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  • Chris Roemer
    replied
    I wouldn't go smaller than 4"id for a (high Xmax) 12" sub. In 3.0cf, 20Hz will be around -6dB (so, you'd need about +3dB boost if 20 means that much to you; can NOT really recommend that kind of boost BELOW the (24Hz) tuning freq. (about an 18" long 4" port) as that is contradictory to your attempt at protecting uncontrolled displacement using a high pass filter;
    however, w/out boost, that box should function (-3dB) well enough in the bottom-most octave from 25Hz to 50Hz. If you MUST have an F3 that hits 20Hz, and you can't go > 3.0cu.ft., perhaps a different driver is in order.

    ANY bend shape will have less effect on "port noise" than having a (generous) "roundover" at the port's exit.

    Leave a comment:


  • gp4Jesus
    replied
    what is the recommended radius for port bends or curves in a given diameter port? Planning to use either PVC or cardboard.

    Dayton Audio RSS315HF-8 12" Models to 20hz in a 4.6 cu ft (net) closure according to PE using Bass box.

    I plan to low pass them around 45hz and will employ a a 10-15hz subsonic filter.

    How to get the same FR in a more WAF sized ported 3 cu ft closure? I have some DSP on hand and 500W rms on tap.

    how long should the port be assuming 3”, 3.5”, or 4” ID?



    Many, many thanks for your help and patience.

    Tony

    Leave a comment:


  • Chris Roemer
    replied
    WinISD is free at linearteam.org (-sc).
    It should do 20Hz in a 4cf (internal) box w/a 4"id x 16" long port.

    I'm talkin' about the (current) 315-HF"A" -8.

    Leave a comment:


  • gp4Jesus
    replied
    Dayton Audio RSS315HF-8 12" Reference tested TS parameters? It models ported to 20hz* based upon published specs. Is this* realistic?

    also a friend wants a proprietary driver tested. Company* from which it comes - not much help.
    *Martin Logan

    Huge thanks. Tony

    Leave a comment:


  • Chris Roemer
    replied
    Unless there's been some significant mfg. change in that driver (which, more often than not, would result in a revision to the model number - but NOT ALWAYS), the WT3(DATS) data SHOULD be good. This thread was initially posted 3-1/2 years ago, from data the OP had collected over some (previous) time. So . . . THAT Pyle driver MIGHT have been measured 10 yrs. ago (or even more), but certainly at least 4 yrs ago.

    Qts is really not a measured value. It's calculated from the measured values for Qes and Qms, which are almost always VERY accurately measured with something like a DATS or WT3 system (as opposed to Vas, which can/will vary due to operator errors). Fs is also very accurately measured.

    Qts = (Qes x Qms) / (Qes + Qms)

    In the case of that Pyle: Qts (approx.)= 1.8*4.6 / (1.8+4.6), or . . . 8.3 / 6.4, or about 1.27 (I'm rounding, a LOT).
    So that measured (calculated) Qts value that's listed as 1.29 is most likely accurate.

    Leave a comment:


  • swarrfrat
    replied
    Anyone know the source of "actual measured" parameters for the Pyle PDW15125 ? Those numbers are not even remotely close to advertised (Qt = 0.4 vs Qt = 1.295) I'm looking at this driver, but not if the specs are anything close to the ones in this spreadsheet.

    Leave a comment:


  • neildavis
    replied
    This thread hasn't had a new post since Sept 2013. It's useful information, but it takes up valuable space as a sticky on the main page. Can we move this to the OmniMic Forum or can PE find a place to host this Excel file? The Excel file has all of the T/S data posted in this thread in a single place.

    Leave a comment:


  • colofan
    replied
    Re: Measured T/S Parameter Thread Sticky

    Would you desire information generated by DIY people on more details. Examples would be the non-linear aspects of the drivers , free-air measurements (on and off axis), impedance curves both 1 watt and high power?

    Leave a comment:


  • neildavis
    replied
    Re: Measured T/S Parameter Thread Sticky

    The schema for the proposed database is shown below. This is somewhat expanded from the database I am currently using, so I've got to rebuild the database to include this new data. Some parameters that will *not* be saved in this database include: outside dimensions, bolt patterns, cone material, voice coil diameter, surround type, etc. Most entries will have a link to the datasheet to allow looking up this additional information.

    The "My entry" field is a flag to indicate that the row was entered by the user. This field should help with merging database files from other sources.

    The primary key is the "name" field, which is a concatenation of the MFG and Part Number fields.

    Leave a comment:


  • neildavis
    replied
    Re: Measured T/S Parameter Thread Sticky

    Originally posted by siggma View Post
    Anybody still working on this project?

    Tom
    Yes and no. It's still being worked, but probably not in the way you expected.

    I will be publishing another version of PSD-Lite that uses a file-based TS database (using the Microsoft Compact Edition database). I came to the conclusion that a centralized database for DIY'ers is too much work and not enough payback, and didn't want to follow in the footsteps of the now-defunct www.thielesmall.com effort. But with a file-based approach, people can have their own database and use some local tools to merge in database files from the web. I think that this file-based model will work OK and support a good degree of collaboration. It's not a model that purists will like, but I think it is a good practical solution that solves some difficult security and maintenance issues.

    I've got all of the drivers in the PE and MCM woofer selection guides, all of the ones in Mattp's posts, and all of the "good" data from the thielesmall.com database. Right now this data is in Excel and I need to move it to an "SDF" file for CE. I'm not on the computer where I have the schema, but I'll post it when I get back in a couple of days.

    I made an error in thinking that I could keep databases out of PSD-Lite. However if I want to keep all of the modules that are common to "PSD-Pro" and ASD identical, I had to include the TS database in PSD-Lite. Rats!

    Leave a comment:


  • siggma
    replied
    Re: Measured T/S Parameter Thread Sticky

    Anybody still working on this project?

    Tom
    Attached Files

    Leave a comment:


  • Pallas
    replied
    Re: Measured T/S Parameter Thread Sticky

    Originally posted by mattp View Post
    Not sure about the copper but the decimal is in the right place.
    Odd. Maybe the motors are different between the Aura MR and Aura NS series, because I just looked up my NS18-992-4A and I measured 0.35mH on it. I also just measured my NS15-992-4A (the NS18 being less convenient to reach; they use the same 4" vc motor) and got 0.41mH on it. 0.4133mH, if one demands the 'precision' provided by a WT3.

    Has anyone measured the Aura MR12.4 that PE was closing out? I have three different NS12-794-4A's and can measure the Fs and Le of each.

    (Note: nothing else to contribute here because I never measure complete T/S any more. Getting a good Vas measurement is time-consuming, and I don't see much point in it unless one is doing some sort of vented or bandpass box. Which I never do any more. Really, I just measure impedance peaks and derive Qtc of finished closed boxes.)

    Leave a comment:


  • mattp
    replied
    Re: Measured T/S Parameter Thread Sticky

    Originally posted by Pallas View Post
    I think the Le might be off by a decimal place here.

    If memory serves, my NS18-992-4A measured in the 0.2mH range. I thought the MR18.4 was just the NS18 with a funky colored cone and different basket paint. If it doesn't have the copper sleeve on the motor than the NS18 has, never mind.
    Not sure about the copper but the decimal is in the right place.

    Leave a comment:


  • Pallas
    replied
    Re: Measured T/S Parameter Thread Sticky

    Originally posted by mattp View Post
    Aura MR-18.4 18" NRT Subwoofer Speaker (269-187)
    Re: 3.382 ohms, Fs: 21.53 Hz, Qts: .492, Qes: .593, Qms: 2.847, Le (1kHz): 1.707 mH, Vas: 6.8 cuft, Effective Diameter: 15.25"
    I think the Le might be off by a decimal place here.

    If memory serves, my NS18-992-4A measured in the 0.2mH range. I thought the MR18.4 was just the NS18 with a funky colored cone and different basket paint. If it doesn't have the copper sleeve on the motor than the NS18 has, never mind.

    Leave a comment:


  • dlr
    replied
    Re: Measured T/S Parameter Thread Sticky

    Originally posted by killa View Post
    The problem with sharing frd is that you need to know exactly how they were measured. Things like baffle size, distance, and spl. There needs to be a standard or a description of how they were measured.
    I think this does go beyond my previous post about using Bill Waslo's extension. You can enter info on a line for display, but I'm not sure just what data is embedded. Praxis reads the older LAUD files, his previous product that I use and I'm not sure what data is used. Certainly there's nothing that identifies specifics as being discussed here.

    I don't think the file should include this sort of data. The db would be the place for that so that the user could then decide what to do if anything.

    dlr

    Leave a comment:

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