talnlnky, enlighten me about rear speakers.

[goku87]

Okay, okay, so we all know you think they are a waste of money. Personally I have a hard time understanding things because I'm just stupid, but I try to keep an open mind. I just want to know what makes you so adamantly against rear speakers.

Whenever I mess with the fade in both my Yaris and my Cavalier, I can hear very noticeable differences to the sound. I would like to hear your point of view.

[talnlnky]

At work right now (school), and only have a few minutes for now... I'll try to scratch up some links for further reading and make more comments later.

Ok, without even considering the cost disadvantages of rear speakers lets take a look at why they exist. Back in the day.... you know, just after the dawn of car stereo audio shops began getting hold of a cool little tool called a Real Time Analyzer (RTA)... RTA's could show what frequencies were being played, and at what volumes. Cool thing for audio because if you have any big dips, or spikes in your frequency response your music will sound wierd. Those shops also started to find out that by adding more speakers in different places you could usually minimize those peaks and dips... The OEM market usually falls behind the aftermarket scene by a few years, and thus we began seeing both front and rear speakers being installed. Today is pretty much standard in any vehicle you buy.

Now, the problem with RTA's is that they only show frequency response, they don't show you time delay(time alignment), phrase, or any of the half dozen or so aspects of the sound stage and imaging. By adding more speakers, you actually complicate any problems you have with your soundstage. When I say soundstage i'm talking about a virtually created stage where you can pinpoint where each vocal & instrument is coming from.
To test this, to get an idea of what i'm talking about. Put on a cd, preferable a live recording of a band, orchestra or whatever. Close your eyes, and imagine a stage in front of you. Now, where is the stage located? Is it at your left foot, dash height in front of you, in the center of the dash, or slightly above your head? This can be hard to figure out sometimes, and it is common for your stage to move around depending on what instruments are being played.
The goal is to be able to put in a well recorded live CD, and be able to hear the stage right in front of you, and to be able to pinpoint exactly where each instrument is at. And for them to be playing all on the same plane/level... sure they might be at the exact same spot left to right, but the same up and down.

So... thats a pretty basic idea of the SQ reasons why rears ruin things. But even eaiser to understand is the fact that the only reason that 4 speakers were ever installed was because of the RTA... it's not like Home Theater where they went to 4.1 & 5.1 systems over 2.1 because of cool positioning tricks... No... CD's are recorded in stereo, not quad channel so there is literally almost NO SQ benefits to having rear speakers UNLESS you have a DVD deck, and play DVD or DVD audio. However, even if you do have a DVD deck, the rears are only used about 5-10% of the time... so it's still fairly pointless.

Also... people think rear passengers can't hear the sound if they don't have rear speakers. That is a horrible misconception of physics. You are in an enclosed box which is pretty darn small. The air that is disturbed in the front due to a speaker will translate equally well in the back. Think about it. someone sits in your back seat and talks to you... can you hear them? OF COURSE YOU CAN... even if they talk quietly you can hear them... THERE IS NO INVISIBLE WALL behind the front seats.

Unless you pack your passengers in your trunk, they will have no problem hearing your music.

Lastly, any pair of speakers with a modest amp with a 50x2 rms rating will drive front speakers to be just as loud (if not louder) as four speakers running off of deck power.

In the end, all you gain is a few dB's of volume, but those few dB's aren't even really noticeable by human ears unless compared back to back, A/B style.

Bah, I got a lesson to finish prepping.

[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.

[Slick]

I have rear speakers... two big ones... I love them lol. I know, not useful. I like to stir shit :)

[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.

[jefferelli]

talnlnky - I had never thought of rear speakers that way, you made a great point. I am glad I read these posts.

Do you have a suggestion for someone who is happy for now with the stock deck (08 plays MP3's, not as much happy with it as I dont have much $$) I want to improve the sound and was thinking speakers. Should I just get a couple front ones. I was only looking to spend about 150 total if possible. Or is it a waste without an Amp?

Thanks-
(EDIT) Found my answer in another post from you. THX

[talnlnky]

Originally Posted by jefferelli

talnlnky - I had never thought of rear speakers that way, you made a great point. I am glad I read these posts.

Do you have a suggestion for someone who is happy for now with the stock deck (08 plays MP3's, not as much happy with it as I dont have much $$) I want to improve the sound and was thinking speakers. Should I just get a couple front ones. I was only looking to spend about 150 total if possible. Or is it a waste without an Amp?

Thanks-
(EDIT) Found my answer in another post from you. THX

no clue what i said in that other post... but here goes...

1: I'm a huge fan of doing install at once, get all your gear, then do the install once... that way you only pull apart the car once.. .not 3 times, not 23 times.
2: I'm a huge fan of ALWAYS matching speakers with amps.
3: Any decent aftermarket speaker should give you sq improvements, you will however will probably lose some bass output... and volume, but the quality of the sound should be much better (less distortion, less muddy) EVEN WITH A STOCK DECK/AFTERMARKET DECK.

[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.

[sqcomp]

sup,

What you just represented was .9 of a milisecond. 9 miliseconds is represented as .0009 of a second, which is what your calculation says;"x = 0.000882" is about 9 miliseconds. We're saying the same thing ultimately.

Taln,

Oh NOW you want to throw volume levels in there! :) I'm reading what you're saying. The deck power with the reference level we would be playing at would almost certainly distort.

It's funny, people like to think that a few chips on a board in a deck will outperform an outboard amplifier. I suppose to settle everything, I just use tuner/preamps. No worries about power issures there.

[supmet]

Originally Posted by sqcomp

9 miliseconds is represented as .0009 of a second

9 milliseconds = 0.009 seconds, not 0.0009

[sqcomp]

C'est la vie. I suppose I'm wrong. Oh well...put the rear speakers in your back deck.

It'll make YOUR car sound better.

[talnlnky]

Originally Posted by sqcomp

C'est la vie. I suppose I'm wrong. Oh well...put the rear speakers in your back deck.

It'll make YOUR car sound better.

even if your math was wrong... was your premise wrong too? is it 30cm that is audible like what you though and you were off on the math... or was your math wrong and also the premise? Is it actually 300cm?

I've listen to people swear up and down that they can hear a difference between the difference of speaker distances up front... Example... the left front speaker is about 3-4ft from your head, the right front is more like 5-6ft.

course... other variables are being talked about in that example as well.


regardless, running rear speakers will make it sound like you are in the center of the stage surrounded by the band, UNLESS you do some tweaking with crossover points, time alignment, and/or the fader control.


EDIT: On a side note... last night I threw in some 2pac and also Lil Scrappy cause I needed a fix of bass.... it's amazing how rap sounds good on distorted/muddy speakers. Rap is awesome in that regard.... it almost doesn't sound right if you play it on a really good sq system... lucky for me I'm running two 8's and stock fronts.

[sqcomp]

Indeed.

You mean I'm NOT the only one who thinks that rear fill pulls the soudstage back off the dash?

Oh! I found a very well recorded techno type track yesterday. What else besides system planning and equipment purchasing can I do out here? The track is called "Cardiac Arrest" it's the Sensifeel Remix. Some artist by the name of...wait for it...Ace Ventura. It's actually pretty sweet sounding. Less random than some of the Don Dorsey stuff, and tight enough to keep your mids/subs working like dogs. He's also got some nice high end effects in there too. You should check it out.

I too have specific tracks and artists for my rap fixes as well. That need doesn't come around too often anymore thank the lord!

[goku87]

I get what you're saying about the sound stage, and I think that's where my opinion differs from what appears to be most people. I don't want the sound to seem like it's coming from in front of me. I want it to be like it's all around, similar to the effect of headphones. It seems like the music is in your head, you know?

Awesome information though, thanks for the input! :D

[sqcomp]

And you know...it's all about what the owner wants to hear.

I think Goku is feeling the 5.1 wave.

[talnlnky]

cool, if you want that fully engulfed feeling, then You should go for the 4 speaker setup. I will admit, at one time I was all about that same sound/feeling.

[goku87]

Originally Posted by sqcomp

And you know...it's all about what the owner wants to hear.

I think Goku is feeling the 5.1 wave.

4.1 lol

Originally Posted by talnlnky

cool, if you want that fully engulfed feeling, then You should go for the 4 speaker setup. I will admit, at one time I was all about that same sound/feeling.

Hmmm... so one day I may grow out of it?

[talnlnky]

Originally Posted by goku87

4.1 lol



Hmmm... so one day I may grow out of it?

it's always a possibility... for me... it wasn't until 1) I went two weeks not using rear speakers, and 2) I got to listen to some well built SQ installs.