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specs for a speaker

Discussion in 'Amps and Cabs [BG]' started by Count Bassie, Aug 27, 2007.


  1. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    Hey folks, I'm on a quest:

    I modified an old Peavey 2x15 band-pass cab, and now I want to tune it properly. I am scouting around for the Thiele-Small parameters for a Peavey Black Widow 1502-8, so I can run the specs on WinISD and get some narrowed-down posibilities for tuning the cab's response.

    Anyone happen to have a spec sheet handy?

    Thanks!... here's the auld beastie:
    DSCN7434.
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Peavey specs can be found on the Peavey site.
     
  3. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    I'll go back and dig, thanks.
     
  4. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Just on recollection that driver would sit pretty nice in about 2.6 cf apiece and tuned to 58 Hz. I like the 1505-8 better, in the same size (2.6 cf) tuned to 48 Hz. Farts less easily and has a little more upper mid presence on-axis.
     
  5. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    Okay, I don't know off-hand what cf is, but if it's volume of space then there' more than that right now. I've got the specs for the 1502 handy in the "Favorites" Explorer button, and tonight I'll spend a few minutes with it, and download WinISD...

    I have noticed the 1502 gets some 'brap' with a little provocation. I'm going to tune this as tight as I can, then move to the next level. I did see that link to the Carvin LS series PA cab (you mentioned its usefulness as a bass guitar cab). That might be interesting, if this doesn't work out well enough. Then there's the Schroeder idea... that's an investment of a higher caliber. But I played one- very nice.
     
  6. jtc_hunter

    jtc_hunter

    Feb 16, 2007
    Just for comparison , I have a 1505-4 ohm in just an old TNT combo casing(NO AMP SECTION) and use it as a practice room cab w/ a GK head. It can take 150-200 watts continously w/ alot of lows and never skip a beat. It really suprised me. I thought it would fart out alot sooner. Peavey stuff is underatted and very tough.
     
  7. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I don't recall off-hand which Peavey drivers were built this way, but quite a few of their 4-ohm drivers are like the 8-ohm versions save for one thing: they shortened the voice coil of the 8-ohm build by about half to achieve the 4-ohm rating. This means the 4-ohm versions run out of useful excursion that much earlier. In other words, with those driver models the 8-ohm versions have better xmax.

    Since Peavey baskets are interchangable on the magnet structure of that type I strongly recommend checking out their printed 2007 speaker component guide (available from Peavey or a dealer) to compare the xmax. And anyone who is using say the 1502-4 I really would say they would find more performance and possibly a better tonal signature from the 1505-8.
     
  8. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    So you guys generally are favoring the 1505-8 over the 1502-8, it appears... better efficiency, yes?
     
  9. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    No. The 1502 are actually around a dB more sensitive. But look at it this way: if you have more than 150 watts per driver you can actually get more SPL out of the 1505 because they don't run out of xmax - in fact they'll take almost 3 times the wattage before running out of useful excursion. When amps often only had a couple hundred watts the 1502 made more sense. But now that most people have more watts at their disposal the 1505 will actually allow them to use it.

    Truth be told a better retrofit would be a couple of Kappalite 3015 (not the LF version in this case! - I think you box is probably too small for that). The 3015 would have the great sensitivity of the 1502, more power handling and more excursion than either the way-old designs of the 1502 or 1505, and has the upper-midrnage bite of the 1505. It'd also allow you to shave over 18 pounds of cab weight!
     
  10. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    If something like that were to work out, it'd be much more favorable than buying a whole new cab... the point of this experiment in the first place. I'll look into that, I think. Thanks!
     
  11. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    What's the internal dimensions on that cab, Count? And what are the port dimensions?
     
  12. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    Inside the box is approx:
    15"+W x 17"D x 15 1/4"D

    Ports (2 per speaker) are 4"W x 5"D

    I cut a slot about 2" x 12" or so into the partition between the chambers, so air now passese between them- they're not really individual chambers anymore.

    The original baffle wall that the speakers were internally mounted on are still in there, eating up just a little bit of that internal volume.

    As a band-pass box (originally an RBS-1) the tuning freq is written as 65 & 85 Hz.
     
  13. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I'll try to do some calcs tonight.

    There is probably some problematic port interaction going there. I'd enlarge that cut until the panel is acting as a brace and not a slot port between subcabs. I'd cut some slots or holes with bracing strength between them so that it doesn't do that.

    That still has two 15" cutouts? You could cut a bunch more holes in it in such a way as to not lose integral strenght but gain a little more open space.
     
  14. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    P.S. The internal dimensions I wrote here happen 2x- one set of numbers for each chamber. You probably figured that out- but just for clarity...

    Thanks, greenboy! We've been in house-re-hab hell here, and I've had no actual time to get into any of this (just got the kids' rooms plastered and painted in time for school's starting). I'm gigging a good bit though, and thought I'd throw this "out there" and see what came back. Not trying to get others to do the work for me! I'm looking into that WinISD this evening, if I can get to it.

    Anyway, I do appreciate the contribution of your time! :cool:
     
  15. PJaye

    PJaye

    Feb 2, 2004
    Boston/Worcester
  16. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    I found these on another site yesterday- but that's great, thank you!

    I may find this link comes in handy for another project... I have some blown Eminence 10s that might need a purpose someday.
     
  17. Thor

    Thor Moderator Staff Member Gold Supporting Member In Memoriam

    I'll email you over my copy of winISD, I have it here at work
    in some amp folder somewhere.
     
  18. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    Dude, you are the ****. Thanks Thor!
     
  19. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I'd say the few extra minutes learning to enter T-S params in the correct order in WinISD Pro is well worth it. Download it at linearteam's site - Pro shows you much more about what's going on with any driver and cab. The cone excursion stuff alone makes it worth going that route.

    As far as Peavey T-S params, as I said somewhere the 2007 Peavey transducer components guide can be had from Peavey or a Peavey dealer, and is comprehensive.
     
  20. Count Bassie

    Count Bassie Supporting Member

    Jun 10, 2006
    Smithfield, RI
    I'm fooling with it now, though it's going to take a little curve here to get it. I did the T/S params I have, and plugged in the dimensions of a box, shape of ports, etc... now getting an answer I can understand is the trip!

    Help Files... thanks guys for the directions and links! I'll post a success story when I have one!
     

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