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Building a bass cab

Discussion in 'Amps and Cabs [BG]' started by hater-ade, Apr 2, 2003.

  1. hater-ade


    Feb 11, 2003
    First off, i'd like to say i've searched this forum and done some research on the drivers i plan on using. I have experience with building home theater speakers/subwoofers so a lot of the same knowledge applies, but i don't have experience with pro-sound drivers. But feel free to get technical, ill understand :) . Also feel free to suggest other 10" drivers that are in the same price range that you feel would suit my needs better, or that you have had success with.

    I play on a 5-string, and use (half step?) dropped tuning, FCGDA. I mostly pop and slap and need an amp that is punchy and can deliver the lows of my dropped tuning. I prefer a carved mid kind of sound so the mids are not as much as of a concern, but still need to be reasonably loud and clean.

    I plan on either building an 8x10" cab or a 4x10" and a 1x15", either design will also incorporate a horn tweeter.

    The 10's i'm planning on using are the Eminence BP102's. My search has concluded that these drivers like about a 2cu.ft. enclosure tuned to 38-40hz. I would prefer to use about 1.5-1.7 cubes for each though. I would like to stick with an SBB4 enclosure alignment but i'm unsure of the volume and tuning required for this. The lower sensitivity seemed to be a problem for some, but since i'm using an 8x10" with lots of power, this shouldn't be a concern, as the low sensitivity can be overcome by using more power and by using multiple drivers, correct me if i'm wrong. I also have to buy an amp, how much power would you recommend for this design?

    If i go with, lets say, a 12 cu.ft enclosure, which gives each driver 1.5cu.ft. and tune it to about 37hz, is my low string going to overload it when using full power? I guess i could just EQ it a bit and cut off a bit of the super low end, i'm willing to sacrafice it a bit, as i think the 8x10" design will sound best.

    This is where my other design comes into play, because i don't know if the 8x10" can handle the lows. This design uses a 4x10" and a 1x15" for the lows. I planned on using the Eminence KappaPro 15LFA for this design. Can someone provide an enclosure design for the 15? Would an 18" be better maybe?

    Also, it seems to me that SWR's Megoliath uses the eminence BP102's, they look very similar, is this true? I played and SWR 2x10c recently and really liked its sound, it also appears to use the BP102's. This amp seemed to handle my low string just fine and it would be nice to know if it uses these drivers. Does anyone know of any other commercially available bass amps that use these drivers?

    Thanks for any input!!!

  2. ESP-LTD


    Sep 9, 2001
    I'd sure rather carry (2) smaller boxes (or just about anything else) than an 8x10. It's a no brainer if you can biamp.

    For power, figure your worst-case and double it. I found a QSC RMX-1450 was pretty good bang for the buck (like $400 delivered).

    I ended up going with (3) 1x12 boxes; one Avatar B112 and a pair of 1x12 subs underneath. I traded a lot of loud for low, and that may not work in a lot of cases.

    You might find that a pair of 1x15's under a 2x10 balance pretty well. The Omega Pro 15 is a nice driver.
  3. Petebass


    Dec 22, 2002
    QLD Australia
    A few things to bear in mind. A normal 5 string produces a fundamental of 31.5 hz. YOur low A goes even lower again, probably about 28 hz. Wether or not you have to reproduce that fundamental is open to debate. A lot of commercial bass cab are tuned to high 30's because a standard 4 string produces a fundamental of 41hz. Problem here is that reproducing 28hz would almost certainly require a larger driver, a good 15 at the smallest, an 18 being more likely. You've gotta decide wether or not this is an issue. Personally I believe that it's not essential and that 8x10's should couple well enough to produce a decent bottom end. Your alternate design with the 15 (or 18) and 4x10 will probably reproduce the low a note better though. (I usually use a 15 with either a 4x10 or a 2x10, so I'm biased).

    Looking at the specs of the BP102 driver, it looks like this driver would be happier in a sealed enclosure. It has a QTS of 0.46 and a rather long Xmax. Generally any speaker with a QTS above .4 is more likely to work better in a sealed enclosure. YOu mentoned SBB4 which suggests you were planning to build a vented cab. There are exceptions to this rule but I'd either look at other drivers or make the cab sealed.
  4. I would not use the BP102 drivers for this purpose.

    As pointed out above, they are a high Qts driver, and have a bump at resonance and the significant rolloff below resonance that is characteristic for high Qts drivers. 40 Hz is the resonant frequency, and this is a long way up from the 27.5 Hz you want to hit with your dropped B tuning.

    The BP102 driver requires a substantial cabinet volume for correct tuning. SBB4 is 2.19 cubic feet at 40 Hz. Optimal Flat is 3.49 cubic feet at 35 Hz. Eight of these drivers will require access to your own personal Bekins Moving Van.

    The Group Delay numbers (mud) are pretty crappy for this driver in a vented box near the tuning frequency. In a sealed B2 alignment of 1.66 cubic feet, the GD is excellent, but F3 is 61 Hz, F10 is 35 Hz, and it is down -15dB at 27.5 Hz.

    If you have never heard the 27.5 true fundamental of your bass, you may not need a cab that goes down this low. If you are happy with the 2nd harmonic (55 Hz) you will save yourself a lot of size and expense. Producing 27.5 Hz requires lots of cone area, lots of cone movement (Xmax), and lots of power if you want small cabinets.

    The JBL 2245 18" (out of production) will do the job, but requires 9 cubic feet. A Rockford RFR-2215 or Dayton 295-130 Series-II in 5.3 cubic feet will go down even lower, but requires 4x more amplifier power. There are several 10" premium subwoofers that will go down this low, and many are designed for small sealed boxes. All are power hungry, and the cost of eight 10" subs is very expensive.

    If you truly want an F3 of 27.7 Hz, bi-amping is mandatory. This means an active crossover and two channel power amp. You will need at least two 15" subs and 450 watts (each) to make any appreciable noise. I use a PLX 3002 with 900 watts per channel into 4 ohms, and my Lows channel is nearly redlined in a loud bar venue. I can add another PLX and two more subs if I have to play a huge venue and be really loud.

    Are you sure you really want all this grief in order to accurately hit 27.5 Hz?

    The B102 (not BP102) 10" drivers make very nice Highs for a bi-amp rig.
  5. hater-ade


    Feb 11, 2003
    Hmmm, ok, i think i'm gonna change my design a bit then. Thank you Bgavin for pointing out all the difficulties in my design!

    Lets set a goal of 38hz maybe and i'd like to use a single amp for this. I think a 4x10 and 1x15 combo would suit my needs for this. Would the eminence kappa pro 15LFA still be a good choice for the 15" cab? Or should i steer clear of this driver and choose another 15"? Can you suggest another eminence 10" or other brand that would be good for the 4x10" combo? I like the B102 but its not necessary for me to go that high with the 10's because i plan on using a tweeter so i wouldn't want to sacrafice the lows of the 10's. I heard that the B102 isnt really good for anything below 100hz, i dont know if that is correct or not.

    Thanks for all your help so far!

  6. Petebass


    Dec 22, 2002
    QLD Australia
    I had a quick look to Eminence's website and they didn't have a Kappa Pro 15 LFA listed. THe KAppa's 15 and 15LF won't go deep enough (Fs in the 40's).

    Have a look at the Gamma 15 (Fs=33hz, Qts=0.30, Vb=4.37cu.ft). Also, look at the Ledgend CB15 (Fs=34hz, Qts=0.30, Vb=3.70 cu.ft). They're not as big on the watts as the Kappa's but the other specs make them better options in your situation. And 300w isn't exactly scrawny.

    The other one that looks interesting is the Magnum 15HO (Fs=33hz, Qts=0.27, Vb= only 2.64cu.ft, that's pretty small). And it's 650 watts. I'd expect this one to be pricey though.

    I'll have a scroll through the 10's when I get a chance.
  7. Kyle,

    Download my Excel spread sheet from my signature. Sort it any way you want, and find what you want.

    You can sort it by driver size, box volume, tuning frequency, F3, etc. Each driver is also identified as a BB4 or SBB4 type. I avoid using BB4 because they are the higher Qts types mentioned above. Look for a tuning frequency at/below your lowest note. A few Hz higher is not a big deal, no more than 10%.

    A Magnum 15HO + B102 is a good match. The sensitivity are the same and both operate well in modest cabinet sizes.

    IMO, a better match is the Magnum 18LF + B102 because it has more low end response. Both are tuned around 32 Hz in SBB4, making them safe for 5-string or drop-5 use. This is the combination I'm prototyping for commercial release.

    The Adire Maelstrom, B&C 18PS46, Fane Colossus 18B-600, and several RCF drivers are all worth investigation. The Adire is -3dB less sensitive than the Magnum 18LF, but it goes down lower and has a bit better GD.

    None of these are cheap drivers.
  8. ThunderStik

    ThunderStik Guest

    Jun 25, 2001
    Claremore OK.

    Is your mail down? I tried to e-mail you but it keeps getting kicked back.
  9. I block hundreds of subnets used by spammers. It sounds like you are on one of them.

    Send email to: compudox@yahoo.com

    I will inspect your incoming mail header and see what is going on.
  10. Thunderstik,

    Your mail is coming in from an unidentified IP address:

    04/03/03 11:20:06 dns
    No reverse DNS (WSANO_DATA)

    There is no mail exchanger (MX) at this IP that will respond to SMTP requests.

    I block all IP addresses that fail to provide reverse DNS lookup. This is basic anti-spam 101. Your outgoing emails will be blocked by all mail servers that require reverse DNS lookups prior to accepting mail.

    Contact your ISP and ask why the mail server does not have an RDNS record associated with it.
  11. Petebass


    Dec 22, 2002
    QLD Australia
    Good to hear. I often wonder why guys like yourself don't make cabs for resale. Good luck.

    Hey can I be your Australian correspondant?
  12. hater-ade


    Feb 11, 2003
    I had a look at the Legend CB15 and I like it, although i couldn't make much of it in my box modeling program. Is it capable of about 35hz in a 4cu.ft vented enclosure? Do you know what the SBB4 alignment would look like for it? I also like the Gamma 15 but i think the CB15 is a better driver, judging by price, construction and x-max, but i may be wrong.

    I also tried to download bgavins spreadsheet, which i think would be very useful, but for some reason the program won't work, excel just tells me that the program is invalid whenever i try to use it
    :( . I really wish this progarm would work!!!

    Im still stuck on the 10's, the B102 looks ok, but are a little out of my price range. I looked at the Gamma 10A and it looks ok also, but i still really don't know what 10" to choose.

    The magnum 15o is also out of my price range, i'd like to keep it below $175 for the 15" and $90 for the 10's.

  13. hater-ade


    Feb 11, 2003
    Sorry, that should be more like $120 for the 15" and $60 for the 10's, USD
  14. Wes Whitmore

    Wes Whitmore

    Mar 10, 2003
    Columbus, OH
    Has anyone every tried the EMINENCE KAPPA PRO-12A 12" CAST FRAME DRIVER before? It seems to take a ton of power, play pretty low, and the response curve is super flat in the box I modeled up...
  15. I have that driver in a 3.6cu ft box witha 4"dia x 6" port and 2" of stuffing and it KILLS!!!! I damaged the orig driver in my Nemesis n112p ext cab and it was cheaper to replace the whole driver than replace/recone the origianl Eden. It was nearly the best gear decision ive ever made. 300+ shows and I still get gushing compliments. I actually only use this cab now, I didnt need the rest (2x 410s) because thsi cab will cover everything Im doing these days (I dont play with triple rectos and marshalls, tho')
  16. Because it requires a lot more than a good design and a shack full of power tools to sell bass cabinets.
  17. Petebass


    Dec 22, 2002
    QLD Australia
    Good speaker, but wouldn't suite this situation. We need an Fs in the high high 20's but have comprimised and decided low 30's will do. High 30's would be to stretch the comprimise out even further.
  18. hater-ade


    Feb 11, 2003
    Hey Petebass,

    so what do u think of my ideas on the CB15 in my last post?
  19. Petebass


    Dec 22, 2002
    QLD Australia
    Looks good to me. I don't have a box modelling program but the Formulas my textbooks tell me that SBB4 alignment would need a box 3.7Cu.ft in volume. You'd need a single port about 4 inches in diameter and 5 inches long. Guru's can you please check if these figures and let me know if I've interpreted the formulas correctly.

    I'll look at 10's later. Gota a gig to get to now. Sorry......
  20. hater-ade


    Feb 11, 2003
    hey, ya i checked it out on win ISD and for a 3.7cu.ft enclosure with a 4" dia x 5" port the tuning appears to be about 36hz. the group delay is low which is great but the f3 is like 60hz, is this different on your modeling program? i think the f10 is about 35hz though. I'm still looking at 10"s but no real luck yet...

    Thanks Petebass, hope your gig went well!