Announcement

Collapse
No announcement yet.

Midrange horn beaming.

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

  • Midrange horn beaming.

    Midrange horn beaming

    Today, 01:47 PM
    I installed pair of mid-horns with hi-eff Timpano drivers (107dB SPL).

    An L-pad is turned down to about 7:00 position, which yields very smooth and even transition from woofer to mid to tweeter. Tweeter is die cast solid aluminum bullet horn, and is silky smooth. No issues whatsoever.

    Problem: When seated, ears are right in line with mid-horns. Certain freqs, I'd say around 2Khz to 4Khz, sound peaky or seem to beam (ring).

    Am considering a diy phase plug to reduce said effect. Ideas on how to fashion a plug for standard 1 3/8" throat?

    My speakers are built based on old Mach One design. The original Mach One mid-horn featured a bullet type phase plug, I do believe.

    The Timpano drivers I use are very well made. But there is only a mesh screen in front of the driver, facing the throat. This mesh may act as a phase plug of sorts. I don't know if it is enough tho.

    The plastic body of horn may also cause ringing/peaking in sensitive mid-freqs. I did fill mid-horn chamber with polyfil to reduce hi-freq resonance.

    I also thought of lining inside of horn throat, near driver, with 2mm self-stick craft foam. I am wondering if doing so will eliminate resonating effect?
    I am assuming resonation could begin in throat, only to be amplified by horn effect.

    Other than the peak/ringing, mid-horn is very smooth and detailed. I do not want to alter xover or mess with limited EQ settings.

  • #2
    A phase plug won't affect beaming. Plastic horns sound the same as metal or wood, unless you hit them with a stick. What's actually going on would require an SPL chart and polar plot to diagnose. It may be possible to tame the upper end by stuffing some open cell foam into the throat, which would attenuate the highs more than it would the lows. How much foam to use would be pure trial and error.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

    Comment


    • #3
      Originally posted by Stash View Post
      Midrange horn beaming I do not want to alter xover or mess with limited EQ settings.
      EQ is not optional with horn loaded compression drivers in most cases so you may have no choice. What you need to do is stick a mic in front of the horn to take some measurements, and look for any nasty peaks in the response in the range in question. If you find some try to determine if it's related to a resonance in the horn or something else mechanical, if it is some damping material may be a solution but if it's not notch filters may be the only solution.

      Paul O

      Comment


      • #4
        Originally posted by Paul O View Post
        EQ is not optional with horn loaded compression drivers in most cases so you may have no choice. What you need to do is stick a mic in front of the horn to take some measurements, and look for any nasty peaks in the response in the range in question. If you find some try to determine if it's related to a resonance in the horn or something else mechanical, if it is some damping material may be a solution but if it's not notch filters may be the only solution.
        Agreed. To get the most from a horn it takes EQ.
        Francis

        Comment


        • #5
          Thx Paul O & fpitas.. I'm thinking possibly a notch filter. I've never used a notch filter. I'm old school. Interested to see (hear) the effect. I did do a brief mic measurement a few weeks ago. I noticed a possible peak around 1Khz-2Khz which coincides with what I hear..

          But that measurement was rushed. I'll do a more precise test in the near future. It's not bad. I only notice it on certain music selections.

          Lol, to make matters more confusing, I'm not entirely certain the peaks may not be intentional (in the recording).

          I 'll post test results here in the near futre.

          Comment


          • #6
            billfitzmaurice,
            A phase plug won't affect beaming. Plastic horns sound the same as metal or wood, unless you hit them with a stick. What's actually going on would require an SPL chart and polar plot to diagnose. It may be possible to tame the upper end by stuffing some open cell foam into the throat, which would attenuate the highs more than it would the lows. How much foam to use would be pure trial and error.

            Haha...funny you should suggest foam. I had some extra open cell grlle foam. I cut a piece, rolled it up and inserted in throat. I thought, as you stated, any attenuation would be more in the upper range.

            Results were a very slight improvement. Almost nothing. What may have helped more is I turned the L-pad all the way OFF. Then, just a fraction clockwise. Sound seemed smoother, although I did not have time for a serious listen. I'm wondering if reflections are causing some of the anomalies. Peaking is obviously worse at mid-level or louder volumes.

            I'll def test on-axis and some polar responses and post results.

            Comment


            • #7
              It's very unlikely that reflections are causing problems. Horns simply don't work that way. You can run into resonance problems with horns that have parallel surfaces, but midrange horns very seldom have parallel surfaces.
              www.billfitzmaurice.com
              www.billfitzmaurice.info/forum

              Comment


              • #8
                It's common for horns to narrow dispersion at certain frequencies. That results in a raised area, and the solution is to measure on-axis and EQ it flat. Generally speaking, unless that takes more than a few dB of EQ, it's harmless otherwise. Even horns that don't have narrowing dispersion often aren't flat. Take a look at the goofy EQ curve for the JBL M2 horn sometime.
                Francis

                Comment


                • #9
                  Yeah. I expected some beaming or slight peaks.

                  Since I turned down L-pad a bit more, the peak is attenuated. Overall, sound is well balanced.

                  i think this horn driver is simply much louder than the tweeter and woofer. Louder than I anticipated.

                  The tweeter is rated 96dB, but it is a 4 ohm driver. So i used a 4 ohm padding resister in series which probably reduces output by -3 to -6dB, and brought it in line with the woofer, rated 90dB. Those two drivers sound very well balanced.
                  Looking back, I probably should have done the same with the mid- driver. I didn't think to add an 8-ohm resister in series and then re-calculate crossover values. That would have attenuated mid output to more reasonable levels.

                  It may be ok as-is. I just have the mid L-pad turned way down, almost completely off. I'm guessing as long as L-pad does not overheat, all is good. I originally counted on the L-pads to fine tune the treble drivers without altering their characteristics. But I didn't allow for such a difference in SPL for the mid driver. My mistake. Live and learn .

                  Comment


                  • #10
                    Yeah, horns are often more like 110dB/w.
                    Francis

                    Comment


                    • #11
                      I based my speakers on the old school MACH ONE. My mistake was I didn't follow their design. That is to say, The MACH ONE included resistors for both mid-horn and tweeter horn, as well as mid and tweeter L-pads.

                      When I designed my crossovers, I was very afraid of the tweeter horns being overly shrill. I absolutely despise shrill treble. And so, I added a resistor to dampen output, with excellent results.

                      My mid-horns are crossed over at 800Hz and at 8Khz. I incorrectly assumed shrillness would be avoided. I never even considered the sensitive 1Khz-3Khz region. Lol, idk why? In my car, I installed component 6.5 woofers & 1" dome tweeters and an upgraded receiver. The receiver features an 8-band EQ. I have the1Khz band attenuated by -8dB, because I find the shrill resonating sound so very annoying.

                      If I had money to blow, I'd buy an old school amp or receiver with preamp in/out and a 31-band/ch EQ to patch in. Then I could really fine tune the sound.

                      It's too bad modern surround receivers do not come with preamp in/out loop. My old Pioneer 80's receiver included the loop to patch in another component. But I was too dumb to make use of it back then

                      Comment


                      • #12
                        Well, I caved...turned on my receivers built-in EQ. Only 7-bands per channel, but seems to make a difference.

                        Attenuated 160Hz by -3dB. Really smoothed out deep bass. All other bass bands at 0dB.
                        BASS control bypassed.

                        Attenuated 2.5Khz by -2dB. Much better! Peak seems gone. Midrange sounds just as full, but a little warmer. Seems very smooth now. Will listen for a while and fine tune if neccessary.

                        You guys were correct about using EQ. Many thx 👍. Much prefered over opening up my speakers and altering crossovers

                        Comment


                        • #13
                          Btw...all other mid/treble bands at 0dB. TREBLE control also bypassed. Enhancement OFF.
                          playing Marian Hill. Incredibly smooth and detailed. Wow

                          Comment


                          • #14
                            I've never understood why some have an adversion to using EQ. Perhaps because they've never seen one of these?
                            Click image for larger version

Name:	church3.jpg
Views:	113
Size:	30.9 KB
ID:	1458637

                            www.billfitzmaurice.com
                            www.billfitzmaurice.info/forum

                            Comment


                            • Steve Lee
                              Steve Lee commented
                              Editing a comment
                              Transporter Room?

                              :D

                            • AEIOU
                              AEIOU commented
                              Editing a comment
                              Because the vast majority of us cannot afford a many kilobuck setup like that, and what we can afford has audible artifacts.

                          • #15
                            I can tell you, for me, it's the thought of altering the sound with negative results, or no longer being pure. Also, it can be frustrating trying to find that right sound with multiple bands.

                            Comment

                            Working...
                            X