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Need sub building advice

Discussion in 'Home Cinema Building DIY' started by BigToe, Jul 3, 2003.

  1. BigToe

    BigToe
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    Hi,

    I've decided to take my first step into the strange and magical world of DIY audio.

    I've pretty much decided on the Shiva MKIII driver and the BSBP 200/8 sub amp from B K Electronics HERE

    [edit - corrected link]

    I have a brilliant joiner capable of some fantastic work - he does anything from staircases to delicate furniture and quite soon he'll be specialising in making sub enclosures ;)

    As it's my first time I've decided on a simple vented box, but this is where I get stuck. I understand that the box can't be any old size because the bass response will be crap. I need some help finding out what dimensions I should use for this. It's going to be a basic downwards firing cube design.

    Any help for a DIY audio n00b appreciated!

    Cheers,

    Chris
     
  2. IronGiant

    IronGiant
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    Try this freeeware package:
    www.linearteam.org/winisd.html
    Put in the speaker parameters and choose a vented cabinet and it will
    suggest the volume, port size/length and give you a graph of probable performane.

    Not infallible but a good starting point.

    Dave
     
  3. BigToe

    BigToe
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    Thanks, this looks promising :)

    I'll report back on my progress.

    BTW - Have I picked a good combo with the driver and amp I mentioned?
     
  4. Exeter Man

    Exeter Man
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    BigToe,

    See link below for PDFs of Adire's suggested Shiva designs.

    http://www.adireaudio.com/tech_papers/shiva_apps.htm

    With subs, you can really use any dimensions you want, provided that the volume is correct.

    Both products that you suggest are well respected. Maybe someone else could advise you on whether to go for the BSB200/4 or BSS200/8 - usually the Shiva voice coils would be joined in parallel giving a 4ohm load. Link below explains about wiring voice coils.

    http://www.adireaudio.com/tech_papers/tech_central.htm

    Hope this helps.

    Regards
     
  5. ReTrO

    ReTrO
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    The 200/4 would be more suitable for the Shiva III wired in parallel.

    I'd stick with with one of the Adire reference designs as Exeter Man has suggested. Keep to the volumes certainly, though the enclosure shape can change.

    Keep us posted with info on your build.:smashin:
     
  6. BigToe

    BigToe
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    Thanks for the help fellas.

    Going for the 4 ohm amp seems the most sensible.

    I'm also going to go for the 85 litre design in the Shiva tech paper and have the sub firing horizontally rather than into the floor as I have learnt that gravity will affect the Xmax.
     
  7. Exeter Man

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    BigToe,

    There's a paper in Adire's 'Tech Central' regarding suitability of drivers for downward firing. If you work through it, you should find that the effect on the Shiva is very small, although with other drivers, this may not be the case.

    To be honest, the DPL12 I used in my sub project is a bit marginal for downward firing, but forward firing doesn't look as neat IMO.

    Regards
     
  8. BigToe

    BigToe
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    hehe, just after I made that post I read the part about the Shiva and Tempest subs being suitable for downwards firing, so I will probably go back to the original design. As you say, it does look neater and I'm not bothered about a grill.

    I have another question though - I just noticed that B K Electronics do another sub amp called the "DT300". With delivery included it is approximately a tenner more than the BSB200, yet has 300W of power instead of 200W!

    What is the main difference between these two amps besides the power rating and physical shape? The DT300 is apparently a "Class D" amp, what does that mean?
     
  9. 64kym

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    Big Toe
    Great choice of driver, are you looking to utilise the sub for Music or theatre or a bit of both??
     
  10. BigToe

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    64kym

    Mainly leaning towards music as I can't get enough of it. Mostly electronica and dirty analogue stuff.

    Although it will definately be used for films too, as I have just invested in a nice home theatre setup:-

    JVC AV28T25EKS 28" flat-tube
    Denon AVR-1803 receiver/amp in "champagne"
    A pair of Wharfedale Diamond 8.4s for the front speakers
    Diamond 8C for the centre channel
    Pair of Diamond 8.1s for the rear speakers

    I use my computer for DVDs, DivX, MP3 etc. with an SP-DIF output to my receiver for a clean signal.

    I currently have the Yamaha YST-SW80 sub as it impressed me a good 5 years ago in a hifi showroom, although it's getting on a bit now and doesn't satisfy me as it used to. Plus, DIY audio has grabbed my attention in a big way.
     
  11. Exeter Man

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    BigToe,

    I'm using DT300 with my sub, and pretty pleased with it so far.

    Key differences seem to be:

    1. BSB200 has separate high and low level gain controls. I guess that your AVR1803 can't have different sub levels assigned to different inputs (my SR6300 can't), and therefore this feature could be useful if you like different gains for music and movies.
    2. DT300 has bass compensation feature. Haven't experimented with this yet, but basically it can provide a few dB of boost, centred on a given frequency.

    Dan_Gleebles is probably the best person to comment on how SQ compares between these amps, and the merits (or otherwise) of Class D.

    Regards
     
  12. micb3rd

    micb3rd
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    Hi Big Toe, (im Micb from tech-pc) did you check out the reference disigns on the AdireAudio website, these give plans for the dimentions for the Shiva Mark III.

    Here is the link there is plenty of information here.

    http://www.adireaudio.com/Files/VentedShivaApplications.PDF

    The standerd 85 liter vented Adire Alignment will be a great subwoofer.

    The Shiva is perfectly fine for a downfiring subwoofer.
     
  13. BigToe

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    Hi micb, thanks for introducing me to these forums - I've learnt a lot from here :)

    Yeah I found the designs and decided to go for the 85 litre alignment in the end. I'm really looking forward to building this.

    I've ordered the Shiva and a reflex port from design3dw3, JC was more than helpful and provided me with a lot of info.

    I think I'm going to go for the 250W plate amp from CPC as it seems excellent value for money at approx. £100.
     
  14. BigToe

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    Well, I've got my Shiva and reflex port now :)

    It's quite a beast and weighs a lot:-

    [​IMG]

    [​IMG]

    [​IMG]

    Apologies for the crap pics, this camera is a bit useless.

    I just need a sodding amp now!
     
  15. ReTrO

    ReTrO
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    Nice isn't it!:D :smashin:
     
  16. 64kym

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    Big Toe
    Keep us informed progress ? I have a strange feeling that your going to like the results of your labours
     
  17. BigToe

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    Ok, got an update on the situation :)

    The enclosure is very nearly finished! Hoping to get the DT300 sub amp today, in which case I'll be able to get the hole cut for it and get the thing sealed.

    The enclosure is the 95 litre Adire Alignment specified in the Shiva reference papers and has been beautifully crafted in high quality Birch Ply :D This stuff is actually quite pricey at around £60 for a sheet of 8x4. Luckily, I got this stuff for free :)

    The photos I am about to show you don't do it justice as the camera is crap and hasn't picked up the lovely grain:-

    [​IMG]

    [​IMG]

    [​IMG]

    After the the back panel has had a hole cut for the DT300, the next step is to get it stained (I want it darker, closer to maple) and laquered by our french polisher :) The end result is going to be very classy. I'm toying with the idea of routing the edges before this actually, as I've seen a sample and it looks quite nice.

    The enclosure has been sealed with silicone and the screws holes have been filled. I am thinking of perhaps adding some wadding, but I'll see what it sounds like first. The entire frame is extremely solid and weighs approx. 10kg without the driver or anything else. This is an estimate from just picking the thing up, so probably isn't completely accurate.

    Once all this is finished and everything wired up etc. the most important part comes...

    The rubber feet! Got 4 on order for £1.50 from design3dw3, hopefully they'll be here tomorrow and I can finish it off. I'm excited about this, as you can probably tell :D

    I think it's going to look and sound awesome when finished. I'll keep you posted :)
     
  18. BigToe

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    Had to include the following images in this post, as the board wouldn't let me post them all in one message:-

    Some shots with the Shiva and reflex port sat in place, to give a rough idea of size and look etc.

    [​IMG]

    [​IMG]
     
  19. Exeter Man

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    BigToe,

    Coming along very nicely :smashin:

    I'm a big fan of birch faced plywood myself, but I can never bring myself to spend that much cash on a sheet of plywood. In reality, you can make quite a lot out of one sheet, but I guess that i'm just too thrifty for my own good !

    Regards
     
  20. IronGiant

    IronGiant
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    Nice design and well put together by the look of it, where's it going to go ;)

    Dave
     
  21. BigToe

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    Well, it's going to sit in place of my Yamaha YST-SW80 - in the corner under my worktop :)

    Something tells me it's going to be *slightly* more impressive than the Yamaha :D

    Looking forward to messing with the 6db boosts the DT300 allows.
     
  22. BigToe

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    Well, I've got my amp now and very nice it is too :)

    No soldering done yet, just a temporary hookup job to see what the sub sounds like until three weeks time when I can get the unit stained and lacquered, which is when I'll fit the components properly (if I do it now it will make things difficult for the French polisher).

    So far so good anyway, this thing pumps out some impressive bass! Been listening to some electronica with some mad bass sweeps - this unit cuts through the lowest notes with ease.

    It's not in an ideal place at the moment, either. I'm looking after my parents house whilst they are on holiday and they have a large and cluttered lounge with no spare corners, so it's been sitting next to the sofa booming away all day. Needless to say I'm impressed, as when I used to live with my parents my Yamaha could not fill the room with sound. This goliath had everything rattling to the point where I thought the shelves were going to fall down! Can't wait to try it back home in my bedroom with my setup.

    Oh yeah, had a bit of an "experience" earlier where I thought I'd blown the amp or something :eek:
    It was on very loud when I decided to turn the crossover frequency up to get it blasting with more aggressive bass. It stopped working, I browned my pants. I must have been pushing the amp too much and it cut out to avoid damage. Won't do that again!
     
  23. ReTrO

    ReTrO
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    Hows it going?

    Got my Temepest sub running at home now, in a tiny room 2x3m and stacked full of things including my bed!:D
    I've got nice deep bass in my music now.
     
  24. BigToe

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    Hi ReTrO,

    My god, I'd be careful with the amount of bass you have in a room so small! What sort of enclosure do you have and what amp are you running?

    Update: Got the rubber feet, a length of gasket for sealing the components extra tightly and some M4 inserts so I can remove the driver when needed without the fear of loosening the grip. Still need to wait a couple of weeks for the French polisher though :(
     
  25. ReTrO

    ReTrO
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    I've got an enclosure sized 450x450x500mm approx with a DT110 Mk2 amp, at approx 150W.

    See the DIY sub thread for the RTP-15.
     

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