How can I tell if I'm hearing comb filtering?

[Dave B.]

Apologies if this has already been answered elsewhere ...

I've got a bunch of speakers in various configurations that I play with a variety of system components. I've seen a lot of discussions on AK about comb filtering.

How can I tell if my setups are causing it? What does it sound like?

Thanks!

Dave

 

[damacman]

Sit down and then stand up. Or walk from side to side. Do you hear a change in the high frequencies as you move about?

 

[turnitdown]

The "front" of the sound will be stronger in some positions than others, particularly between the drivers

 

[petehall347]

i am curious to learn as never heard of it before ..skimmed through this and cant take it in how it works .. https://www.soundonsound.com/sound-advice/q-what-exactly-comb-filtering

 

[Dave B.]

Thanks for the advice, guys. I do some tests and see what happens.

Dave

 

[bowtie427ss]

 

[4-2-7]

Sit down and then stand up. Or walk from side to side. Do you hear a change in the high frequencies as you move about?

?

The "front" of the sound will be stronger in some positions than others, particularly between the drivers

?

These two comments don't really say anything or explain it. Tony I would think when you are sitting or standing your head moves higher. You will get more from the tweeters so I would think you would here a change. If you walk around the room out of the sweet spot, you should here a changes as well being closer to one or the other speaker.

turnitdown
Can you explain what your comment meant?

 

[4-2-7]

How can I tell if my setups are causing it? What does it sound like?

Thanks!

Dave

Hi Dave, comb filtering isn't always a bad thing as it might help or hinder the sound in the room or the music. We have to remember a sweet spot is the sweet spot and we should be able to get that in any room with any speakers IMHO.

Controlled Dispersion. From ML
Another key attribute of an electrostatic speaker is its naturally dipolar radiation pattern. A true dipole transducer radiates with equal intensity from the front and back of its diaphragm, but the outputs are in opposite phase. As a result, sound waves rippling out toward the sides meet at the speaker's edge and cancel. That and the relatively large size of a typical electrostatic panel cause output at the sides to be very low relative to that of a conventional loudspeaker, which in turn minimizes side-wall reflections that tend to muddle sonic detail and stereo imaging. While the reduction in output to the sides contributes to the astonishing clarity for which electrostats are revered, the energy reflected off the wall behind the speaker opens up and deepens the sound.

Here and remember I recorded with a iPhone and it records in mono with Dipole speakers. However I'm standing and sitting as well as moving side to side but the whole room sounds pretty even, and one could consider it Comb Filtering.. But the sweet spot at the beginning end of the vid it the target.

Now look at the drastic change in every movement in the room I make.

 

[Dave B.]

I'm standing and sitting as well as moving side to side but the whole room sounds pretty even, and one could consider it Comb Filtering.. But the sweet spot at the beginning end of the vid it the target.

First, thanks for all the posts in response to my question.This seems to be a hard concept to pin down, precisely. However, and I think 4-2-7 brings it into better focus for me, I think a lot of comb filtering -- maybe the majority of it, both "good" and "bad" -- is highly room dependent. Yes, some degree of it can be due to speaker configuration (stacking, for example), but the propagation of sound waves as they interact with room dynamics is apparently at the center of the issue.

This all brings me back to the central issue of "what sounds good" vs. "what is proper and correct." Being the annoyingly lazy person that I am puts me in the "what sounds good" category. I move stuff around and make fuzzy subjective judgments about the relative degree of pleasure various configurations give me. When I find a particularly pleasing one, I stick with it until boredom inspires me to try something else.

If I were in the "what is proper and correct" category, I would have a Mac MEN220 and be chasing all the "bad" reflections and tweaking the heck out of crossover frequencies. I'm not motivated (or smart) enough to attack my music listening to that extent.

Maybe the bottom line for me is that if comb filtering (either "good" or "bad") is happening in my room, but it still sounds pleasurable to me, then I'll just let the reflections fall where they may.

Dave

 

[turnitdown]

turnitdown
Can you explain what your comment meant?

Probably not smart ass. Haha. If thought of as a visual - picture two waves in the ocean/lake as viewed from above. The lull between the two waves can be seen and the two crests of the two waves would represent the "front" or audio as combing. The absence of combing would be one continuous swell.

See? No clearer then before.

 

[4-2-7]

Probably not smart ass. Haha.

I realy did want to know

See? No clearer then before.

Correct, and I think the ocean wave analogy is Null points?

 

[4-2-7]

Maybe the bottom line for me is that if comb filtering (either "good" or "bad") is happening in my room, but it still sounds pleasurable to me, then I'll just let the reflections fall where they may.

Bingo

I use my Martin Logan speakers for specific music and mood. There is no denying it they add space and make the room sound much larger like a concert hall. I enjoy them.

 

[damacman]

I was on my cell when I replied ... Too briefly in hindsight.

See video in below post.

 

[Dave B.]

So, there are multiple possible soundstages, depending on your location between the speakers.

Tony, now this makes sense to me! I had never looked at it (or had it explained) that way before. Thank you. Something for me to think about as I ponder my speaker placements.

Dave

 

[604man]

 

[damacman]

Here is a great video that explains comb filtering in great detail.

 

[opnly bafld]

That video is a waste of time IMO.
Left and right center channel speakers = comb filtering.
A properly designed and set up single center channel speaker = little or no comb filtering.

 

[chef free]

Play one frequency through your speakers. Move around the room, does the sound change volume? That's comb filtering. Try moving your speakers around to hear the difference. My speakers have less when they are not toed-in...

 

[604man]

Let's go back to mono ;-)

 

[E-Stat]

I simply think of it in terms as multiple drivers radiating the same wavelength-but separated by a greater distance than the wavelengths reproduced. Consequently, it not a usually a problem with woofers. The result is multiple-pebbles-in-the-pond situation with overlapping waveforms that reduce focus.

Doubling speakers intended as singles creates that effect. I ran double New Advents (one inverted over the other to minimize distance between tweeters) in the garage for a while. Ultimately I prefer singles because of a more precise image. Stacking speakers one stop the other exaggerates the downside because of the added distance.

It is one of many factors relating to the overall perspective of coherency, a characteristic I discovered a high sensitivity to as a teenager. Which is why I favor single driver full range stats.

Multiple driver line arrays address the challenge by eliminating the space between them with tightly grouped mounting vis Roger Russell’s IDS-25, Infinity IRS or Scaena 1.4 among others.

Short answer - confuses image with multiple incoherent wave fronts.