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Is there a "standard" decibel level for measuring frequency response?

Discussion in 'Amps and Cabs [BG]' started by millard, Nov 11, 2005.


  1. millard

    millard

    Jul 27, 2004
    SoCal
    I was looking at a manufacturers web site and noticed that one version of their spec had frequency response of 50Hz-20kHz. Their PDF data sheet for the same produce said the frequency response was 70Hz-18kHz.

    That felt like a real difference, so I emailed them. They got back to me and said the wider measurement was done with a +/- 6db tolerance while the tighter measurement was done with a +/- 3db tolerance. He explained that response tapers off at the ends and this was normal.

    Yet most people, including this manufacturer, don't seem to typically disclose the tolerance for the test. Is that because they all do it at +/- X db and this case is a fluke or do they all pick a tolerance that suits their specs well?

    Thanks...Millard

    PS: Maybe I've been doing this wrong all along -- if the cab is "rated" to 46Hz, I've been EQing away any signal below that level, not wanting to pump a bunch of low-end into a cab that, by admission, isn't interested.
     
  2. Ask 'em to show you a plot of actual measured response, and how it was taken...

    Then watch 'em back pedal.

    :D

    Phil Jones is the only one I know that publishes actual measurements of actual products. It is easy to claim bullsh!t specs of DC to Daylight when you don't have to prove it.
     
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    There's nothing wrong with stating response +,-3dB or +,-6db, both are acceptable. The problem lies in not knowing which of those tolerances were used, if not an even wider one. Bruce is right, ask to get an actual measured SPL chart and all you'll get is a lame explanation why they can't provide one. There oughta be a law...
     
  4. millard

    millard

    Jul 27, 2004
    SoCal
    I agree completely. I had always naively thought (since the number is never mentioned) that there was an accepted standard and I just wasn't aware of it.

    Assuming I can get the number stated, any idea what the normal roll-off is between 3db and 6db tolerances? In this particular case, it is the Bag End S15X-D that goes to 50Hz at +/- 6db and to 70Hz at +/- 3db. Props to them at least for offering both numbers.

    Lovely, now I can't actually compare or EQ cabs based on that value. I'm guessing just about anyone's cab can get to 41Hz if you open up the tolerances enough. :meh:

    Thanks...Millard
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    On average most tens are down 3dB at 90 Hz, twelves at 70 Hz, fifteens at 60Hz, but that's a very general assessment. Down 3dB at 90 Hz sounds not so good, but if that's down 3dB from a 100dB broadband average you're at 97dB at 90 Hz. You can find tens that are down 3dB at 60Hz, but if they are running at 95dB broadband to begin with at 90Hz they still won't do 97dB. That's the problem. There are so many variables involved that the manufacturer can give you enough information to make the product seem good, while in reality leaving out one spec can make all the others worthless.
     
  6. Passinwind

    Passinwind I Know Nothing Supporting Member

    You can't EQ or compare by the numbers in any case, unless maybe they were derived in the room you're playing in. And even that can be very misleading. Say your cab is -10dB at 41 Hz, relative to full range response. You seem to want to hack everything at that frequency, but many other folks would want to boost their EQ to flatten out the response. I have no idea what I'd choose without actually hearing how it sounds. :cool:
     
  7. SteveC

    SteveC Supporting Member

    Nov 12, 2004
    North Dakota
    Unfortunately there are no standards. Manufacturers can twist specs however they want.

    I wish there was an "industry standard" so we could actually compare "apples to apples" for a change.
     
  8. seamonkey

    seamonkey

    Aug 6, 2004
    What about a "Talk Bass seal of approval"?
    Smart people on TalkBass come up with standards of measurements and testing (they probably already exist) and publication, and if a manufacturer meets these they can get a Talk Bass seal of approval and use it freely in their advertising. And put a little logo on their cabinet.
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    They do, but getting the industry to toe the line? Hey, is that a flock of pigs I see flying by?
     
  10. seamonkey

    seamonkey

    Aug 6, 2004
    I don't blame the manufacturers. They'll get away with whatever they can as long as their customers still buy their products.

    What amazes me is the cash people are putting out for these cabinets and yet don't really push manufacturers for specs.

    The claim seems to be that specs wouldn't matter, and wouldn't reveal how the cabinet would perform in the field.

    I contend that people would be surprised that measurements can actually predict real world performance. And it would keep manufacturer honest.

    Those who don't believe in specs can just ignore them.
    Others will find them to be a valuable tool.
     
  11. The consumer has the power to force manufacturers to tow the line, but consumers will never exercise that power. Same with the ghastly DRM copy protection scheme that Sony is landing on your computer when you play a copy protected Sony CD.

    The solution is simple: do not buy an unplotted bass cab or a copy protected CD. Never. Immoral corporations don't get the point until the equation "Sales = Zero" hits home. Then they fire some workers, reorganize, fall back, and call it progress.

    The above solution is fantasy, and ain't gonna ever happen because consumers continue to buy bullsh!t products, no matter what.

    I'm (not) surprised that BP magazine has never done analysis of bass cabs. Then again, every magazine is revenue driven, and they would lose revenue if they shine a bright light on bass cab cockroaches.

    I finished my new digital recording station, so perhaps the time is ripe to post a series like Luknfur is doing, but for bass cab response. I have ready access to D410-XLT, and a few Ampeg 6x10 for starters. I think an unbiased comparision of bass cabs posted here would be a great idea.
     
  12. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    I agree, that would be a great idea. :)
     
  13. seamonkey

    seamonkey

    Aug 6, 2004
    Agreed - this would be great.

    The manufacturers may dis your findings, but then maybe they'd be more motivated to provide their own.
     
  14. theshadow2001

    theshadow2001

    Jun 17, 2004
    Ireland
    Yes it would be great to do this. If someone had a room with correct acoustics and all the equipment needed to this as well as a whole range of brand new unused cabinets and the time. So if there are any bored, millionaire, acoustic engineers who wan justice for the bass world reading this.... It really would be great if it were possible to this though then publish the results for the world and manufacturers t o see.
     
  15. That would be great if all the bass players performed in anechoic rooms.

    I figure a repeatable measurement can be taken outdoors which is a real life indication of how a cab performs under worst-case conditions.
     
  16. Pneuma

    Pneuma

    Feb 14, 2004
    Arkansas
    If it looks like an illegal rootkit, and it works like an illegal rootkit...

    Hey, why didn't my AV software tell me I had a wurm?!

    Digital Rights Management my foot. Digital "We Ownz0r Your B0XX3n!" Management more like it.

    P.
     
  17. seamonkey

    seamonkey

    Aug 6, 2004
    The point is to get reference of the cabinets measurements. No grass roots movement is going to be able to afford and anechoic chamber, and testing outdoors is going to have variable parameters, reflective surfaces near by, sea level or in the mountains, air temperature, humidity …

    Still if somebody does the measurements, to the best of their abilities, in a reasonable test environment, the results will mostly balance off of each other.

    If manufacturers dispute the findings they can retest themselves. If you dispute the findings you can retest also. I would just like to see attempt at proof of manufacturer's claims, and honestly - people's opinions.

    "Classic" cabinets could also be measured and duplicated if people are after a voicing.
     
  18. millard

    millard

    Jul 27, 2004
    SoCal
    My interest in hacking below some point is that I'm thinking there is a point of diminishing returns and forcing a bunch of low-end into a cabinet that it won't handle well is just asking for trouble.

    Of course you are right that you have to listen to it, but I don't mind jump-starting the experimentation process with real data (or what I thought was real data).

    Millard
     
  19. Passinwind

    Passinwind I Know Nothing Supporting Member

    That's perfectly reasonable, and data that's a bit more real certainly would be a good start. :cool:
    I use different low end cutoffs depending on room and playing situation mainly, but there are some cases where I've done it to protect a driver that's flopping too much for my taste as well.

    To clarify my feelings about specsmanship:
    I'm all for good solid information, and I applaud anyone willing to provide it. I've worked with acoustic transducers of various kinds professionally for over 30 years, and in some fields like SONAR work I've depended heavily on real test measurements. The best test intrument I've found for audio is my ears though, for better or worse. Plots taken in (even semi) real environments would be great; outdoors is what most of us could manage, and if carefully done could be useful. But I don't believe the bass cab market is likely to drive this any time soon. I also don't share the disdain for current commercial bass cab products that some of you mention, I think a lot of them are fine as is. Just IMHO, of course.
     
  20. theshadow2001

    theshadow2001

    Jun 17, 2004
    Ireland
    I would love to see standardised testing. Thats consistent and repeatable come in to play by some international standards organisation. Those manufacturers who are confident of their product could only benefit from doing such tests proving that their product is what they say it is. Although this doesnt happen so maybe they really do have something to hide.....is that Harke cabinet really much different from that bergantino cabinet???