PSD-Lite

Discussion in 'DIY' started by ultrabike, Nov 12, 2018.

  1. ultrabike

    ultrabike Measurbator - Admin

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    I wanted to share some results from modeling different DIY speakers with PSD-Lite. Whatever the results, this is more a reflection on PSD-Lite performance than any of the DIY speakers modeled.

    I find PSD-Lite a very nice free program because it's relatively easy to use, does not require Excel, and adds baffle step response to the development of the crossover. It is an integrated design tool.

    A few things one should know about the tool (nothing is perfect):
    1. The impedance response shown does not include the effects of the port which are not integrated.
    2. If a new set of drivers are to be used, shutdown the program and start from scratch.
    3. One cannot save the plots, and one may need to do screen captures.
    4. How responses add at the cross over point is a little suspect (may have to play w it more).
    5. Edge diffraction is not well modeled (as far as I can tell). But baffle step is good (also as far as I can tell).
    6. Only 1, 2 and 3 way. No straight forward support for 2.5 and other stuff.
    All that said, I find this a fantastic tool.

    Anyhow here it goes:

    Paul Carmody's Amiga:

    xover_woofer.PNG

    port_box.PNG

    I think Paul specs 30 liters instead of 34 liters, but I don't think it makes that much of a difference. Adding some stuffing might help with the small peak at 40 Hz. According to the model, the speaker is tuned with a little punch. Very smooth response. The first stage of the woofer crossover is a notch to deal with the woofer break up. After that, we have a 2nd order filter. Very nice response.

    Jeff Bagby's Tango:

    xover_woofer.PNG

    port.png

    Jeff's Tango deals with the RS180 cone break up in a masterful way. There are two inductors, just like Paul's approach, but it has less capacitors and no resistors. The null takes care of the break up really well. The port is very smooth and takes it down to 42 F3 with no peaking. The Amiga, being a tower does go lower using the same woofer though. The crossover between the tweeter and the woofer is very smooth.

    John "Zaph" Krutke's ZRT:

    Xover_Woofer.PNG

    Port.PNG

    This is an amazing combo. The woofer needs only two components (the impedance is intrinsic to the inductor). It goes to show why everybody and their mother likes the Revelator. Note how the port extends the response down to an F3 of 31 Hz! This is the default Zaph port configuration. The tweeter cross over is a bit more elaborate though.

    Paul Carmondy's Overnight Sensation:

    Xover_woofer.PNG
    Port.PNG

    Well, it's not shit. But it's not as good according to the model as the speakers above it. The HiVi B4N is an $11 bargain. But it's not a very smooth driver. Paul mitigated a major break up with a notch. That said, there seems to be a bit of a hump in the 2 to 3 kHz region. More baffle step compensation may help, but note this is a small speaker with little room inside if using big caps. The extra punch from 200 Hz down to 60 Hz might help mask the slight depression 200 Hz to 1 kHz. Note these issues are still between +/-5 dB.

    I know Paul's model does not show this issues with the OS. So again, this maybe more of a reflection on the PSD-Lite tool than anything else. All that said, an ND105-4 might be an easier driver to work with on a OS form factor. But maybe $10 more expensive.
     
    Last edited: Nov 12, 2018
  2. ultrabike

    ultrabike Measurbator - Admin

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    So anyhow, here is a quick an dirty possibility of an OS type of solution: Same box size and even port dimensions. But replacing the HiVi B4N w the ND105-4 (even the same tweeter ND20FA-6):

    Port (F3 @ 50 Hz, F10 @43 Hz similar to the OS w same box and port dimensions):
    Port.PNG

    Baffle:
    Baffle.PNG

    Crossover Woofer:
    Xover_Woofer.PNG

    Crossover Tweeter:
    Xover_Tweeter.PNG

    Note this shows the woofer and tweeter connected out of phase. But I'm not sure this is necessary because I don't trust the tool on this that much. In fact, I don't trust the tool that much period.

    Impedance (above port):
    Impendance.PNG

    Impedance (port):
    Port_Impedance.PNG

    Maybe one day I'll do it. Maybe not.

    These are models. The proof is always in the pudding.

    Whatever the case, I like the ND105-4 more than the HiVi B4N, because it's black yo!
     
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  3. ultrabike

    ultrabike Measurbator - Admin

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    BTW. I modeled the C-Note just real quick. @ $100 a pair right now, IMO it beats the OS right now in value. It is a real steal... Assuming it sounds as the PSD-Lite and their model says it sounds. It looks moar bettar too:

    https://www.parts-express.com/c-not...r-kit-pair-with-knock-down-cabinets--300-7140

    Note however that it is a little bigger than the OS and is indeed in the range of size of pro monitors.

    EDIT: But fuck it I might buy it tomorrow. Need to think about it.

    Port.PNG

    Xover_Woofer.PNG

    The above shows a little tilt up from 200 Hz up. But note the port takes over 200 Hz down, keeping things relatively flat down to 50 or even 45 Hz. Below Parts-Express frequency response w port response added:

    ResponseManufacturer.PNG

    Dunno if the above is measured or if it's modeled. Dunno if modeled if the baffle step is considered. Changing the 1.4 mH inductor in the woofer to 2.0 mH can fix the apparent raise around 1.5 kHz (maybe 2.5 mH is better, would have to experiment with the actual speaker). But overall I feel things are in reasonable agreement.

    Again. I would proly buy this guy instead of the OS. Specially at $100 a pair for such a good looking monitor.
     
    Last edited: Nov 12, 2018
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  4. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    This is a cool piece of software. I very much recommend checking out Speaker BoxLite. It has a pretty large database of drivers to simulate and is perfect for window shopping.
     
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  5. zerodeefex

    zerodeefex Grumpiest admin

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    I'll run the s2000 through this as well. Seems like a good upgrade from the OS.
     
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  6. ultrabike

    ultrabike Measurbator - Admin

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    Indeed. It helps give one some insight on the speaker performance.

    But I did use this tool to design my own little cute pair of speakers (making 3 more soon to complete my HT setup replacing my nanosats):

    https://superbestaudiofriends.org/index.php?threads/usm-2-diy-speakers-nd91-4-nd16fa-6.5460/

    So it's not just window shopping this thingy is good for.

    BTW, does BoxLite allow you to design crossovers? I found other pieces of SW too, but one of them was a bit buggy and had a hard time adding baffle step. Bagby's Unibox seems like super awesome, but I need to install Excel for it. My understanding is that PSD-Lite is based off Unibox.

    Here is the PSD-Lite diyaudio linky which also has a download linky:
    https://www.diyaudio.com/forums/software-tools/235549-psd-lite-final-beta.html

    Another SW I haven't tried is this:
    https://www.speakerdesign.net/WinPCD/index.htm

    Might check it out tonite. Main thing I would look for besides functionality is how the hell one adds baffle step comp to it.
     
    Last edited: Nov 12, 2018

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