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New B112

Discussion in 'Amps and Cabs [BG]' started by Quadzilla, Jun 3, 2002.


  1. Quadzilla

    Quadzilla Supporting Member

    Man that was a once in a lifetime ssssssmoken deal. Wish I would have spottted it...
     
  2. geshel

    geshel Supporting Member

    Oct 2, 2001
    Seattle
    It's hard to get an idea of what it is you're saying Magman without knowing how much power you were putting into them. My instinct tells me you were probably not putting 100W of pure 40Hz into it.

    Taking the Delta 10 specs from Eminence's website (the Xmax is tiny!) and putting them in Perfect Box with a box of 1.5 cu. ft, tuned to 65 Hz, it shows the Xmax being exceeded at 40Hz at 20W, producing 90dB (it would also be helpful if you do tests like that to use a dB meter to see how loud the tone you're hearing really is, objectively). At 30Hz, the numbers are 12W and 78dB respectively.

    Xmax is the limit of the motor system to drive the speaker, but not necessarily the limit of the speaker to move. I'm pretty sure the physical excursion limits on the Delta 10 are much higher than the Xmax (which is 1.6mm, BTW - that's what you get for high sensitivity!). So, this means that at power levels higher than those I mentioned, the sound is distorted because once the voice coil leaves the magnetic gap it's no longer under control and instead runs on momentum. So, even if you turned it up past 12w at 30Hz, what you were hearing was likely 60Hz, 90Hz, and 120Hz overtones from the resulting distortion.

    Since Eminence doesn't list the physical excursion limits, I couldn't say how much power it could handle at 30 or 40 Hz before it bottomed out. I wouldn't want to push it however.

    I'll say again, this sort of behavior is really fairly common in MI speakers. And there's even something to be said about not reproducing the fundamentals because that can make the sound in the venue harder to control.

    So. . .I guess my reason for starting this was just that I feel there's a lot of misconception out there of what speakers do and can do, and what people are getting for their money.
     
  3. well, mine was all totally subjective. The cab probably is down -12db at 30hz or something - but it still puts out that frequency without farting.

    I've done similar things with home book shelf audio speakers (not with my bass amp!!!) and though they will do ~40hz (just about) they are flapping around like crazy.

    I'm not even sure how much fundamental my bass puts out anyway. I guess I could sample it and run a spectrum analysis.

    Also, 30hz has a long wavelength ---- you can;t properly hear it unless you are stood back I would think. Thus the cab might be down a lot at 1meter at 30hz, but at 10 meters, the higher freqs would loose energy a lot quicker.

    With music - position in relation to the cab made a difference in sound, mainly the tweeter I think - at head level it had the best sound (straight on). To use as PA definitlely would want to get them off the floor.

    So I say hook up your computers, get an audio program and pump some sine waves through, its quite interesting.
     
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  6. Those EB-MM 2x10's are still poking around a few of the GC's...$250 each. I saw one in San Leandro. Light but those B&C speakers are very nice. those "neodynanium" speakers everyone is going on about these days. The specs vary wildly on that website of theirs tho'....
     
  7. That's it! I'm outta here...
    :D
     
  8. geshel

    geshel Supporting Member

    Oct 2, 2001
    Seattle
     
  9. sure go ahead, I am interested.
     
  10. BillyB_from_LZ

    BillyB_from_LZ

    Sep 7, 2000
    Chicago
    In the thread that I started about the B112 (I have one) I measured the tuning frequency with a signal generator, DVM etc. and found it to be something like 77 Hz. The cabinet has two ports in the back. Closing one up would drop the tuning frequency to the mid 50s...just like the Compact 15 (of which I have two).

    The B112 really comes to life sitting on top of the Compact 115.

    Bear in mind that programs like WinISD give a design that is based on one "pretty looking" alignment that Thiele and Small came up with. Other alignments (or designs) are valid though their graphs might not look as nice.

    The Avatars sound better than the graph might suggest.

    I'll have to plug one of the ports on my B112 tonight and see how it sounds. I'll report back later.
     
  11. I'm sure the Avatar 12" would excel at extending the range of an existing 15", adding punch while avoiding mud. My Mesa RR, EV 15" and 2x10's sounded great together because of how they complimented each other. They stayed out of each others way, avoiding "clutter." On their own they sort of lacked something but together....
     
  12. geshel

    geshel Supporting Member

    Oct 2, 2001
    Seattle
    :confused: What are you talking about? You can put your own box and port parameters into WinISD and create any alignment you want.

    So what makes an alignment "valid"? Because it has a name? Sure you could make a 6th-order Chebyshev alignment with 10dB of passband ripple, and it won't "look as nice" as a QB3. Of course neither one might work as well as some other set of parameters you choose. I don't understand "look as nice". If the response is down severely at 40Hz it's down severely. If there's a big hump at 100Hz there's a big hump there.

    Rearrange this to, "The Avatars might sound better than the graphs suggest" and I'm on board 100%.
     
  13. geshel

    geshel Supporting Member

    Oct 2, 2001
    Seattle
    Well it's a little bit hard because I'm not sure what led you to believe what you said. Did you think it took some time/distance for the wave to "get started"? What is supposed to be going on in the space between the speaker and where the wave gets going?

    Like waves in a pool, they start where you start them and radiate outwards from there. The fact that the wavelength at 30Hz is something like 40 feet doesn't mean you have to be 20/40/? feet away to really hear it. Otherwise, how would headphones have any bass response? Put 30Hz through some good headphones, you'll hear it just fine.

    Or, once you get a dB meter :), move it closer to the woofer at 30Hz (or the port). It'll go up.
     
  14. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Im sorry, but Im also a non-believer.

    If I remember correctly, it took a box more than 7 cu ft to bring my 2-15" cab down to 30hz.

    They were Carvin drivers which arent the best, but arent bad either.

    I just think that it'd be really hard to design a speaker that reproduces low frequencies well in a box that size.

    I guess it may sound good to you, but it wouldnt do it for some of the rest of us.

    Peace
    Nick
     
  15. geshel

    geshel Supporting Member

    Oct 2, 2001
    Seattle
    http://www.sunfire.com/

    :D just goes to show you, it can be done (takes a lot of power though, and some tough drivers).

    edit: and that's cheating, that's an active design with EQ. :)

    Actually the main problem tuning a small box to a low frequency (the volume of the box is really only a factor of the driver parameters - car audio woofers are designed to get good bass from very small cabinets (at the sacrifice of efficiency and high-end reproduction)) is port length. As the box gets smaller the port length *increases* for a given tuning frequency. Pretty soon it's too long to fit! Hence the Sunfire subs use passive radiators - very similar to a port but they use a denser mass than air (a cone with weights on it).
     
  16. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    I wasnt saying that its difficult to design a box, rather the actual driver.

    Peace
    Nick
     

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