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Join Date: Mar 2006 Location: Faridabad
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taken from sounddomain.com
Component Install Guidelines: Imaging Simplistic-Part I
Since I pride myself on my objective judgment, I will give a thought on component speaker placement and tuning regarding power and db level attenuation.
You purchased/acquired (legally we hope) your component set to improve sound.
We hope you have purchased an outboard amplifier to go with your component set. Wattage on most decent sets (i.e. Focal, Diamond, CDT, Image Dynamics, Infinity, JL XR, Rainbow, Alpine...etc) are happy with 50-100 watts RMS. keep in mind this is all that is needed to get decent to good sound.
NOTE* 3-Way component sets require a bit more power. 75-125 watts to accomplish ref levels.
Sound Stage: Lets pay attention to mounting choice; no speaker should be AIMED at the listener. This creates directed audio channels, and ANY misalignment will destroy our goal- tonal and accurate sonic delivery. What you need to invision is this, imagine your entire front dash area is breming with sound and the flow of music is coming AT you and not specifically from the side. You want to be able to close your eyes, and have it almost impossible to tell where your tweeters and midranges are mounted. There are tricks to accomplish this. They are explained later. This invisible sound-stage should only need medium volume to be accomplished, and should not make you deaf. Remember, we want to be listeners for 50+ years.
OUR GOAL: We want a sound stage- to imitate a live performance of which we have FRONT ROW, Middle seat positioning; and all the musicians are placed where they should be- ON STAGE.
I am going to use that word, STAGE, a lot, so bear with me.
We have multiple ways to accomplish this. Please bare in mind, these are some techniques I’ve used and they work , and work well.
1. Create Kick-pods- This usually yields the most neutral sound on average, and allows a decent stage to be set.
Pros- The origin point of the sound from the speakers is nearly equidistant as possible to the listener measuring each speaker POD. Meaning, instead of the door/A-piller mounting of 12-16 inches from the listener (our drive in this Article), and the OTHER passenger door mounting 3.5 –4 feet, the pods close THAT ratio. By over half. This is an excellent choice if you have the time and money to get them done.
Cons This cost additional money and time. This also removes some floor space in your vehicle. Sacrifices have to be made on this one.
2. Door Mounting- This yields factory locations and sound is 1 step below properly created kick-pods.
Pros- The install is simple, the wires are already ran and you can usually do these yourself. Also, with current vehicles taking acoustics in mind lately, this is entirely a viable option for the NON-IASCA SQ+ competitor. Notice I said NON.
Cons The imaging will never be as accurate as kick-pods on average. That’s about it.
We now have our goals set. So here are some basics.
Step 1: decide on what you want to do.
-If we choose to use the doors, We can ALWAYS make kick-pods LATER. My sound advice -pun intended- , MEASURE the speakers and depths NOW before you put them in a door, so you have a ref point later.
If you are worried about door holes and air leaks, they seal up fine with rubbing alcohol wipes to clean the surface- and applying liquid-nail- or my personal favorite- Silicon Compound from a caulking gun/tube applicator.
-If we choose kick panels, seal the holes in your door with a small circle of MDF and silicone with 4 securing screws. This involves running new wire and possibly new floor mats to fit the kick-pods. But imaging achieved this way is usually excellent.
Step 2: Decide how much power you have to give, and at what Ohm load. I mention this, because some component sets are 3 Ohm DIN. This may or may not cause a problem to some amplifiers; most decent amps can handle 3 Ohm loads fine.Examples are Orion Comp., Focal, US Amps and others....
Step 3: Install the component set. This usually involves screw drivers, a drill -I use an 18v DeWalt Hammer Drill - This is obviously overkill -, you only need a 14.4v drill. Get driver bits, drill bits and a sleeve-sold at Sears, Lowes, Home Depot and Ace Hardware-these things will help prevent you from poking a hole in the surround of your MID-range while mounting it. For your own vehicle-check the intarweb for a forum, similar to this one for door removal instructions and wiring schematics. This is a valuable tool, and leave a thanks on the website for the author. Make sure to either use a MagnetPlate for your screws and whatnot, or a plastic bag. Lost screws cost time. The one thing we cannot get BACK.
Step 4:Make sure all amps have the Negative Ground disconnected before connecting any wires. CHECK your polarity. What I do is Select the Positive for ALL speakers to be connected first. Test with a basic multimeter. Then, connect all negative wires. This falls in line with connecting the Negative Lead on the amp last. To test the speakers polarity, connect +P to +P, and then -N to -N with a 9V battery from a regular department store. The cone should move out slowly, as 9V wont damage the speaker once or twice. This makes sure the wires are proper polarity. Or use a digital Multimeter . Once done. Connect all wires, SECURE the wires- I use regular ZIP ties and 3M Electrical Tape. Do not close off anything yet-don't rebuild door or amp racks just yet.
Testing- the fun part.
Rule # 1 for Testing. Choose the cleanest, most UNDISTORED CDs you can find. First choice should be Reference CDs or Classical Performances. Why? Because they most represent what we are trying to accomplish- Pure sound.
Turn off ALL BASS, TREBLE, TONAL and EQ settings.
These will hinder our goal right now.
Next, turn on Head Unit.
At this point we have a few choices, O-Scope, Test speaker or digital multimeter to test clipping. Use what you have. In the upper audio spectrum 1000 Hz+, distortion is much easier to hear and prevent.
Check for clipping- then turn it down until you CANNOT hear it at all.
Gains are set now. At this point, TAKE out your -3db reference CD. Do not use a 0db CD because it is more complicated and may fool you into thinking you have more headroom than you actually do.
Sit in your seat, with a remote, and turn volume to where you actually listen to music. No subs involved. See what you like. Make sure you have a Music Reference CD -remember, Classical, Live Jazz, something with Volcals as well-.
Play a good track, and to be honest, play something you don't normally listen to. Why? because you become less into the music, and more objectively biased to judge the sound, and not the artist. I don't listen to Brittney Spears, and neither should you; at least if you want to continue being called a male in the car audio world.
If this setting works- turn on the vehicle -make sure garage is vented if you do- and leave engine on. now listen again. If this works for you. you're done with the front side of things. If not, adjust with tonal settings.
Now, we need to check phase. Phasing is complicated, so I will try to decomplicate phasing.
It is essentially the planar origin of a wave. In our case, a sound wave. We want all phasing to be correct. Phasing corresponds to X-overs. you dont want 24db X-overs in the highs, because you then form a dip in your system, or Delta^change in your bandwidth. meaning, 20hz-200hz may sound normal, 201Hz to 5Khz may have a dip that seems like the volume is lower. My point- aim for 18db or 12db X-over. Set them accordingly. If you use the Head Unit X-Overs, adjust 90 degrees Phase for every 6db.
meaning, 18db on amp, 12db on Deck, now adjust phasing on deck to either 0 or 180 degrees. If you have 90 degree settings, use it. The reason? out of phase speakers leave a hollow sound in the car. This is bad. hollow is bad. We want warm and smooth.
-Moving on-
Earlier , I mentioned the use of a live CD for finer tuning, the reason? live instrument music -in tune that is- will test the TONAL, TRANSIENT and TIMBRAL reproductive ability of your components. ANYONE can use a MIDI system to generate sounds. BUT OUR component set is better than that remember?
We want ACCURATE. We can add bass, treble and everything else LATER.
Now, we are moving on to Audible Time Alignment. rule of thumb, for every 14 Inches, set time alignment back on the OPPOSITE channel .5 ms. Meaning, if your passenger side speaker is 48 inches from your head, set time alignment to 7.1 ms slower on the Drivers side. Test it, tweak it. Then leave it alone. alignment is math, there is no opinion, if it seems to arrive somewhat sooner on the left, adjust it. If your Head Unit does not have time alignment, you have two options, Turn balance down 1 click on the drivers side OR leave it alone and move on. I am not going to even try to explain psycho-acoustical volume theories. Think midget house, Michael Jordan. |
18th August 2006, 23:40
