Boxes for small speakers - anyone know how to work out size for tight bass ?

S

stevewestern

Messages
5,106
Edit My Images
Yes
Following on from my thread about modifying a site radio ( https://www.talkphotography.co.uk/t...ita-site-radio-modifiers.642007/#post-7657042) I have decided that I want to build a portable stereo housed in one of these -


systainer 3 by stevewestern on Talk Photography

The plan is to fit a 4" bass/mid range to each side, with a pair of tweeters to the front.
I'll be using a car stereo head unit of some sort, an ipod or possibly my phone and if I can find a way, either 18v Makita batteries or mains to power it.
I guess it would be best to build an mdf box that I can drop into the systainer so it can be rigid to give the speakers some chance to work and just cut out some holes with grills into the systainer.

My big problems are a total lack of knowledge about sizing the boxes for the speaker units, and power supplies.
Anyone here know anything about either ?
 
Tandy/Radio Shack used to do little books, including one on making speaker enclosures. Might be available on line. I reckon a 12V battery would be a better power source for a car head unit.
 
Nod said:
Tandy/Radio Shack used to do little books, including one on making speaker enclosures. Might be available on line. I reckon a 12V battery would be a better power source for a car head unit.
Click to expand...
I'll take a look Nod.
As for 12 volt, I have some 18v batteries so it would be good to use them, and I assume (blindly guessing here..) that dropping from 18 to 12 volts can't be too hard
 
You need to look up Thiele/Small parameters and then there are lots of cabinet calculators on the net (or at least there were 10 years ago when I did this kind of thing).
 
Immerse yourself in here! - http://www.diyaudio.com/forums/loudspeakers/

I've made quite a lot of homemade hifi including speakers and monitors. You need to find out the specs for the actual drivers you intend to use in order to determine the required box volume / dimensions. You also need to decide whether you want sealed boxes or ported speakers. As a generalisation, (for the same dimensioned boxes) ported speakers have better bass extension and a slightly greater sensitivity, but sealed boxes have a more controlled, tighter bass.

You also need the driver specs in order to design and build a suitable crossover for each mid/bass and tweeter combination.

A quick practical tip is that unless you already have drive units, sometimes cannibalising a cosmetically poor pair of cheap second hand speakers for components including drivers and crossovers provides a good starting point, and also gives you an idea of appropriate box volumes.
 
DeadpanDodo said:
Immerse yourself in here! - http://www.diyaudio.com/forums/loudspeakers/


A quick practical tip is that unless you already have drive units, sometimes cannibalising a cosmetically poor pair of cheap second hand speakers for components including drivers and crossovers provides a good starting point, and also gives you an idea of appropriate box volumes.
Click to expand...
Looks like a plan for a wet Sunday morning..!

I might take a look on an auction site or two for an old car stereo to give me some practice - another great idea - Thanks !
 
Last edited:
DeadpanDodo said:
A quick 5 mins on eBay found a number of likely candidates for canibalisation. Early 1990s wharfedale diamonds, currently 99p plus 8 quid postage would be a good choice. See - http://m.ebay.co.uk/itm/322405247129

Alternatively the innards out of a home theatre centre speaker may be a potential source of components for a DIY boombox. Plenty of Kef Cresta centres going. For example - http://m.ebay.co.uk/itm/KEF-Cresta-Center-Speaker-/112278126532?nav=SEARCH
Click to expand...
Thanks for your suggestions - I looked at the Wharfedales but think the drive units would be too big to fit, and have now won a pair of 4" coax car speakers which will do the job for now.. I can start experimenting on box sizes once I have got the rest of the bits, so for now my main problem is looking like working out what power supply and working out the wiring loom on the back of a head unit - I know nothing about such things....
 
I wouldn't be messing about with mids and tweeters you would need to make crossovers. Just buy a tidy pair of full range speakers drivers. Mark Audio have a great reputation they have also have a built in baffle step compensation which is another thing you won't need to worry about.

I would also consider just buying a Bluetooth class d amplifier module from ebay rather than using a head unit. Then use apps on your phone rather than faffing with a headunit.
 
Last edited:
rjbell said:
I wouldn't be messing about with mids and tweeters you would need to make crossovers. Just buy a tidy pair of full range speakers drivers. Mark Audio have a great reputation they have also have a built in baffle step compensation which is another thing you won't need to worry about.

I would also consider just buying a Bluetooth class d amplifier module from ebay rather than using a head unit. Then use apps on your phone rather than faffing with a headunit.
Click to expand...

OK, thanks - what is a class D amp ?
 
You must log in or register to reply here.
Back
Top