SOONGSC
In the whole audio path, any capacitor, from the recording mikes to the final loudspeakers, and any distance, from the sound emitters to the mikes and then from the loudpseakers to the ears, alter the waveforms. A series capacitor in series has an effect of symetrisation on the waveform of the signal. However musical intruments reproduced by loudspeakers remain still perfectly recognizable. The ear seems to work as a spectrum analyser and seems to be not very sensible to the waveforms.
In the whole audio path, any capacitor, from the recording mikes to the final loudspeakers, and any distance, from the sound emitters to the mikes and then from the loudpseakers to the ears, alter the waveforms. A series capacitor in series has an effect of symetrisation on the waveform of the signal. However musical intruments reproduced by loudspeakers remain still perfectly recognizable. The ear seems to work as a spectrum analyser and seems to be not very sensible to the waveforms.
forr said:
I'm trying to identify why I hear differences by comparing test results with little tweeks I make. Many sounds can be recognizable, but it may not sound like it's there live. I'm sure lots of people will find it hard to believe. I hope to be able to release some reversible speaker driver mods for people to try for themselves, and based on that modifed driver, possibly they can experiment for themselves.
forr said:
Of course people will have different preferences depending what they expect and what they experienced in the past. But it's really fun when fumbling around for a while and suddenly you hit a G spot, it's just pure exciting. Then another round of fine tuning hoping you don't mess things up is even more a challenge.
I recently pulled out some old recordings (1958~1970) that sounded bad on my system. Once I flipped the polarity at my speakers, they sounded much better. The difference is quite significant. So now I'm confident that the better the speakers are in revealing the original sound, the more absolute polarity can be noticed. 
But now recordings really sound worse if the polarity is not correct. 
One thing that I found in the process of exploring absolute polarity, is that mostly older recordings are phase inverted. It would be interesting to hear what others have experienced.
But now recordings really sound worse if the polarity is not correct. One thing that I found in the process of exploring absolute polarity, is that mostly older recordings are phase inverted. It would be interesting to hear what others have experienced.
Listening to a CD "Paquito D'rivera Hana Cafe" Checky JD60, I noticed the sax and the percussion instruments seem to be out of absolute polarity of each other. In one direction, the sax is well focused but the percussion instruments are not, the other way around the percussion instruments become more focused but the sax is not so focused.
Hi soongsc
Have you seen Rode NT4 Stereo Microphone
K a n w a r
Have you seen Rode NT4 Stereo Microphone
An externally hosted image should be here but it was not working when we last tested it.
K a n w a r
I think most mics have the heads around 20cm or so apart to get better focus on individual instruments. I've never tried them so close.
Once I did a recording with mics on my ears in a hotel hall, the focus was not so good, now to think of it, the sound had some syptoms of inverted phase. I'm thinking about trying something like this again with a better portable recorder than an MD.
Now that this kind of polarity seem more obvious on my system, I wish there were a phase inverting switch.
I'm not sure what kind of head the NT4 uses, but if they are the electret condenser type, most likely they are phase inverted unless it is inverted back somewhere in the mic preamp.
Once I did a recording with mics on my ears in a hotel hall, the focus was not so good, now to think of it, the sound had some syptoms of inverted phase. I'm thinking about trying something like this again with a better portable recorder than an MD.
Now that this kind of polarity seem more obvious on my system, I wish there were a phase inverting switch.
I'm not sure what kind of head the NT4 uses, but if they are the electret condenser type, most likely they are phase inverted unless it is inverted back somewhere in the mic preamp.
We have designed a custom made complementary HEXFET mic preamp for these mics, and fortunately it also features phase reversal and along with vocal management system[echo,reverb,compression,expander,bandpass-filter]just to fine tune according to the specific environments...
have a look at this link for rode mics:
http://www.rodemic.com/downloads/NT4_White_Paper.pdf
have a look at this link for rode mics:
http://www.rodemic.com/downloads/NT4_White_Paper.pdf
Hi Soon,
the spaced mics don't work as well as the coincident cardoids.
However, if you put a head sized board between the spaced mics and closed them down to about 150mm then you have the makings of dummy head recordings. When listening to this type of recording on headphones the effect is unlike a conventional stereo recording.
Which reminds me.
Does anyone know where I can download a copy of the dummy head recording of a play made for the BBC with Andrew Sachs as the main character.
I think it was made in the 80s.
The whole play has no dialogue and for a radio play that is some achievement.
the spaced mics don't work as well as the coincident cardoids.
However, if you put a head sized board between the spaced mics and closed them down to about 150mm then you have the makings of dummy head recordings. When listening to this type of recording on headphones the effect is unlike a conventional stereo recording.
Which reminds me.
Does anyone know where I can download a copy of the dummy head recording of a play made for the BBC with Andrew Sachs as the main character.
I think it was made in the 80s.
The whole play has no dialogue and for a radio play that is some achievement.
I was recently listening to a CD from TACET that demonstrates recordings using different mics. There were three tracks that used the "Petite masse solennelle" dummy head. The recording was not as good as others, and it seemed to be recorded out of absolute polarity. So it means that recordings using the dummy head is best played back through headphones? That makes some sense.
From my own experience, dummy head recordings are only sensible when played back through headphones. (In which case they are superb!)
For loudspeaker playback of small-scale acoustic performances, either a co-incident crossed pair of cardioid mics, or (my preference), an M-S recording with co-incident omnidirectional + figuure-of-eight microphones gives a wonderful audio image. (This is easy to decode into conventional L-R channels using a very simple matrix).
I have also heard 4-speaker playback of a surround-sound M-S recording using a co-incident array of an omnidirectional mic, with two figure-of 8 microphones. The two figure-of-eight mics were at 90 degrees to each other. The matrix to produce the four channels from this array is also very simple. Even the full 3-D M-S array using three figure-of-eight mics (plus one omni) provides signals that are much easier to decode into the separate channels than the ambisonic 'soundfield' trapezoidal array.
For loudspeaker playback of small-scale acoustic performances, either a co-incident crossed pair of cardioid mics, or (my preference), an M-S recording with co-incident omnidirectional + figuure-of-eight microphones gives a wonderful audio image. (This is easy to decode into conventional L-R channels using a very simple matrix).
I have also heard 4-speaker playback of a surround-sound M-S recording using a co-incident array of an omnidirectional mic, with two figure-of 8 microphones. The two figure-of-eight mics were at 90 degrees to each other. The matrix to produce the four channels from this array is also very simple. Even the full 3-D M-S array using three figure-of-eight mics (plus one omni) provides signals that are much easier to decode into the separate channels than the ambisonic 'soundfield' trapezoidal array.
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