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Will a scoop bin work?

Discussion in 'Amps and Cabs [BG]' started by link wray, Jul 29, 2005.


  1. Tonight there will be a jamsession at the place where i do the sound. I promised the organiser i would bring my bass amp. Problem is i did not build the speaker yet. They have some scoop bins for bass speakers in their PA-system. Would it sound OK if i used one of them as speaker for my amp? i know this is technically possible but i wonder if it sounds any good. Is this an emergency solution only or will it be a different but equally good solution compared to a normall bass cab?
     
  2. A lot of bassists go directly to the PA for amplification. Does your amp head have a direct output jack?
     
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You can use a scoop temporarily, though it might be shy on mids. But going forward scoops are very much outdated technology, not something that you'd want to consider for a stage rig.
     
  4. Well, it will only be for this jamsession tonight, and i can ofcourse plug into the PA, but the same scoop bins cover the bass in the PA rig and the monitors cannot really handle bass guitar. I think i will just use one scoop as a cab for my amp and the other for bass in the PA.
     
  5. It worked fine; thanks for your input.
     
  6. Wesley R

    Wesley R Supporting Member

    Reagga(sp) baassists like to use scoops. Itwas some how build a cabinet site.

    Wes
     
  7. notrt

    notrt

    Jun 29, 2004
    :bag: I'll bet you'll find that your band mates on stage wonder what happened to your sound if you do...they are "long throw" cabinets, sound better the farther away you get from them, and are definately not close to near field fidelity in the "got to be heard onstage" context.

    For gigging, IMHO, I'd avoid using P.A. cabinets for your stage sound and/or ambient sound for the same reasons. Yes, the audience will hear it fine, but you and your bandmates on stage won't...I tried this many years ago in two different band contexts on the theory that all that was right with my sound would be better if my stage sound, using the same P.A cabinet(s) was the "same" as the P.A. mix sound, since "that's what the audience is hearing, anyway..."---very bad call on my part, and almost caused me to be aced out of a band about 12 years ago.

    RC a/k/a "notrt"
     
  8. This effect was noticable, but not as bad as you might expect. Also no mid dip as Billfitzmaurice suggested. But anyway, this was a one time only solution: it was either this or no bass-amp at all... As soon as i have the time i will build a 2x12 cabinet with eminence delta 12 lf's.
     
  9. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY
    Never seen a reggae player use a scoop.
     
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That's a myth in need of relegating to the junk pile. Speaker outputs become directional only when the size of the radiating plane and/or baffle approaches 1 wavelength. At 100 Hz, the frequency usually accepted as where true bass begins, a wavelength is 11.3 feet. The type of speaker matters little, in this case it really is size that counts. Reggae players tend to like scoops as they often have a peaked response in the 2nd harmonic zone, 80 to 320 Hz.
     
  11. I think this myth is caused by the low bass not seeming to eminate from the speaker, but more like 'resonating the room as a whole'. With bassreflex systems you can point the source of the low bass better. The mids had no dip but did beam quiet badly, probably due to the woofer being 18''.
     
  12. notrt

    notrt

    Jun 29, 2004
    ...that's not what I ( or others, either ) "heard" on (or off) stage with that sort of rig setup. In one of those bands, I was using a biamped Ev setup which used the same mains and subs as we used for the big PA, just less of them, obviously. The notion was that it would be a good thing for the stage sound to be the same as what the audience was hearing. It simply didn't cut it up close; it sounded great 20+ feet away. No disrespect is intended, but after 35+ years of this, I've learned (sometimes the hard way, too...) to trust what my ears are telling me, too.

    RC
     
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    For sure, an 18 is going to beam from 500 hz at best.

    Actually, you can't pinpoint the source of low bass with any kind of speaker; that fact makes the entire sub/satellite concept possible. Being able to discerne the direction that any sound is coming from has nothing to do with the source type, it has to do with the distance between your ears. The arrival time differential at the two eardrums must be long enough for your brain to be able to process directional information; with the long wavelengths of the bass that condition doesn't exist. What you can easily pinpoint is frequencies above 200 Hz or so, and direct radiator subs tend to have a lot of content there due to Doppler distortion, while pure horn subs don't, as their folding geometries filter out the midbass and only allow the low bass to pass.
     
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    There's no question about what your ears are telling you, but this syndrome seldom has anything to do with the speakers being used. This particular situation is usually caused by speaker placement. Let's assume you're within a wavelength or so of both the backline boxes and the PA. Everywhere within that zone you can get massive peaks and valleys in the bass response because both sources are combining in various stages of phase, depending on how far you are from each source. Once you get at least a wavelength or so away from both sources those interactions dissipate, and with a wavelength at 50 Hz being about 22 feet long that jibes quite well with what you've experienced.

    Another source of bass 'dead zones' on stage are the walls behind and beside and the ceiling above. If those boundaries are within a wavelength of the backline cabs reflections off them can cause all sorts of phase related problems as well, problems that the PA, being farther out from boundaries, generally won't suffer. In this example also the further one is from the confluence of the direct and the reflected waves the less obvious are the response anomalies.
     
  15. The "long throw" thing never made sense. Was the cabinet desgned by a ventriloquist? :D

    I always figured it was just that some cabinet designs in some situations tend to generate a trough where your head is at, where maybe front and back wave of the cab tend to cancel each other out due to phase issues. That or a short cabinet tends to provide more sound to your butt than your ears. Ears tend to be more sensitive to sound, therefore....

    Randy
     
  16. There shouldn't be a "trough" where your ears are, unless as you mention, there's an undesirable "standing wave" (which we always try to avoid)...

    I've seen a lot of other people think that sound wavelengths somehow imply a certain distance that you must be from the speaker. So I'm going to take the liberty of explaining how sound waves work...

    You're at the beach, standing in waist deep water, and waves are rolling in. The water at your waist goes higher, then lower, as the waves go by. It's up to your chest, then down to your knees, then back up to your chest, then down to your knees. Every few seconds a new wave comes by... the water goes up to your chest, then down to your knees. The distance from the top of the wave to the bottom (from your knees to your chest, at the beach) is the amplitude, the distance from the crest to the trough. The time interval between each successive crest of the waves is the period, in this case a few seconds.

    Sound waves are exactly the same. The period is the inverse of the frequency of the sound wave. For example, an A-440 has a frequency of 440 Hz. 440 waves go by your ears every second. The inverse--the period, is 1/440 of a second. A wave crest goes by your ear every 1/440th of a second.

    The volume of the sound wave is the amplitude--the distance from the crest to the trough.
     
  17. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    Quite a few years ago now, the cabinet I was using with my bass rig died. I had several gigs to do and had to throw something together. All I had on hand was a 1x15" scoop and an el cheapo top box which had 1x12" and a small horn. I biamped that and as I recall it sounded quite nice. I actually got quite a few compliments on it's sound. It was a bitch to haul around. They don't call 'em sugar scoops for nothing............. :cool:
     
  18. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Now imagine that you're in a wavepool, one with a wave generator at either end delivering identical waves. At some points in the pool the two waves will meet with both of their peaks in the same place, so the amplitude will be twice that of each individual wave. At other places one wave will be at the peak of its amplitude while the other is at the minimum, and as a result the combination of the two is zero amplitude. In between these two extremes there will be anywhere from zero amplitude to double amplitude, and it's all a matter of where you're standing what it will be. Substitute your ears for your body and a pair of speakers for the wave generators and you can understand why placement, of not only the speakers but also the ears listening to them, can make all the difference when it comes to what you may hear.
     
  19. It would only be at one particular freq, cause all the wavelengths would be different. I was just speculating on the origin of the "long throw" myth, if the port output bouncing off the floor tended to cancel the main driver where your head is for an E, you wouldn't hear much output at a certain note, and in the audience it would be louder. You'd still get reflections off walls, only the close main 2 sources would cancel (port, spkr) at that particular freq. So you notice that one note weak and think its "thrown" out into the crowd bypassing you. Bam, an urban legend is born. Something like that.

    I never meant to imply the whole cab output across the spectrum would "null' out at your head level.... I should have been more explicit....

    My real vote would be more the cab shooting out under your legs and not having the dispersion to get lots of ear if its short and you're close.

    Randy
     
  20. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It's easy enough to calculate. A boundary 1/4 wavelength away from the source will cause a reflection back to the source at 1/2 wavelength and you'll get a source cancellation. Most livingrooms with 8 foot high ceilings and a sub with the cone a foot off the floor will thus have a cancellation node where 7 feet is a quarter wavelength: 40 Hz. Bye-bye low E fundamental. Roy Allison quantified this effect some 50 years ago, and his advice remains part of the sound engineers bible: put speakers either very close to or very far away from walls, floors and ceilings.

    When Tom Holman set about designing THX he had a massive response hole, over 24dB deep, around 120 Hz. It was caused by the 30 inch deep woofer cabinet's distance from the wall behind it. He fixed the problem by specifying that the front of the cabinetry be flush mounted in the wall.