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What's wrong with my C-notes?

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  • #16
    Originally posted by DeZZar View Post
    Is that the 6ohm resistor under the tape there on the left?
    Yes

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    • #17
      Here's an easier to see picture of the tweeter xover, my phone has trouble at night, which is when I took the last photo.

      https://i.imgur.com/pgShMz8.jpg

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      • #18
        Without looking at any of the pics, my guess is that I think you may have made an error in the crossover construction. I've designed and built dozens of speakers over the years and I STILL have trouble getting crossovers right the first time. Don't feel bad at all, it gets confusing. All those WIRES!!!

        Driver break-in really is a thing, or it can be.

        Look at the specs that Dayton supplies with their woofers online, and then DATS them yourself. Although Dayton drivers are very good and consistent, they are almost never the same.

        Break in the driver with some bass-heavy tunes or tones for an hour or so and the suspension (mostly the spider) will loosen up a bit. I can DATS a driver and flex the cone 3-4 times and get 2-3 Hz lower FS just from that. It shouldn't make a HUGE difference, but it can be audible, it's not hocus-pocus stuff... if the specs change after a good break-in, then so will the sound.

        Crossover components are carefully chosen due to a driver's specific frequency response and characteristics, if those characteristics are off by a bit because of a stiff spider or suspension, the resulting sound will also be 'off.'

        Production parts and processes can also be a factor from unit-to-unit.
        For example, I purchased some passive radiators from PE a few years ago and two of the same exact model had fairly different stiffnesses when pushed in. I could actually FEEL it!

        Anyway, keep at it, I hope you get it figured out!
        TomZ

        Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
        *Part 2 *Gluing multiple curved laminations of HDF

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        • #19
          I hope PE in house people can help because this is proving to be extremely unhelpful. Why on earth am I getting multiple suggestions about driver break in when that clearly has nothing to do with my issues?

          It may be helpful to look at the photos of my xovers before commenting on their construction.

          I removed C3 entirely from the xover and get the same response. Do I have it in the right place?

          Comment


          • billfitzmaurice
            billfitzmaurice commented
            Editing a comment
            I can only surmise that they're not comprehending what you're saying. To the extent that driver break in will have any effect it will be with the woofer, not the tweeter, and it's mainly seen in a downward shift of Fs.

        • #20
          I would think you have one of two issues:

          1) improperly wired crossover
          2) incorrect crossover component values

          Double and triple check them both.

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          • #21
            I have double and triple checked the wiring, it is correct.

            I will test the components.

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            • djg
              djg commented
              Editing a comment
              Sometimes the manual XO diagram is wrong, but you'd think with the C note popularity, that would have been remedied.

            • billfitzmaurice
              billfitzmaurice commented
              Editing a comment
              When I first looked at it all I could think was WTF??? With a third order high pass C2 is typically at least twice the value of C1, not less than half. What C3 is doing there I can't imagine. Plugging the FRD and Z into XSim along with the suggested values it looks really odd. Changing C2 to 12uF and deleting C3 looks much better.

          • #22
            Check the woofers is one out of phase (no bass) crossover looks good if + and - are correct on tweeter and woofer.

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            • #23
              Originally posted by 129Decibel View Post
              Check the woofers is one out of phase (no bass) crossover looks good if + and - are correct on tweeter and woofer.
              Did you read the thread at all?

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              • #24
                In your first graph in the first post, I see the tweeter level rising at 15k maybe 2.5 to 3 dB over the average (1 k) level. That doesn't look ALL that bad to me, although depending on the person, it may sound harsh. I wouldn't plan for a response like that myself.

                But your point is I think that it's not the response that is shown in the manuals and resources section of the C-Note product page. And you're right, It looks to have a fairly flat response where yours rises above 5k. There is a difference there.

                My guess is that the tweeter is somewhat out of spec. That is the item that is subject to several different procedures when it comes to assembly and uses several different materials. In all the testing I've done of caps, resistors, and coils, (ones that I purchased from PE) none of them was out of spec more than just a little bit.

                BTW, I wasn't suggesting that woofer break-in was the cause, just providing a bit of information based on my experience since you seemed to dismiss it pretty quickly.
                And since I'm not the best a doing my own crossovers, I'd hate to open my mouth about your crossover layout and get it wrong, so I didn't even attempt a visual.

                You may be able to insert a series resistor after the tweeter crossover (after the 2 uF cap) to tilt the response down a bit if you're willing. I don't know if you have spare resistors to mess with, but maybe start with a 4-6 ohm resistor and then work up from there? Not the best solution especially since you bought it as a kit and shouldn't have to customize it as such, but it's an idea. I'm sure others better qualified may be able to offer a more accurate guess on the value of the resistor.

                R1 which is placed before the tweeter crossover should not affect the tilt of the tweeter response, mostly just the overall level, so I don't think that would be it if it were off-spec.

                Yeah, I'm not much help.

                TomZ
                Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                *Part 2 *Gluing multiple curved laminations of HDF

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                • #25
                  Have you tried over at DIYaudio forum? They're really smart over there.

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                  • #26
                    I looked at the xo schematic, and it should work, assuming everything is wired correctly, I used PCD to calculate a notch for the top end.

                    .1mH 1.5uf 3 ohms (In series with each other, and placed across the tweeter terminals.)

                    I assume you have confidence in the measurement setup, and that no tone controls or effects have been mixed in by accident.

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                    • #27
                      Why 2 wires on the ground side of the crossover?

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                      • #28
                        Originally posted by duanebro View Post
                        Why 2 wires on the ground side of the crossover?
                        Look at the layout in the manual for the answer to this.

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                        • duanebro
                          duanebro commented
                          Editing a comment
                          One should go to the ground and the other the woofer?

                      • #29
                        Hello Josh,

                        I have been looking over this thread, and the rising response on the tweeter is unexpected. From what I can tell, your crossover looks like it is wired correctly, so I don't believe that is the issue.

                        If C3 (2 uF in parallel with the tweeter) is open, or removed, then the response will tilt up slightly, but that would only cause about 1.5 dB increase at 15,000 Hz. I can't see any immediate issues or changes that would cause the 4 dB increase that you have measured.

                        Just to make sure, I will pull one of the ND25FW-4 and measure the response, just to check to see if anything has changed.

                        In the meantime, I will have one of our customer service reps get in touch with you so we can try to work though this discrepancy.

                        Thank you,
                        Chris Perez

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                        • #30
                          Thanks so much Chris. I'm hopeful we can figure it out.

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