Comb Filtering - Quick way to Tell
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Kosst, Comb filtering due to array specific issues will be shown in the vertical, not the horizontal plots. The reason is simple: The acoustics offsets to all tweeters is identical across the horizontal plane. Across the vertical plane, the acoustic distances to each tweeter is changing. That is where comb filtering would appear. Everything else I see is due to "normal" 2-way design choices. However, I go back to listening. Listen to see if the off-axis performance is what you like or not. @timlub Thanks for the vote of confidence! Tim, sounds like you are discussing something similar to a Bessel Array. One of several ways to deal with real comb issues. Another simple way of course is to use smaller number of tweeters as the frequency goes up, which is what Tekton seems to do. Best, Erik |
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Nice thread Erik and good, simple explanation for Comb Filtering. Way back in my Marcof/SpeakCraft days, we built a tower with a 15" in a 2way and 3way version and 4 Audax HD's on top. Comb filtering was minimal and this was a fairly smooth and refined speaker. On the tweeters, we tried different variations of series parallel wiring as well as taking specific drivers out of phase and changing the slopes on these tweeters in sets. The end affect was that Comb filtering/lobing effects were minimal. So my experience is closer to Eriks. Tim |
. If you look at the horizontal response plot in the link, that is exactly where they begin to decouple and soon after their off axis response plummets Except with a vertical array, horizontal "decopuling" as you call it (not a term I’ve ever heard in speaker design) is exactly what would never happen even in the most poorly designed arrays. What you are seeing is the normal off-axis drop off of the tweeter, combined with the unusually large mid-woofers (see JA’s comments in the measurement texts). We usually refer to this as lobing, and is a type of comb filtering inherent in almost all multi-way speakers. A combination of the woofer’s output, crossover and rapidly changing acoustic offsets with angle. We can argue about who does it better, and whether speaker A vs. B’s coverage sounds better, but to call this a fault of the line array itself is simply not accurate. A better place to see this line-array comb filtering is the vertical plots, and comparing it to how a similar 2 way would function. In this sense the Enzo’s array offers superior coverage below axis, and, like many other speakers, above gets wonky. As I try to mention, comb filtering of the type you are complaining about happens very very quickly, in a matter of a few inches, and goes back and forth. That is, as you move the microphone the nulls and valleys shift rapidly. This smooth drop off across the horizon is anything except that. It does, overall, suggest a narrow dispersion which in many rooms will be a good thing. But based on the charts, I don’t see any of the types of array / comb filtering mistakes that have been discussed for it. Best, E |
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Comb filtering really sounds bad. It is best avoided. i think the Enzo only uses 1 of those tweeters in the top octave. example https://youtu.be/4qgmY8jIGi0 |
Another way to tell about the quality of the speaker in terms of dispersion and combing is the off-axis plots. I haven’t seen one for the Tekton Double IMpact, but for the Enzo, which uses a much simpler array, the vertical and horizontal plots look really good: https://www.stereophile.com/content/tekton-design-enzo-xl-loudspeaker-measurements Based on that, I’d say the designer achieved the goal of wide horizontal and tight vertical dispersion, without evidence of comb filtering. I would expect a nice wide sweet spot and very usable horizontal listening location with enhanced detail thanks to limited reflections from the ceiling. None of which means you should buy it, but that the issues being discussed regarding Tektons and comb filtering were not shown in these measurements. Again though, your ears are going to be just as good at hearing those issues as measuring devices, and I have no particular interest in whether or not you like them or not. Just want to remove a lot of techno clutter from the debates. For heaven's sake, listen! Charts, theory and calibrated microphones don't enjoy music, nor do they save, budget and work hard to have the money to afford our dream speakers. All I want to do is remove the FUD, and let you know with confidence that you can tell if any of this debate is a problem for you or not. |
