shouldn't be too difficult but would be a faff and also risk damaging that lovely finish, because I don't know about you, but me and screwdrivers near polished surfaces is just an expensive accident waiting to happen... :laugh:
     
  16. bmkev

    bmkev
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    Memx

    Taking the drivers out is not to much agg as I had to remove them to transport the sub anyway.
    Yeah you're correct, one terminal per driver is fitted.
    I'm going to adjust the DSP and limit the power to where you suggested.

    Hopefully my Mike will turn up soon and I can play properly [emoji38][emoji38]
     
  17. MemX

    MemX
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    Will look forward to some graphs! :p

    Set the power limit thing up for a bit less, perhaps 800w, and then you can always tweak upwards slightly if needed :)

    (I would point out now that I've no idea how it exactly works as I haven't got one, and am not sure if you will need to take account of the fact that each side is apparently 3000w Peak but only 1700w RMS and will therefore have to have a higher limit numbers-wise to give the lower RMS figure you are looking for... :eek: lol)
     
  18. bmkev

    bmkev
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    Lol I'll try figure it out later and let you know how I get on.
    Thanks again for your input, really appreciated [emoji106][emoji106]
     
  19. jk330ci

    jk330ci
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    To tall for me, I had looked and looked and measured and looked at them but I'm restricted to 22" by whatever width and depth I fancy so a Gordy box for me unfortunately.
     
  20. bmkev

    bmkev
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    That's a shame mate, would've been ideal othwrwise[emoji16][emoji16]
     
  21. MemX

    MemX
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    Can't you put all the rest of the furniture in the room on 3" blocks of wood so the 25" high boxes now fit? :p LoL
     
  22. jk330ci

    jk330ci
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    Got to fit under the screen, so I'm stuck unless I change the screen.
     
  23. bmkev

    bmkev
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    I'm assuming that's then only possible place for the subs to go then [emoji58][emoji58]
     
  24. MemX

    MemX
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    Can you chop some floorboards out? :p lol
     
  25. jk330ci

    jk330ci
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    Front wall 1m in from side walls, or rear wall is only real options.
     

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