anybody whos built a sub

Discussion in 'Amps and Cabs [BG]' started by leper, Jul 29, 2001.

  1. leper

    leper Guest

    Jun 21, 2001
    just wondering what drivers some of you guys have used to build your own subs? I havent invested any money into materials yet, so Im just curious what drivers some of the more experienced people here (joris, bgavin) have used...
  2. I assume you are inquiring about true subwoofers and not just bass drivers. My definition of subwoofers is generally flat down to 31 Hz (low B) or lower.

    I use Rockford and JBL. The older series Rockfords RFR-2210, RFR-2212, RFR-2215 are year 2000 models and getting hard to find. I much prefer this model in 10" (rfr-2210) over the current new model (rfr-3110).

    Another sleeper is the JBL GT-1041d series car subwoofers. They need more cabinet volume than the Rockfords, but they can be had for $65 each on eBay right now. I scored one a few days back for $15.67 (!) just to play with it. The specs are good, and I figure it will perform well.

    Every single one of these subwoofers is power hungry. Check out the threads in the Amp section on the Carvin RL118, and the Ports and Vents. There is a lot of discussion going on now in these two threads.
  3. Hey, this has nothing to do with your question (the title fooled me for a second there...) but it got me thinking...

    ...well, it's an interesting site anyway (check on the animation as the mouse goes over the links in the left table...

    I think those kids did a great job...

    - Wil
  4. leper

    leper Guest

    Jun 21, 2001
    cant seem to find those anywhere...

    been workin with winISD today and came up with this:

    2 infinity perfect 12s in 221 liters. would handle 700 watts, be 2 ohms, and be -3db at 20hz :). 99db 1w1m

    also, one more question...if i brought a drawing to a cabinet builder how much would it cost to have them build the cab (i would wire etc)?

    and one more thing ...if it was built out of 1" mdf would I still have to brace it?
  5. merlin

    merlin Guest

    want cheap subs.. they are American so its a pain in the ass for me. They have 18 inch subs starting from $37! the response and specs aren't too bad.

    go to products i think.

  6. Having been through the Big Cabinet thing, how about putting them into two cabinets? If you are going to design properly, you must have the correct volume either way, and two smaller cabs are easier to handle than one big one.

    I'd be very careful about the 2 ohm thing. Many amps won't go there. But, I am guessing these 12s are 4-ohm coils, so you could wire them in series for an 8 ohm load.

    Always :D
  7. leper

    leper Guest

    Jun 21, 2001
    as for the cabinets being big, I probably should have mentioned that Im 6 foot 2, 250 pounds...big and heavy is my natural inclination :)

    they would be the same size as my goliath sr, but two inches deeper. I dont have a problem with the sr, so its not a big deal for me.

    the 2 ohms thing should be ok cuz ill be using them with a crest 6001 (purchasing soon), and an sm400s, both of which deal with 2 ohm loads without hesitation.

    so, since im still going to need to brace...what is the best way to set that up? X brace the panels? connect oposite sides together?

    and while im asking questions, i figure ill ask something I havent seen anyone cover in any of the recent threads (ports/vents, carvin18, and cab 101)...

    Whats the deal with dampening material? Do you need to use it always? sometimes...if then in what situations? how much? where? Basically gimme the low down ;)
  8. Yeah, but the L5 disc in your back is about the size of a marble, same as us runts' :D

    Sounds like you have it thought out. I can live with my 31.5" x 21.5 x 20 sub cabinets ok, it's my 165 pound rack that gives me no end of grief.

    Two things about 2-ohms: it puts the most stress on the amp, and makes it work the hardest. 2-ohms is NOT bridgeable. When you bridge, each channel is combined, but each channel sees only have the impedance of the load. An 2 ohm cabinet is seen by each amp channel as 1 ohms when bridged. Not acceptable, and will smoke the amp.

    Bracing is an "as needed" adventure. 3/4" MDF will cure a lot of buzzing issues, but is heavy. I did a cross brace inside my 15" cabs, speaker board to back board, the left-to-right. All my joints are cleated and glued/screwed. The cross is glued/screwed at the junction. When you are done and testing the cab, if you notice any buzzing, you will have to brace. Buzzing is a power loss. Use a mechanics' stethoscope to find buzzing and any air leaks. Be careful of your ears.

    Bass cabinets do not have problems with internal standing waves because the wavelengths are so long. They are immune to shapes (cubes, etc) that would ruin a higher frequency cab. The damping material isn't really necessary in a bass cab. If you install, a single layer on all surfaces except the speaker board is just fine. If you stuff the cab full of material, you will change the tuning of the cab, as it makes the cab about 20% larger, acoustically.

    The single most important item to pay attention to is the port. It must be sufficiently sized to avoid port noise from excess air velocity. The port should not be obstructed, and should not be any closer than 1 diameter to any cabinet wall.

    This link will get you right for port size. This is also where you are going to do the most head scratching because big ports require long ducts. It is perfectly acceptable to bend the port inside the cabinet 90 degrees. Get your pvc and elbows from a sprinkler supply yard, not Home Depot. Much better selection, and cheaper too.
  9. leper

    leper Guest

    Jun 21, 2001
    wow...ive actually retained all the stuff ive read here over the past few weeks, cuz I was like "yeah, i know this cool!" when readin the parts of your post concerning the whole 2 ohms/bridging issue, and the port stuff.

    I probably should have explained the 2 ohms thing better...theyrll be 2 of these cabs, only brought to some of the large rooms we play in...small stuff, or places with a big ass pa will be only the gol sr. so, im not bridging the crest, but using it parallel mono, where its fine at 2 ohms.

    I have rough figures on ports from winISD, just need to sit down and figure things out real precisely.

    Thanks for the info on bracing, dampening, and all the knowledge youve dished out in this thread, and in the other speaker construction threads. I really appreciate not having to search for hours for an answer to a relatively simple question. all hail the speaker construction gods!

    ps, as for bridging into 2 ohms, some amps can do it...its pretty common in nice car amps. As for pro sound amps...i know the crest 10001 can bridge into 2 ohms delivering 15000 watts (!!!!!!!!!!!!!!!!!!!!)