Need advice...Sub biulding

Discussion in 'Archived Threads 2001-2004' started by Shawn.G, Nov 26, 2002.

  1. Shawn.G

    Shawn.G Second Unit

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    I want to build a sub on a limited budget.I am looking to buy a sub cabinet, woofer(10 or 12), and plate amp(100-200w). Is this all I need to build a sub? Any recommendations? I am looking around on parts express especailly. I'm looking to spend about 200. Thanks a lot.
     
  2. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    That may be more than you need. Is there any opportunity for an IB setup ? (Crawlspace above or below room, closet space that shares a wall with the room etc, do search on "infinite baffel"). There goes the need for the cabinet. If you have any old funky amp or reciever laying around, these work fine as sub amps. The plate amp features are nice but not neceaasry when the sub is fed from an LFE out. Leaves more budget for what really mattters- a high quality driver(s).
     
  3. Shawn.G

    Shawn.G Second Unit

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    Would under a bed work? I don't think putting the sub in the wall or anywhere else like that would work in my case. But I'll keep looking. I will use my receiver, 100w to the sub(is that enough?), but I would like to buy or build a cabinet. I haven't ever built a cabinet before, how do I do that? But if I buy/build a cabinet and buy a good driver and use my receiver-will that work or do I need to buy crossovers or extra wiring or does that come in the driver? I am looking foward to it.
     
  4. Jonathan M

    Jonathan M Second Unit

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    Hi Shawn,
    You don't need anything else other than driver, cabinet, a bit of wire, and something to power it with. You say you have a receiver to power it with - is this a separate unit from your receiver for the rest of your speakers? Most HT receivers do not have a sub amp incorporated - they only have a preamp out for the sub. You will require an additional amp in this case. If the receiver is a separate unit that you have lying around, then you're all set - all you need is some speaker wire, a driver, and a box to put it in.
    For the box, you can buy ready made from places such as Parts Express, or you can build your own. How you do it is fairly dependent on the following:
    How big can the box be? (The bigger the better, generally)
    As far as building the cabinet yourself goes, it's not too difficult. Basically it's just a box with a hole for the driver, and another hole for the port (If you go ported). Depending on the size of the box it'll also need internal bracing. All this can be built out of MDF which is easy to work with (easy to cut etc.), but does makes an awful mess [​IMG]
    If you post your dimensions, I'm sure that the fine people here will help you choose a suitable design/driver.
     
  5. Shawn.G

    Shawn.G Second Unit

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    The receiver is a RCA 5.1. I have a passive sub hooked up with speaker wire, though I will probably get an amp if I can't use the receiver. For wire, do you mean normal speaker wire? You say building a box is simple. I would like to have a large but not huge box, less than 20(height) by 20(width) by 24(depth). Can I make it out of plywood and dampen the inside and use polyfill. What is MFD? Is it expensive? I have an idea of internal bracing, but what exactly can I use for it? Also, what does ported mean, is that better than non-ported. In that case, how big should the port hole be? Is it better to have more than one port? I would like a front firing 10 or 12 in ch driver. So I pick a side on the box, cut a 10 inch circle, put the driver in and then what? or do I have this all wrong? Thanks a lot for puttingup with my questions. I am new at this and want to really do a good job. Thanks everybody.
     
  6. Jonathan M

    Jonathan M Second Unit

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    Firstly, amplification:
    The receiver will be fine, as long as you are not running anything else off the receiver other than the sub. Sub's use a lot of power, and so you probably won't want to run any other speakers off of the receiver. You'd just hook it up using normal 16 gauge or larger speaker wire.
    As for the enclosure, with those dimensions, you are looking at around a 120 litre enclosure (By the time bracing + driver etc. is taken into account). You'd probably definitely go ported in this case - for instance with a Shiva 12" driver or similar. Note that with the Shiva, you can go as low as around 85 litre's and still get good low output. I would suggest using one of the alignments from Adire Audio - they have plans available in the Vented Shiva Design white paper in their Tech Section. Have a look at them, and see if you can build them yourself, or if you will require more of a kit.
    As for timber, most people use MDF (Medium Density Fibre board) It is easy to work with, and can be purchased cheaply at places such as Home Depot (Around $20 for a 4'x8' sheet approx.)
    If you don't want to go the whole hog on the box, you may wish to pop over and look at Acoustic Visions as they supply enclosures in kit form - you just screw and glue it together, pop the driver in the hole, and finish it off (paint/veneer etc.) how you want. They also sell the Shiva driver (Around $125 or so) and completed enclosures etc. as well.
    I strongly suggest you also pop over to somewhere like DIYSubwoofers.org and read up on the subject - you need to have a basic understanding of the various things involved in order to have the most success.
     
  7. Shawn.G

    Shawn.G Second Unit

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    I'll read up and let you know. Keep up the advice please. Thanks so much!
     
  8. Shawn.G

    Shawn.G Second Unit

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    About amplification: the receiver has 3 other speakers running off of it. It is 5.1 with 100w dedicated to the sub. What do you think. Can I run the sub with 100w or do I really need another receiver or external amp?
     
  9. Jonathan M

    Jonathan M Second Unit

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    Hi Shawn,

    What model receiver is it? Most sub drivers in use now have dual voice coils, which means that you can run them off separate channels of a receiver, and each channel's power will combine. Each channel will also only see an 8ohm load, so it is pretty easy on the receiver.

    If you can get away with using the receiver you have as the amp, it'll mean you can put a bit more $$ into the driver (The most important thing). You can always get a plate amp etc. to drive it later.

    We also need info as to how you have the sub hooked up. You say it's running off a receiver - that's fine. We need to know the model of receiver, which channel(s) it's hooked up to etc. Also, how is the signal getting to the receiver - are you utilizing a sub woofer pre-out on another receiver, or is this receiver your main one?

    Once we figure out the amplification issue, then we can budget for a driver and get started!
     
  10. Brian D B

    Brian D B Auditioning

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    Enclosure size and design are usually dependant on your selection of driver. Once you have selected a driver, I would contact the manufacturer to determine the right internal volume and the diameter and length of the port (if needed) to tune your enclosure for peak performance. Too small = no bass. Too big = too boomy and no punch.

    Internal bracing makes your enclosure stronger and prevents it from flexing and degrading sound quality. Doesn't sound like it is really necessary with the dimensions and power you are talking about.

    As for materials, I would use 3/4" MDF lined w/ fiber glass insulation or Polyfill and seal the thing up w/ silicone based sealant. Use screws in predrilled and counter-sunk holes to save yourself some headache. You can make ports out of PVC pipe (I would round over the edges with sand paper to prevent whistle). These supplies should cost you no more than $50 at Home Depot. The right enclosure for the right driver can make all the difference!

    Other hints:
    1. Try not to make your enclosre cube shaped. The fewer equally sized or parallel sides you have the better.
    2. Offset your driver, don't mount it in the center.

    Finally, I would encourage you to get a cross-over. It doesn't have to be expensive, but if you don't use one chances are your sub will be more directional because of the higher frequencies. This is not desireable for propper sound staging (i.e. Darth Vaders voice will be coming out of your sub). Let the sub do what it is designed for - producing low frequencies. The manufacturer of your driver should also be able to tell you what cross-over frequency is best for your situation.
     
  11. Jonathan M

    Jonathan M Second Unit

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    Just a comment on Brian's post:

    For subwoofer frequencies (ie less than 200Hz or so), box dimensions and driver location on the baffle are irrelavent. Feel free to make a cube and put the driver bang in the middle - it'll make no difference to the sound quality etc.

    Also, if you are using the sub-out on a Dolby Digital 5.1 receiver it'll already have a 2nd order low pass crossover on it.
     
  12. Jonathan M

    Jonathan M Second Unit

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    Just a comment on Brian's post:

    For subwoofer frequencies (ie less than 200Hz or so), box dimensions and driver location on the baffle are irrelavent. Feel free to make a cube and put the driver bang in the middle - it'll make no difference to the sound quality etc.

    Also, if you are using the sub-out on a Dolby Digital 5.1 receiver it'll already have a 2nd order low pass crossover on it, so won't require another one. If you are not using a dedicated subwoofer output, and instead are using a full-range output, then you will definitely need a lowpass crossover before the amplifier.
     
  13. Brian D B

    Brian D B Auditioning

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    Enclosure size and design are usually dependant on your selection of driver. Once you have selected a driver, I would contact the manufacturer to determine the right internal volume and the diameter and length of the port (if needed) to tune your enclosure for peak performance. Too small = no bass. Too big = too boomy and no punch.

    Internal bracing makes your enclosure stronger and prevents it from flexing and degrading sound quality. Doesn't sound like it is really necessary with the dimensions and power you are talking about.

    As for materials, I would use 3/4" MDF lined w/ fiber glass insulation or Polyfill and seal the thing up w/ silicone based sealant. Use screws in predrilled and counter-sunk holes to save yourself some headache. You can make ports out of PVC pipe (I would round over the edges with sand paper to prevent whistle). These supplies should cost you no more than $50 at Home Depot. The right enclosure for the right driver can make all the difference!

    Other hints:
    1. Try not to make your enclosre cube shaped. The fewer equally sized or parallel sides you have the better.
    2. Offset your driver, don't mount it in the center.

    Finally, I would encourage you to get a cross-over. It doesn't have to be expensive, but if you don't use one chances are your sub will be more directional because of the higher frequencies. This is not desireable for propper sound staging (i.e. Darth Vaders voice will be coming out of your sub). Let the sub do what it is designed for - producing low frequencies. The manufacturer of your driver should also be able to tell you what cross-over frequency is best for your situation.
     
  14. Shawn.G

    Shawn.G Second Unit

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    If I have a plate amp and 10 inch driver, what size enclosure should I build? Please tell me in liters, length, width, depth, cubic feet and any other info. I am new at this and have been reading up but some things don't make sense. Please help me out.
     
  15. Jonathan M

    Jonathan M Second Unit

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    As Brian said:
     
  16. Shawn.G

    Shawn.G Second Unit

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    These are for the Dayton 10 inch Series 2 woofer: Power handling: 250 watts RMS/350 watts max * Voice coil diameter: 2-1/2" * Voice coil inductance: 1.23 mH * Nominal impedance: 8 ohms * DC resistance: 6.2 ohms * Frequency response: 35-3,000 Hz * Magnet weight: 56 oz. * Fs: 34 Hz * SPL: 91.7 dB 1W/1m * Vas: 2.78 cu. ft. * Qms: 9.50 * Qes: .33 * Qts: .32 * Xmax: 5.5mm * Net weight: 12 lbs. * Dimensions: A: 10", B: 9", C: 4-3/4", D: 6-1/8", E: 1-1/2". What would be the best sized cabinet?
     

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