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the right speaker for dsp in small cabinet

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  • Scarface1
    replied
    i have found this driver. It have good xmax to depth ratio, strong big neodium magnet and 0,2 liter Vas. i want to put 4 of them in a 1 liter enclosure( winisd predict 1,8 liter for flat responce, but i use DSP) feeding 90 watt RMS( should reach 94 db ). i just bought 1 to test against the nd65-8...

    pictures are cone excursion, pr excursion and spl
    Attached Files

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  • tvrgeek
    replied
    Might I suggest folks go over to True Audio and read some of John's topic papers on speaker tradeoffs.

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  • Chris Roemer
    replied
    How "low" a driver will play (its "F3", or -3dB "down" point) is determined by its Fs (resonant freq.) and its Qts (which is calculated from Qes and Qms).
    F3 goes down proportionally to Fs, and also goes down as Qts rises (to a point).
    In GENERAL, at a Qts near 0.40, a driver's F3 comes close to matching its Fs in a properly tuned (ported) box. (Within a not-all-that-wide-range, every 0.10 rise in Qts can lower the F3 by roughly 10Hz; so if a driver has a "high"er Fs (like 80Hz) and a higher "Q" (like 0.70), it may be able to get down to approx. 50Hz (vented).
    Typically a closed box will be about half the size of a vented box, at a loss of about the bottom 2/3rds to one full octave.

    Box size (to achieve that F3) is determined by Vas AND (also) Qts.
    The box gets smaller as Vas AND Qts DROP.

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  • tvrgeek
    replied
    DSP will not let you violate the laws of physics. Do model (WinISD is one good free tool) and look at excursion vs x-max. It takes AIR to make base. Lots of air. Little drivers and little boxes do not move much air. Mother nature always wins. Also be aware, published specs are advertising. They tend to be a bit optimistic.

    If you add mass to a driver, yes, it lowers the Fs. It also kills efficiency and rolls off much lower. If you want deep bass from small drivers, it is called "headphones"

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  • LOUT
    replied
    Not sure how well it'll work with that particular PassiveR, but this tiny woofer seems to model well in 0.25-0.3liters with minimal DSP required:
    https://www.parts-express.com/tecton...-ohm--297-2172
    The ND64 also seems to model well in 0.3L.

    When I say these may perform better in that small, ported/PR box it's because they can reach the same 50-60hz as the ND65 but they should be able to make 50-60hz about 3-6db louder because the ND65's low-end can get a little squished/limited from such a small container while these shouldn't.
    That's a decent, but not nightVSday difference though, so you might not really notice unless you're comparing them side-by-side with 60hz sine waves since the ND65 is louder up around 100-150hz if you don't have it fully flattened with the DSP.

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  • Scarface1
    replied
    Originally posted by Millstonemike View Post

    That's true. And WinISD will tell you that for any driver after you enter its T/S parameters
    Thanks Mike, where can i find or read this? I now where to find Vas but don't know where they put any suggestions.
    Last edited by Scarface1; 01-07-2021, 09:01 PM.

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  • billfitzmaurice
    replied
    You may be able to realize flat response to 60Hz via DSP, but with how much EQ boost at 60Hz? Every 6dB of boost doubles the excursion and quadruples the power.

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  • Scarface1
    replied
    Originally posted by LOUT View Post
    I think it's a combination of many parameters that let a woofer work well (or poorly) in a tiny box, so I doubt you'll have much luck looking at one or two specs specifically....that's why looking at the entire modeled response of different woofers in something like WinISD can be such a big help...at least after you get a fairly large collection of woofers modelled in there to choose from.

    That said, I think with 0.3 litres you'll probably have better luck with smaller drivers, and something like the DMA58-4 may be worth a look if your cabinet is ported (or using a PassiveRadiator).
    If the box will be sealed then it does look like the ND65 is pretty difficult to beat.
    How do you mean, because most drivers model well to 60 hz with enough weight to the pr and the dsp correct the peak in higher octaves. It seems that if you put a driver with bigger Vas in same enclosure as a speaker with lower Vas it will lose efficiency, the nd65-8 need 2 times more power then speakers with lower Vas. I have to say the PR i use is pretty heavy (65 gram moving mass).

    Also if i push the PR, the driver move out and go back while i expected it to stay out while i kept pushing the PR. Maybe an air leak? I sealed every side, does the surround foam let air escape.
    Attached Files

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  • Millstonemike
    replied
    Originally posted by Scarface1 View Post

    Thanks! I use winisd but i have read online that a speaker will perform bad if you put it in a to small or to big enclosure ....
    That's true. And WinISD will tell you that for any driver after you enter its T/S parameters

    Leave a comment:


  • Scarface1
    replied
    Originally posted by billfitzmaurice View Post
    All moving coil drivers have a spider. You're never going to get deep bass out of a driver with 120Hz Fs, modeling the TB driver in WinISD would have shown that.
    I can move the cone to the left and right wich is not possible with other drivers..yes they are 120hz but with dsp i can tune them flat to 60 hz. 4 of them make 94db at 60hz but they sound awful below 100hz. Tangband themself use it in a 80hz tuned pr kit.

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  • LOUT
    replied
    I think it's a combination of many parameters that let a woofer work well (or poorly) in a tiny box, so I doubt you'll have much luck looking at one or two specs specifically....that's why looking at the entire modeled response of different woofers in something like WinISD can be such a big help...at least after you get a fairly large collection of woofers modelled in there to choose from.

    That said, I think with 0.3 litres you'll probably have better luck with smaller drivers, and something like the DMA58-4 may be worth a look if your cabinet is ported (or using a PassiveRadiator).
    If the box will be sealed then it does look like the ND65 is pretty difficult to beat.

    Leave a comment:


  • billfitzmaurice
    replied
    All moving coil drivers have a spider. You're never going to get deep bass out of a driver with 120Hz Fs, modeling the TB driver in WinISD would have shown that.

    Leave a comment:


  • Scarface1
    replied
    Originally posted by billfitzmaurice View Post
    Use speaker modeling software, like WinISD. You can use DSP with any driver. What you can't do with DSP is to make any driver deliver what it's not capable of.
    Thanks! I use winisd but i have read online that a speaker will perform bad if you put it in a to small or to big enclosure because of the compliance of the spider...i have bought 4 tangband w1-2121S and put them in a enclosure tuned to 60 hz but it sounds awful(they don't have a spider i gues). The nd65 in same enclosure sounds way better and with dsp tuned to 60hz and flat responce it sound pretty good(better as cheap bleutooth speakers).

    Leave a comment:


  • billfitzmaurice
    replied
    Originally posted by Scarface1 View Post
    how do i know wich i have to choose..things like Vas?
    Use speaker modeling software, like WinISD. You can use DSP with any driver. What you can't do with DSP is to make any driver deliver what it's not capable of.

    Leave a comment:


  • Scarface1
    started a topic the right speaker for dsp in small cabinet

    the right speaker for dsp in small cabinet

    Hi, i have a question. I want to make a small portable speaker with DSP so i can tune it how i want, like low bass! What are some speaker specs or parameters i have to look for to get good sound. You cannot put every speaker in an enclosure but how do i know wich i have to choose..things like Vas? I have tried the Dayton nd65-8 in a 0,3 liter enclosure and it sound pretty good. One thing is that the bass seems a little bit out of control but better then i expected. The speakers have a Vas of 0.7 liter and are in a 0,3 liter enclosure but i don't know where i have to look for? Speaker with lower Vas or some other specs i have to look for?

    Thanks
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