SLC Punk

I bought these speakers (Kenwood 1679ie) for my boat. I am custom making everything, and one thing I need to make is speaker boxes. They are going to be mounted in a place where water won't be a problem. But I had a question on what kind of box I should make. Should I make sealed boxes or just make a front panel so I can mount them? What will make them sound the best?

LBC994runner

It will sound a lot better in a sealed box.

SLC Punk

Thanks for the response. Should put the sound filler in it (looks like cotton), sorry I can't remember the name.

DavidA

Typically filler is to slow the wave propogation down and make the speaker react like it is in a bigger box. So if the box volume is smaller than the speaker requires then I would put in fiber batting. BUT if you have a large enough box then you don't need it.

Hope that helps.

SLC Punk

Thanks.
The boxes are 8 1/2" X 8 1/2" X 2 1/2
This leaves 1 inch around the speaker and 1/2" behind the magnet.
Is that big enough?

LBC994runner

should be more than enough

COYOTA $x$

You should always put some polyfill in . if the box is small as David A describes, then you should start stuffing it with more and more.

""from the net""

Audio speakers that dont have enough damping material sound "loud", even at low volume. Damping material is necessary to absorb sound from the rear of the cone, sound that would otherwise be bounced around the box and reflected out through the cone. Damping material suppresses mid-range peaks, making the response curve smoother. If you are building a port, keep the port free of damping material. Put damping material on the interior of the back panel, one side, and either the top or bottom. The idea is one layer of material in each dimension will absorb reflections. Some builders will put damping material on all the interior walls. Make sure the walls near the woofer are heavily covered. In addition to absorbing reflections, damping material can be used to increase the effective cubic volume of the speaker enclosure. A 20% effective volume increase can be achieved by stuffing the enclosure will material. Dont compress the material. For adjustment of how much to material to use, judge by your ear. Add more material to the enclosure that sounds "loud" at modest volume levels. Fiber glass is the most widely used material. Acoustical grade fiber glass can be bought for this purpose. You can also substitute other materials such as polyester batting, rug underlayment, even old rags. Dont use dense materials that would significantly change the enclosure volume.


""more from the net""

Q: Do I really need to use acoustic insulation inside the box?

A: I have never met an enclosure that didn't sound better with some type of acoustic insulation inside. Damping material is necessary to absorb undesirable sound from the back of the cone that would otherwise bounce around the box interior and reflect out through the cone. Since this sound is out of phase with the sound emanating from the front of the cone, this causes cancellation and reduced bass response. Also, damping material can help to reduce peaking, providing a smoother response curve. Finally, damping material can help suppress cabinet resonances that would degrade bass performance. Use it!



Q: Does acoustic insulation increase the box volume? How much volume can I hope to attain by stuffing my box with insulation?

A: 20% is a realistic maximum figure for sealed enclosures. A sealed enclosure is almost never to big! So even if it is "optimum", it can still benefit from the damping. Damping material changes the operation of the box air from adiabatic (constant heat) to isothermal (constant temperature). With the isothermal process, the damping material absorbs and gives up heat which maintains a more constant temperature inside the box. This also has the added effect of reducing sound velocity, which shortens the wavelengths and makes the driver "think" it is in a larger air volume.

Don't stuff a ported system - just line the walls with fiberglass or lightly fill with polyester batting. Stuffing a ported box may decrease the speaker systems efficiency, and it is difficult to predict how much a large quantity of acoustic insulation changes the tuning frequency.

SLC Punk

Thanks for the quick responses.