Ever use Beam Blockers?

Discussion in 'Amps and Cabs [BG]' started by mmbongo, Jun 2, 2019.

  1. mmbongo

    mmbongo I have too many basses. Supporting Member

    Good solution, or solution to a problem that doesn't exist?
    Beam Blockers - Gadgets

    I've used these in the past with guitar cabs, and as I'm reading about how 4x10 bass cabs have beaming issues I wonder if these would help? Barefaced even eliminates the high frequencies in one column of drivers in their 4,6,and 8x10 cabinets to eliminate the beaming problems. I wonder if these would help other cabs, either in front of all speakers or just one column of them?
  2. Goatrope


    Nov 18, 2011
    Sarasota Florida
    Hmm :bookworm:

    For me, if I’m not perceiving a problem, or being told there’s a problem, I’m not pursuing a solution, no matter what I read.

    Interesting concept, though.
    pellomoco14 likes this.
  3. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    those things don't actually work because they get the fundamental physics wrong.

    the treble "beam" doesn't come from the center of the speaker, it comes from the entire speaker; you hear that treble when you're lined up with the center of the speaker because that's where all the surface area is equally distant from your ears, so there's no phase cancellation from one side of the cone being further away than the other side.
    Pilgrim, dkelley, Rich Fiscus and 2 others like this.
  4. A lot of drivers do in fact produce treble in the main from the dustcap.
  5. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    They work via diffraction, the bending of sound waves as they move around obstacles. When sound strikes a hard, non-porous obstacle it may be reflected or diffracted, depending on the size of the obstacle relative to the wavelength. If the obstacle is large compared to the wavelength it acts as an effective barrier, reflecting most of the sound and casting a substantial “shadow” behind the object. On the other hand, if it is small compared with the wavelength sound simply bends around it as if it were not there.

    Where a 4x cab is concerned low passing one vertical column of drivers would work better, with even wider dispersion if beam blockers were used on the column that wasn't low passed.
  6. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    The problem exists but these do not fix it. And if used on stuff that does radiate the treble from the centre of the cone, makes it worse. They can make the polar pattern less predictable, so you can hear them do something.
  7. Seems a bit like elephant repellent.
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  8. JRA

    JRA my words = opinion Gold Supporting Member

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    Spacecase likes this.
  9. arbiterusa


    Sep 24, 2015
    Well, one guy got it right. This is also how directional radio antennas work.

    To answer the OPs post, I don't find my 4x10 cabs "beam" at all. From my work with guitar, beam blockers don't seem to do much for guitar amps either.
  10. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Had this discussion a long time ago. I lost interest in it when someone said, "I've never heard a bass player who drilled me with too much treble like guitar players can do."
  11. Marcus Willett

    Marcus Willett

    Feb 8, 2005
    Palm Bay, FL
    Endorsing Artist: Bag End - Dean Markley - Thunderfunk
    On a tangent, years ago I was doing a regular jazz gig in a smallish room. Just based on an idle thought I’d heard someone mention, I put my (combo) amp on its back, driver pointed at the ceiling.

    It actually worked surprisingly well. The bass seemed to have this quasi-upright quality of coming from everywhere and nowhere in particular. Obviously beaming was eliminated as well, at least in the sense that no ears were in front of the driver.

    As would be expected, there was some loss of articulation detail but the loss was less than I expected and the trade off in the “large and warm but not boomy” tone I got was worth it.

    Pretty sure this would only work within fairly narrow parameters but it was interesting.
    maxmaroon, dkelley, ctmullins and 6 others like this.
  12. JW56789

    JW56789 Guest

    Feb 18, 2017
    Thinking about this intuitively, in the illustrations, they are using these on guitar combos with a single speaker, an open-back box.

    I'd think this would introduce a lot of randomness to the pattern on a multi-driver cabinet like a typical 4-10" bass guitar bin, the 'I-can't-hear-myself-but-I'm-frying-everyone-else-on-stage' phenomenon would increase by several factors, and I'm adding even a little more weight. Wouldn't be a choice I'd take, personally.

    See, this is why you buy single 15's, way harder to introduce the comb filtering that I always sense on 410's. Or just buy cabs with those funny
    Wizzer' drivers, they're built in !
    dkelley likes this.
  13. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    If your "tone" from your bass is ear piercing treble and bothering you.

    Beam blocker can help little. Or just turn down the treble I guess. I couldn't imagine the horrid bass tone someone would have to use to actually justify a beam blocker. Likewise even if using one. The tone choice would probably still be rather horrid.

    But in general bass drivers don't usually have incredible ear piercing treble. Things end at 2 to 3 k

    The ice pick treble peaks from guitar speakers is different situation. Good sign of a cheap poopy speaker. Annoying tone death guitarists with nauseous amp settings. Nauseous bridge pickups. Or using some common overpriced famous underhung" British" guitar speakers or millions of other speakers that copy the same design. That just sound like garbage.

    Beaming" is from wavelengths being smaller than the actual larger cone size . And will be focused into a beam.

    In English that means like most speakers. Stand in front. Lots treble upper mids.
    Walk to the side or off axis. Treble response drops.

    This can only be fixed by using smaller drivers for certain frequencies.

    The term " beam blocker" is more damper to tame down the annoying frequency peaks from typical guitar speakers. This is mainly from the overhung design and thin cones of musical instrument speakers for high sensitivity drivers. Makes horrible treble peaks in the response.

    Yes technically a 10" or 12" guitar speaker is " beaming" cause any wavelength smaller than 10 or 12 inches will start to narrow in dispersion. But that squak ice pick treble is not a beaming problem technically. It's just a huge peak from the speaker design.

    Problem is guitar player cranks the treble cause he is standing off axis. To make up for the poor off axis response.

    Then anybody standing directly in front of the guitar speaker gets blasted with over boosted treble. That the guitar player doesn't hear as well off axis.

    Beam blocker doesn't fix beaming just blocks the annoying treble peaks of a overdriven thin cone ,small voicecoil , overhung over priced guitar speaker.

    Many vintage guitar cab designs using a heavy weave guitar grill. Which is a built in beam blockers. Or if you ever seen about 3 pieces of duct tape over the grill where the speaker cone centers are. So when close mics are placed to the cone edge. The duct tape can still tame the squaking from cone center
    Last edited: Jun 2, 2019
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  14. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Unfortunately the solution to beaming has been solved with the use of 2 way systems and using smaller diameter drivers for high. Unfortunately it promotes higher cost and a passive/ active crossover network.

    Otherwise a zillion years ago speaker manufactures and instrument manufacturing have solved most the problem with combing and off axis response with larger speakers.
    By one..using a dual cone or twin cone design. Which uses a smaller second cone to improve off axis response.

    Good example is dual cone Eminence Beta 12lta


    Likewise a zillion years ago SUNN fixed off axis problems for guitar by using heavy cone 10" eminence drivers to kill the squaking. Then use a crossfire or splayed baffle to help with off axis response and combing.

    For guitar you had the SUNN 610L or 610S


    And bass had Sunn 415M or 415L


    Crossfire and full range speakers fixes most the off axis or beaming problems. And still uses simple large full range instrument speakers.

    Can only imagine. People hear with there eyes not your ears.
    It doesn't " look right" so it must not sound right. In reality it fixes the problem but I'd assume sales then and now are effected by the not look right but actually sounds better issue.

    People wanna re invent the wheel , they figured this krap out 40 plus years ago

    Duct tape, heavy weave grill, dual cone, or crossfire
    Last edited: Jun 2, 2019
  15. Wasnex


    Dec 25, 2011

    If you have two drivers side by side, you will get a primary lobe that beams out directly in front between the drivers. To the sides you will get secondary lobe. The shape and angle of the secondary lobes are determined by frequency and spacing between the acoustic centers of the drivers, which determine the phase angle. Where the signals form both drivers come together in phase they add and form the secondary lobes. Where the signals come together out of phase, you get cancellation and a null.

    I believe the Barefaced solution is a .5 alignment. Basically an LPF filter is applied to the drivers on one side of the cabinet to limit their output, so you get the dispersion pattern of a vertical column of speakers. At low frequencies all drivers work and the spacing between the drivers is such that no lobes are produced along the horizontal axis.

    At relatively high frequencies, individual cone drivers become beamy. I don't think the .5 alignment has much impact in this frequency range as the sound is pretty much shooting straight out the front of each driver instead of being dispersed horizontally. On a guitar amp, the beamy high frequencies can create an ice pick in the ear effect. This is probably magnified by the frequency response of a typical guitar speaker which is typically quite peaky in the high mids. This is where the beam blockers are supposed to help. The beam blockers are intended to diffuse the beam of high frequencies so they are softer and dispersed more evenly.

    From the review I have read the results, are highly unpredictable. In order to get better results, the beam blocker would need to be designed for the specific driver it is being used with. Some people do like certain drivers with beam blockers though, at least in guitar application. Whether it will improve the sound of your 410 is impossible to say because sound quality is subjective.

    I have actually seen what is essentially a beam blocker on some older commercial subwoofer designs. I believe the intent was to reduce distortion by blocking or diffusing the sound coming off the center of the cone.
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  16. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    There wouldn't be any point with a sub, since even a 500 Hz wavelength is 2.25 feet and will go around anything smaller than that, let alone an 80 Hz 14 foot wavelength.
  17. Wasnex


    Dec 25, 2011
    I don't think it had anything to do with the fundamental with a subwoofer, and if it was very effective, I think it would be fairly common, which it is not. But I have seen several designs over the years that have a slat that goes in front of the driver or a round disc that primarily obscures just the center of the driver like a beam blocker.

    This company calls it a phase plug for more SPL. But I have seen other companies say the idea is to reduce distortion.

    Whippet likes this.
  18. sawzalot

    sawzalot Supporting Member

    Oct 18, 2007
    Isn't beaming in part caused by the speaker drivers proximity to each other? It creates a "beam" that can be (and is) useful if you're setting up line array configurations, etc. A 4x10 tends to beam above certain frequencies (5-600 hz or so, IIRC), but it's more of a comb-filtering type of thing so I'm not sure how this gadget would help with that. I use stacked 2x12 and 2x10 speakers, so I don't experience this issue, but I'm not sure it's really a problem in need of a solution unless you just want to try it for fun.
  19. Wasnex


    Dec 25, 2011
    This is exactly the distinction I tried to make in post #15. Two drivers side by side will interact and cause the formation of primary and secondary lobes...beaming. But beaming also relates to individual drivers.

    With individual drivers: At low frequencies there is no pattern control. As the frequency increases the driver begins to exert some ability to control the dispersion of sound. The control increases with frequency. At high frequencies the sound may emanate from the driver in a tight cone shape. The amount of control relates to the size of the wavelength and the size of the radiating surface. So a 15' driver will begin to beam at a lower frequency than a 10'. Of course there are some tricks that can be used in the design of a 15' driver to broaden the high frequency dispersion. For example Electro Voice EVM drivers used curvilinear cones to help with dispersion.

    Take a look at Fig 3 and Fig 4 of the attached.

    Attached Files:

    Whippet likes this.
  20. Bodeanly


    Mar 20, 2015
    Never even heard of this until now. Heard of beta blockers tho.