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I would like to capture the sound of speakers, playing music, from the listening position. Is such a thing possible with realistic results?
So far, I have tried 20hz-20khz omni condenser microphones in AB configuration. Both with an absorber between the mics and without, placed at ear height on the listening chair.
The recorded sound does not represent at all what I hear from the speakers in real life. There is far too much room echo picked up, and the recording sounds very bad, as if I had used a cheap camcorder microphone. Not true fidelity at all.
Is there a type of microphone and configuration that will pickup a good representation of what I hear in real life, from my speakers?
Follow Ups:
You will have to do what the rest of us do and that is use trial and error. For my recordings I do for local educators for bands and ensembles in the large halls I prefer the spaced omnis as the most natural, but they do pick up everything and can sound magical if the room is large enough to hold back reflections.
The HVAC noise is there regardless of the mic type. I hate it as much as the next recording engineer, but it is what it is. I try and get it turned off, but usually the band directors must call the school engineering days in advance to reprogram their systems, and usually forget. If they want to hear the AC I can capture it for them.
With Uni's you will just have to experiment with placement vertical and distance and deal with your side walls. You might try a version of ORTF with the capsules not "aimed" quite so wide and work your way to wider and see how it sounds to you.
I just did a recording of an excellent high school symphonic band using the Tascam DR-2d and DR-07 flash recorders. The DR-2d @ 2496 got my Rode NT1As in ORTF with the DR-07 at redbook the spaced omni's. the Omnis had more low end, but both were excellent, but it was a large venue with a 3/4's full auditorium with carpet on the seating floor.
I wish there was an easy solution for you, but at every venue I show up early to experiment during the group's practice with mic placement. What placement worked the last time in another venue, may not work at all in the next one.
Good luck and keep trying as a few inches either way may be the spot you are looking for.
ps The Tascam recorder are killers. I should have bought them sooner.
Jim Tavegia
I think you're posting in the wrong thread.This thread is about recording the sound of the playback speakers, not live ensemble recording.
Edits: 03/18/11
OMNI directional microphones are notorious for picking up room acoustic reflections. You would have to set up in an anechoic chamber (floors, walls, celling made of pyramid acoustic absorbing material and suspended wire floor) of absolutely no reflections and use the mic as a probe on axis with each speaker and even then it would not be as realistic or as forgiving as your ears. Ray
"The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." LeCorbusier (Edward Jenneret)
GR, are you saying "no!" to what Adriel did (and found sorely lacking in the desired results), or what Tom described (using both an outdoor approach as well as an indoor variant)?Regarding the use of omni-directional mics, they're the best way to go. Cardioid, hyper-cardioid, etc. all pick up room reflections also, but with much more coloration than good omnis. I've never seen a cardioid mic with anywhere close to uniform response at more than about 45-60 degrees off-axis. Even the best ones sound noticeably different at 90 degrees compared to on-axis. Omnis also have an increasingly directional pattern at upper frequencies, but the effect is much less obvious than with cardioids.
A person could place the mics closer to the source, rather than at the usual listening position, as long as they're not so close that the balance of sound from individual drivers becomes an issue. But as long as the room is still a factor, omnis are the way to go.
Edits: 02/24/11
I respect your opinion. I've been recording since I was about 17. It is my experience that omnis are only best when you have TOTAL CONTROL in a dead acoustic space. There they are wonderful. When ever I have tried to use them, I get too much boomy bass almost reverberant bass that overshadows the whole recording. Mind you I have to record in gymnasiums, school auditoriums, band rooms, and spaces that are not DEAD and I have no control. I don't have access to a recording studio designed by an acoustic engineer or architect. And I have some condenser mics that I can change the polar pattern from omni to cardiod to fig 8. Omnis are also notorious of picking up everything; the HVAC vent/motor blowing, the noisy kitchen down the hall, folding chair rustling, music page turning on the stands, musician shoe shuffling, semi tractor trailer rigs rolling past outside, car horns, low flying air craft, jack hammers while i am trying to record MUSIC. Using a cardiod has solved most of that. With omnis you have to back them off not to pick up the music page turning or the shoe shuffling or the throat clearings. After you back them off then the music ensemlble sounds like they are in the next county. I realize there are fringe frequency effects of the polar pattern of cardiod mics. But the sound seems nearer and more defined to me and not as distant. IN fact there are some recent recodings on CD by engineers who insist on omnis that sound like the ensemble are in the next country. Inverse square law and all that. I've had my hearing checked so don't tell me that I'm just old or my motorcycle has damaged my hearing. I wear earplugs then and when I am forced kicking and screaming to rock concerts. Cheers! Ray
"The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." LeCorbusier (Edward Jenneret)
You're just old or your motorcycle has damaged your hearing. ;)
Seriously, I don't disagree with most of what you wrote. Except maybe the part about page turning and shoe shuffling. The placement distances I usually end up with (in location recording) don't present more or less of a problem in that regard, based on pickup pattern. When you get into really live rooms, like the gymnasiums or very live churches, then, yes, you really have to use cardioids. And don't even get me started on noisy HVAC vents!! Our buddy MarantzGuy surely has a thought or two about the topic.
But what I was addressing was the topic at hand: recording the sound of the speakers and room in a home living room.
And you (or someone) noted our hearing ability to discriminate and effectively ignor a certain amount of ambient sound, and that affects our perception of the sound quality. That's certainly true. I might add the comment that when we record and subsequently play back, all of that directional information and the associated discrimination ability is lost, because ALL of the recorded sound is now coming from the speaker (the source!), rather than from all around. This is a huge contributing factor to why Adriel was so disappointed with the recording results. Not knowing the "liveness" character or size of his room, I suppose it's possible that he should try a good cardioid. My main point is simply that an omni will give you a better quality of reverberant sound. But it could well be that the quantity will be too much.
In any case, something like what Tomservo described for an outdoor approach would be best if one wants to eliminate the room, but it doesn't appear that Adriel wants to eliminate the room, he wants to record what he hears at his listening position IN his room. Maybe his question is the wrong question. ;) Either way, this experiment into recording and psychoacoustics certainly will provide him with an opportunity to learn something about both! :)
Hi
At work they have compiled a small library of loudspeaker sounds which can be listened to.
What we do is a variation on the old “generation loss test” used in the old days of analogue tape.
This does not provide a “measured” result but instead allows one to hear an exaggeration of exactly what is wrong with a speaker.
The DSL generation loss test is done this way.
You pick several demanding musical tracks and put them on a CD track about 3 min long or so.
You get a 24/96 multi channel recorder and known quantity measurement microphone.
You place the speaker up in the air (outdoors) with the mic at say 2 meters (also up in the air). This placement insures the direct sound is much louder than any of the reflected sound. If you do this outside, except for the ground, there are no reflections.
You play the music through the speaker at a modest level and record it directly on track 1, on track 2 is the microphone signal.
Then play back the recording except you play track 2 into the speaker and record it on track 4.
You play back track 1 and re-record it on track 3.
Now one has two generations of reproduction, most speakers already sound bad after two generations our best sound funny after 3 to 5. Obviously a “perfect” reproducer, microphone and environment would allow an infinite number of generations.
Each generation exaggerates whatever was wrong with the speaker and becomes more and more obvious.. The farther it is from “perfect” the fewer generations it takes to sound bad. Also, one is recording the original signal as well so if you wish, you can sample the degradation during the repeated AD/DA processes of the direct signal.
One comment about hearing;.
We hear with two ears located at two different points in space.
Not only that, but unconsciously, we have learned to associate the large changes in our ears frequency response with incoming angle as positional information instead, that is how we hear up/ down and behind etc.
Thus, we can hear much more than a two channel system should be able to discern. Not only that but without being aware of it, we automatically ignore a great deal of information as we listen for something in particular.
For example the deep / dramatic looking effect of low frequency comb filtering in a room from reflected sound, is relatively minor to your ears and often it is the delayed signal not the response which one hears more.
As a result, a perfect microphone, picking up pressure variations from one point in space without discrimination, will never sound exactly like what you hear with ears listening from two places, with an aural processor which discriminates the un-important and allows spatial detection in 3D from two points in space.
The condition you describe (hearing you room etc) is real (assuming your mic is proper) but is part of what we automatically / unconsciously reject when listening.
One way this same test can be used to “hear” the room interactions or lack of. You do the same test in a normal room, each generation exaggerates the room and speaker’s flaws. Here, a speaker with much more directivity exhibits much less room coloration.
So far as hearing exactly what your speaker does, you need a reflection free condition, preferably very quiet relative to your test level.
Even then, keep in mind the little mentioned differences between hearing it and recording it.
This all kind of illuminates part of the overall problem making a “good sounding” recording.
Best,
Tom Danley
Danley Sound Labs
and you have total control of acoustics. We also are very far from creating a microphone that is as versatile and forgiving as the human ear-brain mechanism. Omni directional microphones are notorious for picking up reflections and accentuating reverberations.
About the only place omni mics are used in music recording is in classical music and they go to great lengths to control acoustics and reflections. They choose the correct architecture, bring in deep valour-velvet drapes to cover empty seats, cover mirrors or reflective surfaces. Omni mics are also used in anechoic chambers as test microphones in real time analyzers, generally ON AXIS with the sound source BUT those are carefully controlled rooms (those rooms with the pryimidal arrayed walls, no flat surfaces and suspended wire floors). Ray
"The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." LeCorbusier (Edward Jenneret)
The farther away you have the mics from the source the more your gonna get the room sound
Move the mics closer to the source and try a Blumlein pair
The First question is WHY are you trying to do this?
What are you hoping to gain from it?
knowing that would help to give answers and suggestions.
But as a test, use a piece of mirror at least 2'x2' and put the mic in a PZM mode (with the element as close as possible to the glass as possible. A mic with a grill will not work. It needs to be much closer.
Depending on how low you want to go in freq, you will need a larger piece.
But room modes will still affect what is going to.
The only time to use a mic in front of a speaker is in a ANECHOIC CHAMBER and a sweep frequency recorder and plotting chart,,Other wise what you want to do is just plain stupid..
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