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Does anyone think about comb filtering when buying cabinets?

Discussion in 'Amps and Cabs [BG]' started by Lia_G, Feb 19, 2008.

  1. Lia_G


    Oct 27, 2005
    Just curious. Do any of you consider comb filtering when buying cabs? If not, is it because you don't think the effect makes a difference? I'm just wondering ... since one of the standard cabs that gets the most use, the 410, almost seems designed to produce comb filtering.

    I'd especially love the input of engineers.

  2. Blues Cat

    Blues Cat Payson Fanned Bass Strings Owner Commercial User

    May 28, 2005
    Katy, Tx
    Payson Fanned Bass Strings Owner
    Yea, now that I know about it I'm looking into vertical alignment of speakers that produce the same frequencies.
  3. As a small aside, I wonder where cabinets like the NV-610 stand in reference to comb-filtering? Technically, the drivers don't share the same horizontal axis, but they still overlap.

    So would a cabinet such as this act more like one with vertically arranged drivers, or like one with horizontally arranged drivers... or just some middle-of-the-road improvement on designs like the typical 4x10?
  4. amos


    Oct 23, 2003
    SE Portland Oregon
    No. However understanding it has led me to experiment with aligning my cabs differently.
  5. I actually don't. I've never achieved the tone I personally enjoy with vertically stacked 210's, and I've heard so, so, so many 410's out front over the years that sound absolutely wonderful and even and BIG in medium rooms without PA support.

    To me, the 410 is the 'smallest footprint with the biggest boom' single cab form factor out there. I do use a stacked 2x112 rig on occasion, and don't really notice a 'better, more even' tone off axis on stage.

    I'm not saying that this effect doesn't exist, but for my tone, volume and 'single cab solution' needs, the 410 remains king to me, and I've been told my tone is full and even out in the room by many players.

    I also don't notice any difference between my 'offset' 210s like the Berg's and 'straight across' 210's like the Epi regarding off-axis performance.

    I would think this effect would be a bigger deal with full range programmed music.

  6. MikeyD


    Sep 9, 2000
    I don't think it's a significant factor for bassists in most common cabinet configurations. If comb filtering were the problem that some people have made it out to be, guitarists would not have been using 2x12, 4x12, and similar speaker arrays for many decades. The constructive/destructive interference caused by multiple drivers is even less pronounced with bass. Moving around or standing in front of your speakers is likely to have a much more pronounced effect on what's heard by the audience than comb filtering of the higher frequencies.
    - Mike
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You're not going to be concerned about something that you don't know exists, and I'd say 99% of bass players haven't the slightest idea what comb filtering is. Nor are you going to look at alternative options when there are no alternatives. Face facts, the most important design feature for the vast majority of bass cabs is to 'look right', and what looks right is what you're used to. As for what guitar players use, if the smart guys in the band (bassplayers) don't know diddly about audio engineering concepts how can you expect flatliner guitar players to be any more well informed?
  8. Kenny Allyn

    Kenny Allyn

    Mar 25, 2006
    I never really thought about it until last year ...

    I started vertically stacking some cabs because that is the way they were designed, and my then newly aquired MB LM II head fit nicely on top. I noticed they sounded great, but what really sold me on the vertical stack was a comment from my singer. She almost never notices any change the musicians in the band make, but when I stacked the cabs she said whatever it is you just did don't change it.

    Now when we started working on the Mini cabs we actually did walk around test from dead on front to 90% off to the side and determined that yes something like comb filtering must be taking place in a non vertical cab. That said I agree with Ken J a good standard 410 still works fine in many situations.

    Here is where we are finding the most difference or evidence of some comb filtering effect. It seems to be in the way onstage musicians either do or percive to hear each other. About the time I switched to vertical stacking my guitar player switched to a single 12" cab vs the 2x12 combo he had been using and I can hear him much better now from a single point source. Also visiting musicians that come to hear us play even in small clubs where nothing is miced comment on how even the sound spread is, non scientific I know but even trained ears are hearing a difference, so it seems even in the house you can hear it. The most telling thing to me has been from drummers who say they have never heard the bass so well as when they play next to a vertical stack.

    ;) ... So yes now I think a lot about comb filtering and cab design
  9. jz0h4d


    Apr 26, 2005
    Yes I do think about it , but if it sounds OK i don't worry about it.

    I try and use matched speakers all of the time.
  10. fokof

    fokof One day ,I'll be in the future

    Mar 16, 2007
    I do.

    I use only Mackie SRM450 as my bass amp ( now that the v2 is out , they're gonna be stupid cheap! )
    I often use two of them. With the opening at 60° horizontal ( when placed as a wedge ) you have to check this out.
    Like you would with any two monitors setup......
  11. seamonkey


    Aug 6, 2004
    I have. And a 4x10 has a null right where most would stand - off the upper right or left of the cabinent.

    Also when stacking, tricks like it's best to keep the mids and high drivers as close as possible. The top cabinet should be upside down on the bottom. It may not look right, but sound wise it is.

    There's two points of view to the sound. It may sound perfectly fine to you on stage as you're close to one or the other driver, but out in the audience they're getting an entirely different mix. It's hard to know unless you have a good set of ears out in the audience.
  12. seamonkey


    Aug 6, 2004
    I tried those out once. They're very good speakers. Built in loudness contouring. Very effective. Any bass player should try sound reinforcement cabinets as they're often well designed.

    If you're doing a 60° outward splay, You might want to consider cross firing those instead. Bill FM has an article at his site about why this is a good idea.
  13. Nope. I would say the thought has never crossed my mind. I'm much more concerned with the fact that the sound man is on his 5th beer already and we don't go on for another hour!
  14. ggunn


    Aug 30, 2006
    Austin, TX
    At what frequency?
  15. guy n. cognito

    guy n. cognito Secret Agent Member Gold Supporting Member

    Dec 28, 2005
    Nashville, TN
    I have, but only because TB has told me too.......


    Seriously, I've never given it much thought and haven't noticed the effects. Of course, I typically play to a room full of drunks, so.............
  16. pedro


    Apr 5, 2000
    Madison, WI.

    Bill I'm also curious about this.
  17. ggunn


    Aug 30, 2006
    Austin, TX
    OK, I'm an engineer (BSEE), so I'll take a crack at it. Even if speakers were point sources (which they aren't), and assuming 2 12's normally mounted so their centers are about 13 inches apart, one would have to be 90 degrees off axis to see a path differential of 13 inches, which happens to be the approximate wavelength of a 1000 Hz sound wave. That means that at 90 degrees off axis, 1000 Hz is the lowest frequency where comb filtering could occur. As you come around closer to the axis, that frequency goes up as the path length differential comes down. At 45 degrees off axis, the path differential is about .26 meters, which translates to about 1.5kHz for the lowest comb filtering effects.

    But remember, these are 12" speakers, not point sources, so the radiating areas speaker to speaker are actually a lot closer than the 13" assumption.

    I don't think comb filtering is much, if any, consideration.
  18. pedro


    Apr 5, 2000
    Madison, WI.
    :meh: Could you explain that to me in english?
  19. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If there is any path length difference the two sources will either augment or detract from each other's output. That means there will be response peaks and dips at every frequency above the 1kHz example in this case, and those peaks and valleys will constantly shift as the listener's position shifts. In effect, you don't have a single response, or tone if you will, you have hundreds. You're not aware of it as you're standing too close to the cab and usually pretty much in one spot. The audience is. Eliminating comb-filtering is one reason why between roughly 1998 and 2005 the pro-touring PA industry trashed all of the cluster array cabs they owned in favor of line arrays. They didn't spend $5-15k per cab to do so over something that can't be heard.
  20. Per my previous post, and others above, I think for programmed music and full range front of house sound with lots of stuff happening at those higher freq's, I would guess there is a meaningful effect (although every big PA I've seen recently is stacked 10-12 high and 4 or so across (proportionally similar to an Ampeg Fridge!)... so not sure if that would be considered a 'line array'. For bass cabs, I'm just not so sure from all the listening I've done in clubs with guys using 410's and 810's with no PA support... just don't hear it.... sounds quite similar off axis versus standing right in front of it. IME!

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