Sound System Help
Thread started by
richtotheie at 01.3.09 - 10:53 pm
Hey guise,
Both speaker cabinets from my music trailer have been destroyed,
I want to build a new custom cabinet. Particularly out of plexiglass. Anyone have any ideas on where to get some cheaply?
OR if anyone has some laying around and wants to donate it that would be awesome! This guy is getting pricey!
reply
Were they destroyed as a result of malice?
Or, did they simply succumb to old age?
bentstrider01.3.09 - 11:13 pm
reply
the box and things in it were disrespected!
mikeywally01.4.09 - 10:53 am
reply
Man that fucking sucks.
I don't know that plexi will be the best sounding boxes, but it is worth a try.
You could try
hastings plastics in Santa Monica. They also tend to have a lot of scraps for sale which could be useful.
There is always a delicate balance when making a speaker cabinet between: weight, durability, and audio quality.
I have never known plexi to score high in any those areas of speaker building bu I am sure they would look sweet.
There is reams of info on speaker building and many know much more than me (I've only built 2) but here are a few little things to keep in mind.
1) You probably want to match the volume (as in inside space) and venting of the old boxes even if you change the shape.
2) a wedge shape is more efficient than a cubic box shape. parallel surfaces cause sound wave to crash into each-other creating "phase cancelation" and lessing the over all output.
3) other than vents (if necessary) a box should be air tight.
4) a material that vibrates a lot will dissipate sound through the walls making the box less efficient. This can be mitigated in a few ways. like having "ribbing" and/ or stuffing the box with acoustic filling.
There are a lot of conventions for making speakers but most speakers are not used the way you are intending to use them so it is fine to break with convention. On the other hand it's always good to know why things are done a certain way so you can decide weather or not that fits your purposes.
trickmilla01.4.09 - 11:17 am
reply
If you do go with plexiglass, dont forget the pimpin led lights!!
speedybrian200001.4.09 - 11:31 am
reply
^^^^^^^^^^^^^^^^
Who's that guy? speedybrian? Some old washed up rida? :)
When's BARCHOPZ!?!?!?
Leetard01.4.09 - 3:52 pm
reply
i would think that wood would be stronger and would absorb more shock from the ground. if you do go that way, you could super-reinforce the corners, and hopefully the end-product would be stronger than a traditional cabinet.
In addition, you will be able to add fasteners to the cabinet. in conjunction with the tie-downs, that should prevent any shifting as well.
tortuga_veloce01.4.09 - 5:34 pm
reply
Parts Express is a treasure trove of info and specialized parts for speakers.
They have speaker plans on there and sell stuff like metal corners for cabinets and cable ports.
They also have specialized material like sound dampening spray and acoustic filling.
trickmilla01.4.09 - 5:39 pm
reply
I spent some working on a box for another rida, but never figured out exact dimensions because there was no trailer so nothing ever came of it... Plexi glass would suck for a box. It will most likely sound like an old shitty car with huge speakers vibrating more than reproducing your program material.... But it might not if done correctly ($$$$$$$$)
Build a four speaker array that fit's nicely onto your selected bicycle trailer. See sketch attached.
This setup would allow sound to be radiated at 180 degree's... Better than one speaker facing backwards in my opinion.
Use 4 cheap 6" or 8" full range woofers in a sealed MDF box, and get an inexpensive 50W amp to drive the array. A decent amp should be able to drive down to 2Ω's , and double the power output at 4's and double again at 8Ω's. There is a lot of creative marketing in the car audio industry, so watch out and read up on what your going to buy.
I would also recommend summing the left and right channel signals into mono to reduce any sound anomalies you might find in varying environments due to phase cancelation.
here is a 8" speaker with very good frequency response at a good price:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-379
and some specifications of this driver:
Power handling: 50 watts RMS/80 watts max *VCdia: 1-1/2" *Le: .63 mH *Impedance: 8 ohms *Re: 7.05 ohms *Frequency range: 50-20,000 Hz *Fs: 47 Hz *SPL: 87 dB 2.83V/1m *Vas: 1.01 cu. ft. *Xmax: 2.0 mm *Qms: 3.82 *Qes: 1.48 *Qts: 1.07 *Dimensions: Overall Diameter: 8", Cutout Diameter: 7-1/8", Mounting Depth: 3-1/2".
So with these numbers, we can start to think about the volume of space the speaker need in a box to operate properly, and how many watts you need to drive the speaker to an estimated SPL.
For the speaker box, each speaker need's 1.01 cubic foot, just multiply this number by the number of speaker in the array and build you box so that number is the inside dimension. This box will need 4.04 cubic feet of space.
Now for how loud this array will be. The specs say this speaker will be 87dB at 2.83v, at 1 meter. remember when I said marketing is creative? This is one example as most speakers are rated in Watts per meter, and not volts, so we need to figure out how many watts 2.83v into 8Ω's is. Ohm's law tells us Power = I*E = E^2 / R
so, with that in mind, we are at about 1W into 8Ω's, per meter. You need to double the power to the speaker to slightly increase the SPL. Here is a chart I found on the interweb: (see attached)
The human ear is most linear in terms of frequency response at 85db, (that's pretty rockin' loud) but most people who will enjoy the system won't have there head at 1 meter away from the speaker box, they could be 50~75' back, so we need to figure out how how much sound will get to the back of the pack. If I recall, the loss of sound threw free air, not paying attention to temperature and humidity is a function of the inverse square law. For sound, this is expressed as:
Snew=Sref + (20 * Log (Dref / Dnew)
Where:
Dref = Reference Distance
Dnew = New Distance
Sref = Reference Sound Level
Snew = New Sound Level
So, if I choose distance reference of 3' at 85dbSPL (I would stay around 85db's to avoid police intervention) at 75' the dbSPL would be about 57dB.
I'm not sure how to figure out how many watts you really need to get these numbers, but I know it's a bit more involved than just using the chart I posted. A 50W amp into 4Ω's turned up 1/3 of the way should put you where you want to be .
~Mook
Mook01.4.09 - 6:08 pm
reply
Here is my trailer sketch.
Mook01.4.09 - 6:11 pm
reply
I'm not sure if they still have it, but I gave a bunch of parts, a frame, and some wheels all for a trailer to the oven. See them if if they have anything.
It doesn't seem that hard to build a trailer from scratch with those plans. Something like this is also what I had in mind. Using car stereo stuff would make things alot cheaper. Dudes that are into electric bikes would be a good source to find out where to get a good battery/charger system. Unless you have that covered already.
What did you think something like this would cost Ben?
User101.4.09 - 6:39 pm
reply
Awesome read Mook. I remember speaking w/ you on a ride... of putting a box together. Very interesting stuff.
Allen.. you've got skills on putting a cabinet together for this right?
I can't push this link below so much but this is something that would kick ass. I have no idea what these guys are talking about but I'm sure you do. Check it out!
http://www.archive.org/details/12vsoundsys
They use PA horns for the mids and highs... and have one 12" sub. I've always wanted to put something like this together but I don't know the know how. It would be awesome to put this thing together.
digablesoul01.4.09 - 6:46 pm
reply
Thanks for the replies!! i really like the shape of your cabinet Mook!!
Here's my issue. I want to re-use the speakers i have since they are good. I've already spent a shitload of money on this trailer and system so i want to do it for as cheap as possible as to not compromise performance. I am going to thoroughly go through this thread when i get home!!! LOVE YOU GUYSSS
richtotheie01.4.09 - 6:49 pm
reply
I CANT BELIEVE ALL THE DRAMA ON THAT/THOSE VIDEO, JUST BUILD IT, WHY GET ALL TECHICAL? JESUS FUCKING CHRIST.
SLOW ORATION SUCKS
eddieboyinla01.4.09 - 6:56 pm
reply
I CANT BELIEVE YOU HAVE NOT EVEN ASKED ME FOR MY 2 CENTS RICHIE. AY CAN I COME BY TONIGHT?
eddieboyinla01.4.09 - 6:59 pm
reply
Yeah Al, I could build the cabinet. I don't have my work space any more or a table saw though. Rollers said he has that. Have to get in touch with him to see what the details are on this.
User101.4.09 - 7:02 pm
reply
You could incorporate the trailer into the box... Just add an axle or something onto the speaker box and a yoke to pull it with.
Using your old speakers and making inside dimensions guesses based on the old style cabinets will probably get you where you want to be for much less.
Use 1/2" MDF to save weight. Should be cheap at Home Depot.
You could probably build the box with one sheet of MDF, a bottle of wood glue, some finishing nails and a 18 pack of beer.
Skill and proper tools help too...
Mook01.4.09 - 7:06 pm
reply
Use 1/2" MDF to save weight. Should be cheap at Home Depot.
-------UNTIL IT GETS WET.
eddieboyinla01.4.09 - 7:09 pm
reply
Also, some smaller lumber places will chop up your sheet of MDF to your speck's for cheap. You end up with a "kit" and will probably only need a 12 pack of beer to finish.
Mook01.4.09 - 7:10 pm
reply
Cover the box with plastic veneer to keep the water out, and make it look like a 70's waffle house.
Doesn't rain much here.
Mook01.4.09 - 7:13 pm
reply
Calm down eddie! This thread is so i can get everyones 2 cents. Good stuff flowing here. Just need to build this cabinet.
Mook - my last speaker cabinets were destroyed due to water damage. So as far as material goes, is there anything besides wood? Or is that still the cheapest and can i waterproof that from the outside?
richtotheie01.4.09 - 7:17 pm
reply
They have sealers you can use. After all decks are made of wood yeah?
Anyways talk was going on for awhile regarding replacing Dan's trailer. So hopefully we'll have something this summer.
User101.4.09 - 7:24 pm
reply
There is waterproof MDF available for marine applications but it's very, very expensive.
There are many ways to seal MDF. Some idea's:
Thick laquor coat, like a bar top.
Fiberglass it and paint it like a boat. Maybe it will float like one too.
Google around for whatever is cheapest.
Also just remembering....
I might have a full sheet of black, semi transparent plexi type stuff at work to donate if you want to try that, but I think it will seriously sound thin and shitty. It also sucks to cut. shoot me an e-mail
Mook01.4.09 - 7:32 pm
reply
I was thinking another good idea would be to go down to a "pick'n'pull"
and find a trashed ricer with some untainted sound-equipment inside it.
bentstrider01.4.09 - 7:36 pm
reply
I'd use 3/4" plywood instead of MDF. Lighter and stronger by far. Waterproof with a coat of wood stain and two coats of polyurethane.
frumble01.4.09 - 10:47 pm
reply
waterproofing the actual cabinets is DEFINITELY a good idea. also, consider covering the whole thing with a TARP.
works for wall street, it will work for you! [sfx: hi-hat]
tortuga_veloce01.5.09 - 10:43 am
reply
Plywood is nice for applications that require a speaker to be moved and potentially bumped alot.
MDF is more dense than plywood, so at the same thickness Plywood it is lighter but since it is less dense it also dissipates more sound.
MDF is soft, you can get amazingly clean edges with it, its really easy to sand and you can make look totally seamless.
If streangth is of primary concern ... i agree with using plywood.
1/2" or 3/8" would be fine as long as you reenforce it inside.
....................
megaprops to all the audio nerds coming up with all the useful knowledge.
trickmilla01.5.09 - 11:10 am
reply
Waterproof MDF sounds awesome. Yeah please dont use plexiglass - the pimp my ride crowd might like it but it wont sound nearly as good as a proper material (even plywood). I have fantasized about building a MR speaker rig for quite some time. I would bet there are quite a few people on this forum that could help you out a lot.
Just briefly looking at your drawing it seems like you want to go with four mid-size speakers. You would get a much better sound if you went with some kind of crossover network and added a tweeter to the mix. You could try and emulate a popular design like this:
Teque501.5.09 - 11:48 am
reply
btw, if you do end up going w/"plexiglass" there is an important distinction to be made.
Plexiglass = complete utter brittle shit
Lexan = Godly unbreakable hockey glass
People think that both of these are "plexiglass" and end up asking the home depot guy for the wrong stuff. I have made this mistake myself.
Teque501.5.09 - 11:52 am
reply
let me know if you're going to work on this at the BRW. I'd love to swing by and help you laquer.
tortuga_veloce01.5.09 - 11:53 am
reply
I was dooling and came up with an awesome upgrade to your cabinet design. Very similar to what you have, but here it is. - This is in addition to your battery/amp obviously -
(1) 10" Sub
(2) 6" Midranges
(1) Cerametallic Tweeter
The second part of the image is how you would split the chambers inside the cabinet. If you email me i can calculate cabinet volumes for you or help you put together some better specs.
teque5 at g mail dot com
Excuse the quality, it took a picture from my phone and i dont have photoshop at my work (just shitty free gimp).
Teque501.5.09 - 12:26 pm
reply
oh also:
Orange County Speaker has really good deals and are within driving range if you want to build this sucker soon. They have a huge range of drivers. They do stadium speakers to home theatres and their store is HEUJ. I have made many a purchase there.
Teque501.5.09 - 12:30 pm
reply
Teque5, I like your design. I designed mine to use minimal math, and cheap full range components that don't require x-overs.
That being said, I'll make the crossovers if needed. I have tons of parts around to build something custom.
When it's done I can plot it's frequency response in a quasi anechoic environment to see how well it turned out.
Mook01.5.09 - 6:50 pm
reply
Seems like you would want more than one tweeter since they're very directional, easy to mount, and don't use alot of power.
On the speaker cabinets. Isn't there some open source software that helps you design your cabinet? I recall running across something like that before. I think it was on the parts supply link above.
User101.6.09 - 1:02 am
reply
yeah there is some cool cabinet software, but he says he doesn't want anythink complicated.
mook: just make sure you dont put your speakers opposite one another like in your sketch - you would effectively be losing dBs and increasing distortion in the process. Even putting a divider down the middle would help your sound.
I would so love to see an audiophile level speaker system on midnight ridazz. As an engineer i just start fantasizing whenever i see some guy with some 50$ circuit city car-audio kit in front of my playing tunes. I have some extra acoustic research speakers from the 80s that i refurbished and would be the MOST BADASS trailer setup ever, but it would weigh like 250lbs. :( Some day maybe.
But i do love music on the rides, even from the circuit-city car-audio kit.
Teque501.6.09 - 2:42 am
reply
I'm thinking about this. Taking mook and teques design and making THIS ---->
I would be using all the speakers i already have and in much more of a compact way! YES!!!
What ya think?
richtotheie01.6.09 - 11:39 am
reply
whoops my post got cut off..
i was going to say that you should only incorporate a
ported design in the subwoofer cabinet, if at all. They can be tricky to tune for the appropriate cabinet volume, but can sometimes be beneficial.
Teque501.6.09 - 2:07 pm
reply
Distortion in loudspeaker systems is negligible. The crappy fidelity of an iPod after 50+ watts or amplification will add more artifacts than a poorly designed cabinet.
Speakers radiating 180 degrees off axis will create loss, but would only really matter if your in a room with reflections. We are outside, with few reflections.
My original specifications called for the source program reproduction device to be summed together with two 1K resistors. You could also do it actively with a single IC (NE5532). This will improve frequency response.
Ritchie-
Mounting the HF drivers away from the others off-axis like that is not recommended, people might not want to ride behind the cabinet, and I think it will sound really fucked up. Because they are "far" apart, you will get a short delay from one set of drivers to another as the information reaches your ear.
Mook01.6.09 - 2:29 pm
reply
Can we build a system that's 100 lbs or less? I think the cabinet can also be the trailer if built right. Also getting away from lead acid batteries would help.
User101.6.09 - 2:55 pm
reply
the thing is that i do'nt want to BUY anymore!!! (besides the wood for the cabinet)
I have a 700w amp with 2 crossovers and one dedicated sub channel.
http://www.sonicelectronix.com/item_9833_TIS+Audio+T510PK.html
Thats the amp.
i figure that i can use the dedicated sub for the single 12" woofer that i already own, 2 channels for the 10" and than one other channel for the tweeters.
Here is what used to be my setup (see picture)
And it sounded great. All coming from one channel, mono sound, and solid. Because of that, i feel confident in being able to find a good balance in a new cabinet. Is that what the issue would be right now with that design?
richtotheie01.6.09 - 5:44 pm
reply
"Also getting away from lead acid batteries would help."
well unfortunately there really isn't any way to get away from lead acid without doing some really fancy shit. A typical small car battery has the capacity of about 540 watt-hours. It would take about 60
lithium-ion cells to do an equivalent job. And it would require some crazy charger for it too.
A $65 car battery vs. $90 in cells (+ $30? for a charger) for the fancy lithium ion solution. It would be cool though. But I think it would involve more work than this builder wants.
Teque501.6.09 - 5:52 pm
reply
actually your old setup looks pretty sweet
Teque501.6.09 - 5:54 pm
reply
Ritchie let me put you in contact with my colleague. We were going to build a trailer too on a tandem bike.
Our trailer would include a sound system, mixer and an RF out, meaning a radio transmission strong enough for those in the perimeter of the ride to catch the music on their boomboxes and blast it.
Decentralized speakers is where the music is at.
He'll contact you on facebook.
Mohicano01.6.09 - 5:57 pm
reply
I have a sheet of 3/4 ply you can have if you want it. 1/2" would be lighter but I don't have that material laying around. Heavy = Free. I could even cut it into the sizes you need as long as it isn't super-complicated compound angles and shit. Those make me crazy.
frumble01.6.09 - 6:02 pm
reply
OOOO LALAAA!!!! That would be awesome frumble!!! Whats yer email?
mine is richtotheie @ gmail . com
DECENTRALIZED SOUND!! YESSSSSSSSS!!!!!!!!!!!
richtotheie01.6.09 - 6:24 pm
reply
just keeping the thread alive
Teque501.7.09 - 2:04 pm
reply
thanks!! I'm pickin up the PLYwood next week from Jason! Should be done for C.R.A.N.K. MOB!!!!!!!
richtotheie01.7.09 - 2:07 pm
reply
Man.... this is the best "sound systems" thread out there! I'm totally trying to read up all the stuff you guys are saying... so much good info.
digablesoul01.8.09 - 12:52 am
reply
Teque5 or anyone else,
What do you know about class-d amps? There's other classes now that are even more efficient yeah? What's the price of some of these amps?
User101.8.09 - 10:08 pm
reply
-->
Ridazz Roulette!
COMPARTMENTS FOR EACH SPEAKER.