sub size for venom 10

3.077ft^3 is the ideal size with a f3 of 45 hz and a qtc of 0.707 which is 87.130937 L which is very roughly 50cm by 45cm by 40cm thats using the calculator from https://www./help/Articles.cfm?id=26 which i think may be wrong as the ported enclosure should be larger but it says there 45L, basically id just fill your 35L space then use some deadner if you want cheap a house fiberglass you have laying round pillow stuffing or something fluffy basically but you can buy real stuff for about $10. anyway hope that helps :)

hey thanks for that, yeah those calcs sound pretty small, i tried a few calcs but ddint have all the details to complete so i couldnt trust it.its for a car and dont have much space and not even a a square space to work with

i got some old duvees there how tight should i stuff it?.

have you considered using fiberglass boxes as they can save you a fair amount of space filling in all the nooks and crannies, and allowing the sub to protrude further into the boot without taking up lots of space.

as for stuffing humm yes that much, ideally you stuff some load the sub check the sound then add more or subtract sum until you get the sound you want, but this is very time consuming and unless you have a good ear, i dont, you are bound to failure. i use as my rule of thumb i layer over the whole box.
you can look around and find better more technical answers to the reasons behind doing it and you could with a few years of engineering figure it out to an exact science but the idea behind the filling is that as sound travels between a two matrix it basically slows down, fluffy insulation is built from hundreds of air pockets surrounded in fiberglass and polyester and other stuff so as sound travels through it, it passes in and out of different substances alot, making it take a long (relatively) time to get to the back of the box. and sound is well stupid so it only knows size by time taken to reach the end. therefore by slowing down the sound and making it take longer you are in effect causing the box to appear bigger.

as a general rule the larger the box the better it will be (everyone will argue here) :) but as you increase the size you increase the QTC which changes the subs response to be boomier a and peak higher at certain frequencies. it unfortunately also reduces the response times of the sub and makes it sound sloppy.

now my advice and this is only my thoughts and by no means am i an expert. is to build the box to your full 35L then pack the back with your duvet unless you can buy some from your local audio store it will make a difference. and pack the box so its fairly full but it is not all jammed in and the sub easily slides in.
this should give your box its best chance at being the biggest it can be, and take you the smallest amount of time. but it wont be perfect if you have ages to experiment then just line the inside slowly adding more padding till your happy :)

awesome thx for the reply, re the fiberglassing this is my first stereo install so going with the solid boxes at the moment BUT i do have carbon fibre laying skills and experience so no doubt will venture into more custom boxes once i get this up and running.thx again.

btw its in an toyota mr2 so space is not exactly your friend.the whole car is about the size of your average subwoofer :D.

good luck i hope it all ends up good, i know what you mean about the MR2 they are tiny especially the boot.
i wouldnt be too scared of fiberglass i personally find it easier then MDF boxes because you can cover them never worked out how to cover a square box without cutting and gluing everywhere :(.

so sides of the box go the whole way across the back of the car? if they are fixed why do you still cover the bottom of the box sorry im a little confused

the back, bottom and sides wont be seen , the front and top wich is aslo part of the sub will blend in to the sides of the car, there is a tunnel in the middle of the car so there will be 2, seperate subs. A  picture speaks a thousand words so will post one when done, thx.

look forward to seeing it :)