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What is frequency response and maximum decibals

Discussion in 'Amps and Cabs [BG]' started by Steve S, Sep 20, 2008.


  1. Steve S

    Steve S

    Jul 26, 2000
    What does it mean with descriptions for the Schroeder 1515L when it states that the "'FREQENCY RESPONSE" is 35hz-14khz and "MAXIMUM DECIBALS" 104db SPL @1W@/1M?

    The Epifani PS 115's frequency response is 36HZ-16KHz but doesn't list maximum decibals. It has "SENSITIVITY" 97 db 1W1W. How can I tell which cab goes deeper?
     
  2. fenderhutz

    fenderhutz Supporting Member

    Jan 28, 2007
    Harpers Ferry WV
    Trying them out with your bass and amp.
     
  3. 62bass

    62bass

    Apr 3, 2005
    That's right. Try them with your amp. These specifications are pretty well meaningless because nobody rates their stuff using useful numbers and they use ratings systems to make their stuff look more powerful and to snare guys like you who read specs and think they're very important. Try everything before you buy it.
     
  4. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    I agree with try them out.

    Just from the specs, they both have basically the same bottom end but the Schroeder should be louder.

    However, trust the specs about as much as you would trust a Politician's promise :p
     
  5. Bass cab specs are pretty meaningless these days because they don't all use the same standards.
     
  6. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Aside from everything else, specs alone are meaningless because the ear can be fooled. A cab with lots of low mids can sound deeper than a cab with a lot of lows.
     
  7. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    +1
     
  8. Steve S

    Steve S

    Jul 26, 2000
    I'm trying to make decisions on cabinets that are located too far away so wonder what those specs mean..
     
  9. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    You need to find somebody with both those cabs and ask them. I would create a new thread that mentions those two cabs specifically. Really, those specs tell you nothing.

    It implies the Schroeder is louder, but considering one it a 1x15 and the other a 2x15 I would expect that anyway.

    And the sensitivity and maximum decibels are the same thing.
     
  10. lfh

    lfh

    Dec 18, 2003
    Stockholm, Sweden
    Both designations are technically incorrect:

    An actual frequency response is described by at least one graph: The magnitude of a so-called transfer function. Such a graph simply illustrates how loud the output is at various frequencies when the input signal is kept at a constant level, i.e. independent of the frequency. The traditional way of measuring the frequency response is to use a sine-sweep, and plot the output level vs frequency. (To fully describe the system, the phase response should also be given, but this graph is of little importance to the end-user.)

    What is listed in the spec is merely a frequency range, but the data is totally meaningless since it's not stated how much the level varies within this range, e.g. if the tolerances are +/- 3 dB or +/- 6 dB or some other interval. Furthermore the measurement conditions must be given (free field, half space, quarter space, ...) for the spec to be meaningful, since the floor and walls close to the cabinet have a huge impact on the bass response.

    As to the "maximum decibels" it should rather read sensitivity, i.e. what output level in dB an input power of 1 W (or actually rather the voltage 2.83 V RMS for an 8 Ohm cab) generates at the distance 1 m from the front of the cabinet (at a given frequency or frequency band). The higher the sensitivity, the less power is needed to generate a given SPL.

    As brought up by several posters, specs are often meaningless or even wrong, like the one in question. Even if manufacturers would adhere to a stringent standard, there's much more to it -- room acoustics and psycho-acoustics play a significant role in how the cabinets work and are perceived in real life.

    Bottom line: Try the cabs and let your ears be the judge.

    Edit: This rant was not meant to pick on the cab mentioned. The intent was just to illustrate that data given by manufacturers are often fishy to say the least.
     

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