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Building a cabinet....

Discussion in 'Amps and Cabs [BG]' started by Hi_Im_Mark, May 26, 2003.


  1. Hi_Im_Mark

    Hi_Im_Mark

    Mar 9, 2003
    Hey...I'm new to the whole Bass Guitar scene and I'm currently in the market for a bigger and better amp. I was browsing through various speaker cabinets and enclosures and realized that it doesn't seem too difficult to build a large cabinet. I have an extensive background in building enclosures, but only for car audio systems. Ie. Subwoofers and such.
    I was just curious to find out what type of speakers are generally used in Bass cabinets?
    Not really brand names, but more specifically speaker specifications.
    Any help would be greatly appreciated.

    Thanx,
    -=Mark=-
     
  2. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    Use the Search feature on this board for a lot of good info. "Cabinet Building 101" was an excellent and long thread.

    Generally, most of the commercial offerings use cloth accordian surround woofers in ported enclosures, tuned to 30-60hz. I would expect to find Qts between .25 and .4 and Xmax of 4-6mm or so, with a driver sensitivity of 94-99db. Most of them have big magnet structures and voice coils of 2.5" to 4" and power ratings of 200-800w RMS.

    Eminence owns a lot of this market and makes drivers OEM for lots of companies, but there are plenty of other players out there.
     
  3. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Looking at speaker cabs in the shops, the carpentry is easy to spot. The science behind it isn't. There are ways to work out the correct box size and porting, but you need to know the Thielle/Small paramaters of the speaker you're planning to use.

    What sort of cab were you thinking about building? How many strings does your bass have?
     
  4. Hi_Im_Mark

    Hi_Im_Mark

    Mar 9, 2003
    I've got a 4-string fender bass, and I was looking to construct a 4x10 cabinet.
    :D
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    4 string 4x10 shouldn't be too hard. Have a look at the websites for the major speaker manufacturers (Eminence, EV, JBL, RCF, P.Audio, the list is endless).

    The main specs you'll need are a resonant frequency (Fs) as close as possible to 41Hz, a Qts of 0.36 or lower (lower is better).

    If you want the cab to end up being 8 ohms, you will need 4 speakers of 8 ohms each. If you want the cab to end up being 4 ohms, you will need 4 speakers of 4 ohms each etc....

    At this point you're gonna need to hunt around because only you have the ability to choose based on price, availability, the number of watts you reckon you'll need, brand preference etc.....

    When you've got an idea of which speakers you like, let us know and we'll help you determine the right box size and porting.
     
  6. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    maybe i'm a sucker but i don't think i'd build my own
    the improvement of cabinets has been unreal in the past 20 years or so and computer aided design really seems to match speakers to their enclosures to produce excellent results
    i wouldn't frell with it unless you really know what you're doing
     
  7. Mark:

    What ESP-LTD said.

    10" speakers used in bass cabinets are often PA midbass drivers. Relatively high Fs (50-60 Hz), limited excursion (2-4 mm), very tight suspension, magnet weight over 50 oz.

    Designing a bass guitar cabinet is somewhat different than a car sub. Car subs are low-power (yes they are) low-efficiency (less than .5 percent) cabinets, bass guitar cabs are high power, extremely high efficient (over 10%) cabs.

    Because of the high power and efficiency, the cab has to be literally built like concrete, with multiple bracings, and one has to take into account that acoustic behaviour changes at high SPL levels.



    IvanMike:

    Some of us on TB have gone through endless lengths to obtain the knowledge to design a very good bass cabinet. I've been obsessed with loudspeakers for the last 15 years, and I think I know pretty much the same as a professional designer. Hell, I am a professional designer. And I dare say I can do a better job than (insert brand name here).

    Now, the fun thing is, we're not into making money, so our knowledge is shared with other TB members. We feel proud of what we know and love to help others out. That's the basic function of a forum isn't it?
     
  8. Wes Whitmore

    Wes Whitmore Supporting Member

    Mar 10, 2003
    Columbus, OH
    Fellas, what do you think of this speaker for a full range cab? I also have a 2x10 if it would help in the midrange.

    They are on sale!

    http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-346

    I know it isn't a subwoofer, but it is cheap.

    I modeled it, and it looks like it will need to be in a pretty big box to get any extension out of it.


    Wes
     
  9. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    I don't think you'll get full range out of it; I bet it does off pretty badly above 1000hz, but with a 2x10 that's not a problem. The bigest deficiencies are the Qts=.45 (really wants to resonate at 34hz) and Xmax=4.3mm (voice coil travels outside the magnetic gap pretty fast on low notes).

    It is a good price and I've considered Selenium drivers; they seem decent. I'd say for a 4 string it would be a good buy. A 5-string might get into trouble at 34hz.
     
  10. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    I had a quick glange at the specs......I hope you modeled it as a sealed enclosure. With a QTs of 0.45 that's what is appears to be designed for. And it will definitely need help with midrange upwards....
     
  11. Wes Whitmore

    Wes Whitmore Supporting Member

    Mar 10, 2003
    Columbus, OH
    Well, I don't mind using the 2x10 GK for now, until I get some time to build something to replace it, and I only play 4 string, sometimes dropped to D, which should still be above 34 Hz. It's $109. I modeled it in a ported enclosure because the power bar on the WINLSD hinted that direction. I will model it with a sealed next. I was thinking that I would be able to work with that low xmax as long as I kept the tuning freq below whatever note a drop D is, and expect it to flop around below tuning freq. If you guys want to mess around with some modeling, feel free. I am more used to the actual carpentry of building enclosures than the design, and I am learning as much as I can. It would be nice to check myself against someone else.
    THanks,
    Wes
     
  12. Selenium publishes complete information on their drivers, including power compression factors. These appear to be premium grade drivers in every respect and the price shows it.

    The better Selenium drivers are very interesting to me. The one you mentioned from Parts Express (WPU1805) has a high Qts, and is probably better suited as a PA driver. I was surprised to see the anechoic response plot carry all the way to 2,500 Hz, considering the size of the driver.

    The 15SW1P is a lot better driver, runs in 2.62 cubic feet at 36 Hz (SBB4), but runs out of upper end around 300 Hz. The larger 18SW1P is a fine driver all the way around, except it requires more than 6 cubic feet for proper tuning.

    When you get into this price range, I suggest you opt for *the* driver that best suits your needs. Eminence Magnum drivers are in this upper price range, and there is a wide variety to choose from.

    I've added the Selenium drivers to my spread sheet for comparision purposes.