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.
Replies
We used rubberized horse hair in side some large Voice of the theatre type enclosures , not sure of it's exact effect .
dusty
Take a look at partsexpress.com They have all the components for speaker building and have some design info. as well.
Robert
You should be all right doing that as long as box volume stays the same.
If the speaker is ported, you should maintain both port length and diameter in the new enclosure. Any stuffing in the box should be duplicated. Driver mounting to the front baffle should also be duplicated (ie. front mount, recessed, back mount). Use the same crossover and connect it in the same way.
I'd be very wary of building them into the unit. It will be a bit of a trial if you ever get the urge to upgrade.
In entertainment cabinets that include speakers, I usually use the existing speakers and put them behind a shop-built speaker screen (see image). Vibration is definitely a problem with the sub woofer. To minimize this, I cut out the bottom of the cabinet and put the sub on a platform that rests on the floor.
If you would like advice on how to make the screen, let me know.
David
I should have been more clear. I use a separate powered subwoofer so it will not be in the entertainment unit.My hunch was that as long as I maintained the volume and similar construction I wouldn't notice any big difference. I also seem to remember needing to avoid having the same depth and width.Something about "standing waves", whatever they are. I only learned enough at the time to keep from making any major goofs.I do plan on placing the speakers behind screens so maybe I will oversize the speaker compartment and have the new speakers simply housed within. Would allow some aiming and give a little flexibility should I change drivers someday and need to adjust the speaker cabinet size.
Standing waves are caused by parallel walls, and are exaggerated if the parallel walls are equal widths front and back...it's best to avoid parallel walls if possible. If not, avoid using widths that are multiples of the sides, front, and back dimenions. Brace the enclosure well, and dampen it well with dense foam, wool, etc., or combinations.
Also, I'd avoid using a ported design for mounting in the enterntainment center since the proximity to walls can cause resonances and boomy sound. Since you've got a separate subwoofer that shouldn't be a problem to avoid.
It's really important to get the tweeter and mid as close together as physically possible. If the distance between those drivers is greater than the wavelength of the crossover frequency you'll get some audible phase shift that's tough to overcome. It's a good idea to reduce the reflective surface area of the front baffle if possible, but you can add dampening felt/foam to the front to help. It's also a good idea to compensate for the depth differences of the voice coils...even if you simply angle the entire enclosure. Use good wire, good drivers, and good components, and do all the little tricks you know of...they'll add to a nice audible improvement in the end.
Good luck! (Pics please!)
I read your followup to David's reply but I wanted to echo his sentiment nonetheless. I've done several built-ins that incorporated home theatre components and stashing the speakers in dedicated sections with shop built speaker grills to match the built-in is by far the easiest and most visually appealing strategy. I did this in my own home as well and while I have a free standing powered sub woofer, I really wish I had designed my entertainment center to accommodate it.
The grills are a breeze to make, buy bulk speaker grill cloth from Parts Express and make simple frames out of MDF that friction fit the sections, use 3m spray adhesive to attach the grill cloth to the frames. Super easy and they look great.
From what I remember from my teenage years, Volume and shape are important. The shape of the enclosure dictates the "interaction" of the waves as they pass through the box, but more-so in a Sub enclosure. However, as long as you don't create an irregular shape, you should be fine with your mid to high range speakers. Just maintain the same inner volume, porting and insulation as the original.
A couple of key things to doing built ins for speaker design.
The high frequency drivers (midrange, tweeter) have a dispersion pattern that assumes the edge of the box is a particular distance away. When you mount a speaker into another cabinet the controlled diffraction affects can cause phases problems that sound really bad. The only way to solve this is different speakers or a major change to the crossover to compensate for the longer front panel.
Finally in the bass region avoid boxes with even or odd multiples on the inside of the box. This is due to having the box resonate at high volume that will again cause very strange output problems.
There are many books and Website available to ask more detailed questions as well a AES (Audio Engineering Society) which has journals on this stuff. After doing this for more than 30 years nothing is obvious but you can get something that sounds pretty good without costing a lot of money.
OK, you seem to have touched on some potential issues.If possible, I'm trying to avoid spending too much time "researching the wheel" but it looks like I need to check out some things. I know there is a ton of material out there regarding speaker and crossover design but I liken the issue to reading the Encyclopedia of Furnituremaking in order to build a birdhouse. I'm trying to keep it simple and just avoid any serious mistakes.I'll check out the speaker builder sites but was wondering if possibly just lining the speaker compartment with sound absorbing material (eggcrate foam, acoustistuff, wool batting?) would help with some of the reflection issues.And regarding the "even or odd multiples" I'm afraid you have me completely baffled. (pun intentional) Do you mean don't build a box that has one dimension that can be divided by another dimension i.e. 6 inches wide x 18 or 24 high?Lastly do you have any books you would recommend?Thanks for the pointers.
The Loudspeaker Design Cookbook.
Vance Dickason
Fourth Edition
ISBN 0-9624-191-7-6
................................................
Men will never be free until the last king is strangled with the entrails of the last priest.~ Denis Diderot
When I've purchased speaker screen material, it was stated by the manufacturer to be audibly transparent much like the screen that is on the front of most speakers. When I put the speaker in the cabinet, I remove its screen then position it just behind the new screen making sure that it is not blocked by the frame of the new screen. I always thought of it working the same as putting the speaker on an open shelf.
David
Yes the multiples I am referring to is the relationship between the three dimensions. The "Loudspeaker Cookbook" is about the best for getting the basics right and it is paperback to make it cheaper as well.
Another treatment method is to put dense soft foam around the speakers to minimize the indirect reflection problem though it will have a tendency to reduce the high frequencies from the speakers it will reduce phase problems.
Thanks all, guess I'll need to pick up a copy and visit a couple speaker forums.Shouldn't be too bad considering my modest goals.
A lot of information on calculating speaker enclosures can be found here:
http://www.lautsprechershop.de/english/index_tools.htm
Just a thought for you to keep in mind.
First off I love BASS! And more of it. Probably because the only sounds I hear well or maybe jut feel it? I put up with the side issues. However, it can be very annoying to people that DO NOT!
In general, home theatre demands high output at low frequencies. Music the other way around.. I think..
Not sure of you use a turntable but it can be a disaster with improper use of the bass enclosure.
I made a cabinet for my son-in-law, who is a Professor (PH something in teaching), AND a hard rock nut. He has a LASAR / LASER? Whatever turntable. It is a very expensive one of the best quality. Not sure what brand.. The SubWoofer would even ruin the tracking of the laser.
And for some reason the subwoofer when in the cabinet made the sub frequencies rumble throughout the whole house. Even at moderate sound levels.. Well, for hard rock.. I would think the whole cabinet acted like a tuned port?
I had to remove it from the built-in and move it into another room. My son-in-law hired a sound engineer because the rumble was carrying through the rafters.
The subwoofer enclosure is now in a small coat closet in the next room. On a metal frame without an enclosure except for the closet room!. Sound is wonderful!
The speaker is on some kind of 'pad'. I looks like very thick cork?
My son-in-law also plays classic on a grand piano? I wonder about him sometimes! But a good husband and father... He is so opinionated he would argue with the Pope about religion....
Edited 1/18/2009 1:36 pm by WillGeorge
Will,Thanks for the info.Those audio guys will go to unbelievable lengths for their hobby. Not like us woodworkers. ;)Wow, a whole closet used as a subwoofer enclosure? In any case I do use a powered subwoofer and yes I do really enjoy feeling the rumble of those frequencies around 30hz. But the sub will stay separate, exactly because I wanted to avoid any issues of vibrations in this project even though I don't use a turntable.I once did a job doing a custom speaker enclosure for a fellow that played metal guitar. He used it for recording and would it was a speaker and microphone inside a box. Isolation cabinet I think it was called. Complex thing, two chambers lined with sound blocking and sound absorbing materials. He could crank his 100 watt tube amp with this thing and you could speak in a normal voice 2 feet from it. It had a very good latch on the door, wouldn't want to accidentally open up and blow the windows out of the house!
Ok my first post in a woodworking forum and it deals with one of my lifetime passions...music or as my wife puts it...another FREAKIn money pit! Here are the sites that I would suggest to re-educate yourself on speakers, their design and some design suggestions. There are vary from full range (single speaker) to horn designs. Depending on the application of the speaker will really determine what you want to build. Also if married, Wife Approval Factor (WAF) could be the final determination...http://www.diyaudio.com/http://www.zaphaudio.com/http://www.planet10-hifi.com/http://www.diytube.comBTW the german site listed earlier is a frequent visit for me...You can spend too much time on any one of these forums, lose track of a few hours, maybe even a weekend...good luck and hopefully it doesnt turn into another disease../e
Edited 1/19/2009 11:37 am ET by 77seriesiii
No, woodworking for a living and old cars for a hobby are a bad enough combination. I've seen what a slippery slope the audio thing can be.I'm simply building an entertainment credenza and need to place my speakers inside the cabinet.I'll rebuild the speaker boxes to get them to fit and will take steps to minimize the affect this arrangement will have on the sound. But as a woodworker the design of the credenza takes priority so there will be some compromise I'm sure. Now if I designed home theaters for a living it would be another story but part of this credenza's purpose is as a portfolio piece.
but part of this credenza's purpose is as a portfolio piece.
And then you should state ALL the IF, ANDS, AND Maybes!
"And then you should state ALL the IF, ANDS, AND Maybes!"Will, you've lost me...Maybe you mean the restrictions my design will place upon acoustics?Basically just wondering what to minimize and steps to take when you place speakers INSIDE a cabinet. I know this immediately doesn't serve acoustic performance but wanted to do what I can despite this design restriction.I've gotten some good advice and I can nudge the design to allow for best performance. But its a piece of room decor first and a housing for A/V equipment second.
Maybe you mean the restrictions my design will place upon acoustics? ... Yes!
Just pullin' your leg a bit.. I think you got into a bag of worms!
"I've gotten some good advice and I can nudge the design to allow for best performance. But its a piece of room decor first and a housing for A/V equipment second."
Perhaps after asking the questions, getting some good advice, and doing the research, it will be both! I'm interested in what the result will be.
david
I'll post pics when its done. I'm trying to do my own thing now design-wise and I'll admit its pretty different.I've gotten some good audio advice. Mostly wanted to avoid putting all the work into it and having some A/V geek tell me "you never want to do what you've done". The design takes priority but I'm trying to at least "do no harm."
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