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TCP115-4 desktop speaker

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  • #16
    IMHO, a smaller cap on the tweeter would be beneficial.
    Don't listen to me - I have not sold any $150,000 speakers.

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    • #17
      Originally posted by johnnyrichards View Post
      IMHO, a smaller cap on the tweeter would be beneficial.
      Thanks for the feedback, I've been tweaking a bit more and reduced the cap size on the tweeter a hair.

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      • #18
        I tried the Peerless XT25SC90-04 in place of the ND28F-6 today, it seems to be another good low budget option to cross low. I was able to get a bit flatter response in the treble with it but couldn't get the phase to track as nice. Also has some problems with the overall impedance. Zobel on the woofer plus the really low inductance rise on the tweeter dropped impedance below 4 ohms up high. I tried using just a series resistor on the tweeter instead of an l-pad but it's up around 10 ohms, any downside to that?


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        • #19
          I'm coming up with fairly similar results to your fist sim, but changed a few things. I'm using WinPCD and for some reason response cuts off at 10K with your files. Not sure why. I don't think crossing the ND28 at 2.5K LR4 would be a problem for a desktop application unless you plan on cranking it up loud so you can hear it in another room. Click image for larger version

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          Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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          • #20
            Originally posted by tom_s View Post
            I'm coming up with fairly similar results to your fist sim, but changed a few things. I'm using WinPCD and for some reason response cuts off at 10K with your files. Not sure why. I don't think crossing the ND28 at 2.5K LR4 would be a problem for a desktop application unless you plan on cranking it up loud so you can hear it in another room. [ATTACH=CONFIG]n1368858[/ATTACH][ATTACH=CONFIG]n1368859[/ATTACH][ATTACH=CONFIG]n1368860[/ATTACH][ATTACH=CONFIG]n1368861[/ATTACH]
            Hi Tom,

            Yours does look a bit smoother through the midrange and has the margin of safety of a higher crossover point.

            I notice the series resistor for you tweeter l-pad is before the crossover, PCD defaults to placing it after, is there an advantage either way? Also curious to see what you think about the two large peaks in the woofers natural response at 4.5K and 10k, one of my goals with the low crossover point was to push the peak at 4500hz down as far as practical without adding additional components,

            Jason

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            • #21
              Hey Jason,


              Moving your series resistor before the network can sometimes let you tilt the response as you juggle the values. But in this case, it let me use a much smaller shunt coil and smooth out the slope a little. I've also been trying to eliminate the breakup from the woofer. A small cap across the main inductor will take care of the the peak at 4.5K, but response still rises after that. A bottomless series notch using a 5.6uf & 0.15mH is a little more effective, but that adds a few more dollars to the total cost. I'm not really well versed when it comes to notch filters, so there may be a much easier way to tank the top end of that woofer. I'm also curious if the breakup is really as pronounced as the provided data shows.

              Heck, I'm intrigued enough with this woofer/project that I have some parts in my cart....but I'm still pondering other tweeter options. Click image for larger version

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              Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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              • #22
                I just noticed I had changed the main inductor on the woofer to a 0.7mH. I was just noodling around, trying different options. The 1.0mH you had does look better through the midrange.

                I'll likely build these for my boss to use for his video editing system, so I'll be looking for the least expensive options when it comes to caps & coils - like the 33uf electrolytic in the zobel and the Dayton 1.0mH 18 AWG iron core for $3.65. I'm sure many values will change slightly after measuring in the box.
                Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

                Comment


                • #23
                  Originally posted by tom_s View Post
                  Hey Jason,


                  Moving your series resistor before the network can sometimes let you tilt the response as you juggle the values. But in this case, it let me use a much smaller shunt coil and smooth out the slope a little. I've also been trying to eliminate the breakup from the woofer. A small cap across the main inductor will take care of the the peak at 4.5K, but response still rises after that. A bottomless series notch using a 5.6uf & 0.15mH is a little more effective, but that adds a few more dollars to the total cost. I'm not really well versed when it comes to notch filters, so there may be a much easier way to tank the top end of that woofer. I'm also curious if the breakup is really as pronounced as the provided data shows.

                  Heck, I'm intrigued enough with this woofer/project that I have some parts in my cart....but I'm still pondering other tweeter options. [ATTACH=CONFIG]n1368872[/ATTACH][ATTACH=CONFIG]n1368873[/ATTACH]
                  Tempted at all to buy a pair of the MK402 speakers and modify the crossover? That was my first thought before this project. I'm surprised that no one has yet. If the TD20F tweeter is decent it's a bargain for sure.

                  Jason

                  Comment


                  • #24
                    Originally posted by jasonb View Post

                    Tempted at all to buy a pair of the MK402 speakers and modify the crossover? That was my first thought before this project. I'm surprised that no one has yet. If the TD20F tweeter is decent it's a bargain for sure.

                    Jason

                    Yep - I had thought about buying a pair to mod. That tweeter is so cheap - it can't be any good....can it? It does have a 65mm cutout, so the ND28F or the XT25SC90-04 should drop right in. Hmmmm....
                    Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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                    • #25
                      I just couldn't bring myself to order the MK402s. I would likely end up ditching the tweeter and all of the crossover components and simple black boxes are cheap & easy to build. I did order TCP115s though. I had been eyeing those for a while now. I needed to order some caps and coils anyway, so we'll give those little woofers a whirl. I'll pair them up with a budget tweeter from my stash - probably the BC25SC06-04.
                      Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

                      Comment


                      • #26
                        Originally posted by tom_s View Post
                        I just couldn't bring myself to order the MK402s. I would likely end up ditching the tweeter and all of the crossover components and simple black boxes are cheap & easy to build. I did order TCP115s though. I had been eyeing those for a while now. I needed to order some caps and coils anyway, so we'll give those little woofers a whirl. I'll pair them up with a budget tweeter from my stash - probably the BC25SC06-04.
                        That looks like a great little tweeter for the money. I'll bet with that waveguide tweeter faceplate your drivers end up pretty close to physically time aligned. I'm still tweaking my crossover, hope to post something final this week to see if anyone has further input.

                        Jason

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                        • #27
                          That is a very interesting looking little woofer. I might pick up four and build a small pair of MTM's with a pair of ND25FW tweeters I have.
                          Craig

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                          • #28
                            Jump on board Craig! The price sure is appealing. I'm curious how you would attack the breakup.
                            Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

                            Comment


                            • #29
                              Originally posted by jasonb View Post
                              I tried the Peerless XT25SC90-04 in place of the ND28F-6 today, it seems to be another good low budget option to cross low. I was able to get a bit flatter response in the treble with it but couldn't get the phase to track as nice. Also has some problems with the overall impedance. Zobel on the woofer plus the really low inductance rise on the tweeter dropped impedance below 4 ohms up high. I tried using just a series resistor on the tweeter instead of an l-pad but it's up around 10 ohms, any downside to that?

                              Could you share your measured FRD and ZMA files for the XT25sc90-04 also?

                              Thanks!

                              Comment


                              • #30
                                Originally posted by ceiol View Post

                                Could you share your measured FRD and ZMA files for the XT25sc90-04 also?

                                Thanks!
                                XT25SC90_4.frd XT25SC90_4.zma XT25_simmed_minphase.frd XT25_simmed_minphase.zma

                                My files were created by tracing the graphs from the driver spec sheet. I've attached the raw files as well as the ones simulated for my enclosure, baffle layout, and 3db of baffle step.
                                Attached Files

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