What strips vocals from audio when a 1/8' audio jack is partially unplugged?
electronics.stackexchange.com
electronics.stackexchange.com
Here it happens because when the earphones' ground connection is disconnected from the source, the earpiece drivers remain connected to the L and R hot signals and their former common grounding point floats and leaves them in-series. This means that any signal present equally on L and R results in no current through the transducers. You hear only the difference signal in both ears, although to be precise, one is actually opposite in polarity.
What do you mean by 'dead center in the mix'?
There are a lot of fun things you can do acoustically with stereo sound. Some phasing effects can actually be pretty 'tripy' for lack of a better word.
There are other ways to do this via more complex 3D acoustical modeling. Mostly focusing on modeling of reverberation effects but you don't see that much in music recording. It is used a lot in games though.
(I'm rusty at this, but when I read 'phase', I think of a time difference between two signals. In this case, there's no time difference.)
Side note - welcome to hacker news! Assuming your the same kortuk from the EE stack exchange I believe we've interacted a few times. My account there is: http://electronics.stackexchange.com/users/1438/mark
You should make hacker news your website on EE? Your account looks some bare there, add some information!
http://www.howtospotapsychopath.com/2012/05/16/the-music-goe...
I'm assuming it's because the vocal track had to be removed pre-master, so the instrumental version would then mastered differently. Also the original track was a high quality cd rip, where as the instrumental was a downloaded mp3, so that would have had an adverse effect.
-As mentioned earlier, how the mp3 was prepared, whether split or joint stereo encoding.
-The source of the instrumental version. If the source is vinyl, all bets are off. If the source is a proper "Instrumental Version", it would have been mastered from an identical mix but without vocals and vocal effects (ex. reverb), and with the exact same settings as the original master. That is how major labels typically do it --- if it's apparent that the album will be popular, they'll usually have an instrumental mix (and master) created at the same time. This is done because the label wants to have instrumental versions for later potential use in films, TV shows, award ceremonies, commercials, etc. It's much more expensive to go back and "recall" settings in order to "mix-down" instrumental versions. This usually requires hiring the original mix engineer or one of their assistants and renting the studio at which it was mixed. Many pieces of "analog" mixing gear are not "stepped" with repeatable settings. Analog gear also has differences between individual pieces of equipment, even if the same model. Equipment breaks, is sold or removed, and this makes the task of a recall that much more difficult. Recalling mastering settings isn't nearly as daunting, as mastering studios typically retain all of their equipment and keep it in working order. This means that good documentation is required, similar to the software development process. For many of your all-tim favorite albums, there exists binders full of charts, diagrams, and notes detailing microphone types and positioning in the room and relative to the instrument/speaker, channel assignments, mixing equipment settings, the type/speed/bias/etc. of tape, lyrics and notation, even the types and tuning of instruments. It's a very complex process to document and recreate.
I'm just guessing here, though. Definitely not an expert.
You could do wideband modulation that would be much harder to detect, but only if your music is repetitive...such that you subtract, say, the instrumental content of the first verse from that of the second to reveal your hidden message. That's not so difficult, given the ubiquity of loop-based and electronic music nowadays.
One other issue with all these schemes is that the more well-hidden your steganographic message is, the more likely it is to be corrupted or destroyed by conversion to lossy data formats such as mp3. If you absolutely had to hide a message in musical form, I think it would be better to do in the manner of the purloined letter, ie haiding it in plain site. Encode it into the rhythm of the cymbals, or the sequence of pitch differentials in the primary melody or some other foregrounded musical element. You can use binary strings or a sequence of rational integers as musical elements very easily, and said sequences can be pre-encrypted. Sure, the signal is even more visible in that context, but who's to say that it's covert or merely artistic?
In most cases with older desks, this will be fine (you'll only get the left channel from the source). Some newer/smaller desks have a balanced jack input instead or as well as a balanced XLR, and plugging in an audio source will get exactly the same effect as described in the thread, since the left and right channels will be treated as a balanced pair and subtracted.
Cheapest approach to connect such a device to a mixer is a 3.5mm to 2x phono plugs and a pair of phono to 1/4" jack adaptors, connect to two channels on the mixer, and fully pan left and right.
(Never really thought about it before, but here in the UK it seems perfectly normal to refer to 1/4" and 3.5mm plugs at the same time)
Seems like you could easily create an encoder that didn't do that, and just e.g. encoded each channel at 64kbps when a total of 128kbps is requested, but maybe none of the real-world encoders actually do this.