Small Speaker Box's - Building - Components - Materials - Testing

[lersince1991]

Ok to keep it short and snappy. for my product design A2 course I'm fitting removable speakers into my product. I wanted to research and test the best way to build the case to mount the speakers in.

The case should be 80x80x80mm on the exterior.
On my PC speakers they have an insulative material behind the speaker and then a sort of tunnel from the back of the speaker to the front which I can only presume boosts the bass.

Any advice on the internal shape, the materials and stuff?
Also what would be a good way to test the actual output apart from sound?
Record and analyze the output of the speaker with different cases and materials?

any help appreciated!

--------------------

Well I've learnt a bit from my first prototype.

I need to make some improvements such as:
- padding for the magnetic block on the back of the speaker to reduce unwanted vibrations and 'noise'
- Improve airflow to the rear of the speaker so it doesn't create a vacuum and produce muffled audio
- The driver bracket needs to fit the speaker more precisely to hold it more secure
- If possible use the airflow/vent to improve bass output
- make sure the positive and negative are soldered the right way round

Mark I sounded pretty decent for a first try. I used the speaker components from my existing PC speaker and un-soldered them from the case they came with.

Would anyone like to suggest where I can buy some high quality speakers with a diameter no bigger than 65mm?
Can I buy the drivers that companies such as Pioneer, KEF or Bose use/make?

[Moondog55]

Not really possible to answer that set of questions until you give a little more information on your budget.
We could reccomen a pair of "Jordans" (( "google is your friend"))

[lersince1991]

Its probably a low budget compared to the type of people from this thread.

I tried google but it was hard to find drivers around 7mm/2.5"
especially since the results kept coming up with speakers systems with cases...

As for budget probably in the £5-£40 for the pair. To be honest I haven't a clue how much they should cost.
I have a pair of cheap labtec PC speakers which I took the drivers out of and they cost about £20 (for the sub/amp and x2 sat) and the drivers are actually really impressive.
So I'm thinking these speakers would cost around £5 the pair...?
What if I could go for £10 a pair and get a much improve performance (clarity, bass and volume)

Can someone help please?
Thanks for your time!

[lersince1991]

I thought it might be helpful to upload a few pictures of the first prototype.





I looked at Bose technologies and for their speaker systems they have pipes from the driver to the front of the case which supposedly improves sound performance. They try to make the waveguide (pipe) as long as possible too.
Would this be recommended to do and would it work with full range speakers? (I know Bose use it for subs but not sure about high range drivers)

thanks again people

[sreten]

Hi,

http://www.zaphaudio.com/smalltest/

You are probably looking at 3" drivers.

Easiest source is cannibalising PC speakers, I do not know
of a good cheap source for these type of drivers in the UK.

A few generalisations of 3" drivers :

Need around 1.5L to 2L of box internal volume, possibly a little
lower if well stuffed. The parameters nearly always suit sealed.

Double (or more) the volume and venting becomes possible
but your always better off with a bigger driver (+ tweeter).

So stick with simple sealed boxes (unless you want a boom box).

For no subwoofer the NS3 or similar has the best bass output,
but the best value 3" drivers are about half the cost of the NS3.

Active or passive EQ can be used to improve quality.

Here is an example of passive, note the box could be smaller :
http://www.zaphaudio.com/audio-speaker18.html

In a commercial product, EQ if applied would be active, built
around the feedback loop of the power amplifier, costing
far less and utilising amplifier power more efficiently.

Jordan / Bandor do nice 2"ers but they are far too expensive
for a normal "commercial" product and need subwoofers.

http://www.bmm-electronics.com/Produ...uctgroep_ID=73

The smaller you go the smaller the boxes
and the higher the bass cut off point.

If the driving amplifier has low power then looking for higher
sensitivity is a good idea but you again will lose some bass.

/sreten.

[Dr.EM]

You might also consider the Monacor SPH-30X, nice little driver towards the top end of your budget and can work in a small enclosure without too much of a "bump" in the response . Also has good sensitivity so will produce a louder output for less power (watts).

[lersince1991]

Thanks for the reply, it really helps.

Just a few more questions;

1) You said that 3" drivers could need about 1.5-2L of volume. My box has about 0.5L, I'm very limited to the width and height of the case to pretty much 8cm possibly 9. I could go very deep though, but if I get the volume up by adding depth, wouldn't it sound bad because of echos etc...?

2) Quick question so with a small box and 3" drivers, the case can be sealed leaving no gaps for the air except through the actual speaker (if that)?

3) The Monacor SPH-30X drivers look really good. But on BMM audio they total at £65 delivered with VAT and everything when there only ~£23 each. I would prefer these speakers but they might be out of budget with the total price, any other recommended places to buy that model. Also I couldn't find the Aura NS3 available to buy on google :/

4) Would adding an amplifier to the pair of speakers that suit them (possibly making an electronic PCB Amplifier) take much more research. I would like the amp to match the max output on the speakers so I wont be able to blow them when running audio from say a PC.

5) I briefly read somewhere about impedance 4 and 8 Ohm in my case. Would I have to match the impedance's up with the right amp and sub?

6) And finally would it be best to have anything in the case behind the driver... cotton wool? :P

THANKS AGAIN FOR THE HELP ITS REALLY APPRECIATED!

[Dr.EM]

The little Monacor driver works well in a sealed enclosure of just 0.6L. Obviously won't produce much/any bass but should sound fairly balanced otherwise. You can also get them here where delivery is free but at the moment the site seems to have dissapeared into hyperspace; hopefully back soon:

http://www.soundsec.com/

Definately use BAF (polyester) wadding or better, lamswool, inside the enclosure.

[lersince1991]

ya that link still doesn't work, weird...

Anyone help me clear up the few questions above that haven't been answered please. Then I can finalize my design and start building.

Thanks for all your help!

[lersince1991]

Ive been speaking to a local specialist and hes advised that I should buy a couple of cheap tweeters because it will definitely be worth it so I should connect a 2.2uF capacitor before the tweeter then a 1mH fermite core coil before the Monacor driver (which he also recommended). I would also need an amp so he advised just buying an electronic DIY amp kit from like Maplins or something that could go about 50W per channel that I could run the signal through.

I asked about adding a sub and he said it would be a bit more complex and I said ill just stick to having a port for an external active subwoofer.

Could anyone help me confirm these last few queries before I go ahead and finalize my design?

I added up that with the 2x capacitors, 2x sph-30x, 2x coils, some cable, some sound material for the enclosure and some wire it totals at just under £100. Is this the right thing to do?

CHEERS