How-To Guides
Everything you need to start installation well and make smart kit decisions — written for real beginners and improving installers.
Car Speaker Size Chart: Cutout, Depth and Bolt Pattern for Every Size
A 6.5 inch speaker needs a hole 5.5 to 5.75 inches across, has a flange about 6.6 inches wide and wants 2.0 to 3.2 inches of clear depth behind the baffle. Trade sizes are tooling names, not measurements, so the only three numbers that decide fitment are hole diameter, available depth and screw spacing. Measure those, then read the table.
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Speaker Wire Gauge by Run Length and Load: A 5% Power-Loss Chart
Hold total round-trip wire resistance under about 5% of the load impedance and you lose 0.22 dB, which is inaudible. For a 4 ohm load that means 16 AWG stops at roughly 26 ft, 14 AWG at 42 ft and 12 AWG at 66 ft. Double all three figures for an 8 ohm home run, and cut them by a third for copper-clad aluminium.
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2, 4 and 8 Ohm Speakers: What Your Amplifier Delivers Into Each Load
Nominal impedance is a label averaged off a curve that dips below 3 ohms near port tuning and climbs past 30 at resonance. Halving the nominal load roughly increases available power by 1.5 to 1.8 times, not 2, and every amplifier class has a floor below which it is simply not rated. Work out your final load from the wiring matrix before you connect anything.
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RMS, Peak and PMPO: Restating Advertised Watts at One Test Condition
Only the continuous rating is measured against a defined test; program is conventionally twice continuous, peak is four times, and PMPO has no standard at all and typically runs 10 to 15 times the real figure. Match an amplifier at 1.0 to 1.6 times the speaker's continuous rating, because a clipping small amplifier destroys more tweeters than a large clean one ever will.
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Sensitivity in dB: Turning 88 dB/W/m Into the Amplifier You Need
Sensitivity is quoted two incompatible ways: 1 W/1 m and 2.83 V/1 m. On a 4 ohm driver those differ by exactly 3 dB, and on a 2 ohm driver by 6 dB, which is the difference between needing a 90 W amp and a 360 W one. Normalise to 1 W/1 m first, then add 20 log of your listening distance to find the watts required.
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2.1, 5.1, 7.1 or Atmos: Sizing a Channel Layout to the Room
Channel count is a geometry constraint, not a ladder. 5.1 needs roughly 150 sq ft and two to four feet of clearance behind the seats; 7.1 only separates from 5.1 once there is five feet or more behind the listener, which usually means 250 sq ft. Below that, extra surrounds land inside the same arc and stop resolving as distinct sources.
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Car Speaker Faults, Diagnosed by Meter Reading Before You Pull a Door Card
Put a meter across the speaker terminals on the 200 ohm range before you order anything. A healthy nominal 4-ohm car driver reads 3.0 to 4.2 ohms and a healthy 8-ohm one reads 6.0 to 8.5; open circuit means a burnt voice coil or a broken conductor, and under 1 ohm means a shorted coil that will keep putting the amp into protect. The reading discriminates between faults. The symptom does not.
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Bookshelf vs Floorstanding: Where the Low End Stops and a Subwoofer Starts
The two formats differ by roughly one octave of low-frequency extension, 3 to 5 dB of sensitivity and about 40 litres of internal volume. A bookshelf needs a subwoofer once its -10 dB point sits above the lowest fundamental you actually play, which is around 40 Hz for most music and around 25 Hz for film. No floorstander removes the need for a sub in a film system, because the LFE channel is a separate feed calibrated 10 dB hot.
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Coaxial vs Component Car Speakers: What the External Crossover Buys, and When It Buys Nothing
Components buy you two things a coaxial cannot give you: a tweeter you can mount on-axis at ear height, and a real second-order crossover instead of one capacitor. Both only pay off if the tweeter can actually go on the pillar or sail panel and you have 50 watts RMS per channel behind it. On factory head unit power, or for rear fill, a coaxial is the correct answer and it saves four hours of labour.
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Surround Speaker Placement Angles and Heights, Layout by Layout
Front left and right go at 22 to 30 degrees off centre with the tweeter at seated ear height. 5.1 surrounds go at 100 to 120 degrees, 60 to 90 cm above ear level. 7.1 splits that into sides at 90 to 110 and rears at 135 to 150. Overheads for 5.1.2 sit at 45 degrees of elevation, 30 to 55 acceptable. Every one of those angles converts to a tape measurement with a tangent, so you can mark the wall before you drill.
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What Size PA Speaker Do You Need? Size It Backwards From Required SPL
Start at the furthest seat, not at the box. Decide the peak SPL that seat needs for your programme material, add back the distance loss of 20 log of the distance in metres, subtract the cabinet's sensitivity, and convert to watts. A 12-inch top rated 99 dB at 1W/1m, asked for 103 dB at a seat 15 m away, needs about 560 watts on its own or 280 into each of a pair. Driver diameter falls out at the end.
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Speaker IP Rating Chart: What Each Digit Is Tested To, and Where It Can Be Mounted
Each IP digit is a specific laboratory test with a nozzle diameter, a flow rate and a stopwatch. IPX4 is 10 litres a minute of splash from any direction for five minutes; IPX7 is thirty minutes under a metre of still water; IP65 is dust-tight plus a 6.3 mm jet at 12.5 litres a minute from three metres. None of those tests covers UV, corrosion, vibration or time, which are the four things that actually finish an exposed driver.
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