Results 1 to 16 of 16

Thread: Bose 302 subwoofer rebuildable?

  1. #1
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like

    Bose 302 subwoofer rebuildable?

    Hello again friends!

    This is the second time I have spoken on this subwoofer. The first was to ask what you thought it was worth. After talking to the previous owner of the box, we traded some gear for it. I had an old MRC 16 box that I haven't used in two years and he wanted it so we traded.

    See the pics below for the problem:

    I was wondering if someone had an idea of what drivers to replace these with. I would like to get a good sounding box out of it after it's all said and done. I don't mind spending several hundred dollars if I will be able to get use out of it for quite some time. I would be using it in conjunction with the L1 Model 1's for mainly weddings but would LIKE to get decent bass out of it if possible.

    Budget around 400-600 dollars for passive.

    Is there a way to make this baby active, maybe with a built in crossover? If so my budget could increase another 200-400 dollars.

    I already have plans to get it sprayed with the rhino lining and all the components are already out of the box.

    Any help is greatly appreciated! (Barry, I ask that you put aside your previously talked about bias and share your knowledge. I know you will have some interesting ideas!)

    This thing is 26 years old, and has lasted this long, so I don't want to put it in the graveyard just yet! I like nostalgia pieces if you will.
    Attached Images Attached Images
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  2. #2
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    Here are a few more pics.
    Attached Images Attached Images
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  3. #3
    Join Date
    Jun 2009
    Posts
    125
    Post Thanks / Like
    Why replace them? Why not re-cone them? Have you called around to see if you can get a kit? I have really old Community VBS-415's that you can still get recone kits for.

    Call around. I'm sure someone has them.

  4. Thanks musicjeopardy thanked for this post
  5. #4
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    Quote Originally Posted by musicjeopardy View Post
    Any help is greatly appreciated! (Barry, I ask that you put aside your previously talked about bias and share your knowledge. I know you will have some interesting ideas!)

    This thing is 26 years old, and has lasted this long, so I don't want to put it in the graveyard just yet! I like nostalgia pieces if you will.
    OK, now lets get some of this BOSE stuff out of the way... heh.

    Seriously... what I think you need to do is determine the box volume (grab the ruler), and from that you can try to mathematically fit a variety of available drivers to see whose Thiele-Small specs will allow the driver to work properly with that box volume.

    You'll also need to modify or add properly tuned ports (adjust diameter & length) to tune that enclosure for the driver you want to put in it. BTW - the ports can be small diameter and small length, or large diameter and larger length and have the same tuning. Ideally you want about as much port surface area as driver surface area... provided you can tolerate the needed port length in the enclosure.

    I am assuming that this old box is sturdy, solid and built like a tank. If it isn't, it just won't be a great subwoofer enclosure no matter what you do.

    So, figure the box volume (cubic litres or cu ft) and somebody like myself, or harmonycat, or others who know the TS math can help you find a compatible driver.

    Now... is it worth it? I don't know...

  6. Thanks musicjeopardy thanked for this post
  7. #5
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    Quote Originally Posted by Booms View Post
    Why replace them? Why not re-cone them? Have you called around to see if you can get a kit? I have really old Community VBS-415's that you can still get recone kits for.

    Call around. I'm sure someone has them.
    Bose sells a recone kit for 50 bucks each. It might be the way to go but if I'm gonna rebuild it, i was trying to see if there was an alternative that may have bigger kahona's.
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  8. #6
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    Quote Originally Posted by Booms View Post
    Why replace them? Why not re-cone them? Have you called around to see if you can get a kit? I have really old Community VBS-415's that you can still get recone kits for.

    Call around. I'm sure someone has them.
    Because they're el-crapco Bose stamped frame woofers with foam surrounds like cheapie hifi woofers.

    Reconing these things would be like putting $40k worth of pimping into a rusty 1976 Ford Pinto.

    Also, due the the age and the Boseness I seriously doubt that there was any serious science involved in the original design. It shouldn't take much to create a superior sounding box than this thing was originally... provided that the cabinet is solid and it's worth the cost of some good prosound drivers, a handfull of fibreglass (the not-so-itchy stuff, please) and a bit of cabinet work to set up the tuning.

  9. Thanks musicjeopardy thanked for this post
  10. #7
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    ...if you want to make a cheap active box, folks like partsexpress offer plate amplifiers
    http://www.parts-express.com/wizards...AT&srchCat=505

    One of these larger plate amp units may work ok, but they are marketed at the home hi-fi segment, not for pro-sound use which is more demanding - so I'd certainly go larger than smaller. I'd have most comfort if this thing was driven by Crown, Crest, QSC etc.

    If it were me, I think I'd be considering some kind of setup where I had an electronic crossover in my rack, feeding the highs (>100 hz) to the L1s, and the lows to the amp that's driving this box. Usually when you have the mains trying to reproduce the same frequencies as the sub, the system has irregularities in the bass response and just doesn't sound proper. Of course, the L1s already probably filter the lows out of the columns.

  11. Thanks musicjeopardy thanked for this post
  12. #8
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    Here is the specs for this box, the measurements are more than likely ouside measurements. I am pretty handy with saws and drills too. I not only own them, I use them too!

    Nominal impedance: 4 Ohms
    Power handling: 400 Watts RMS
    Sensitivity: 98dB SPL (1W, 1metre)
    Filter: 180Hz low pass
    Dimensions: 810 x 580 x 410mm
    Weight: 52kg

    The box really is built like a tank. It was purchased new and once it was in this venue, it never left until I brought it home 26 years later. The ports in the front are fairly large. Look at the 4th pic in the first set, There is more cu/ft on the back side of the woofer that the front side.

    You are correct, the L1's to the best of my knowledge already filter the lows out of the towers.

    These drivers seem to be pretty impressive and cost effective!

    http://www.peavey.com/products/brows...0SPS%20BWX.cfm


    I would feel better with names like crown too if I go the active route or wait until the new Peavey amps come out. At 7 lbs for 200 watts, these will be hard to beat. the 1600 watt version is 7 lbs and 299.00.
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  13. #9
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    That box is a bit of a funky design. I'd try to modify it's chambers so it's a standard enclosure (without the angled funky stuff) holding one or two woofers. This will also give you a bit more interior volume, which is a good thing.

    I'm suggesting a 4th order ported enclosure because I think it's the best compromise. Sealed boxes are not very efficient (unsuitable for PA duty), you really can't modify this thing to be a horn, and it's unlikely you're prepared to construct companion customized active filters to support a complex 6th order design.

    Small box, Big SPL/High Efficiency, Deep Bass - you may (only) have TWO.

    Figure the interior volume that each driver will have, and then you can run the numbers on a few drivers (using specs like vas, qts, qes, qms, fs, ro etc) which are provided by all the better speaker manufacturers to see what driver will live happily in that box. You can totally predict system performance mathematically.

    That peavey driver looks nice, and it may BE nice... but you can't tell how it will behave in your box until you run the numbers.

    I might do some speaker shopping at http://www.usspeaker.com looking for cast frame woofers, preferably with accordion style or rubber (not foam!!) surrounds, and ample magnet structure (although it IS possible to have too much magnet for some applications, making the Q too high).

    I wouldn't be at all surprised if you call the customer service folks at usspeaker, madisound, partsexpress -- or the driver companies like 18-sound, RCF, JBL, EV, Eminence etc on a slow day, and tell them the enclosure volume, and they may be willing to do some of the legwork for you and suggest compatible drivers.

  14. Thanks musicjeopardy thanked for this post
  15. #10
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    Just broke out the ruler!
    Each driver has 3248 cubic inches of airspace. (16x14x14.5)
    and approximately 29.75 square inces of port. (4.25 X 7)

    Measurements are with NO fiberglass fill.
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  16. #11
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    Quote Originally Posted by musicjeopardy View Post
    Just broke out the ruler!
    Each driver has 3248 cubic inches of airspace. (16x14x14.5)
    and approximately 29.75 square inces of port. (4.25 X 7)

    Measurements are with NO fiberglass fill.
    OK, so that's about 1.9 cu-ft, and I'll call it 2.1 cu ft with fiberfill (stuffing makes the box appear a bit bigger).

    I'll poke around to see if I can find a 12" woofer will live in that space, and give you decent results.

  17. #12
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    I'm assuming each driver has it's own sealed space of 2.1cu ft.

    OK, after running a handful of drivers, the best fit (I've seen yet) is a Beyma 12BR70 ($125/ea). Put in a port tube that is 4" diameter and 8" long, or 4x4 square and 10" long. Line the interior with fiberglass. Get some 4-6" thick stuff without the paper backing. Staple it to the cabinet to hold it in place. The white stuff seems less itchy than the pink...

    I could not find many nice drivers that offer response below 60hz in that box, and I tried to stay away from really expensive choices (> $275/ea).

    This will be flat to 50hz, and -10db at 35hz. Should offer deep bass. Should be in the ballpark of 97-98db/w/m, 250w RMS/500w program. I suspect it will have plenty of output for a pair of L1s.

    Remove all the crossover junk in the box, and wire these two speakers parallel. It will be 4-ohms at the terminals. Use a 500+ watt plate amp with built in subfilter, or an external amp w/ filter or electronic crossover.

    Good thumpin to ya

    If you go for it... please let us know how the results are.

    -Barry
    Attached Images Attached Images

  18. Thanks musicjeopardy thanked for this post
  19. #13
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    Quote Originally Posted by barryw View Post
    I'm assuming each driver has it's own sealed space of 2.1cu ft.

    OK, after running a handful of drivers, the best fit (I've seen yet) is a Beyma 12BR70 ($125/ea). Put in a port tube that is 4" diameter and 8" long, or 4x4 square and 10" long. Line the interior with fiberglass. Get some 4-6" thick stuff without the paper backing. Staple it to the cabinet to hold it in place. The white stuff seems less itchy than the pink...

    I could not find many nice drivers that offer response below 60hz in that box, and I tried to stay away from really expensive choices (> $275/ea).

    This will be flat to 50hz, and -10db at 35hz. Should offer deep bass. Should be in the ballpark of 97-98db/w/m, 250w RMS/500w program. I suspect it will have plenty of output for a pair of L1s.

    Remove all the crossover junk in the box, and wire these two speakers parallel. It will be 4-ohms at the terminals. Use a 500+ watt plate amp with built in subfilter, or an external amp w/ filter or electronic crossover.

    Good thumpin to ya

    If you go for it... please let us know how the results are.

    -Barry
    Yes Barry, each driver has that amount of space. My question is this:

    Are you saying it needs to be ported 4" x 8" in addition to the already 4.25" x 7" that each space already has?

    And If so, I assume I would need that size port for both drivers?

    Thanks,

    Dan
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  20. #14
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    Quote Originally Posted by musicjeopardy View Post
    Yes Barry, each driver has that amount of space. My question is this:

    Are you saying it needs to be ported 4" x 8" in addition to the already 4.25" x 7" that each space already has?

    And If so, I assume I would need that size port for both drivers?

    Thanks,

    Dan
    Each woofer needs one port, that is about 4" square x 10" long. Perhaps you can add onto the existing port to extend it's length a few inches. If not, maybe we can recalculate the port opening size to match your existing length and you can line the interior of the port with a slice of wood to get it to the right surface area to work with it's existing length.

  21. Thanks musicjeopardy thanked for this post
  22. #15
    Join Date
    Dec 2005
    Location
    St. Louis, MO
    Posts
    1,252
    Post Thanks / Like
    So as is, I need a total amount of port to equal 40 square inches correct? I currently have 29.75 so I would need to add 10.25 square inches.

    I am seeing 2 options:

    1) use a hole saw bit to cut 2 holes in the side of the box to increase the port 10.25 square inches.

    2) add a piece of wood to reconfigure the inside cu/ft of space.

    I would rather add because I think it may look out of place to have 2 holes on one side of the box.

    What are your suggestions to fabricate the box and leave the current porting at 29.75 sq/in per chamber?

    Thanks!

    Dan
    Quote Originally Posted by mixmastermachom View Post
    God help me be a professional here and not bust their ass.

  23. #16
    Join Date
    Sep 2006
    Location
    Mpls/St Paul-Minnesota
    Posts
    3,496
    Post Thanks / Like
    Quote Originally Posted by musicjeopardy View Post
    So as is, I need a total amount of port to equal 40 square inches correct? I currently have 29.75 so I would need to add 10.25 square inches.

    ...what are your suggestions to fabricate the box and leave the current porting at 29.75 sq/in per chamber?
    Sorry for any confusion...

    OK, if you want a port that has an opening of 4.25 x 7 then the length needs to be 20 inches long to get the right tuning. But, I don't think you can fit a 20" pipe into that box.

    Ideally you want a big port, so it has enough output and so that the wind velocity is slow enough that it doesn't whistle. But, you can get away with much smaller ports, but lets stay 3" diameter or bigger.

    Maybe it would be simpler to fit a piece of wood to seal up the existing port hole, and insert a 4" diameter piece of PVC pipe that is 7-1/4" long. Paint it all gloss black... nobody will know

    ...of course, both chambers need similar treatment.

  24. Thanks musicjeopardy thanked for this post

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •