Announcement

Collapse
No announcement yet.

Off axis "flares". Why do they happen? How to fix them?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Some of the Dayton RS100's have an off-axis peak around 2khz. It might be worth checking if that older RS100ps is the same. If it IS, then it might help to cross to the tweeter a little lower below that point (unless there's another way to fix it maybe?).
    My first 2way build

    Comment


    • #17
      If I remember correctly, Grimm Audio had a white paper on their website about the development of the LS1. It was a pretty good read on their development and thought process concerning the large roundovers and how they turned the DSP for off axis performance

      Comment


      • #18
        Originally posted by LOUT View Post
        Some of the Dayton RS100's have an off-axis peak around 2khz. It might be worth checking if that older RS100ps is the same. If it IS, then it might help to cross to the tweeter a little lower below that point (unless there's another way to fix it maybe?).
        This off axis peak is so big I actually thought it was the driver. I have seen diffraction, but this is far too much... and far too prominent. Unfortunately, the peak starts at 1.5 KHz, so crossing over that low, even a Dayton RS28F, is cause for concern (and the reason why I started using 8th order filters).

        One of the reasons why I also thought about the RS driver being the culprit is that the tweeter doesn't exhibit any off-axis flares, and I'd expect them too. And simulations never showed this issue.

        Do you know where I can find info on the off axis performance of the RS-100?
        Last edited by fjhuerta; 02-02-2021, 10:26 PM.
        Line Array: IDS-25 Clone, FE-83.
        2-2.5 Way:
        Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
        3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

        Comment


        • #19
          Well, this is interesting.

          Small 2-Way... Dayton RS100-4 doubts - diyAudio


          Line Array: IDS-25 Clone, FE-83.
          2-2.5 Way:
          Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
          3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

          Comment


          • #20
            Well that is interesting! I have a pair of RS100-8 sitting and waiting to do mid in a 3 way project, I wonder what they'll do.
            Electronics engineer, woofer enthusiast, and musician.
            Wogg Music
            Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

            Comment


            • #21
              Some exotic cone breakup going on?
              Francis

              Comment


              • #22
                Am I correct in my memory that Jeff said something about how you can use a trap and smooth out an on axis spike, but the off axis power response will still be funky?
                (I'm probably wrong....)
                I once had a 3 way were I was trying to use a Vifa TC9 mid slightly recessed. It sounded great on many music cuts, but real funky on some.
                Not trashing the Vifa, it might have been my misguided attempt to rear mount it.
                The only thing I found was a little bit of a hot power response right in the middle of it's passband.
                I finally gave up, and flush mounted a different mid, and it immediately sounded better.

                I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                My Voxel min sub Yet-another-Voxel-build

                Tangband W6-sub

                Comment


                • fpitas
                  fpitas commented
                  Editing a comment
                  You can EQ an on-axis peak down, but then you're also EQing the off-axis response, which is most likely already depressed since the energy was focused on-axis. You can get away with a few dB in my experience, but it's not an optimum situation.

              • #23
                Originally posted by fjhuerta View Post
                This off axis peak is so big I actually thought it was the driver. I have seen diffraction, but this is far too much... and far too prominent. Unfortunately, the peak starts at 1.5 KHz, so crossing over that low, even a Dayton RS28F, is cause for concern (and the reason why I started using 8th order filters).

                One of the reasons why I also thought about the RS driver being the culprit is that the tweeter doesn't exhibit any off-axis flares, and I'd expect them too. And simulations never showed this issue.
                I think other folks have had decent results crossing some versions of the RS28 tweeters as low as 1500hz...plus I don't think those tweeter's will ever see more than ~15watts when paired with an RS225 and RS100 (assuming there's some BSC).
                Of course, if there's a better way to solve this, then totally go for that instead..I'm just saying that crossing to the RS28 around 1500hz might be a viable backup plan if there isn't a better solution.
                My first 2way build

                Comment


                • #24
                  Did you filter (EQ) the mid to follow a 4th order target on axis, or did you just dial in a 4th order filter?

                  Comment


                  • #25
                    Originally posted by rpb View Post
                    Did you filter (EQ) the mid to follow a 4th order target on axis, or did you just dial in a 4th order filter?
                    No, I eq'd the drivers and measured for a flat on axis response. Once I arrived at it, I applied the crossovers. I then re-measured everything, to make sure I got the proper curves.

                    I did some measurements today and have a definite idea of what's going on. It's diffraction from the edge of the baffle.

                    I took some scotch-brite pads (got the idea from a DIYaudio post) and taped it to the edge of the speaker, next to the mids and tweeter. The hump at 2 KHz did not disappear, but it dropped 1 dB, and I flattened the response on the tweeter a lot.

                    Obviously, I will not leave the scotch-brite taped. I wanted to get some 1/2" x 2" F10 felt from McMaster-Carr. But they won't send the material to Mexico. So, at least for now, this plan is a no go.

                    What I did was - I started taking off and on-axis measurements, and discovered that a 2 dB BBC dip on axis flattened the response off axis, and created smooth, downward slopes, Adjusting the woofer and tweeter levels a bit, I got a smoother response than I expected.

                    I then took several measurements on my sitting position and noticed the FR was downward sloping, without any major dips or bumps. So, I assumed that I had properly considered both on and off axis curves.

                    I listened to music, and the midrange glare was gone, replaced by a very smooth midrange and upper mids. The speakers are now really enjoyable.

                    I may try and get some F10 felt, but honestly, at this point, I'm really happy with my speakers. Form followed function in this box. But my next one will be 100% function.

                    Nevertheless, I'm really happy, and I learned a ton with these speakers. I posted this after two months of tuning them. I finally arrived at a combination that I know I'll be happy with (and I'll never design a passive speaker without testing it with the MiniDSP first!).
                    Line Array: IDS-25 Clone, FE-83.
                    2-2.5 Way:
                    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                    Comment


                    • #26
                      Hey, glad to see you back in the DIY world Francisco. I still remember your winning design in Zaph's contest all those years ago. I used a slightly modified version of your SB29 tweeter xover with a different woofer and it turned out great. Thanks for that!
                      "Everything is nothing without a high sound quality." (Sure Electronics)

                      Comment


                      • #27
                        Originally posted by ernperkins View Post
                        Hey, glad to see you back in the DIY world Francisco. I still remember your winning design in Zaph's contest all those years ago. I used a slightly modified version of your SB29 tweeter xover with a different woofer and it turned out great. Thanks for that!
                        Thanks! Yes, I loved that design. I still have 4 boxed ZA14's from that timeframe, which I may use this year.

                        I just decided to get serious about this issue, and post my findings. I bought 1/2" x 2" F13 wool from McMaster (I had to use a forwarder to send it to Mexico) and 1/2" x 2" Neoprene. I'll try to find out which one works best for my issue. I hope it's the neoprene, since I think it'll look better than wool felt my baffle. I'll post all of my findings in thes thread!
                        Line Array: IDS-25 Clone, FE-83.
                        2-2.5 Way:
                        Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                        3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                        Comment


                        • #28
                          Originally posted by fjhuerta View Post

                          Thanks! Yes, I loved that design. I still have 4 boxed ZA14's from that timeframe, which I may use this year.

                          I just decided to get serious about this issue, and post my findings. I bought 1/2" x 2" F13 wool from McMaster (I had to use a forwarder to send it to Mexico) and 1/2" x 2" Neoprene. I'll try to find out which one works best for my issue. I hope it's the neoprene, since I think it'll look better than wool felt my baffle. I'll post all of my findings in thes thread!
                          I doubt seriously that the neoprene will be a benefit. The sound waves needs to pass through the material and absorb some of it. It may also be that it adds some delay as well that changes the phase after it has passed through, but that part is just my conjecture. My thinking on that is that the speed of sound through something such as felt is different than in open air. I have found very few materials appreciably improving diffraction effects.

                          dlr
                          WinPCD - Windows .NET Passive Crossover Designer

                          Dave's Speaker Pages

                          Comment


                          • #29
                            Originally posted by dlr View Post
                            I doubt seriously that the neoprene will be a benefit. The sound waves needs to pass through the material and absorb some of it. It may also be that it adds some delay as well that changes the phase after it has passed through, but that part is just my conjecture. My thinking on that is that the speed of sound through something such as felt is different than in open air. I have found very few materials appreciably improving diffraction effects.

                            dlr
                            From what I've read and seen with data, felt does a definite improvement in the area I need to, and a very small amount of synthetic fiber already got me halfway there. I only need to shave an extra dB off 1.5-2.5 Khz.

                            The idea for neoprene came from here:


                            https://www.courant.com/news/connect...039-story.html

                            https://web.archive.org/web/20120124...ig-tweaks.html


                            From what I understand, wool felt helps with sound dispersion, while neoprene actually does sound absorption.

                            I do believe wool felt is the answer to my problems. But I hope neoprene does the trick, since I'm sure it will look better than the felt. Anyway, measurements will show which one does work.
                            Line Array: IDS-25 Clone, FE-83.
                            2-2.5 Way:
                            Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                            3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                            Comment


                            • #30
                              Originally posted by fjhuerta View Post

                              From what I've read and seen with data, felt does a definite improvement in the area I need to, and a very small amount of synthetic fiber already got me halfway there. I only need to shave an extra dB off 1.5-2.5 Khz.

                              The idea for neoprene came from here:


                              https://www.courant.com/news/connect...039-story.html

                              https://web.archive.org/web/20120124...ig-tweaks.html


                              From what I understand, wool felt helps with sound dispersion, while neoprene actually does sound absorption.

                              I do believe wool felt is the answer to my problems. But I hope neoprene does the trick, since I'm sure it will look better than the felt. Anyway, measurements will show which one does work.
                              Neoprene may be good for panel vibrations, but not for a baffle diffraction application. That name in the first article sounds familiar. It uses misinformation and exaggeration to push the product, using "audiophile" wording to hype the claims, but it's not anywhere close to the claims. Too thin and not a good material in my experience. I've tested similar products and found them, in many cases, to make the situation worse.

                              dlr
                              WinPCD - Windows .NET Passive Crossover Designer

                              Dave's Speaker Pages

                              Comment

                              Working...
                              X