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can someone educate me on these graphs?

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  • can someone educate me on these graphs?

    These two graphs are of 5" woofers , that lower line, if I understand correctly is resistance. One has a higher spike in lower frequency the other one lower. What does level of this spike mean in audible frequency reproduction in this region?
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  • #2
    Re: can someone educate me on these graphs?

    guess it depends on where the crossover point will be and what slope it's at. I'm working on a project now that uses the Silver Flute, great driver for the money, if it was feasible though I would take the SB
    David

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    • #3
      Re: can someone educate me on these graphs?

      if I understand correctly is resistance.
      It's impedance - which is reactive and varies over a frequency range ( X-axis ).
      ( Resistance is constant regardless of frequency )
      Those are impedance resonance peaks; at roughly 42Hz and 38Hz respectively

      Is it possible that one of those graphs has the wrong nomenclature on the y-axis. :D
      "Not a Speaker Designer - Not even on the Internet"
      “Pride is your greatest enemy, humility is your greatest friend.”
      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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      • #4
        Re: can someone educate me on these graphs?

        Originally posted by pernilongo View Post
        What does level of this spike mean in audible frequency reproduction in this region?
        In and of itself, not much. All you know from that spike is the resonant frequency of the cab/driver combination, below which response rolls off.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Re: can someone educate me on these graphs?

          Originally posted by billfitzmaurice View Post
          In and of itself, not much. All you know from that spike is the resonant frequency of the cab/driver combination, below which response rolls off.

          So in simple language the driver with lower spike in a given cabinet will have a roll off that is not as steep?

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          • #6
            Re: can someone educate me on these graphs?

            Originally posted by UGP View Post
            guess it depends on where the crossover point will be and what slope it's at. I'm working on a project now that uses the Silver Flute, great driver for the money, if it was feasible though I would take the SB
            If you don't mind me asking what would be the criteria that makes sb a choice over silver flute.

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            • #7
              Re: can someone educate me on these graphs?

              Originally posted by UGP View Post
              guess it depends on where the crossover point will be and what slope it's at. I'm working on a project now that uses the Silver Flute, great driver for the money, if it was feasible though I would take the SB
              If you don't mind me asking what would be the criteria that makes sb a choice over silver flute.

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              • #8
                Re: can someone educate me on these graphs?

                Originally posted by pernilongo View Post
                So in simple language the driver with lower spike in a given cabinet will have a roll off that is not as steep?
                This isn't worded correctly.

                The amplitude of the impedance peak isn't what you need to worry about. The frequency of the impedance peak tells you the box tuning and therefore, how deep that woofer/box combination will play before starting to roll-off.

                Now, regarding your statement... the "steepness" a.k.a. SLOPE of the roll-off will be the SAME for both woofers. (12dB/octave in a sealed box, 24 dB/octave in a ported box.)

                By the way, you're not going to get much DEEP bass from a five inch woofer, but they'll do ok in a bookshelf speaker or computer speaker.

                This looks to be a sealed box impedance sweep. If it were ported, you'd see TWO of those impedance peaks.
                ~Marty

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                • #9
                  Re: can someone educate me on these graphs?

                  Also note... there is no way to compare the amplitude of both impedance peaks. One of the graphs has OHMS listed, the other doesn't. So you really don't know which peak is higher in amplitude.

                  But as I mentioned in my previous post, the amplitude of the peak doesn't really matter all that much. There are about 25 other things that are far more important.

                  The main thing to take away from this is that a woofer/box combination will have a tuning frequency.... and that is what you are seeing when you look at the impedance peak.
                  ~Marty

                  Baby Eidolons
                  Sapphos
                  Cables (Post #54)
                  Other speakers (Post #21)
                  Design Thoughts (Posts: 6,10,13,33,35)
                  Boundary Augmentation
                  Dispersion/Interference

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                  • #10
                    Re: can someone educate me on these graphs?

                    Originally posted by pernilongo View Post
                    If you don't mind me asking what would be the criteria that makes sb a choice over silver flute.
                    I've got a couple of the 8" really nice, as for a the 5.25's sb has a better motor(most likely) probably lower distortion, will go a little lower in the same size box(actually SF from what I'm getting won't go quite a low as advertized) more X-max, even though the SF has fantastic build quality for the price the SB is even better.
                    But I've not tried the SB so who knows I could be wrong on most counts.

                    P.S. above I thought you were speaking of the freq. peaks not the Imp peaks.
                    David

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                    • #11
                      Re: can someone educate me on these graphs?

                      Originally posted by ReissM View Post
                      This isn't worded correctly.

                      The amplitude of the impedance peak isn't what you need to worry about. The frequency of the impedance peak tells you the box tuning and therefore, how deep that woofer/box combination will play before starting to roll-off.

                      Now, regarding your statement... the "steepness" a.k.a. SLOPE of the roll-off will be the SAME for both woofers. (12dB/octave in a sealed box, 24 dB/octave in a ported box.)

                      By the way, you're not going to get much DEEP bass from a five inch woofer, but they'll do ok in a bookshelf speaker or computer speaker.

                      This looks to be a sealed box impedance sweep. If it were ported, you'd see TWO of those impedance peaks.
                      Oh I see , its starting to make sense.

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                      • #12
                        Re: can someone educate me on these graphs?

                        Originally posted by UGP View Post
                        I've got a couple of the 8" really nice, as for a the 5.25's sb has a better motor(most likely) probably lower distortion, will go a little lower in the same size box(actually SF from what I'm getting won't go quite a low as advertized) more X-max, even though the SF has fantastic build quality for the price the SB is even better.
                        But I've not tried the SB so who knows I could be wrong on most counts.

                        P.S. above I thought you were speaking of the freq. peaks not the Imp peaks.
                        I think they are right about them not playing low. I have them in 0.35 cuft box and they don't play any lower than overnight sensations. I tried different size ports also without much success. They are a lot louder though than OS. I think SF have more xmax than 3.5mm however. Maybe a bigger box will do the trick but maybe not.

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                        • #13
                          Re: can someone educate me on these graphs?

                          MOST typically, those graphs are generated by the driver manufacturers and are commonly NOT "in box". The driver is often mounted on a "large" board (like 2 meters by 2 meters) with the back open or exhausting into another room. It's usually an anechoic setup.

                          All that "free-air" peak shows you is the resonant frequency of the driver (the T/S parm. called "Fs"). When input into a box modeling program ( like WinISD from www.linearteam.org ) along with Qts and Vas, it is used to predict what the actual "in-box" impedance curve would look like. For a closed box, the peak will rise in freq. and lower in amplitude. For a vented box, the single large peak will be replaced by twin peaks with the valley (in between) centered on the box's tuning freq. (Fb).

                          What exactly are you trying to learn? I though you already had the SF woofer and were going to use it in Paul's "Orient Express" box?

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                          • #14
                            Re: can someone educate me on these graphs?

                            Don't "guess". WinISD is FREE. Learn to use it. That's a large part of the fun of DIY (for most people, anyhow). BTW, the OS are atypical in their bottom end reach for 4" drivers.

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                            • #15
                              Re: can someone educate me on these graphs?

                              Originally posted by Chris Roemer View Post
                              MOST typically, those graphs are generated by the driver manufacturers and are commonly NOT "in box". The driver is often mounted on a "large" board (like 2 meters by 2 meters) with the back open or exhausting into another room. It's usually an anechoic setup.

                              All that "free-air" peak shows you is the resonant frequency of the driver (the T/S parm. called "Fs"). When input into a box modeling program ( like WinISD from www.linearteam.org ) along with Qts and Vas, it is used to predict what the actual "in-box" impedance curve would look like. For a closed box, the peak will rise in freq. and lower in amplitude. For a vented box, the single large peak will be replaced by twin peaks with the valley (in between) centered on the box's tuning freq. (Fb).

                              What exactly are you trying to learn? I though you already had the SF woofer and were going to use it in Paul's "Orient Express" box?
                              I did download winsd right after that OS thread and have been playing with it ever since. It's a really nice and easy program . Thanks for recommending it to me.

                              I wanted to learn how to pick and chose drivers I guess . For example with silver flute I know how it sounds and I wanted to make a correlation between this graph and real life experience , I don't have the sb driver and I only chose it because its different from most 5"s to have a vague idea what to expect from different woofers. I am building orient express , this driver selection was purely theoretical not really connected to orient express or desire to build smth else. I think I got a very good understanding of what those impedance peaks represent. I guess I could have asked just about the peaks with no driver examples.

                              P.s. this 0.35 box is just smth I had arround its not an orient express box.

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