Anyone competent with working out subwoofer box sizes?

[Chapster5]

As above I want to do a boot build on the astra just a small one along the back of the boot. I have 2 x 12" Mutant MT 1210 subwoofers but need to build a box to hold them but also allow them to give out their max capacity.

Anyone able to help me measure up the boot local to the Warrington area and help me work put the size of the box to build? And if I need it ported or not? I will travel as far as 20 miles from Warrington so preferably local please. Beer tokens/ money in it for you thank you!

Nick

Ps just to help out a bit... My idea of the boot build very roughly drawn by the misses

 

[The Fatty]

your best bet would be to use some speaker cab designer software (like winISD), input the parameters of the sub and play around with the sizes. You will know why you have got it right as the audio curve will be as flat as possible for as much of the low end frequency range as possible.

 

[Chapster5]

Cheers dude ill have to give it a try all though I am literally a sub virgin I know nothing about them just RMS Is important. Ohms and all that Christ knows.

 

[The Fatty]

the mutant subs are quite good for the money, I used to have one connected to a mutant SP280 amp with good results. iirc they are about 200wrms? To get the most out of your amp (if it will allow for it, you will have to check the minimum load ratings), you will want to wire them up in parallel. This will make the amp see half the actual load of the speaker and as a result the amp will have a higher output capability (i.e 2 8ohm speakers wired in parrallel will be seen as a 4ohm load by the amp). You havent mentioned what amp your going to use? for subs, you ideally want a monoblock, they are more efficent than normal amps for driving subs. They also tend to run cooler. Most monoblocks are happy with a 1-2ohm load, so running those 2 mutants in parrallel shouldnt be a problem. Remember to use a good sized power cable for your amp else it will be under-powered.

 

[Chapster5]

Cool thanks for that mate, the more information the merrier. I have asked MTAudio on here to help me pick an amp as once again I am a total newb I think I need a 400W? For the 2 x 200w rms?

The spec sheet of each sub.

 

[The Fatty]

you will need a 2x200Wrms at 4ohms, or 1x400w at 8ohms, or the best option imo as it will be cheaper - 1x400w at 2 ohms.

 

[Chapster5]

and run the subs in parallel?

http://www.argos.co.uk/static/Produ...+and+cd+car+radio+accessories+/+in+car+amps+/

Something like that?

 

[Dink]

i would looking for an amp that outputs 500wRMS into 2 ohms

imho i'm always one for using a sealed box for the subwoofers

 

[Chapster5]

i would looking for an amp that outputs 500wRMS into 2 ohms

imho i'm always one for using a sealed box for the subwoofers

Cheers Dink,

Saves me the hassle of trying to find out how many or how big of a port I need.

 

[The Fatty]

and run the subs in parallel?

http://www.argos.co.uk/static/Produ...+and+cd+car+radio+accessories+/+in+car+amps+/

Something like that?

no nothign like that. not sure you read the spec of this one correctly!

"400 watts 2 channel amplifier. Continuous Power Output 2 x 65 watts at 4 ohms, 2 x 90 watts at 2 ohms, 1 x 150 watts at 4 ohms bridged."

Something like this would be better http://audiovisualworld.co.uk/shopping/mutant-mtor1-origin-1-800watt-mono-amplifier.html

 

[The Fatty]

i would looking for an amp that outputs 500wRMS into 2 ohms

imho i'm always one for using a sealed box for the subwoofers

I agree with this 100%, its always better to have a bit move power than not enougth. I also opt for sealed boxes, makes them much more punchy.

 

[Chapster5]

Ace,

Could you possibly recommend a 500WRMS amp at all if it's not too much trouble please. Here's my idea of the build

In the centre will be where the Amp is mounted.

 

[The Fatty]

design looks good. You going to put a seperator in to keep the subs seperate?

Whats you budget on the amp?

 

[Chapster5]

Would you recommend a separator in between? Or just an open cavity? I'm going on a whim here haha budget I would go between £100-£120 (although the misses will kill me, ill deal with that at a later date).

 

[The Fatty]

Fo rthat price I would either get the mutant I posted above or this fli monoblock (which is slightly better at 600wrms@2ohms) http://audiovisualworld.co.uk/shopp...-fli-loaded-1200-watt-mono-car-amplifier.html

I would probably keep the subs in seperate compartments. You dont want the box too big, else you will get a spike at a certain frequency (which dosnt sound good as that frequency overpowers everything else).

 

[Rob]

I'd have two separators, that'd allow you to have the internal dimensions of each box exactly as you want.

 

[Chapster5]

Fo rthat price I would either get the mutant I posted above or this fli monoblock (which is slightly better at 600wrms@2ohms) http://audiovisualworld.co.uk/shopp...-fli-loaded-1200-watt-mono-car-amplifier.html

I would probably keep the subs in seperate compartments. You dont want the box too big, else you will get a spike at a certain frequency (which dosnt sound good as that frequency overpowers everything else).

Sounds good just shown the misses, she said at first what the f*ck is that.... Then said i'll get it you for Christmas that's that sorted haha! I think i'll build in some separators then as you and Rob advise. Should make for a better sound.

I'd have two separators, that'd allow you to have the internal dimensions of each box exactly as you want.

Cheers for the input Rob,

I will have to measure my boot and get a good idea for how big I should build the box surround. then I can properly make a 3D model on the computer and get a good idea for sizes. That model above is actually in MM the wall thickness is 0.5mm haha I was doing it very quick . If I get some measurements of the boot and tell you guys how much I am willing to sacrifice think you could advise on the size of the box? Or just make it up the the size of the space I can sacrifice? (although probably not advised as I probably wouldn't leave enough room for the subs to do their things).

I am also thinking if I put 2 separators in the center bit one at each size maybe insetting the sub into it's own compartment with perspex over the front and a blue LED. How would be best going about cooling? A computer fan maybe?

Thank you! Great input so far.

 

[The Fatty]

I am also thinking if I put 2 separators in the center bit one at each size maybe insetting the sub into it's own compartment with perspex over the front and a blue LED. How would be best going about cooling? A computer fan maybe?

Thank you! Great input so far.

Im going to assume you ment amp and not sub there ^^. Most monoblocks run fairly cool unless you really push them hard. Also they tend to come with thermal cutouts for protection

 

[Chapster5]

LOL my mistake amp is indeed what I meant I don't think i will push it anywhere near its limit to be fair might be worth a couple of little slots (hidden) and a fan screwed on to dissipate any heat as a backup.

 

[DanEdser]

gonna get the box flocked/carpet/leather?

 

[Chapster5]

Carpet mate ain't cheap though apparently

 

[The Fatty]

you realise this is goingt o be heavy as f**k? What ar eyou ogin to make it out of? I've got in the habbit of making my boxes as small and as light as possible these days.

 

[Chapster5]

I was thinking 10mm plywood/MDF what would you suggest? I'm always up for design changes too

 

[The Fatty]

Birch Plywood is my no1 choice as its the best for weight and is also very strong. Only thing is its pretty expensive and splinters when cutting. 10mm is not thick enougth for the baffle, you want 18mm+ really. depending on how you build the box, you may also want to use 18mm on the rest as well (unless your build an internal frame, in which case 10mm would be ok for the rest).

 

[Chapster5]

I was thinking of keeping costs down and building it straight from sheets with no frame. So you would use 18+mm Ply for the whole box? By baffles do you mean those separators I am going to put in the center?

 

[The Fatty]

no I mean the bit the speaker is mounted to, this is known as the baffle. I woul be using 15 to 18mm for the rest fo th ebox in that case.

 

[Chapster5]

So the 2 selected faces at about 18mm and the rest at 16mm.

 

[The Fatty]

yeah. you will have to build a frame section for the inner side of each of the baffles. the baffle has to be the strongest part of the box.

 

[Chapster5]

If I built a frame inside, would you advise to smooth any sharp corners off the frame inside? Or just leave them as they are.

 

[The Fatty]

leave them as they are.

 

[Chapster5]

Awesome I will probably pick your brains a bit closer to the time of building if that's ok? I had a look in my boot earlier... not as much room as I remember

 

[The Fatty]

lol yeah that drawing did look a little big for an astra boot. No problems

 

[Chapster5]

Your a star thanks mate! I have a lot of crap in my boot at the moment like cleaning gear and exhaust and 2 subs LOL looking cramped. Can't really judge as it is.