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Comb Filtering - Quick way to Tell

Hi Everyone,
Lots going on here, with this odd Golden Ear vs. Tekton debates. I personally don’t care, except there’s a lot of theory being bandied about as proof of the superiority or inferiority of a design. The arm-chair experts are really giving me a headache because my eyes can only roll back so much before my optic nerve gets kinked.

I have no interest in either brand, really, but let’s talk about it in practical terms.

Comb filtering happens when you have simultaneous arrivals of the same signal which are slightly out of time alignment. Really, any multi-way speaker has to deal with this, but arrays in particular. Much has been written and debated, but let’s boil it down to this:
Comb filtering affects what your ears hear in a particular location in space. The frequency response at location A can change rapidly a few inches away at B. In fact, we can use this in a process called interferometry to get very precise measurements of acoustic offsets.
The point?

If you are concerned about an array having comb filtering, move your head. That’s it. If it is a problem, small changes in your listening location will cause significant changes in the frequency response. Stand up, sit down. Is the frequency response changing much? is it pleasant or uncomfortable/weird sounding? Do this for any speaker.  Listen at the center and both ends of the couch.

But please, listen realistically! Listening 1’ away to an array may yield vastly different results than at 9’ so it is important to understand the manufacturer’s design and intention, which is really true for all speakers.
Which speaker should you buy? The one you like the most. For heavens sake, listen to them and look at them.

We should also point out, as I alluded to elsewhere, there are lots of interesting ways to handle potential issues with comb filtering, so the idea that you can measure center to center differences, and diaphragm diameter alone will tell you what the speaker will sound like at the listening location is simply not enough information. Your head and ears however can do an excellent job of discerning these issues.
erik_squires
erik_squires OP
5,268 posts
 
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.
shadorne's avatar
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shadorne
7,333 posts
 
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



erik_squires OP
5,268 posts
 
@shadorne

Yep, agreed to all of that. The crossover has a great deal to do with the results. 

Best,

Erik
kosst_amojan
2,095 posts
 
I looked over the measurements of the Enzo XL. They clearly reflect the comb filtering of an array of 1 inch tweeters placed 2 inches on center, which looks to be about right based on the photograph of them. As I mentioned in my post elsewhere, 1 inch tweeters placed 2 inches on center will begin to decouple as an array at 6500Hz. 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. The diagonal trough cut through the off axis response is what you'd expect to see in a comb filtering effect. I looked at the same plot for the Wilson Alexia, Bowers and Wilkens 702 S2, Golden Ear Reference, and several Focal speakers and none of them exhibited such severe off axis response deviations so low in the tweeter passband. Also, none displayed any sort of diagonal cut like the Enzo XL did. 
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