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  • Paul K.
    replied
    Re: Sad but true

    You're absolutely correct and I'm in total agreement, not that our opinions will change anything.
    Paul

    Originally posted by Sydney View Post
    That reality is a serious issue - my opinion

    Leave a comment:


  • Jeff B.
    replied
    Re: Adding Sensitivity

    Originally posted by 1100xxben View Post
    I didn't realize they were teaching logarithms in elementary school nowadays.
    Interestingly, I was just reading where a young mathematician has recently solved an Erdos Conjecture on gaps between Prime Numbers. It involves the following equation:

    There are enough Logs in there to build a fire. ;)
    Last edited by Jeff B.; 12-23-2014, 06:42 PM.

    Leave a comment:


  • Sydney
    replied
    Sad but true

    There are many adults that can't do even simple math,
    That reality is a serious issue - my opinion

    Leave a comment:


  • Paul K.
    replied
    Re: Adding Sensitivity

    There are many adults that can't do even simple math, like addition or subtraction, in their heads, for instance to "make change", much less multiplication or division or percentages. Helps explain why so many people can't budget and amass huge debts, like from credit cards.
    Paul

    Originally posted by Sydney View Post
    Presuming that was factious; unfortunately I have heard adults say that Algebra was not been a requirement for them - The concept of formula reduction was baffling; along with the relevance to the real world.

    Leave a comment:


  • Sydney
    replied
    Re: Adding Sensitivity

    Originally posted by 1100xxben View Post
    I didn't realize they were teaching logarithms in elementary school nowadays.
    Presuming that was factious; unfortunately I have heard adults say that Algebra had NOT been a requirement for them - The concept of formula reduction was baffling; along with the relevance to the real world.
    Last edited by Sydney; 12-23-2014, 10:24 AM. Reason: gr

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  • billfitzmaurice
    replied
    Re: Adding Sensitivity

    Originally posted by stephed View Post
    Quick simple question.
    If you wire two drivers in parallel how does this effect Sensitivity. Say your tiring to match woofers to mids and you wire two 8 ohm 90 db woofers in parallel. Do you get a Sensitivity of 90 at 4 ohms or will you get something a little higher like a 92 db at 4 ohms.
    That depends on what you use for a signal level. If it's 1 watt you'll get 93dB. If it's 2.83v you'll get 96dB. It's usually best to use voltage sensitivity, not power sensitivity, when making calculations.

    Leave a comment:


  • JRS
    replied
    Re: Adding Sensitivity

    Originally posted by 1100xxben View Post
    I didn't realize they were teaching logarithms in elementary school nowadays.
    LOL, here in New Mexico its not even part of 10'th or even 11'th grade math track. In fact it's a rare student who hasn't had calculus who I encounter that has even heard the term. Of course the problem extends to businessman and politicians as well who have no concept of how things grow (or decay).

    Leave a comment:


  • 1100xxben
    replied
    Re: Adding Sensitivity

    Originally posted by ngjockey View Post
    Would rather use actual measurements than elementary school math.
    I didn't realize they were teaching logarithms in elementary school nowadays.

    Leave a comment:


  • Jay1
    replied
    Re: Adding Sensitivity

    It's easy to figure for a stand mount speaker. The woofers on a floor standing speaker really need to be measured to see how much boundary reinforcement you are getting from the floor.

    Leave a comment:


  • Jim Griffin
    replied
    Re: Adding Sensitivity

    For the post graduate course on sensitivity gain or loss check out my white paper starting on page 17.

    NFLAWP.PDF


    Jim

    Leave a comment:


  • ngjockey
    replied
    Re: Adding Sensitivity

    http://www.audioholics.com/loudspeak...-basics-page-2

    I found this closer to reality when I did measurements with several combinations. Although my results were higher. Depends on the amp too. Would rather use actual measurements than elementary school math.

    Leave a comment:


  • stephed
    replied
    Re: Adding Sensitivity

    Thanks a lot that really helps.

    Thanks Again,
    Ed

    Leave a comment:


  • tyger23
    replied
    Re: Adding Sensitivity

    If you double the cone area (i.e. wire two speakers), you get +3db.

    If you halve the impedance while the voltage stays the same, then suddenly 2.83v goes from 1 watt at 8 ohms to 2w. Since you doubled the amp power, you get +3db.

    +3db from doubling the cone area +3db from doubling the amp power = 96db

    Leave a comment:


  • Paul K.
    replied
    Re: Adding Sensitivity

    If the 90-dB sensitivities of the 8-ohm woofers were measured with a 2.83-volt input, which happens to be a 1-watt input, wiring them in parallel will result in a sensitivity of 96 dB with a 2.83-volt input across their 4-ohm impedance, which is a 2-watt input.
    Paul

    Originally posted by stephed View Post
    Quick simple question.
    If you wire two drivers in parallel how does this effect Sensitivity. Say your tiring to match woofers to mids and you wire two 8 ohm 90 db woofers in parallel. Do you get a Sensitivity of 90 at 4 ohms or will you get something a little higher like a 92 db at 4 ohms.

    Thanks for your help,
    Ed

    Leave a comment:


  • MGrant1957
    replied
    Re: Adding Sensitivity

    96 db at 4-ohms at 1w/m

    Leave a comment:

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