Tweeters in-phase?

I mentioned it before, I think in a few years we'll have gone mostly to an entirely electronic music collection, meaning MP3's or such on hard drives & toss the CD's out the window.  I'm referring to mainstream of course - I still have some virgin vinyl in my collection, but never use it anymore.

Music purchases will be thru the web, downloaded like Itunes.  Satellite radio will feature limitless internet radio choices.  HD-digital radio will go the way of Betamax.  Our home stereo/TV and car stereo will be an extension of the home PC.  Head units will be modelled after this.  (don't get that one, sound quality ain't good).  You will be able to grab the 200gb HD from your headunit, snap it into the computer thru USB (or hell, wireless in your driveway), transfer all your new music in 30 secs & be done.

By 2015, having a CD hanging from your rearview will be the equivelent of fuzzy dice today.  Before all that, I think we'll go to DVD's from MP3-CD's, roughly 10x the size.  Just waiting on the DA converters to be taken seriously.

Just looking in the crystal ball.  I added tweeters to the dash b/c I like the sound there.  Had to play with the angle to get dispersion right, but it works well.

I just re-read this, think I'll make a new thread to stir the pot...

Wow!  Those are new and were not on the Sourceforge website as of our last heavy discussion on this topic.  It is encouraging that some car audio products are finally starting to support flac!  Eclipse?  Are you listening?  ;-)

On this topic, because I still do have a large mp3 collection that I'm slowly moving over to lossless, I have found, taking the advice mp3 nuts on other forums, that these two pieces of software can help make mp3 sound the best it can be.

1)  Shibatch mpg123 input decoder - supports 24-bit upsampling and output, nice if you have a 24-bit soundcard.  The 16-bit output is also regarded as cleaner than the default winamp decoder.

2)  ASIO output plug-in.  Allows the bypassing of the windows API and communication directly with the sound card.  This cleans things up some.  Check that you have an ASIO compatable soundcard before using this.

Boulderguy, you asked what Redbook Audio and Tweeter Lobing are.

Redbook Audio is just the standard retail cd format.

Tweeter Lobing:  (slightly more complex)

I've been searching for a nice graphical representation of tweeter lobing, and finally found one.  Look here:  http://www.kettering.edu/~drussell/Demos/BaffledPiston/BaffledPiston.html

Alright.  Speakers beam energy in lobes.  (A lobe is just some sort of rounded projection).  Scroll down on the linked page about 3/4 of the way down to the heading of "High Frequency."  You'll see that in contrast to low and medium frequencie radiators a high frequency radiator (your tweeter) produces multiple lobes.  Between these lobes are dead spots.  The main lobe is relatively narrow.  In the pictures on that page, you can see that it is optimal to locate the tweeter under 20 degrees off axis.  The dead spots are caused by cancellation.  The side lobes and main lobe have different phase relationships.  As you can see in this next link, here:

http://www.kettering.edu/~drussell/Demos/superposition/superposition.html

under the heading "Two sine waves travelling in the same direction: Constructive and Destructive Interference," "when two waves have opposite-phase [180 degree difference], they interfere destructively and cancel each other out." 

This cancelation can also happen near the crossover point if your tweeter and midrange driver are not as close as possible.  This happens because your midrange and tweeter are essentially playing the same frequencies with similar amplitude near your crossover point.  You have two radiating sources.  Their waves head out and are either constructive or destructive.  At and around the crossover point you want constructive interference - keeping the frequency response flat i.e. briding the gap between the drivers.  Constructive interference is easiest to obtain if the drivers are on-axis and close together. 

Haemphyst once had a nice plain-language explanation that went something like this.  Two speakers are two radiating sources - like two stones thrown into a pond.  If thrown some distance apart they create two distinct circular ripples.  When the ripple edges meet, assuming the stones were the same size, they cancel out.  However, if two stones are dropped very close together they seemingly create one circular ripple together.  This is similar to the additive or constructive effect we want near our crossover point between the midrange and tweeter. 

Haemphyst, Dyohn, others, let me know if I can add to any of this.