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Nd91-4 with nd90 passives doesn't go as loud as i wanted to be

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  • Nd91-4 with nd90 passives doesn't go as loud as i wanted to be

    Hi, i'm trying to make a passive agressive styl speaker but tuned lower and with a build in amp. On paper everything should be fine, i have modelled it with winisd but the results in real life are dissapointed and i have the idee something is wrong but i don't know what. I sealed everything except the passives but they have a sealing and if i push the passives it takes a while for the speaker to move back in so the enclosure is air tight in some degree. Did a 20 hz test tone but no chuffing or something like that. Does someone know what could be wrong? This costed me 300,- and on paper it should be fine.

  • #2
    Used a jbl partybox 100 to measure a 50 hz signal and it came close to the specs( 100db at 50hz ), so roomgain is not that much involved.
    further i used a w6-1139SIF sealed 4.5 liter with a tpa3116 amp at max volume and at volume 13 and the dayton build at volume 13 to.

    So loudness wise it is how it supposed to be i guess but the nd91 is stressing like crazy and over excursion. So i can't get more than 81 db out of it while it should be 92 db. I even tried an amp with dsp and build in highpass at 48 hz but it get even lower like 77 db.
    Attached Files

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    • #3
      Not enough info?

      So.... you've got a PA size box, w/2 PRs (just like the PAs?) but you added mass to them for a lower tune? How much mass? What's your Fb? (IMO the PA was probably already tuned lower than I'D have tuned it!)
      You also used the same tweeter and XO? What does your 2nd graph show (w/the 4 lines)?

      Didn't an internal amp suck up some interior volume??
      Last edited by Chris Roemer; 08-20-2021, 10:06 AM.

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      • #4
        I found when I tried to replicate the PAs modelling I couldn't get much below 60hz, but slightly bigger box with the ND65 I could. I wonder if volume is driving this? Also I had to use some of the supplied weights on the ND90s when modelling to get it down lower which works.

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        • #5
          Originally posted by Chris Roemer View Post
          Not enough info?

          So.... you've got a PA size box, w/2 PRs (just like the PAs?) but you added mass to them for a lower tune? How much mass? What's your Fb? (IMO the PA was probably already tuned lower than I'D have tuned it!)
          You also used the same tweeter and XO? What does your 2nd graph show (w/the 4 lines)?

          Didn't an internal amp suck up some interior volume??

          The graph with the 4 lines is from youtube. Its the frequency chart of the jbl partybox and logitech hyperboom but its to show the spl at 50 hz at max volume, the light green is the partybox and is at 103db, so my in room measurement is quite aqurate.

          I use the same tweeter and the xo is in the amp.

          I have the amp volume calculated but this right speaker is without the amp, i put some mdf on the sides because i first used the nd105 pr but it didn't get loud either, so now i tried the nd90 pr like the passive agressives.

          I used all the weights wich comes with the passives but cut off the dread wich sticks out. So i add 21 gram total for 2 passives! The Fb is at 50 hz!

          A 50 hz signal of 40 watts should give me 93 db peak!! Not 81 db!!

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          • #6
            Originally posted by 3rutu5 View Post
            I found when I tried to replicate the PAs modelling I couldn't get much below 60hz, but slightly bigger box with the ND65 I could. I wonder if volume is driving this? Also I had to use some of the supplied weights on the ND90s when modelling to get it down lower which works.
            Maybe because the nd65 has less spl at midrange so the bass is more balanced?

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            • #7
              Originally posted by Scarface1 View Post

              Maybe because the nd65 has less spl at midrange so the bass is more balanced?
              not sure, all i know what i could model the ND65 with 2 of those ND90's and i think from memory it was an F3 of 60hz and flat from around 70 ish...., but coupled with the larger full ranger it did simiilar to yours where it rolled off from 250hz.

              i'm still a primary school student in this world of speakers, so i only really look for one thing which is the low end and being what i want around that F0.

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              • #8
                Why do you want to add so much weight (tune so low) that your max output @80-100Hz is down -5dB from the normal PA tuning?
                I can SEE that tuning @50 can increase your output about +4dB AT 50Hz, but you're around -18dB down at that point.
                You've raised your F3 (the way that term's typically used) from 75Hz up to around 110Hz.

                So, your internal box volume (not counting an amp) is pretty close to (the "stock") 0.04 cu.ft.box?
                For ME, a pr. of ND105 PRs models about the same as the ND90s (using the same mass).
                EYE would run those PRs (either set) with much less added mass, like maybe 6g (total) ?

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                • #9
                  Originally posted by Chris Roemer View Post
                  Why do you want to add so much weight (tune so low) that your max output @80-100Hz is down -5dB from the normal PA tuning?
                  I can SEE that tuning @50 can increase your output about +4dB AT 50Hz, but you're around -18dB down at that point.
                  You've raised your F3 (the way that term's typically used) from 75Hz up to around 110Hz.

                  So, your internal box volume (not counting an amp) is pretty close to (the "stock") 0.04 cu.ft.box?
                  For ME, a pr. of ND105 PRs models about the same as the ND90s (using the same mass).
                  EYE would run those PRs (either set) with much less added mass, like maybe 6g (total) ?
                  Hi Chris, i use the dsp to flatten the frequency and i wanted to go as low as i can. 92 db at 50 hz is pretty cool i think from a 3.5 liter speaker and on paper it should be possible. Missing 11 db is a lot and it isn't room gain i guess.

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                  • #10
                    How flexible is the DSP (can you EQ 50Hz UP +18dB)?
                    Doesn't that suck up amp headroom?

                    IF (for instance) you can have +12dB (max) @ 50, then I'D add THAT EQ into your WinISD model and mess w/the box tuning to try to lift the 60-80 range or so, no?

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                    • #11
                      Originally posted by Chris Roemer View Post
                      How flexible is the DSP (can you EQ 50Hz UP +18dB)?
                      Doesn't that suck up amp headroom?

                      IF (for instance) you can have +12dB (max) @ 50, then I'D add THAT EQ into your WinISD model and mess w/the box tuning to try to lift the 60-80 range or so, no?
                      I can boost enough with dsp but what my concern is, is that with a normal amp i should come close to the 92db at 50 hz right? Maybe the weight is to much but shouldn't winisd predict that?

                      This week i will try to set a highpass at 45 hz and a lowpass at 55 hz with my dsp amp and put the gain up.

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                      • #12
                        Chris raises a good point, re enclosure sizing, with mine I ended up increasing the box size and loved the extra thump, but was also using a mono 60w Dayton board...plus I haven't used a DSP, outside of my Qualcomm chip amp and it didn't go well, but think it was due to my step up module. I'm interested in how yours goes mate, that would be cool something so small sounding so loud

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                        • #13
                          The ND91 has a thermal limit of 30W.
                          I don't see any way to exceed about 86dB @ 50Hz.

                          In your box (0.05cf, if tuned to 57Hz), if you set a 2nd order HP @ +6dB @ 65Hz, you hit the driver's Xmax @ about 8w w/50Hz down -6dB (but nearly flat down to 60).

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                          • 3rutu5
                            3rutu5 commented
                            Editing a comment
                            my box was a different (smaller driver as well), more making the statement regarding smaller volume due to sacrificing it to components....also what ever DB i reached was loud enough for my 40 year old ears.

                        • #14
                          In 3.5L (0.12cf, from your post #9 above) Dayton's TCP115-4 can take 28wRMS w/an (unboosted) F3 of 50Hz @ 95dB.
                          I'm using it in a vented box of 0.09cf (close to 2.5L) and even though WinISD shows its F3 as 50Hz (using MY DATS parms), its output @ 40 is quite satisfying.

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                          • #15

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