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Dayton Audio GF180-4 Graph

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  • a4eaudio
    commented on 's reply
    I don't find that tweeter with a simple search... Can you provide a link to the tweeter and attach copies of your frd files for both drivers?

  • Jicafold
    replied
    Originally posted by Paul Carmody View Post
    Check the phase #s on your woofer measurement at those frequencies. See if they aren't jumping between 180 and -180 degrees.
    That's beyond my level of experience.

    Leave a comment:


  • Paul Carmody
    replied
    Check the phase #s on your woofer measurement at those frequencies. See if they aren't jumping between 180 and -180 degrees.

    Leave a comment:


  • Jicafold
    replied
    Regarding a different tweeter, I do have a set of Peerless BS25SC02-4. This is what I mapped with those. Same spikes though.

    Attached Files

    Leave a comment:


  • Steve Lee
    replied
    Try using ALT Codes to insert the Omega (Ohms) symbol:

    NumLock = ON, ALT 234 = Ω

    Leave a comment:


  • Chris Roemer
    replied
    This doesn't look horrible to me, for that little tweeter,
    2nd order HP w/L-pad AND series resistance: 1n(ohm) series resistor and 5uF series cap, then a 0.20mH shunt coil (to gnd), lastly an "L": SR=2n / PR=6n.

    (This is what I modeled on the woofer)
    1st order w/Zobel: 0.45mH series coil (w/an RC "bypass" - 4n + 2.2uF cap for a 5k notch), (shunt) Zobel-thing using 8ohms + 33uF.

    Runs around 81dB (full BSC) w/Fc near 3kHz. Tweeter's attenuated about -8dB.

    Try this .frd for the tweeter:

    TD20jica.FRD

    Leave a comment:


  • Jicafold
    replied
    Originally posted by Chris Roemer View Post

    What software are you modeling this with?
    I was using Jeff Bagby's Passive Crossover Designer. Oh....are you saying there may be a different result with different software?

    Leave a comment:


  • Paul Carmody
    replied
    I haven't had to do this in a while, but I used to sometimes have to manually adjust some phase numbers in Excel. In my experience, when I was seeing these kind of jumps, it was because the phase in a driver's measurement was wavering back and forth between 180 and -180, and the simulation software didn't know how to handle these "jumps." So basically, I'd just pick a number, say 179 degrees, and just stick with it for a few Hz until the phase looked like it was truly ready to rotate over to -180. Yes, it's not 100% accurate, but it definitely helped make Frequency Response graphs that were easier to read.

    Leave a comment:


  • a4eaudio
    commented on 's reply
    I have 4 of the 8-ohm woofers but I haven't done anything with them. BUT...they do look great and PWRRYD likes the sound of them. Your tweeters are nothing to be excited about though. I'd say get the woofers and different tweeters that match better and save the TD20's for something else or sell them.

  • LOUT
    replied
    IF you can try it safely (without commiting too much if you don't like it), do you think something like this might work for that TD20?
    Click image for larger version  Name:	Maybe TD20.png Views:	0 Size:	2.3 KB ID:	1480598
    It looks like this should keep under 0.1mm of XMAX for the TD (which I think it has 0.2mm) with the GF180/system given ~20-25watts (where the GF180 in a 21L ported box would also be nearing/hitting XMAX of its own).

    It should also be about -5db at 2Khz...for easier pairing with the woofer down lower.

    I don't have an ear for most distortion (or much of anything, ha) so I can't say whether or not you or anyone else would like the sound of it...but I've been running my TD20's with various similar HP for the last couple of years and they seem happy enough.

    ...Please ignore me if this whole project is using the GF as a midwoofer in a 3way or some similar configuration where the system will be pushed a lot harder.
    Last edited by LOUT; 01-02-2022, 11:52 AM.

    Leave a comment:


  • Chris Roemer
    replied
    "As-is", PE's .frd file has a LOT of phase "swings" (between +175* and -175*) from 300Hz up to 3kHz. (You can see this in the text file, if you look.)
    Phase (which is a 360* phenomenon) is recorded in F/Z files as "zero", plus-or-minus 180*.
    When the data passes +180* (for example), it gets recorded as -179* (or whatever). (This is known as phase "wrapping".)
    In MOST XOsim softwares, this causes no issues (the software is designed to interpret the data correctly).

    What software are you modeling this with?

    Leave a comment:


  • Jicafold
    replied
    Ah...ok. I was using that tweeter because I already had 2 of them. Also, I had not figured in the BSC either in modelling. Just wanted to try out those new woofers but I certainly don't have to. Thank you.

    Leave a comment:


  • Wolf
    replied
    Unfortunately, I am with A4 here, and think the TD20 is not able to go low enough.
    I also agree with DeZZar and A4, in that you need to alter the files to adapt them to your cab design adding BSC and box alignment.

    Wolf

    Leave a comment:


  • a4eaudio
    replied
    I think what is happening to generate those spikes is an interaction of the phase of the two drivers. I note there are no spikes in the frd curves of the raw drivers. I have a feeling this is due to not generating minimum phase data, as I threw the PE files into VituixCAD and got some spikes too, but when using minimum phase they went away. There are several things you need to due to the PE files to get an accurate simulation...model the diffraction/baffle step loss, model the in-box impedance of the woofer, and generate minimum phase. (Probably some more stuff I am forgetting.)

    https://sites.google.com/site/undefi...d-measurements
    http://woggmusic.com/advanced-speake...gn-simulation/

    One other thing to note...that tweeter has slightly less sensitivity than the woofer. Usually you will want to "pad" down the tweeter somewhere between 0 and 6 db due to baffle step loss. If you plan on having no baffle step compensation (BSC) then you may be okay, but otherwise you may need a different tweeter. Additionally, the recommended minimum crossover for that tweeter is 3Khz and 2Khz for the woofer, so there isn't a good overlap there. I believe PWRRYD is the first person to use the new woofer and has good things to say about it, so maybe consider a different (better?) tweeter that can cross lower.

    Leave a comment:


  • PWR RYD
    replied
    Do you want my actual frequency response and impedence measurements of that GF180-4 woofer taken in a real ported enclosure with a 8.00" wide baffle (1/2" roundovers)?

    Leave a comment:

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