Generic box size

[Chrispy61]

I've managed to get hold of some driver's but unfortunately can't get any information on them to design some cabinets and don't have the equipment to test them.

Is there a rule of thumb that I can use to get an idea of what size to make them? Or is it really a hopeless exercise?

 

[scottjoplin]

If you want a sealed box you can't go too far wrong, the size will determine the roll off (system Q). Anything else you'll need the driver parameters

 

[Chrispy61]

So is it literally a case of build a box and see how it sounds?

 

[whgeiger]

Make the effort to test the drivers you have. You do not need much gear to do this. Even if you had published specs, measurment would still remain a prerequsite to obtain a successful outcome.
Regards,
WHG

 

[paulys55]

What drivers do you have? Is it possible that someone here might be able to help you with driver specs? Are they one of a kind?

 

[Chrispy61]

I will look into measuring them myself and how easy it is.

The speakers a 4" woofer's made by DROK. Ive tried contacting them by have had no reply.

Thanks guy's

 

[Chrispy61]

I've noticed in a video on YouTube that the person used a resistor between the amp/signal and the speaker/multimeter. Why is this?

 

[Chrispy61]

Ok guy's, I've measured the speakers and have some ts parameters.

The suggested box volume is 2.1l. If I increase this volume I notice that f3 gets lower and lower. Can anyone explain why 2.1 is suggested and not more to get a lower f3 figure?

 

[scottjoplin]

As a generalisation, the Qtc decreases as the box volume increases which also increases the -3dB frequency, the system resonance decreases which reduces the "knee" of the filter. Sealed enclosure explained in detail and calculator - Audio Judgement

 

[Chrispy61]

Is this the same for a ported enclosure?

So will box simulation software aim for a flat response, which is a Qtc of .707?

 

[scottjoplin]

A sealed box is a 2nd order filter, a ported enclosure is 4th order, the -3dB point it usually tuned lower but the roll off will be steeper. I've never used box simulation software, but I should hope it does what you tell it to

 

[Chrispy61]

Thanks for replying.

Probably basic stuff but it's helpful for me.

When people talk about tuning to a certain frequency, they are looking for a boost in dB at said Freq?

Is it basically a case of playing around with volume of box and port size/length until you're happy with how the plot looks?