Any speaker builders?

[M. A. Espinoza]

Any speaker builders here?

I am designing an entertainment center and thinking of building the speakers into the cabinet.

One of my first projects was a surround sound speaker set but I've forgotten a lot of the principles of speaker design.
I am not an audiophile but do enjoy decent sound with my movies. I have some OK components I plan on reusing from the original speakers.

The old speakers are pretty beat up cosmetically from several moves and would need to be repainted at least but if they are going to match the entertainment center they would probably need to be rebuilt anyway. They are just MDF painted black.

In any case the question is I know that I calculated the volume of the original cabinets based on the drivers specifications; can I re-size the speaker housings to be the same volume but different dimensions without degrading the performance?

I expect to build these speaker compartments out of MDF for its dampening properties and then just adjust my entertainment center carcase to allow for the construction.
Since I use a powered subwoofer I don't expect there to be too much of an issue with vibrations by building the speakers into the cabinet.

Thanks for any info.

[David Christopher]

welcome to the creek, if you know the internal volume the shape makes no difference in sound quality. if you are building the entertainment center why dont you veneer the speaker MDF to match. also theres plenty of sites on the www that will give you all the info you need for building boxes

[Scott Conners]

In any case the question is I know that I calculated the volume of the original cabinets based on the drivers specifications; can I re-size the speaker housings to be the same volume but different dimensions without degrading the performance?
Thanks for any info.

Yep, just keep the internal volume the same. If they are ported, diameter and length of the port need to stay the same, even if it's just the 3/4" depth of the face. Rigidity and dampening are keys in construction, and putting some fiberfill (synthetic pillow stuffing) inside will help absorb and slow down internal reflections. I tend to fill about 1/3 the volume with fiberfill, tacking it loosely to the walls with a staple gun to keep it away from the drivers and crossovers so they can dissipate heat. Fiberglass insulation works as well, but in a home situation I try to avoid it if the cabinets are ported for health reasons. Avoid square boxes if you can, rectangles are slightly better at avoiding internal standing waves.
Changing the shape of the face of the speaker will effect the boundary characteristics of the highs, but almost no one will/can notice that in a typical room. Soft sound absorbing floor and wall coverings will make a big difference too.

[Frank Hagan]

I built two speakers recently (still have to build a third for the center speaker). From my research, I think Scott has nailed it. If you use the same interior volume for the enclosure, and the same port size (if there is a port), you should be fine.

The only thing I would add is that you should keep the configuration of the speakers the same. If there's a mid-woofer and a tweeter, keep them in the same place in your new enclosure. I built a "MTM" style, with a mid-woofer, tweeter, and mid-woofer, and the designer was very specific about the location of the speakers on the baffle (the front panel that the speakers are mounted to). Inside the existing cabinet, you may find the "cross-over", usually a printed circuit board with resistors, etc. on it). Make sure you make a diagram of the cross-over connections and wire the new speakers the same way.

[Eddie Kaden]

I agree with what Scott said on building the new speakers. You mentioned that you were building an entertainment center that the speakers would go into. if you don't want to put a lot of time and work into finishing the speakers, you can hide them in a opening in the entertainment center and build a frame covered with speaker cloth to hide them. It all depends on the look that you are trying to acheive. Just keep in mind the placement of the speakers in relation to the TV screen. Here's some pictures of how I did my enclosures for my basement.

[Eddie Kaden]

Another thing to keep in mind if you are building all of the speakers, in an ideal theater system you want the left, center, and right speaker to be identical in size and componentry. Otherwise you might have your left and right speakers overbearing to the center or visa versa. You want all three to have the same output levels so that you have a smooth transition of sound from one speaker to the next. When the action moves accross the screen, so should the sound and you shouldn't be able to tell which speaker the sound came from.

[M. A. Espinoza]

Thanks guys, its coming back to me now.

I should have stated I have a separate powered subwoofer so the vibrations shouldn't be too bad in the cabinet.

I did use compatible drivers in the original speakers and there is minimal difference if you do a "sound sweep" type of test.

I'm building more of a "entertainment credenza" rather than a big unit. I'm trying to hide the TV when not in use. Aesthetic reasons and here in Hawaii keeping electronics behind doors as much as possible is important to keeping them functional.

As far as veneering the originals its simply a design choice of eliminating separate freestanding speakers, not out of the question but not the direction I'm leaning towards right now.

Thanks for all the pointers, its been a big help rattling loose old knowledge.

[Matt Sollars]

www.hometheatershack.com is an AWESOME source for speaker building information and a huge forum of DIY folks like yoursef. no affiliation, other than a forum member there as well. Great and helpful folks though....so i guess that have that in common with SMC.

[Larry Rasmussen]

I've built a kit or two and some speakers from scratch. If you like the sound of the speakers the way they are just put speaker grill fronts in your cabinet and set the speakers inside. Many commercial designs will make it a cabinet with panel doors with speaker cloth instead of the panel. If you didn't want to make doors just make a framed speaker grill either removable to work from the front or fixed in place and you sneak the speakers in from the back.

I really like partsexpress.com for just about any speaker parts or tools as well as electronics and miscellaneous sale stuff as they buy close out lots. They have a do it yourself speaker design new every few months that a staff member usually designs and presents when a new catalog printing comes out. I went over there just now and see they are having a clearance sale that looks impressive for more stuff than usual so I'm heading back over now.

Good luck,
Larry R
Seattle

[Eddie Kaden]

I wouldn't be too concerned with vibrations if you build the credenza good and solid. I was concerned with that when I built my wall unit. I have a powered 15" subwoofer with a 1500 watt amp and each of my LCR's have powered 10" subs and 150 watt amps. No vibrations in the cabinet, just the rest of the house.