[DeanSheen]

Anyone else feel like playing with their Tonka trucks after reading this thread.. or am I the only stupid one here?   

I'm with you, but I think I'm starting a Jneutron fan club. 

Highly entertaining stuff.  IT started out as a popcorn thread then turned into an applied physics thread.

If you dont want it or dont like it dont buy it!

[jneutron]

I'm with you, but I think I'm starting a Jneutron fan club. 

Only if there are lots of female groupies involved...

Geek groupies, now there's an oxymoron if I ever heard one..

Cheers, John

[Aether Audio]

Gee Guys,

Aren't we having much more fun now?     I vote for a jneutron club!

As far as the beer and the girls go... have fun but I'll have to excuse myself on those... can't stand the prosperity.  

-Bob

[Daygloworange]

To date, all the two channel musical product you buy (with some exceptions of course), are mixed down using pan pots which utterly destroy the localization parametric known as Inter-aural Time Delay, ITD.  This is done primarily to keep the two channel product backwards compatable with mono.  

We had a fun discussion about this a while back.   

When using 2 mics to record stereo, you adjust the spacing of the mics to adjust for mono compatibility. If the spacing is creating a time related out of phase, no amount of panning is going to save your butt. Mono compatibility was much more important years ago, as some records were done in mono, TV's used to be in mono, and AM radio was mono.

The typical (ubiquitous) X/Y stereo mic configuration has one mic capsule (diaphragm) right over the other one. The angles that the diaphragms pointing forward are set usually aimed 45 deg. off center to make a 90 deg, included angle. Essentially the reverse of an equilateral speaker playback setup. The angle can be increased to up to 135 deg. included angle, but beyond that, the image can get a little bizarre.

The general rule is the 3:1 rule when using more than one mic, and combining signals. If you have one mic 1' away from a source, then the second mic should be at least 3' away if you are to combine the two signals and maintain mono compatibility.

If ITD were introduced, or even maintained, the mono result would be heavily combed and rather distorted.

It could be, but not always. Sometimes, it can quite good in mono. It can be hit or miss. If you spent a lot of time on experimenting, you could definitely get it better, but nowadays, it's a pretty moot point. I do check for phase in mono when setting up stereo mics, but it's more about habit than anything else.

There are a number of "ambient" stereo miking techniques, and you can use mics with different polar pickup patterns. The X/Y is the one I prefer, and baffled X/Y can be freakishly realistic in stereo. The other types (spaced pair, Blumlein, M+S etc..), I consider more artful than precise.

This is where the "art" in recording comes into play. Because it's based mostly on experimenting.

I fyou want to know why recordings are all over the map, in terms of sound, it's simply because the first rule of recording is "there are no rules".

Are they taking any more applicants in the "jneutron" club? 

Is there a hazing ritual?

Cheers   

[Russell Dawkins]

There are a number of "ambient" stereo miking techniques, and you can use mics with different polar pickup patterns. The X/Y is the one I prefer, and baffled X/Y can be freakishly realistic in stereo. The other types (spaced pair, Blumlein, M+S etc..), I consider more artful than precise.

Interesting observation, but I can't let this pass, even if it is O.T. (sorry Bob)

"Blumlein" and M-S (which was invented by Blumlein) to me are much more precise and the rest are artful!

If you ever take the time to do a simple comparison between the various major stereo mic configurations, you will come quickly and unequivocally to the conclusion that Blumlein is the only type anywhere near accurate, and all the others are the artful configs.

The simplest comparison involves setting up pairs of the contending configurations and simply walking across the intended sound field while making some sort of appropriate noise (let your imaginations run riot). If the sound field  is literally a stage, just the footsteps are enough.

With Blumlein you will hear a smooth movement of the sound from one side to the other. With any others you will be appalled at the result. I am not alone in trying this, and the results are the same and not in the least subtle.

In spite of this, other techniques have their place, especially, in my opinion, ORTF and Jecklin Disc variants.

[Daygloworange]

Interesting observation, but I can't let this pass, even if it is O.T.

"Blumlein" and M-S (which was invented by Blumlein) to me are much more precise and the rest are artful!

Hey, Russell, I knew you might get a kick out of that. 

I enjoy hearing your point of view. And I don't entirely disagree with you either. It's just that we probably don't record a lot of the same instruments.

Ok, here's why I prefer X/Y.  With M+S , I like the center (on axis) mic idea. I actually use a center mic combined with X/Y sometimes to have L/C/R. But.....I don't like copying the side mic track, and then flipping the polarity to give you two ambient channels as done in M+S.

If you listen to the channels of an X/Y recording independantly, the ambience sounds different due to inevitable differences in room acoustics. At least in the size rooms, and the instruments I've recorded.

The issue I have with Blumlein is that you use  figure 8 pattern mics, and it gets real tricky with room placement due to the slap back that fires in the rear pattern, especially with drums, because of their sharp transient nature, and the type of waveform they create, which is (in reality) a lot of random noise.

It has been years since I've used Blumlein.....after hearing your take on it, I'll definitely try it out again and see. 

I do enjoy the recordings that you sent me a while back. Some of those piano recordings were real nice. I forget if they were all your recordings. There were a few where my only complaint was a high noise floor. I don't know of it was microphone self noise, or tape noise.

Do you remember what mics you used?

It's a bit ironic that some of the best sounding mics have some of the worst S/N ratios....   

Cheers

[JP78]

since we're discussing cable theory, it might be a good idea (inmhumbleo) to include fellow manufactuers / designers, such as steve nugent of empirical audio.  as a long time user, i firmly believe in his practices. 

ps.  bob you owe me prices!

[jneutron]

I defer to you guys when it comes to miking techniques.

Unfortunately, the bulk of the music heard today is of studio origion.  All the artists don't even have to be on the same continent.

Given say, 24 individual tracks that are mixed down to two, ITD loses.  The mixdown engineer turns a knob to position a track in space.

Music content which has been "panned" for position, is a forced response media.  In other words, we humans are forced to interpret the inaccurate localization parameters to determine a position in space.

Unforced, or natural localization, uses both intensity difference as well as time difference.  If you get a chance, try altering one or the other, and listen to how your mind reacts.  If you reduce one ear's intensity (say with a towel, or a plugged ear due to water), note that you can still determine the source location fairly well...this is because you are sensitive to the time difference.  In fact, as you lower one channel intensity, you can "see" that the source direction is "fighting" the intensity error, trying to remain centered.  This is ITD at work.

Conversely, if you have a multiplexed dac feeding two channels into headphones, and the S/H system is not syncronous, you get an 11 uSec interchannel delay (typical of really cheap sound cards).  With a built in 11 uSec delay, there is nothing you can do with the balance control to get the image field correct...  It is really weird.

Nobody measures the ITD information which is presented to our ears to determine if the system has altered it.  Since half the information we use to distinguish direction is ignored in the measurements, how then do we determine the accuracy of the delivery system?

Human ITD sensitivity is in the 2 to 5 uSec range.  Very small number, eh?

Cheers, John