I have been looking at guides for building subwoofers and plan to use this http://custom1.farnell.com/cpc/prod...pc+catalogue&category_name=&product_id=260393 Nothing special but i think it will do the job (i have a yamaha home cinema reciever with a 100w sub out) All the guides use formulae featuring 'Q'. What is Q?
to be honest mate, you would be better waiting for micb to see this thread before you start buying anything as he is well a genius when it comes to subwoofers
Well the woofer cone is ordered along with some connecting gubbins, so i'm just concerned with enclosure sizes etc. Shall wait for micb though.
Is that a dedicated amp? or just a 100w output on that (which is kind of unsusal for a sub out). Secondly a 6 1/2" cone is really not going to give you much omphh at all (at least not in sub terms), you really need 10" minimum to hit the lower frequencies (Heck it only just goes below 40Hz). You can see my sub build at http://matthew.augier.info/?album=/DIY/Relax-12& which is based on a pretty standard classic design. Total cost was about £200 and man does it rumble!
Oh.....is a 6 1/2" not good then? i went along the lines of wattage- and although i know it only goes down to 37hz- that isn't really a problem as I'm looking at reinforcement of bass rather than hitting the really low stuff. I have a set of Eltax Silverado speakers which, although very good for the price I paid (a £79 scoop) are just slightly lacking in low end power. Going back to the sub out- I was sure i heard something about 100w when I bought the reciever (a yamaha HTR-5360RDS http://www.yamaha-audio.co.uk/homecinema/receivers/htr-5630rds/ - probably just got my wires crossed (excuse pun) as thinking about it- I think it is just a crossover style subwoofer out. As you can probably tell, i'm trying to do this on the cheap after my new pc (just built by me) has left me fairly skint. Would it be possible to use a 90w stereo amplifier to power the cone? Or is it possible to just run it passively from the sub out? I know quite a bit about home cinema and hifi- but not when it comes to subwoofers unfortunately- just because I haven't had any experience of them in my 16 years of life. Any guidance would be much appreciated!
Hi, Tom. First things first, You can't build a subwoofer without have all the speaker driver specifications, sticking any old driver in a random sized box will not do well at all. To build a subwoofer you require the Thiele and Small pramaters for the driver, you use these paramaters to model the drivers frequency response curve in an enclosure, then you can try different alingments (Sealed, Ported, Dipole, Isobaric and bandpass) to see what will perform best suit you individual requirements. Total system Q or Qtc roughly explaned is a number related to the response of the driver in a sealed enclosure, the size of the enclosure will change the amount of air trapped inside, this air acts as a resistance againt the driver excurting forward and backward, this will effectivly change the response (how deep and high) the subwoofer will play, define how the subwoofer sounds, power efficency and driver powerhandling. Q/Qtc = 0.707 to 1.0 High damped in general to much mid/upper bass not much low end, tendancy to boom. Q/Qtc = 0.707 Meduim damped, balanced response with both mid/upper and low end. Q/Qtc = 0.707 to 0.5 Low damped, less mid/upper bass much more low end. Lower damped sealed enclosures are better in home as you want subwoofer to play lower bass and let you speakers pick up further up frequencies. The subwoofer driver choice is very important as drivers differ greatly in there suited applications. Cone area from the driver is important (8" ,10", 12", 15", 18") but there are other things to consider such as the drivers x-max excursion limits and indivdual enclosure properties. 6-1/2 inch cones are often not suited to subwoofers as they don't really have the displacement to provide a decent levels of bass in the home. Now the main problems you face are: 1) The driver you have picked does not look to have published Thiele and Small paramaters so it is close to impossible to model it in software. 2) The subwoofer out on the AV Reciver is at signal level so you will require an amplifier to drive the subwoofer to produce sound. If you have a budget (UK pound or USD/CAD) I can advise you on what you can do next. I would be willing to help you, I could do the software modeling/design of a subwoofer using other drivers.
Thanks for the help MICB- are you saying the ordered woofer will be no good? (damn electronics teacher rushing me into a choice so that he can put the school order in) I chose it because I thought the wattage seemed ample for the average room- but there again it was just a guess- as I said earlier, i have no experience of subwoofers. Secondly, the Thiele and Small pramaters might hopefully be documented with the woofer (fingers crossed anyway) Thirdly, is a dedicated subwoofer amplifier necessary or can i just use a 90w stereo amplifier (can be modified as it was free) i have knocking around? As for budget- im not sure just yet, but could you give me some indications of what I can get for what money. Thanks also for the offer of designing- i may well take you up on that once I have purchased components.
Hi, The 90 watt amplilfier should be able to be used depending on its real power output, may I ask what make and model it is? The subwoofer pre-out on the AV receiver has a electronic active crossover (@ 90hz on the Yammaha 5630) to filter and route bass to the amplifier so this could work quite well. You could wait and see if the driver comes with T+S prams but even so it is very unlikley that such a cheap cost driver will perform that well at all. If you want a good but very cheap driver then the BSB 12 from BK Elec is great considering its low price of £25, this is the same driver Mad-D-Rat uses. There is nothing much else at this low price range that could match this driver performance (At this price I am temped to make a modified duel 12 version for my self sometime). It is 8 ohm driver and will run of a single channel of that amplififer. http://www.bkelec.com/Diy/BSB12100.htm The reccommend enclosure airspace is 50 liters or 1.76 cubic foot. You could go a little larger to 57 liters and 2.0 cubic foot to gain a bit of extra efficency as you most likely wont have the full 100-125 WRMS to power it with. This will give pritty good performance, it is a tried and tested design build by many DIY'ers (including some on AVforums).
Since found out amp is a 37wpc (Nikko NA-500)- for some reason stickered as a 90w on the back. I am a bit annoyed at myself now after ordering that woofer- seems like money wasted- is there any way I can still use it and have a good sub at the end? Micb- you truly are the subwoofer king!
Nikko amp, Yes I am familar with the brand, my uncle has a Nikko and it sounds lovely with his classic Celestion Ditton speakers. They are often quite underrated amplifiers (that is a good thing) It should do fine for a efficent subwoofer design, output levels should be OK for a filling in the lower end material, depending on room size of course. I haven't seen the specs on the woofer you ordered but I am very confident you can do far far better with a small extra budget outlay.
I shall try and catch my tech teacher early tomorrow and see if he has made the order- if he has then I will lose a few quid sending the woofer back- but that is better than losing 12 if I keep it I will get the one you (micb) recommended (the 12") EDIT: Since found out that the cheap woofer was not ordered. I shall purchase the 12" tonight
How is it going Tom, did you order the driver? I see you are building a nice rack as well, it is looking good.
Haven't ordered driver yet because I haven't got my PC sorted- Ebuyer have so far sent me a faulty mobo and cpu. I just want to get the PC sorted before thinking about a new project. Glad you like the stand, will post a pic of the subwoofer I have loosely modelled in the same style.
Looking interesting. I'm also looking to build a sub myself quite soon (around easter). Think I'll watch how yours turns out first as at that price that driver looks pritty good
how much r u willing to spend?? i built a 12" subwoofer, 350W amp, 85L box tuned to 22Hz and let me tell u right away, Adire Audio are amazing!!! subwoofer driver is the Shiva, bloody great driver, goes down sooooooooo low, and has sooo much impact as well. truly a remarkable driver! anyway, cos me $1000 australian to build, that included amp, sub, heaps too much wood, circular saw, jigsaw, paint and the port. by the way Adire Audio are an american company and the shiva is $125 US
The AdireAudio Shiva is a good driver, I have been recommending it for years now. The Uk importer of the Shiva does have good prices but I feel the driver is most likely outsides Toms budget. http://www.design3dw3.co.uk/audio/audio-subw.htm It looks like the new MK4 verson of the Shiva is around £125.
Yes very outside my budget. I can't even afford the BSB at the moment. Ebuyer have ripped me off big time and now I need to fork out 75 quid to replace a CPU I didn't break. Unfortunately they have thrown the book at me and I am unable to do anything about it. Will probably start the subwoofer in June now- by the time i have enough cash, my GCSE's will have started and I need to be revising instead of building a subwoofer.
