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  • #46
    Originally posted by LOUT View Post
    I read the whole thing (from new poster JustinBlack). Most of it seemed pretty relavent to small bluetooth speakers and their different qualities as well as being an interesting read in general. Got to the last sentence...."wat"?
    Just wanted to share with you 2 pics of my newest speaker i made for myself, took it to a photoshoot today
    Attached Files

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    • #47
      Looks pretty cool, i like the detail in the middle

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      • #48
        It does look pretty cool, but you'll likely have some weird phasing issues around the top octave of the voice range (w/ 6" of driver separation).
        Their effect could be reduced by standing it on end.

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        • #49
          Originally posted by Chris Roemer View Post
          It does look pretty cool, but you'll likely have some weird phasing issues around the top octave of the voice range (w/ 6" of driver separation).
          Their effect could be reduced by standing it on end.
          Could you explain what you mean with wierd phasing issues and and what is the reason for that and how to solve it ?

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          • #50
            If that's 1 tweeter and one woofer playing the same source material, and they're listened to by someone who has 2 ears (in a horizontal line/plane), then at the crossover freq. (and for a ways on each side of it) the sound will have "lobing" issues (look that up, also "comb filtering"). All speakers have this, but lining them up (vertically) and keeping them as close as possible decreases the severity of the effect.

            You could also leave the speaker on its bottom, and listen to it w/your head sideways (so, like laying down), but then it one of your ears gets covered up, it won't matter so much. (There will just be "nulls" to various extents in different locations - in the horizontal plane.)

            Wouldn't worry about it too much. Does your boombox have a crossover? Is the box tuned?

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            • #51
              Originally posted by Chris Roemer View Post
              If that's 1 tweeter and one woofer playing the same source material, and they're listened to by someone who has 2 ears (in a horizontal line/plane), then at the crossover freq. (and for a ways on each side of it) the sound will have "lobing" issues (look that up, also "comb filtering"). All speakers have this, but lining them up (vertically) and keeping them as close as possible decreases the severity of the effect.

              You could also leave the speaker on its bottom, and listen to it w/your head sideways (so, like laying down), but then it one of your ears gets covered up, it won't matter so much. (There will just be "nulls" to various extents in different locations - in the horizontal plane.)

              Wouldn't worry about it too much. Does your boombox have a crossover? Is the box tuned?
              I will check it out, right now i havent got into much detail since i wanted to test the speaker as it is and see the response of my friends when we go out and party. The tweeter is crossed at about 2800Hz, the woofer is not. The box is tuned yes, F3 is about 55Hz. I could go down to 49Hz F3 but i decided i would rather have a slight boost of frequencies under 100Hz. The place i go to is very noisy, a lot of people talking loudly and bars with music not far away.

              A challenge for forum members: This speaker is plenty loud and has good bass for needs of me and friends. But i was thinking of making an even better speaker, just for me. My goal was to keep the same 55Hz F3 and get a slight dB boost in loudness. This speaker i currently use is a 14€ dayton audio TCP115 4 ohm. So i said, i am ready to pay 60€ for the woofer part (4x the price of current one). So i went searching and i simply couldnt find any speaker that could do the same F3 in this 4L enclosure and even match TCP115 loudness, let alone be better. Could you maybe help me in my search ? 60€ or 60$ is the budget of woofer driver.

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              • #52
                Originally posted by SentinelAeon View Post
                A challenge for forum members: This speaker is plenty loud and has good bass for needs of me and friends. But i was thinking of making an even better speaker, just for me. My goal was to keep the same 55Hz F3 and get a slight dB boost in loudness. This speaker i currently use is a 14€ dayton audio TCP115 4 ohm. So i said, i am ready to pay 60€ for the woofer part (4x the price of current one). So i went searching and i simply couldnt find any speaker that could do the same F3 in this 4L enclosure and even match TCP115 loudness, let alone be better. Could you maybe help me in my search ? 60€ or 60$ is the budget of woofer driver.
                Sounds like you're hoping to keep it pretty small, but speakers that are noticeably more efficient tend to want larger boxes to reach the same bass depth. How big of a box do you think you'd be willing to use for your personal speaker project?

                Will that size be for one box holding all the speakers, or will you be building a pair of stereo speaker boxes that can be positioned apart from each other, or will you want a single larger subwoofer and two smaller stereo speakers...or something different?
                My first 2way build

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                • #53
                  I plan to keep the box size the same as now, 4L. I know that louder speakers want bigger box and i dont expect much difference. If TCP115 4 ohm is 86.8dB and has F3 of 55Hz in that box .. if i find a speaker that can do 55Hz and 88.8dB in same box i would be happy. Just trying to see if money can buy a slightly better speaker in same enclosure or is TCP115 4 ohm the absolute best i can get.

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                  • #54
                    Have you ever looked at the FR plot for that woofer?
                    You keep quoting "86.8dB", but the plot runs from around 86dB near 250Hz, steadily downhill to about 79dB @ 3-4kHz.
                    It's "average" is about 83dB.

                    Also, you know there's a diff. in sensitivity (on drivers that are NOT 8ohm) between dB@1w/m vs dB@2.83v/m?
                    If you'll need an XO (2-way), 2.83v is what you want to be looking at.

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                    • #55
                      I looked at the FR plot yes. The reason i quote 86.8dB is because that is the official data, and it makes it easier for me to search for woofers to compare. For instance if i see woofer with 80dB sensitivity, i will not even put it into graph because i trust that it will be worse than tcp115. But i might be wrong, good point. Yes, i know the difference between 4 and 8 ohm, that is why i always make sure i include at what ohm i mean the sensitivity or if necesary i add or subtract 3dB to make things even. But that is not important anyway since i am only looking for 4 ohm speakers right now due to the amplifiers i have.

                      Btw just a quick question. I use winISD for calculating port and also to check other graphs. It has a neat thing called SPL and MAX SPL graph. So for instance if i run my TCP115 at 30W, i just select 30W and then see the graph of its frequency response - how loud it will be at certain frequencies. So my question is, how realistic is this graph ? I know it can never be a 100% true but, is it close enough so that i can compare different speakers and depending on this graph, choose the right driver ?

                      Just to make my question easier i made a plot of 2 speakers, TCP115 4 ohm and DMA70 4 ohm. Both in 4L enclosure, TCP115 4 ohm has F3 of 55Hz, DMA70 has F3 of 86Hz. First picture is showing their frequency response, F3 and so on. Second picture is absolute maximum SPL of both speakers. We see that despite them both being around 86dB at 4 ohms, there are differences. DMA70 is actualy about 6dB louder than TCP115 in frequencies of 250Hz and up. But under 250Hz, TCP115 performs better. And third pic is SPL, where i put 40W into TCP115 and 20W into DMA70, so their RMS. And that graph shows a different picture than graph of max SPL, which one is to be taken more serious ?

                      So my question is, how reliable is this data. Can i compare two speakers this way and get some idea of which will play louder at what frequencies ?
                      Attached Files

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                      • #56
                        Relying on published sensitivity specs may be misguided. Sensitivity should be listed at a specific frequency, input voltage, and distance from speaker to microphone. Traditionally these are 1000hz, 2.83v, and 1meter but there is no governing body for this and some manufacturers may measure differently. Generally one can compare sensitivity values for the drivers within each manufacturer's catalog but comparing between manufacturers may be misleading.

                        Also, an 8ohm driver of 90db sensitivity will theoretically deliver the same intensity as a 4ohm driver of 87db sensitivity when driven with the same voltage so to disregard all 8ohm drivers only because your amplifier claims to make more power into 4ohms may also be misguided.

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                        • #57
                          Originally posted by Dukk View Post
                          Relying on published sensitivity specs may be misguided. Sensitivity should be listed at a specific frequency, input voltage, and distance from speaker to microphone. Traditionally these are 1000hz, 2.83v, and 1meter but there is no governing body for this and some manufacturers may measure differently. Generally one can compare sensitivity values for the drivers within each manufacturer's catalog but comparing between manufacturers may be misleading.

                          Also, an 8ohm driver of 90db sensitivity will theoretically deliver the same intensity as a 4ohm driver of 87db sensitivity when driven with the same voltage so to disregard all 8ohm drivers only because your amplifier claims to make more power into 4ohms may also be misguided.
                          The problem is that my current amp or amps deliver 50W into 4 ohm speakers and only 25W into 8 ohm, which is 3dB difference. It might be worth checking it out but so far i havent found a 8 ohm speaker that would produce better results at half the power of 4 ohm ones. And if it does, there are usualy also a 4 ohm version of the same speaker which is even better. But i will keep in mind what you said, good point.

                          Also i went through some speakers and found some interesting ones that actualy produce more SPL than TCP115 4 ohm but at more power (or match TCP115 with a bit less power). But still i found nothing that would justify so much higher price. I will have to write to tech support of my suplier and ask if they actualy have something that will be worth the upgrade. What do i deem worthy of upgrade ? Well if its 3dB louder at same F3 than TCP115 in same enclosure, double the price. 6dB triple the price and so forth. Havent found such speaker yet though and went as high as 6x the price of TCP115. It seems physics cant be changed with money

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                          • #58
                            Those FR plots in WinISD are derived from the driver's T/S parms. The top end rolloff is driven mainly by the woofer's voice-coil "Le" parm. It obviously can't take into consideration cone breakup/ringing (bad), or shorting rings or special pole pieces (good). I never even view ISD above 500Hz anyhow.

                            To see what a driver can "take" (and its output), I 1st look at its "Max power" curve (given my planned box size and tuning). From there I set the appropriate power in the "Signal" tab, then see where the low freq. limit is (reaching Xmax @ the given wattage).

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