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Tuning Frequency question.

Discussion in 'Amps and Cabs [BG]' started by Doodaddy, Jan 22, 2005.


  1. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    I'm building a cab for 4 Eminence Beta 12's. What tuning frequency and cubic feet should I do for a *smooth* response down to 35hz or so? It's for a 4 string player, but I don't want 40hz for the E string to limit him. He may play in drop D occasionaly.

    Not looking for flat response. Just a slow roll from around 90 to 35hz. Any suggestions?
     
  2. msquared

    msquared

    Sep 19, 2004
    Kansas City
    Download WinISD. Find out the Thiele Small values for your drivers. Add water, mix, voila!
     
  3. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    WinISD. lol. I build lot's of enclosures for vehicles. I know from experience, that WinISD is one of the most inaccurate programs.

    Anyways, it suggested 41cf tuned to 0. Some program. :p

    I'm just asking for a general tuning frequency for a four string player. He's not a perfectionist and won't be able to tell a huge difference in sound.
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The first suggestion is don't use Beta 12s. With a miniscule Xmax of only .8mm they are totally unsuited for bass.

    After you've downloaded WinISD try it with a variety of drivers to find what works for you, but don't use one with an Xmax of less than 3mm, and preferably more. By the way, nearly all of Eminences driver specs are in the WinISD driver base, so it's a very easy job to compare them. For a smooth rolloff make sure to use sealed box configurations only, not vented.
     
  5. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    This is not for me. The Beta's were given to him. He is 15 and doesn't really have much of a choice.

    *Not using WinISD*. I have other programs that are much more accurate.

    When I said smooth, I mean not a steep peak in the response.I understand that vented boxes have a peak, but so do sealed boxes. ;).

    Just asking for experience with ya'lls cabs.
     
  6. msquared

    msquared

    Sep 19, 2004
    Kansas City
    Just out of curiousity, what other programs are you using which you prefer over WinISD? Do you have some horror stories about it that you'd like to share? :)

    And don't take this the wrong way, but why would you ask a public web forum and trust our opinions over that of a piece of software designed to do specifically what you're asking?
     
  7. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    I am on another forum that extensivley builds boxes.

    www.caraudioforum.com

    Not only have I found it inaccurate, people on that forum, users and people that have an online business just for building boxes, have too.

    I'm using a program called box-port design. I occasionally use a homemade program that someone on the forum made. Neither are perfection, but when compared to Bass Box Pro (a program sold for around $100 at www.partsexpress.com) there isn't a audible difference. While WinISD wasn't consistent at all.

    I have no horror stories, because I avoid the program completely.

    As for asking your opinions, people with experience with tuning cabs for playing bass guitar plays a better part in making a decision than the specifically engineered program building the box all together. ;)

    Just stating my experiences. :)
     
  8. Jim York

    Jim York

    Oct 27, 2004
    As already noted you're wasting your time and efforts even considering the Beta 12s. Just because that's what you friend has is no justification for throwing good money after bad on a cab that just won't work. Have him sell the drivers to a guitarist who can use them and get the right tools for the job. No one uses Beta 12s in bass cabs.
    I've always found WinISD to be very accurate for pro-sound use. I can see it being less than useful for autosound. The needs for cabs in autosound where cabin gain is responsible for most of the output below 100Hz has no relevance to pro-sound, where cabin gain is non-existent.
     
  9. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    Unless they made some typo's in the WinISD software, they are using the same formula's as everyone else. Those formula's may not be the best choice for car audio because the don't include cabin effect, but it doesn't make the formulas inaccurate. It just makes that the wrong tool for your specific application.
     
  10. msquared

    msquared

    Sep 19, 2004
    Kansas City
    Exactly. When building car boxes, you have an entirely different environment to consider than if you are building for a pro sound (or home theater) application. I would love to see some concrete evidence of inaccuracy with WinISD since I use it a lot though.

    I ran the Eminence Beta 12s and it looks like you're going to need almost 30 cubic feet of interior volume tuned to around 44Hz to get a useful response out of them. Even then the group delay at 41Hz (around where your buddy's open E is) will be pretty bad. Seriously, you're not doing this guy a favor by building him a box for these. Have him ebay them or something and get a better driver for the task at hand.
     
  11. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    I'll suggest it too him, but this is a very rural community. (I graduated with 32 people). He doesn't really have a market for them, but I'll see what he says.

    I know cabin gain comes into effect. I would guess that room gain, although much smaller effectively, would pose a problem on small gigs. The inaccuracy of WinISD I was referring to was not the frequency chart, but the port length all together. But this is beside the point. ;)


    The only experience I have is with Car Audio. I just applied that to pro sound and wasn't exactly right? :meh: WinISD may be usefull in pro sound. I don't know. I was just assuming since it was worthless in my area, it would somewhat carry over.

    30cf? :eek: That's rather..........huge. :eyebrow: That's crazy. Why would Eminence make such a useless driver?

    As far as Ebay goes, what do you think he would be able to get for them; if they sell at all? I'll talk to him about it. More than likely, he will ignore me.

    I'm not building the cab because of me being in college and not building boxes/cabs anymore due to time. I still give people plans to do them theirselves.

    You guys are being great help and it is much appreciated.
     
  12. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    Given that the Beta 12 is a bad choice for the application, I would suggest building a cab for a different application. Make a 4x12 closed-back guitar cab, in whatever shape Marshall normally makes (or a pair of 2x12's). Perhaps someday he can swap it to a guitar player for something useful.

    They only have 18mm of XMech so he might destroy them no matter what you do with them (but with tiny magnets they may never move the cones that far). They will sound lousy for bass, but perhaps better than what he is using. You're fresh out of "good" choices.
     
  13. Doodaddy

    Doodaddy Supporting Member

    Jan 11, 2005
    West Monroe, LA
    Are they intended for electric guitar cabs? Would that be "decent"? I'll see what he says.
     
  14. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    "Performance optimized for sound reinforcement systems. Also suitable for lead and bass guitar, keyboards, guitar combos, club music systems, and stage monitors. "

    http://editweb.iglou.com/eminence/eminence/pages/products02/speakers/beta12.htm

    They have a big hump between 1-5k where they approach 100db sensitivity. I'd say they'd fit in PA monitors or low end guitar combo's. They look to me like a small magnet, working a short voice coil; not much for low's, but if you put them in a closed box, they would have a better chance for bass than open back. The Qts is pretty high to go in a ported box.

    They'll start to distort pretty fast when pushed hard and they exceed Xmax; hopefully the user stops before getting to Xmech and mashing the coils. "Decent" is a personal call. What MIGHT work well, is to put a 125hz low-pass on them and feed them in parallel with a cab that goes low.
     
  15. msquared

    msquared

    Sep 19, 2004
    Kansas City
    Eminence makes some good stuff, so I'm guessing that a driver with those specs is useful for someone. Guitarists with regular six string guitars tuned normally will bottom out frequency-wise at 82.41Hz for instance. If you put those four speakers into a sealed box that's got an internal volume of 11500 cubic inches (which just happens to be roughly the same volume as a Marshall 4x12 cab), it turns out that the -3db point is around 81Hz with a very low peak group delay of 3.22ms at the -3db frequency. Perfect for your average rock guitarist. So it would seem that these speakers were designed with guitarists in mind rather than bassists.

    Looking on ebay it doesn't seem that there's much of a market at all for this specific speaker, so I guess he's out of luck there. I would think that the best move he could make would be to build a guitar cabinet out of these and try to sell it to a guitar player, which would hopefully get him enough coin to do something useful with. But as others have noted, he's almost certainly going to wreck these speakers if he tries building a bass cabinet out of them. He may not like it, but one can't argue with physics.