talnlnky, enlighten me about rear speakers.

[sqcomp]

I'd like to add a few considerations to what Taln is saying.

There are key phrases to think about when utilizing speakers in a rear deck. The first one that comes to mind is off-axis response of said rear speakers. When a speaker is placed in a rear deck placement we hear the direct and reflected sounds like resonances and reverberations. The two sounds are processed by the brain as one sound, and this changes the perception of height, width, and depth of soundstage, as well as rearward ambience. For this reason, the off-axis radiation pattern of any speaker in a car environment has a significant influence on how natural the music sounds.

Another phrase to think about is path length differences when placing speakers in the rear deck. Good stereo imaging is reliant on the arrival times of the fundamental vocal frequencies (midrange). Differences as little as 10 microseconds can be detected by the brain. A PLD of 30 centimeters equates to the sound from the nearest channel arriving about 9 milliseconds earlier than the furthest channel. What happens in real life? You get pulled ONTO the soundstage instead of the soundstage being in front of you.

There are other considerations that I've read into that most of us have experienced but could never quantify. Head-related transfer function (HRTF), interaural intensity differences (IID), and interaural time delay (ITD) all play a key role in the optimum placement location for speakers. If you want I can regurgitate what I've read and committed to learning.

There's also the idea of point source referencing. That gets into specific frequency bands that are already screwed up by using rear speakers, so there's no point in talking about that here...yet.

To add an important point to what Taln was saying...

What is your reference?

Do you REALLY know what a specific instrument is supposed to sound like in a given situation? Probably not. How does one truly know how the music is supposed to sound? Have you ever heard an orchestra live, an acapella group live, how about a popular band live? Heck, my last live experience was Mark Chesnutt about 50 feet in front of me. The reference there was certainly NOT behind me! The reference I have before that is Trace Adkins a few months ago. Again, NO rear reference save for the sound reflections behind me. (Side note: I'm not really a country fan either, but this helps my reference for critical listening)

I'd say that one needs to know what they're listening to before one assumes that they know what it sounds like.

Oh, another bolstering to what Taln mentioned, I can GUARANTEE that a 50 x 2 amplifier that is installed, setup, and level matched correctly on two front speakers will sound better than any deck that pushes four speakers.

[talnlnky]

Originally Posted by sqcomp

There's also the idea of point source referencing. That gets into specific frequency bands that are already screwed up by using rear speakers, so there's no point in talking about that here...yet.

I've actually thought multiple times about throwing midbass drivers into the rear speaker locations on the 3dr Hatch of mine.... The only way I could ever justify doing that is that they are MIDBASS drivers and won't be playing above 250hz... but even then... thats still going to push me up onto that sound stage a bit despite being midbass tones which generally are very hard to pinpoint the locations.

Originally Posted by sqcomp

What is your reference?

Do you REALLY know what a specific instrument is supposed to sound like in a given situation? Probably not. How does one truly know how the music is supposed to sound? Have you ever heard an orchestra live, an acapella group live, how about a popular band live? Heck, my last live experience was Mark Chesnutt about 50 feet in front of me. The reference there was certainly NOT behind me! The reference I have before that is Trace Adkins a few months ago. Again, NO rear reference save for the sound reflections behind me. (Side note: I'm not really a country fan either, but this helps my reference for critical listening)

I'd say that one needs to know what they're listening to before one assumes that they know what it sounds like.

Yeah, I wasn't going to say that... but its entirely true... a lot of what most people hear these days is just studio created beats for a pop or hiphop album... thats cool, i'm not bashing that, it just makes it really hard to know what the music is supposed to sound like compared to going to a Carlos Santana concert, and then listening to a live recording of that same concert.

Originally Posted by sqcomp

Oh, another bolstering to what Taln mentioned, I can GUARANTEE that a 50 x 2 amplifier that is installed, setup, and level matched correctly on two front speakers will sound better than any deck that pushes four speakers.

See... I wouldn't take it that far, in fact, i'd even want to take on that bet...if I was a millionaire and had nothing to fill my time. The deck running 4 speakers, even if set up completely correctly, would be quieter, because of the low volumes you'd have to play it at to ensure there wasn't distortion and clipping issues. Also... I'd have to use a passive crossover to filter out most of the frequencies being played from the rears anyways... so it'd be darn near pointless to run rears anyways.


one of the saddest things about decks these days is the complete lack of a Highpass/lowpass/all pass crossover setting on both the front and rear channels. I had a kenwood back in 01 that had those settings, granted it was a $800 deck, but still... technology has come so far. Every deck that costs MSRP of $150 or more should have those options, and really... its the cheap decks that need them the most. The people that would gain the most from them are the people who don't run external amps... They are the ones that need a 12dB/octave or greater highpass at 80 or 100hz or 120hz.

[supmet]

Originally Posted by sqcomp

A PLD of 30 centimeters equates to the sound from the nearest channel arriving about 9 milliseconds earlier than the furthest channel.

--Speed of sound at STP is 340 m/s

--340 m/s is 34,000 cm/s

34,000cm/s = 30 cm/Xs

--cross multiplying gives you

34000cm (times) Xs = 30cm (times) s

--s and cm cancel out

34000 (times) X = 30

x = 30/34000

x = 0.000882

which is about 0.9 milliseconds, not 9



correct me if I'm wrong but I checked it a couple times


edit: I'm not arguing with the general premise. Find me a recording studio with 4 speakers, 2 of which sit behind the engineer. I'm just a math/physics nerd.