A nice post, but...
Seems to me, comb filtering due to walls follows exactly from acoustics theory until you give it 10 seconds of thought. With a pure sine wave sustained, you could, I suppose, map the comb teeth. But every varying music note and every location and every movement of your head makes the whole map go poof.
BTW, there is a certain ontological issue too: you'd need to know the "true" sound in order to know when you are "hearing" filtering.
Synthesizing pop music and delivering it with the intended theatrical effects is a whole different matter. That has nothing to do with the notion of comb filtering off nearby walls. It is processed sound and delivered for your enjoyment. I almost always dislike these distortions, since that is exactly what they are. Not musical to use half-wave rectifiers or comb filters, etc.
B.
I kind of think of wall and room reflections in general as magnifying lenses for delay comb filtering.
They exaggerate what started at the transducers.
My own experience recently is that some albums are much clearer at all frequencies, and others seem to sound about the same as always, with a new design.
I have no idea why this is so, I used drivers and components in a different way than ever I have before, but I'm well familiar with all but one kind of tweeter.
They exaggerate what started at the transducers.
My own experience recently is that some albums are much clearer at all frequencies, and others seem to sound about the same as always, with a new design.
I have no idea why this is so, I used drivers and components in a different way than ever I have before, but I'm well familiar with all but one kind of tweeter.
Nice video illustrating how to distort sound by adding an echo a few milliseconds (some feet) later.
But for speakers at home, that would correspond to having a source of the sound a tiny spot and all the sound echoing from a tiny spot on the nearby wall. That way all you hear would be the original speaker sound mixed with an echo set number of milliseconds later - just like the video demo.
If the speaker cone is not a tiny spot and if the reflecting spot is not a tiny spot, poof goes the analogy because all the time and delay parameters are smeared all over the spectrum.
The video makes an interesting claim. He says if you mix a stereo recording into mono, it would sound atrocious since the sound reaching the two mics from each instrument would be differentially off by a bit resulting in comb filtering (unless Blumlein method was used). Anybody find that to be their experience? (Of course, recordings are made from single mic tracks or in multiple mic halls where the theory gets weird, or sometimes at CBC live concerts of chamber music, two mics.)
B.
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There's no "of course" at all.
Obviously the guy in the video is talking nonsense, but that's normal for non-sound engineers.
Any decently trained sound engineer checks stereo/mono compatibility routinely.
Coincident microphone recordings with their many variants have no such problems.
Blumlein pairs are just ONE of the methods used to record, mid-side is a BBC favourite, while multi miking is well known for producing artificial & difficult to control results which Michael Gerzon stated was the reason why people were put off classical music, nothing to do with "weirdness".
Comb filtering as such, very commonly comes from bad recordings & poor acoustics.
I don't have such a problem on my reproduction system, it measures pretty much flat across the audio spectrum particularly from 25hz-2khz.
First of all, let's agree to stop talking about recordings. All kinds of distortion show up in recordings - including intentional effects resembling comb filtering - and we can't control that. The only issue for this forum is audio reproduction.
Hard to grasp what you mean by boasting about your "flat" plot since any mic plot looks like the Himalayan mountains until you impose some smoothing. And the more smoothing the more flat. I've never seen an REW plot that necessarily implied comb filtering was visible in the trace.
What about your system combats comb filtering? Are you saying everybody else must have comb filtering - while I'm wondering if anybody has detectable comb filtering?*
Personally, I think every picture of a room on this forum I've seen suggested reverberant awful sound. I know that sounds strong - but it goes along with modern taste in spare furnishings and little carpeting or heavy drapes. Tired brains from doing the Haas Effect all day.
B.
* the sound that gets to your ears has been exposed to vast numbers of instances of wave additions and subtractions including bounding off walls and all over the sound spectrum. But that's not the same as hearing comb filtering in the way it looks to the eye in a textbook like a comb destroying the flatness of your speakers.
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Comb filtering is the basis of two of the most popular guitar effects: The Phaser and the Flanger.
I'm not an engineer, and have no mixing experience.
I can't comment on the cause for a change in tonality of some old Beatles songs being or not being due to comb filtering.
I do know some mono recordings by them do not sound the sae as hearing remixed stereo versions with a preamp selector switches to mono playback.
The mono setting collapses all impressions of ambience, and resolution seems to drop off.
It's purely subjective of course, but selecting mono playback in a stereo system playing a mono.recording is inaudible to me, so I don't think it's only the effect of an extra summing circuit added in.
Have you ever seen the plots from a typical Bruel & Kjaer microphone or DPA? It's RULER FLAT from 20hz-30khz. Even my Neumann microphones are perfectly OK for measurements as are many others I have used. I see old (noisy) Gefell, & reso labs (siberia) X41 we use are also quite nice.