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MT Peerless 832873 and Vifa BC25SC06-04 1"

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  • MT Peerless 832873 and Vifa BC25SC06-04 1"

    Thought I would post my progress. I am reworking some old boxes to give these a temporary home. Tomorrow I am going to try to clear coat them if its not to humid. I am going to try some Krylon Triple Thick Crystal Clear Glaze. The can says do not use in high humidity. I wonder what they think is high?

    Peerless 832873

    Vifa BC25SC06-04

    Last edited by caleb; 06-18-2009, 12:20 AM. Reason: tech difficulties
    Caleb b

  • #2
    MT Peerless 832873 and Vifa BC25SC06-04 1"

    Got them clear coated and one is waxed and buffed there are also more pics in my album. Should be auditioning with prototype crossovers soon.

    Last edited by caleb; 06-25-2009, 09:52 AM. Reason: missing link
    Caleb b

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    • #3
      Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

      Looks like you will have some nice speakers. The 2nd picture in the 2nd post is not working now.

      Do you have any picture of how you made the irregular cutout shape?
      "...this is not a subwoofer" - Jeff Bagby ;)

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      • #4
        Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

        I cut the round with a circle jig and the straight part with a utility knife. Sorry no pictures of that. I wasn't happy with the finish on the waxed one. I don't think the Krylon triple glaze clear is all that at $4.00 a can. I just coated the second one with normal clear coat.
        Last edited by caleb; 07-09-2009, 03:25 AM.
        Caleb b

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        • #5
          Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

          Nice work on the recesses and the finish looks great (better than any rattle can finish I've ever did). You didn't state the box volume and final port length you've settled on, but it looks shorter than I'd expected for that woofer?

          How does it sound?

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          • #6
            Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

            The box volume is approximately .34 cubes / 9.6L, 13" H x 6.75" W x 10" D you can see the brace in the pics. The port is 3" long 1.5" diameter with a 5/8" outer round over I don't know what the effective length is 2.75" maybe more. Tuning is around 60hz. The boxes were some I had already that just happened to come close to what I needed. Eventually I will build a 5.1 or 7.1 set, probably on wall. Might do MTMs for LCR and forget about 7.1 as I only have 8 tweets and midwoofers.

            Right now I am listening with a 2nd order parallel that I modeled with PCD. Compared to my Vifa 7" MDT33 MTMs I kind of miss the thicker lower midrange. Then again the baffles are 4' 5" from the back wall and the room is 12' 6" front to back. They back up to a partition that blocks the stairs up to the room. So I am limited on placement upstairs. I suspect that the lower midrange would fill out better if they were backed up to the wall more.

            Whats the most convenient way to generate the crossover schematic and post it?
            Caleb b

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            • #7
              Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

              Originally posted by caleb View Post
              Whats the most convenient way to generate the crossover schematic and post it?
              The Linkwitz way: Draw it on paper and take a photo of it.;)

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              • #8
                Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                I found this thread and got a schematic put together with LTspice and MS Paint. So here it is for all to critique. Give your honest opinion. I am still learning.
                Attached Files
                Caleb b

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                • #9
                  Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                  I pushed the crossover point up the tweets didn't seem to like the low X-over. here is the new X-over.
                  Attached Files
                  Caleb b

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                  • #10
                    Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                    Originally posted by dcsoundz View Post
                    Nice work on the recesses and the finish looks great (better than any rattle can finish I've ever did). You didn't state the box volume and final port length you've settled on, but it looks shorter than I'd expected for that woofer?
                    Having had a lot of experience doing spray can touch work on cars and speakers, the best MDF paint to get a good (not great/perfect) finish quickly that i've found yet is the rustoleum "specialty appliance epoxy" paint.

                    these below were done just with MDF, a bit of elmers woodglue rubbed into the MDF, about 4 seconds of 150-grit power sanding, and 2 coats of appliance epoxy. (Actually, i think one of them had a rough spot, so i sanded between coats, but that's like 40 seconds of prep work). You can still see a little seam, but the finish is superior to almost all the other ones i've done that didn't take weeks of sanding and recoating. This might also make a good base coat if you're going with something other than black or white, and i'm sure some krylon over it would work well too.
                    Attached Files
                    TM (RS125/TB25-302), TM RS150S / Vifa BC25SC06, RS150-4 / Vifa ML-TL, 3CR-AL Ultra Budget: Electric Blue TM, TMM, MTM, Dragonflies , Mounties: Mini HT Satellite,sub for minions

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                    • #11
                      Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                      Originally posted by caleb View Post
                      I pushed the crossover point up the tweets didn't seem to like the low X-over. here is the new X-over.
                      Electrical 2nd order filters with tweeter wired in reversed polarity do not work due to the drivers' (especially the tweeter's) natural rolloff, as shown below in my modeling result. Used in this modeling are the drivers' amplitude and impedance data I modeled for designs in this thread. Subtle diffractin ripples may be different from ones that would actually occur on your baffle, but no problem predicting overall responses. If you want to try acoustic LR2 (tweeter in reversed polarity), you will need 1st order electrical filters plus notch filters for both LP and HP sections. If you want acoustic LR4 (tweeter in normal polarity), I suggest 3rd order electrical for LP and 2nd order electrical for HP.

                      -jAy

                      Attached Files

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                      • #12
                        Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                        Originally posted by jkim View Post
                        Electrical 2nd order filters with tweeter wired in reversed polarity do not work due to the drivers' (especially the tweeter's) natural rolloff, as shown below in my modeling result. Used in this modeling are the drivers' amplitude and impedance data I modeled for designs in this thread. Subtle diffractin ripples may be different from ones that would actually occur on your baffle, but no problem predicting overall responses. If you want to try acoustic LR2 (tweeter in reversed polarity), you will need 1st order electrical filters plus notch filters for both LP and HP sections. If you want acoustic LR4 (tweeter in normal polarity), I suggest 3rd order electrical for LP and 2nd order electrical for HP.

                        -jAy
                        Glad you caught that Jay. Those sims were not right because I sent him .frd files that did not have the minimum phase extracted. Thanks for getting us back on track.
                        "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

                        Diffraction Happens

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                        • #13
                          Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                          Thanks, JBruner

                          I modeled a new crossover in PCD with the fixed FRD & ZMA files you sent. Here is what I have now. I think I will be really happy with them once I get some low DCR coils.
                          Attached Files
                          Last edited by caleb; 07-20-2009, 05:40 AM.
                          Caleb b

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                          • #14
                            Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                            Thanks, Jay

                            What measurements are you using? Factory specs, Zaphs (from old model #), other, or your own? I am glad you have given this fine little driver your attention.
                            Caleb b

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                            • #15
                              Re: MT Peerless 832873 and Vifa BC25SC06-04 1"

                              Originally posted by caleb View Post
                              Thanks, Jay

                              What measurements are you using? Factory specs, Zaphs (from old model #), other, or your own? I am glad you have given this fine little driver your attention.
                              I used Zaph's IB measurements and modeled from there. In order to predict drivers' summation correctly, it is important to have correct phase data. To obtain precise phase from Hilbert-Bode transformation, you need to have accurate frequency responses at least up to 40,000 Hz, which should include each driver's rolloff behavior at its extreme. In case you don't have actual measurements of this kind, you need to model it properly.

                              It is a correct move to wire the tweeter in normal polarity with your current xover. Due to the recessed acoustic center of the Vifa tweeter and the small size of the midwoofer, the two drivers' relative acoustic offset must be nearly zero. I suggest using 0" to 0.3" for the offset (i.e., the midwoofer's AC is 0" to 0.3" behind the tweeter's). For more in-depth discussion about estimating drivers' relative acoustic offset, take a look at the following thread:

                              http://techtalk.parts-express.com/sh...d.php?t=208562

                              You don't have to read all the posts there. Reading posts number 6, 7, 12, 15, 17, 19, 26, and 29 should be sufficient to get the right information on this particular subject.

                              Using my data, I simulated your updated crossover.



                              With the tweeter in normal polarity, your crossover is close to LR4, but with a very relaxed LP rolloff. So, there occurs a significant phase mismatch above the xover point. This should be okay unless your listening height is much below the tweeter. I'd cross the tweeter a bit higher, though, to get its low-end distortion out of the radar.

                              Below is my suggested LR4 crossover. The LP section is a bit more complicated than yours due to the third order filter and a Zobel, but the result is excellent LR4 phase tracking and summation, and a flatter overall response.



                              Below is my suggested LR2 crossover. LR2 without a complicated all-pass delay circuit is possible thanks to the horn loaded Vifa. The price to pay is a little ragged system response. But if you believe in the LR2 magic (smoother power response), this may be worth trying.

                              Last edited by jkim; 07-20-2009, 12:48 PM.

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