Speaker effciency, frequency response and low bass power handling in the real world?

Discussion in 'Archived Threads 2001-2004' started by Chris PC, Jul 17, 2002.

  1. Chris PC

    Chris PC Producer

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    I have always thought frequency response is a very important specification. Through comparing different speakers and their response, I have found that flatter and wider frequency responses match with better sounding speakers in my experience. Small variations in frequency response limits (
     
  2. John F. Palacio

    John F. Palacio Supporting Actor

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    I didn't know one could post a 12 chapter book in this forum. What's the question, Chris? [​IMG]
     
  3. Tom Brennan

    Tom Brennan Screenwriter

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    Does Barton give specs on compression for his speakers? If not you can't figure how loud they'll play, you'd have to measure. Compression in speakers means that you can't figure that doubling the power in will actually give you 3db of volume out. Compression is little talked about, evidently many speaker makers don't want this dirty little secret to get out. Some pro speaker makers talk about it as their speakers are used as tools by users who are aware of compression and need to know how much of it a speaker suffers from. For instance the JBL Pro 2226 is a high efficiency, high output woofer used in motion picture theaters. JBL states that at the drivers full power rating it suffers from 4.6db compression. This means that the speaker has ceased getting louder and is simply soaking up power and turning it into heat. This is very good in terms of reliability of course but you can see that taking this driver's efficiency at 1 watt, then doubling the wattage and adding 3db and so on isn't going to tell you how loud it will go. Compression is much worse in hi-fi drivers than in pro ones.
     
  4. Chris PC

    Chris PC Producer

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    I know, I realized that when I wrote that thread. I told my frickin life story on how I came to wonder about how much power my speakers can handle in the bass and how loud they can play. Heh heh. Oh well, it is kind of interesting. So the spec for those kinds of things aren't readily available, but anyone can see, that information about low bass power handling and efficiency would be very useful in speakers comparisons. Although not the single most important consideration, it is still one of the most important. If your speakers can't handle lots of power in the bass and/or they are very inefficient in the bass region, then lots of amp power gets wasted, the amp distorts more, and not just over the bass range, but the whole range, midrange treble and all, and this whole compression likely adds distortion beyond just reducing the loudness.
    I have found that my speakers have their limits in terms of how loud the bass can go. It must be a factor of the ported design and the driver sizes, but with 4 drivers, I believe my speakers are quite reasonable in their efficiency and power handling over their entire frequency response, at least compared to my old speakers and a few other speakers I have listened to especially considering speaker cost. 4 drivers for the price of the speaker does produce what sounds like an efficient, clean and loud playing speaker. I have listened to some three way speakers with larger woofers that don't sound as clean as these speakers. I do notice a limit on the bass reproduction though, but thankfully, the bass doesn't compress until the midrange and treble are louder than I care to listen. This is why I would love to be able to have a better bass control than the one I have on my receiver. It doesn't produce the results I want, even with older speakers, but it does work enough to make it useful. For now, I just have to blend my Mirage BPS-400 into the stereo setup and I have all the efficiency, power handling and bass I need in my small room [​IMG]
     
  5. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Knowing all the information on a speaker is nice to have, but when you actually listen to a musical piece, it's often hard to judge whether a response has a certain spike and where. (unless it's severe)
    The questions you're asking relate to frequencies that are very rare (if found at all) in music. Perhaps you should do what I did:
    I used test tones in small increments and a meter. I recorded data for the entire range of sound and ploted it on a graph. I then hung up that graph on a wall and tell people "That's what your are listening to".
    hehe
    All that statistical mumbo jumbo doesn't mean much until the speakers are actually playing in the listening room with your electronics. So I just take the measurements, and live with them. [​IMG]
     
  6. Chris PC

    Chris PC Producer

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  7. Mark Seaton

    Mark Seaton Supporting Actor

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    Hi Chris,

    I believe ALMA has a disc which was developed by Don Keele which has the same signals as what Tom Nousaine uses for his max SPL tests, and what Don Keele used to use for his Audio reviews. Basically it is a short duration, 1/3rd octave burst. The key to testing the max output is to do it with a short burst signal, and not sustained power, which can damage the speaker.

    There are different reasons for limiting, where you will find that the speaker can probably play fairly loud around tuning, until the port chuffs audibly. Just above tuning you will find some reduction in capability as the excursion is exceeded, and again more quickly below tuning as the driver unloads. Getting a feel for maximum output is a good guide to setting your crossover for your subwoofer to allow greater dynamic range and cleaner production from your mains. The trick is to combine the output limitations and the frequency response considerations of placement in the room to get a good balance of output capability and good headroom.

    Regards,
     
  8. Chris PC

    Chris PC Producer

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    Interesting info. I am a little shy of trying to do any high power tests myself regardless of whether they are simply short duration. I'll leave it to the testers. I was just wondering if anyone had seen test or specs for tests done on one or more pair of speakers.
     

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