I had a question that didn't get answered there, and now it seems like the whole New Member area is gone. For a single sealed Koda 10, if I have enough power to push it to full excursion, will there be any SQ or SPL difference between a .5 or a 1.25 cu ft box? Those are the recommended sizes for a sealed box on the adire website I think. How much power will I need to push it to full excursion in .5? How much in 1.0? I have a smallish trunk and it's a daily driver, so I'd like the box as small as possible unless it's going to save me a lot of money by way of a cheaper amp. I was looking at a HiFonics nemesis that bridges to 400x1 for $179. Is there a better choice, or a lower model that would work well if I don't need that much power? Thanks a ton for your suggestions. -Austin P.S. I really like this forum. Everyone seems to know what they are talking about.
If you use greater power to push it to full excursion in a smaller sealed box you lose somew transient responce, risk boomieness and will suffer some power compression. However, if you use a big box and low power you may suffer motor strength as well. It is really a tradeoff, and is why the general rule of thumb of a .707 QTC enclosure is followed. It is simply damped enough to limit coloration and frequency boosts, as well as allow the driver to reach potential.
Well, I think I understood the first sentence somewhat, but then you totally lost me. I think I just need someone to tell me what size box to use for the best combo of SQ/SPL (SQL, right?) and how much power for optimum SQL. Also, assuming this power, cheap yet reliable amp recommendations?
Translation: <!--QuoteBegin-sandt38@Jul 2 2004, 05:00 PM If you use greater power to push it to full excursion in a smaller sealed box you lose somew transient responce,[/quote] The smaller you make an enclosure, the more difficult it is to compress the quantity of air contained within the enclosure... the air in the box behaves more and more like a stiffer and stiffer spring, rather than a cushion, if you will. So, you'll need more power to fight against the stiff spring, just to bring the sub to the same excursion (read: output) levels as it would have had in a bigger box, on less power. Also, the damping of the sub will be worse in a small box compared to a large box... Damping is like a shock absorber on your car. Shocks with poor damping abilities will let your car bounce and oscillate after hitting a bump, like worn out shocks. Shocks with great damping abilities will firmly control the car, keeping the car's ride level, firm, and distance off the ground consistant as you drive, rather than fluctating with the car bouncing up and down. Likewise, a sub's cone motion - and therefore the sound it produces - will more closely mimick the signal it is fed - the music you are playing - in a larger enclosure, with good damping, compared to the smaller enclosure. Another trade-off of a small sealed box is low-frequency extension. In a larger enclosure, your sub can play lower frequencies than in a smaller enclosure. This is at least partly because a sub needs to reach ever-increasing excursion levels as the frequencies decrease to produce the same output levels... and those are harder for the sub to reach in a small enclosure. Power compression occurs when a voice coil heats up... that simply means it becomes less efficient... it'll take more power to effect the same change in excursion level... and therefore heat up more... a vicious cycle. A cool voice coil is an efficient voice coil. Well, relatively speaking anyway. The Qtc is a number that simply corresponds to the shape of the final response curve... and also accounts for these other things, like transient response, impulse response, cone motion overhang... As you go bigger, Qtc gets smaller. 0.707 is considered the "ideal" middle-ground. Higher than 0.707, and you risk getting boomy, losing low-frequency response, efficiency, etc. Lower than 0.707, and you are potentially "overdamped", maybe even too efficient, relative to the amp power that you want to feed it. Note, the latter (lower than 0.707) aren't really bad things... That help?
Geo, thanks for the explanation. I understood most of your first and second paragraphs, but you started to lose me on the third one. To get the .707 middle ground, does that just require a certain box size? If so, what size and I'll do it. Is that the size which can take 350W?
^ | | Yep, that was me... Also, when I just hit the "Reply" button, it automatically quotes the previous post. Is that supposed to happen now?
Yes, I see I am going to have to make a Forum Use Tutorial, I have had ALOT of questions about the new Features............ the "quote" if you look close is quote+ when you click on it the button should turn orange... this enables you to select multiple posts to quote in your reply, you can even select quote FROM OTHER topics (cool huh) the "reply" button next to it functions like the old "quote" button that are fimilar with from the old board here and Other Boards on the internet. to just "add a reply" with no quotes you need to click the "add a reply" button at the very bottom of the page
Yes, it is a specific enclosure size and no, 350 would be overkill in that enclosure. However, 2 things of note... XBL2 motors are capable of being in very small enclosures (for the driver itself I mean) and still perfroming remarkably well, sounding .707 in say a .82 enclosure. Also, with a proper install, and correct gainsetting you can feed that power into the driver in that enclosure... and I am sure there are alot of us here who would help you safely accomplish this task Differant drivers require differant size and types of enclosures (for example ported, sealed, IB, transmission line, dipole, etc) to achieve the same responce. We are able to determine these requirements through a few mathematical formulas based on the "Theil-Small" parameters, otherwise dubbed small signal parameters. Thankfully there is a wonderful freeware design program located at www.linearteam.org called WinISD pro. In this program you may input your power (in the signals tab) and select the "excursion" graph to see how far your driver will travel in the enclosure you have chosen with the power you have chosen . Also available is the QTC of the enclosure... your .707 (.71 for arguements sake) target... Also of note, on my boxbuilder site I do give rough generalizations as to what to look for on WinISD-Pro when designing your enclosure... Please, bear in mind the idea behind the site is to aid a beginner, and you may ask questions here and get considerably more advanced replies, but most all of us here have ISD and can help you through the design process.
