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Brand of drivers most apt to conform to published T/S parameters ?

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  • Brand of drivers most apt to conform to published T/S parameters ?

    I've been sadly disappointed lately by buying drivers that are far from matching their published specs.
    Can anyone suggest a brand(s) that comes close ?

  • #2
    For me Dayton and SB Acoustics have been very close to published specs.
    "Everything is nothing without a high sound quality." (Sure Electronics)

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    • #3
      Dayton drivers will probably be the closest 'cause they're PE's "House Brand" and they probably check 'em (w/DATS) every 2-3 yrs or so.
      Aurum Cantus (I believe) has historically been about the worst (does PE even carry those, still?). You'd think eXpen$!ve drivers would be close, but not necessarily.

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      • #4
        Sadly my recent bad experience has been with Dayton.
        ( DS90-8 and ND90-8 )
        In both cases Fs ~ 20 % high .
        Maybe I'm expecting too much ?

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        • #5
          Originally posted by hitsware2 View Post
          Sadly my recent bad experience has been with Dayton.
          ( DS90-8 and ND90-8 )
          In both cases Fs ~ 20 % high .
          Maybe I'm expecting too much ?
          Are you breaking in the drivers before measuring? Especially for Fs.

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          • #6
            While 20% seems like a lot, it's not impossible to get an increase in Qts, and a decrease in Vas to the point where they still produce about the same box model.
            Feel free to be more specific if you like (I assume you've measured them or had them measured yourself). HAVE you run models w/the new T/S parms?

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            • #7
              No , but I've thought of it .
              Would you suggest a method ?

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              • #8
                Sine waves at or near Fs are a good way to go for breakin. Why near Fs? Because it takes less power. You're not looking to put heat into the coil really, just to loosen up the spider and surround. Don't do this for tweeters, do it for woofers, and don't put too much juice into them, you don't want to exceed xmax. If you're unsure how much movement you're getting, be conservative.

                Also, remember that how something is measured makes a difference. Specs are derived, so measurement systems aren't accurate in an absolute sense and won't always line up well. Seas are notable for consistent manufacturing (or at least historically have been).

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                • #9
                  Originally posted by badman View Post
                  Sine waves at or near Fs are a good way to go for breakin. Why near Fs? Because it takes less power. ...
                  1+. I use a small Windows freq generator app - sinegen.exe - you can download from my Google drive (no malware or other issues, others on TT use it). The app doesn't "install" on Windows, it just runs by double clicking its icon from where ever you save it on your PC.

                  With the driver in free air and very little power, massage the app's frequency until you see maximum cone movement. That's the Fs (e.g., "Fs" stands for resonant frequency). Then you can up the power in bits until you feel like your near xmax.

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                  • #10
                    Recently my opinion of Seas has changed on that note. Those Titan 27TAC/GB tweeters are supposed to be matched pairs, and they were far from it. This really disappointed me and left me feelingless trustworthy of Seas drivers. I did get another pair, and one from each set were a close match, and then modded the other 2 to get them close to each other. We'll see how this all shakes out in terms of FR/etc when I get there.

                    Later,
                    Wolf
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                    • #11
                      Originally posted by Chris Roemer View Post

                      > (I assume you've measured them or had them measured yourself).

                      Yes ...... WT-3

                      > HAVE you run models w/the new T/S parms?

                      Yes ..... That's the problem .
                      .

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                      • #12
                        Originally posted by badman View Post
                        Seas are notable for consistent manufacturing (or at least historically have been).
                        ...unless we are talking about Fs on tweeters or breakup on woofers, that is...
                        Don't listen to me - I have not sold any $150,000 speakers.

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                        • #13
                          Dayton, SB Acoustics, Eminence, B&C, FaitalPro, Peerless (Tymphany) and MCM Audio Select series.
                          https://www.facebook.com/Mosaic-Audi...7373763888294/

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                          • #14
                            As mentioned, break-in the driver for ~10 minutes before measuring.

                            Also be sure to measure at suitably low signal levels. Thiel-Small parameters are small signal parameters, and using improper signals during measurement can distort the results. Read the quoted material below.

                            This quoted material is a small excerpt from "LIMP MANUAL - Impedance Measurement Thiele Small Parameters (TSP) RLCMeter". Full text available at the following link.

                            http://www.artalabs.hr/AppNotes/LIMP..._4_English.pdf

                            3.1. Preparation for TS parameter measurement Before measuring, it is worth reading the seminar 'Loudspeaker Parameters' by Neville Thiele and Richard Small that was given in 2008 (2) and the guidance issued by a well-known driver manufacturer (3). Among other topics, the seminar addressed the conditions for the determination of TS parameters (signal strength, measurement position, mounting or clamping conditions) and driver break-in. 3.1.1. Excitation signal strength Remember that TS parameters are measured using small signals! Small recommends limiting the signal to a level just sufficient to ensure a clean measurement. SB Acoustics, in their Technical Note (3), recommend approximately 1 volt for measuring midrange speakers at their resonance frequency. The default AES2-2012 standard (4) recommends 0.1 volts for typical measurements. As mentioned earlier, the energy contents of the available excitation signal types in LIMP (PN, stepped sine) differ. Figure 3.1.2 shows impedance curves for both excitation signals with identical gain. The red curve is the stepped sine and the black curve is pink noise. The more energy-rich sinusoidal signal gives a lower apparent resonance frequency. Shifting resonance frequency with changing excitation amplitude is a well-known phenomenon (CMS is not a constant), and different strength excitation signals and different measurement methods should not therefore be expected to yield the same results.

                            3.1.2. Driver break-in AES2-2012 recommends that loudspeakers must be driven for several minutes before measuring TS parameters to in order to avoid drifting resonance frequency readings (4). SB Acoustics (3) drive their speakers for about 10 minutes with a sinusoidal signal at around 0.8 times the Fs. The voltage is chosen so that the speaker operates with maximum deflection. The driver should be allowed to cool to room temperature afterwards before measurements are taken. Other sources suggest a break-in period of several hours. Conversely, Vance Dickason suggests that break-in is required only for the early detection of hidden defects in the driver (6).
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                            • #15
                              SB Acoustics, Rival Acoustics, Peerless (by Tymphany), Eminence, and MCM Audio Select have all measured extremely close for me. Dayton drivers use to measure very close to factory spec but the last several pairs of Dayton drivers I've purchased were not very close at all. Disappointing enough that I doubt I'll purchase them again.
                              Craig

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