Car Audio Explained, Part 14: Car Audio Myths He Debunks (1 of 2) (Andy Wehmeyer's Lessons)

4 days ago

27 min read

This is Part 14 of 19 in the series Andy Wehmeyer on Car Audio, Explained for Beginners. Start here · Download the full guide as a PDF

Unofficial guide. Andy Wehmeyer's points are paraphrased from his public forum posts, blog, tuning guides, videos and podcasts, with a link to each source; the plain-English explanations were written for this guide. Not written, reviewed or endorsed by Andy Wehmeyer or Audiofrog.

5. Myths, judging gear, buying and the industry

This section gathers what Andy Wehmeyer says about car-audio folklore, how to judge gear and the claims made for it, how to plan and buy a system and pick a shop, how the business and SQ competitions work, and how we listen to recordings. Points are merged from his DIYMobileAudio (DIYMA) posts (2008–2022), the Audiofrog Tech Blog, podcasts, livestreams and press; installation, tuning and bass detail lives in sections 2–4 and appears here only as short myth entries. Jargon used throughout: DSP = digital signal processor; LR4 = 24 dB/octave Linkwitz-Riley crossover; all-pass filter (APF) = a filter that shifts phase without changing level; Fs = a driver's free-air resonance; "B1"/"B2" = the Absolute Electronix (2023) and CMA Connected (2021) livestreams.

What this section is about: This is the myth-busting and real-world part of the guide. It collects things many car-audio fans believe that Andy Wehmeyer says are wrong or overstated, plus his advice on judging gear and the claims made for it, planning and buying a system, choosing a shop, the business side, sound-quality (SQ) competitions and listening to recordings. The jargon list at the end of the paragraph is a mini-dictionary. A DSP is a small computer that adjusts the sound. A crossover splits the music into bass, middle and treble so each speaker gets the part it plays best. Phase is the timing of a sound wave's ups and downs. Fs is the note a speaker naturally wants to vibrate at when it hangs in open air. B1 and B2 are just short names for two livestreams he appeared on.

5.1 Myths Andy debunks (Myth → What Andy says)

What this part is about: Each item names a popular car-audio belief (the "myth") and then, after the arrow, gives Andy's answer. The items are grouped by topic, such as digital audio, cables and power, amplifiers, and speakers. Items #1 to #38 come first; #39 to #76 follow.

Digital audio, files and sources

5.1 #1 · Myth: hi-res files beat CD → They add data, not audible information.

44.1 kHz captures everything to about 22 kHz; there are no "stair steps", because after the anti-alias filter only one wave fits the samples, and upsampling adds nothing (his image: 8 oz of juice poured into a 16 oz glass). A hi-res release is often just a better master; he hears no benefit above CD and demos 320 kbps MP3s burned to CD. [RARE] Sources: Audiofrog blog Dec 2020 · DIYMA 2021-08-10 · DIYMA 2021-08-10b

In plain English: Many people believe "hi-res" music files, which store more samples per second and more bits per sample, sound better than a CD. A CD stores sound as 44,100 snapshots (samples) per second, written 44.1 kHz. He says that captures everything up to about 22 kHz, which is above the roughly 20 kHz top of human hearing. People often picture digital audio as a jagged staircase. He says there are no stair steps: after the anti-alias filter (a filter that removes anything too high-pitched for the sample rate), only one smooth wave can pass through all the samples, so that wave is what comes back out. Upsampling, meaning converting a file to a higher sample rate, adds nothing new. His image: pour 8 oz of juice into a 16 oz glass and you still have only 8 oz of juice. When a hi-res release does sound better, it is often just a better master (a better-prepared final version of the recording). He hears no benefit above CD quality, and for his demos he plays 320 kbps MP3s burned to CD.

5.1 #2 · Myth: a DSP with more bits or a higher sample rate sounds better → Pick a DSP for its tools.

16 bits already gives about 96 dB signal-to-noise ("like no noise"), and he endorsed 48 kHz/16-bit as enough. What matters is input ranges that match your source, LR4 slopes, fine delay steps and a parametric EQ you can actually use. [RARE] Sources: Audiofrog blog Dec 2020 · DIYMA 2016-05-23 · DIYMA 2021-08-09

In plain English: Many people shop for a DSP by its numbers: more bits, or a higher sample rate. Bit depth sets how far the music sits above the background noise of the digital system. He says 16 bits already gives about 96 dB between the loudest signal and that noise, which he describes as "like no noise", and he endorsed 48 kHz/16-bit as enough. So he says to pick a DSP for its tools instead: input ranges that match the voltage your source puts out, LR4 crossover slopes, fine steps in the delay setting, and a parametric EQ you can actually use. A parametric EQ lets you choose the exact frequency, width and amount of each boost or cut.

5.1 #3 · Myth: MP3 and Bluetooth wreck sound quality → 256k is hard to tell from CD; 320k he can't tell at all.

Perceptual coding drops sounds that louder sounds mask, and data compression doesn't change dynamic range. Bluetooth realistically carries about 320 kbps, so there is no CD-quality Bluetooth; ask whether your experience is diminished, not whether a difference is detectable. [RARE] Sources: DIYMA 2013-01-19 · SQOLOGY Pt 1 @27:05 · DIYMA 2021-08-09

In plain English: Many people believe compressed formats like MP3, and Bluetooth, wreck sound quality. MP3 uses perceptual coding: it drops sounds you could not hear anyway, because a louder sound at nearly the same time and pitch masks (covers) them. Bitrate, in kbps (thousands of bits per second), is how much data is kept. He says 256 kbps is hard to tell from a CD, and he can't tell 320 kbps from a CD at all. Data compression (making the file smaller) is also not the same thing as squashing loud and soft parts together, so it doesn't change dynamic range. Bluetooth realistically carries about 320 kbps, so he says there is no CD-quality Bluetooth. His advice is to ask whether your listening experience is actually diminished, not whether a difference can be detected at all.

5.1 #4 · Myth: the file or stream is the weak link → The playback system and its EQ matter far more.

Bad EQ degrades music more than any format conversion; FLAC into a poor speaker "won't fix that", and most bad systems fail on basics (distortion, missing bandwidth, rough response). [RARE] Sources: DIYMA 2014-07-11 · SQOLOGY Pt 1 @39:06

In plain English: Many people believe the music file or streaming service is the weak link, so they hunt for the best format. He says the playback system and its EQ matter far more. Bad EQ (equaliser settings that boost or cut the wrong frequencies) degrades music more than any format conversion does. Playing FLAC, a lossless full-quality format, through a poor speaker "won't fix that". He says most bad systems fail on basics: distortion, missing bandwidth (part of the range from deep bass to high treble isn't reproduced), and a rough frequency response (some notes much louder or quieter than others).

5.1 #5 · Myth: vinyl (or the hi-res version) sounds better → Not by any objective measure; you're usually hearing a different mix.

Vinyl and hi-res releases often get a different master with less compression, so compare formats only from the same source (rip the same record to each). Mono bass was a vinyl limit (keeping the needle in the groove), not a rule. [RARE] Sources: DIYMA 2021-08-10 · DIYMA 2021-08-20

In plain English: Many people believe vinyl records, or the hi-res version of an album, sound better than a CD or a normal file. He says not by any objective measure: you are usually hearing a different mix. Vinyl and hi-res releases are often given a different master (the final prepared version of the recording) with less compression, meaning loud and soft parts are squeezed together less. So he says to compare formats only from the same source, for example by ripping (recording) the same record into each format. He adds that keeping bass in mono (the same in both channels) was a limit of vinyl, needed to keep the needle in the groove, not a rule of good sound.

5.1 #6 · Myth: every extra A/D–D/A conversion or digital volume control ruins the sound → "Wildly overblown".

His own car converted 3–4 times with digital volume first, and no listener heard a problem; digital volume loses resolution only in extreme cases (1000 W channels played very quietly). [RARE] Sources: DIYMA 2012-04-13 · DIYMA 2013-10-08

In plain English: An A/D conversion turns sound into numbers, and a D/A conversion turns the numbers back into sound. Many people believe each extra conversion, or a volume control that works digitally, ruins the sound. He calls this "wildly overblown". His own car converted the signal 3 to 4 times, with digital volume control first in the chain, and no listener heard a problem. He says digital volume loses resolution (fine detail) only in extreme cases, such as 1000 W channels played very quietly.

5.1 #7 · Myth: content above 20 kHz matters → Its audibility is "highly disputed" and he has never heard it.

Tweeters extend to 40 kHz only to push breakup peaks out of the audible band, so a "40 kHz" spec is marketing. [RARE] Sources: DIYMA 2016-01-16 · DIYMA 2015-04-12

In plain English: Human hearing is usually said to top out around 20 kHz (20,000 vibrations per second). Many people believe music content above that matters. He says its audibility is "highly disputed" and that he has never heard it. Some tweeters (small speakers for high notes) are specified up to 40 kHz. He explains they reach that high only so their breakup peaks land above the range we can hear. Breakup is when a tweeter's dome stops moving as one solid piece, which creates sharp peaks in its output. So, in his view, a "40 kHz" spec is marketing.

5.1 #8 · Myth: an "all-digital" signal path is best → It wastes amplifier power.

Nothing digital exceeds 0 dBFS, yet cars need 6–12 dB more bass than the rest of the range, so never-clipped multi-kilowatt digital systems sound like 300 W ones. A simple analog chain with balanced outputs and differential inputs is fine. [RARE] Source: DIYMA 2017-07-05

In plain English: An "all-digital" path keeps the music as numbers from the source all the way to the amplifiers. Many people believe this is the best way. He says it wastes amplifier power. Nothing digital can go above 0 dBFS, the maximum digital level. Yet cars need 6 to 12 dB more bass than the rest of the range to sound natural. In a digital stream, he explains, you get that extra bass only by turning everything else down (or by giving the subs vastly more power than everything else), so in normal listening the amps deliver far less power than their ratings. The result, he says, is that multi-kilowatt digital systems that are never clipped end up sounding like 300 W systems. He says a simple analog chain is fine, as long as every part has balanced outputs and differential inputs (connections designed to cancel noise picked up along the cable).

Cables, wiring, power and noise

5.1 #9 · Myth: expensive or heavy cables improve sound → "You've been had".

Directional and multi-shield cables are snake oil or band-aids for bad circuits; heavy-gauge RCAs do nothing because amp input impedance makes them unnecessary; of pure-silver power wire he said he needn't eat a foxglove salad to know it's poison. [RARE] Sources: DIYMA 2009-10-03 · DIYMA 2021-07-10 · DIYMA 2021-01-13

In plain English: Many people believe expensive or heavy cables improve sound. He says "You've been had". Directional cables (claimed to sound better one way round) and cables with many layers of shielding are, in his view, snake oil (fake cures) or band-aids for badly designed circuits. Heavy-gauge (thick) RCA signal cables do nothing, because the amp's input impedance makes them unnecessary. An amp's input draws almost no current, so a thin wire carries the signal just as well. Asked about pure-silver power wire, he said he needn't eat a foxglove salad to know it's poison. Foxglove is a poisonous plant; his point is that he does not need to try the product to know the claim is wrong.

5.1 #10 · Myth: heavily shielded RCAs are always quietest → Match the cable to the input.

Differential inputs want twisted pair, single-ended inputs want coax; test with an ohmmeter from RCA shield to amp ground (near 0 Ω = single-ended; hundreds of ohms or more = differential). Differential head-unit outputs reject noise just by twisting the wires. [RARE] Sources: CMA 2022 @50:01 · DIYMA 2021-11-26 · DIYMA 2021-09-25

In plain English: RCA cables carry the music signal from the radio or DSP to the amplifier. Many people believe the most heavily shielded RCA is always the quietest. He says to match the cable to the input instead. A differential input listens to the difference between two wires, so noise that lands on both wires equally cancels out; it wants twisted pair (two wires twisted together). A single-ended input measures the signal against ground; it wants coax (one wire inside a surrounding shield). His test: put an ohmmeter (a resistance meter) between the RCA's outer shield and the amp's ground. Near 0 ohms means single-ended; hundreds of ohms or more means differential. If a head unit (the radio) has differential outputs, he says simply twisting the wires together rejects noise.

5.1 #11 · Myth: speaker-level outputs are dirtier than RCA pre-outs → They are balanced and can be "far superior".

They offer ground isolation and higher voltage; use them when a head unit lacks balanced RCAs (he finds it silly that aftermarket radios lack them). Sources: DIYMA 2013-01-15 · DIYMA 2021-09-24

In plain English: A factory radio often has only speaker-level outputs, the wires that normally drive the speakers. Aftermarket radios add RCA pre-outs, low-voltage outputs meant for amplifiers. Many people believe speaker-level outputs are the dirtier signal. He says they are balanced (neither signal wire is tied to ground) and can be "far superior". They offer ground isolation, which avoids noise caused by ground differences between devices, and a higher voltage, meaning a stronger signal. He says to use them when a head unit lacks balanced RCA outputs, and he finds it silly that aftermarket radios lack them.

5.1 #12 · Myth: noise is fixed by re-routing, star grounds, 0-gauge cable or the "Big 3" → Differential inputs ended that era.

Ground loops now usually come from mismatched input-preamp grounds, which is what a DSP's input-ground jumper is for; otherwise remove the offending device or add an isolator. Today PWM modules all over the car radiate noise, so cable type matters more than routing. [RARE] Sources: DIYMA 2008-12-21 · DIYMA 2021-09-24 · DIYMA 2021-11-03

In plain English: Many installers fight noise by re-routing cables, building a "star ground" (all grounds taken to one point), using huge 0-gauge cable, or doing the "Big 3" (upgrading the car's three main charging and ground wires). He says differential inputs ended that era. Today a ground loop (a noise caused by two grounds sitting at slightly different voltages) usually comes from a mismatch between one device's input ground and another's preamp ground. That is what the input-ground jumper on a DSP is for. Otherwise, he says, remove the device causing it or add an isolator. He adds that modern cars have PWM modules all over (electronics that switch power on and off very fast, for things like motors and lights), and these radiate noise, so the type of cable now matters more than how it is routed.

5.1 #13 · Myth: hiss means a ground loop → Ground loops whine; hiss comes from gain structure, EQ boost or the amp.

Amps with built-in DSP hiss more because their preamp scales every input down to an ADC limit of about 1–1.4 V; unplug the inputs to test. Auto-EQ boosting treble on a rolled-off factory source also makes hiss, so don't tear the install apart. [RARE] Sources: DIYMA 2015-09-16 · DIYMA 2021-10-14 · DIYMA 2021-08-08

In plain English: Many people hear hiss (a steady "shhh") and assume a ground loop. He says ground loops whine, while hiss comes from gain structure (how the level is set at each stage of the system), from EQ boost, or from the amp itself. Amps with a built-in DSP hiss more, because their preamp must scale every input down to the limit of their ADC (the chip that turns sound into numbers), about 1 to 1.4 V. To test, unplug the amp's inputs: if hiss remains and falls when you turn the amp's gain down, the amp itself is the source. Auto-EQ that boosts the treble of a factory source whose treble is already rolled off (turned down) also makes hiss. So in practice: don't tear the install apart hunting for a ground problem.

5.1 #14 · Myth: line drivers and high-voltage pre-outs improve sound → "Possibly the biggest waste of money ever invented".

30 V into an amp built for 4 V just clips its preamp; with a digital source start gains near 2 V. Exception: high voltage can beat radiated noise in very long runs. Sources: DIYMA 2010-11-26 · DIYMA 2015-06-20

In plain English: A line driver is a box that raises the signal voltage before it reaches the amplifier, and some radios advertise high-voltage pre-outs. Many people believe a higher voltage improves sound. He calls line drivers "possibly the biggest waste of money ever invented". Sending 30 V into an amp built for 4 V just clips (overloads) the amp's preamp. With a digital source, he says to start the gain settings near 2 V. His one exception: in very long cable runs, a high voltage can beat radiated noise (interference picked up from nearby electronics).

5.1 #15 · Myth: cable, capacitors and charging upgrades must match the amp's fuse rating → Music draws a small fraction of that.

Average music power is about 1/32 of peak (400 W peak ≈ 12.5 W average), mostly bass. A 2-farad cap isn't needed for 1,000 W (remove it if it blocks charging), and a 1-farad cap to limit sub bass costs as much as a DSP. [RARE] Sources: DIYMA 2021-12-22 · DIYMA 2021-08-02 · DIYMA 2021-08-19

In plain English: An amplifier's fuse is sized for its worst-case current draw. Many people believe the power cable, capacitors and charging upgrades must match that fuse rating. He says music draws only a small fraction of it. Average music power is about 1/32 of peak power, so an amp making 400 W peaks averages about 12.5 W, and most of that goes to the bass. A capacitor is a part that stores electrical charge and releases it quickly. He says a 2-farad capacitor isn't needed for a 1,000 W system, and if one is stopping you from charging the battery, remove it. And a 1-farad capacitor used as a filter to limit the bass going to a sub costs as much as a DSP.

5.1 #16 · Myth: solder is the best connection → Crimp wire to terminal; solder only terminal to board.

Spade lugs held old appliances together for 40 years; solder near the battery invites corrosion; heat on Audiofrog GS terminals can melt the plastic basket's internal joints. Tinned wire under a set screw cuts contact area, and "cinch terminals are not crimpers". [RARE] Sources: DIYMA 2021-07-21 · DIYMA 2021-11-26 · Audiofrog blog Dec 2020

In plain English: Many people believe soldering (joining metal with melted alloy) always makes the best connection. He says to crimp wire to a terminal (squeeze a metal connector onto it with the right tool), and to use solder only where a terminal joins a circuit board. Spade lugs, the push-on flat connectors, held old appliances together for 40 years. Solder near the battery invites corrosion. On Audiofrog GS speakers, heat on the terminals can melt the joints inside the plastic basket (the speaker's frame). Tinning wire (coating the strands with solder) before clamping it under a set screw cuts the contact area. And "cinch terminals are not crimpers": with this he rejects the shortcut of letting a screw terminal squeeze a ferrule (a metal sleeve on the wire end) instead of crimping it properly.

5.1 #17 · Myth: copper-clad aluminium is always inferior → Bad for power cable, good in voice coils

(precise resistance; Audiofrog's flat CCA coils shed heat from both sides). Sources: DIYMA 2015-06-16 · CMA 2021 @19:00

In plain English: Copper-clad aluminium (CCA) is aluminium wire with a thin copper coating. Many people believe it is always worse than pure copper. He says it is bad for power cable but good in voice coils, the coil of wire that drives a speaker's cone. There it gives a precise resistance, and Audiofrog's flat CCA coils shed heat from both sides.

5.1 #18 · Myth: "true 4-ohm" speakers matter, and amps "see" impedance → Nominal impedance is a label for choosing an amp; amps only know current.

Audiofrog's GS "4 Ω" coils measure 2.3–2.8 Ω to suit factory and 2 Ω-rated amps; below rated impedance an amp is fine until its current limit, and modern amps then lower rail voltage rather than shut off. [RARE] Sources: DIYMA 2015-11-07 · CMA 2021 @33:05 · DIYMA 2022-02-14

In plain English: Impedance, measured in ohms, is roughly how much a speaker resists the current an amp sends it, and it changes with pitch. Many people believe speakers must be "true 4-ohm" and that amps "see" impedance. He says the nominal (labelled) impedance is only a label for choosing an amp; an amp only knows how much current it is delivering. Audiofrog's GS "4 Ω" speakers actually measure 2.3 to 2.8 Ω (ohms) so they suit factory radios and amps rated for 2 Ω. Below its rated impedance an amp is fine until it reaches its current limit, and modern amps then lower their rail voltage (internal supply voltage) rather than shut off.

Amplifiers and power

5.1 #19 · Myth: high damping factor gives "superior cone control" → Anything above about 10 is enough.

The voice coil's resistance sits in series with the amp's output impedance and dominates (DF 1000 moves Qts from 0.707 to 0.708); the story was invented to sell transistors over tubes, and makers quote it from habit. His view never changed, 2008–2021. [RARE] Sources: Audiofrog blog Dec 2020 · DIYMA 2008-11-28 · DIYMA 2021-05-08

In plain English: Damping factor (DF) is an amp spec: the speaker's impedance divided by the amp's own output impedance. Many people believe a high DF gives "superior cone control". He says anything above about 10 is enough. The speaker's voice coil has its own resistance, which sits in series with the amp's output impedance and dominates it. So even a DF of 1000 only moves Qts (a number describing how well a speaker's resonance is held in check) from 0.707 to 0.708. He says the story was invented to sell transistor amps over tube amps, and makers still quote DF out of habit. His view never changed from 2008 to 2021.

5.1 #20 · Myth: slew rate is a separate quality spec → It already shows up in the power-bandwidth (THD) rating.

An amp that can't swing full voltage at high frequencies shows treble distortion or must be rated only up to that frequency; swing at 30 kHz is irrelevant. [RARE] Sources: DIYMA 2017-07-07 · DIYMA 2017-07-05

In plain English: Slew rate is how fast an amp's output voltage can change. Many people treat it as a separate quality spec. He says it already shows up in the power-bandwidth rating, which states the power and THD (total harmonic distortion) across the audio range. If an amp can't swing its full voltage at high frequencies, that shows up as treble distortion, or the amp has to be rated only up to the frequency it can reach. Whether it can swing full voltage at 30 kHz, above human hearing, is irrelevant.

5.1 #21 · Myth: class D for bass, class AB for highs → "Backwards"; there are good amps and bad amps.

In randomized blind demos at CES 1996 almost nobody told a full-range class-D amp from a Krell, and the audible difference was in long bass notes. AB and D really differ only when clipped; judge a design, not the class (like condemning marinara after tasting one jar). [RARE] [Conflict: three listeners after 700–800 demos (2022) vs four after about 1,500 (2023).] Sources: CMA 2022 @29:01 · CMA 2023 @25:04 · DIYMA 2022-03-26

In plain English: Class AB and class D are two ways of building an amplifier; class D switches its output on and off very fast and wastes less energy as heat. Many people believe class D is for bass and class AB is for highs. He calls that "backwards": there are good amps and bad amps. At CES 1996 he ran randomized blind demos, where listeners didn't know which amp was playing, and almost nobody could tell a full-range class-D amp from a Krell (a high-end home amplifier). The audible difference was in long bass notes, which he credits to the Krell's huge storage capacitors, not to class D itself. He says AB and D really differ only when clipped (driven past their limit). So judge a design, not a class: condemning class D after one bad amp is like condemning marinara sauce after tasting one jar. The Conflict tag notes that his retellings differ: three listeners after 700 to 800 demos (2022) versus four after about 1,500 (2023).

5.1 #22 · Myth: you can audition "amp sound", and pricier amps are more "dynamic" → You only hear an amp through a speaker.

Unless the same difference appears on many speakers, it's a system difference (output impedance and class-D filters interact with the load). Judges called his car on 18 W chip amps "so dynamic"; he doesn't know what that means. Sources: CMA 2023 @19:05 · DIYMA 2013-01-05

In plain English: Many people believe you can audition an amp's own "sound", and that pricier amps are more "dynamic". He says you only ever hear an amp through a speaker. Unless the same difference shows up on many different speakers, what you heard is a difference in the whole system, because the amp's output impedance and a class-D amp's output filter interact with the speaker's load. Judges once called his car, running on 18 W chip amps (small amplifiers built on a single chip), "so dynamic", and he says he doesn't know what that means.

5.1 #23 · Myth: amps "so good they need no feedback" → Like soles so thick you don't need shoes;

feedback lowers noise, especially in the treble. Source: CMA 2022 @39:05

In plain English: Feedback in an amplifier means sending part of the output back to the input so the amp can correct its own errors. Some makers claim their amps are so good they need no feedback. He compares that claim to shoe soles so thick you don't need shoes. He says feedback lowers noise, especially in the treble.

5.1 #24 · Myth: separate left/right amps (or better channel-separation specs) improve imaging → Car acoustics dwarf it.

At 60 dB separation 1 W leaks a millionth of a watt, while each ear hears the opposite speaker at maybe −6 dB; "a car wash is more likely" to help. [RARE] Sources: DIYMA 2021-11-05 · DIYMA 2022-03-26

In plain English: Channel separation is how little of the left channel leaks into the right one inside the electronics, and the reverse. Imaging means hearing each voice and instrument coming from a clear spot. Many people believe separate amps for left and right, or better separation specs, improve imaging. He says the car's acoustics dwarf it. At 60 dB separation, 1 W in one channel leaks only a millionth of a watt into the other. Meanwhile, in a car each ear already hears the opposite side's speaker at maybe 6 dB quieter. In his words, "a car wash is more likely" to help.

5.1 #25 · Myth: bridging causes phase shifts and each channel "sees half the load" → Neither.

Bridging doubles voltage, so power rises 4×; "half the load" only means each side's current limit is unchanged. [RARE] Sources: DIYMA 2021-09-15 · DIYMA 2021-09-15b

In plain English: Bridging joins two amp channels to drive one speaker: one channel pushes while the other pulls. Many people believe this causes phase shifts and that each channel "sees half the load". He says neither is true. Bridging doubles the voltage across the speaker, and power rises with the square of voltage, so power goes up 4 times. He explains that "half the load" is just a way of saying each side's current limit is unchanged: each channel can still deliver only the same maximum current as before.

5.1 #26 · Myth: too little power blows speakers → "You cannot blow a speaker with too little power."

Clipping pushes a wave toward a square, whose average power is twice a sine's, so a clipped 100 W amp delivers about 200 W, all the extra at high frequencies. Class-D sub amps' output filters spare the sub, but a clipped radio or DSP sends that energy to the tweeters; he calls this the costliest misconception. [RARE] Sources: OFCAP 19 @20:07 · DIYMA 2021-07-01 · DIYMA 2021-07-08

In plain English: Many people believe an underpowered amp blows speakers. He says "You cannot blow a speaker with too little power." The danger is clipping: an amp pushed past its limit flattens the tops of the wave, turning it toward a square wave. A square wave carries twice the average power of a sine (smooth) wave of the same height, so a clipped 100 W amp delivers about 200 W, and all the extra is at high frequencies. Class-D subwoofer amps have output filters that spare the sub. But a clipped radio or DSP passes that energy on to the tweeters. He calls this the costliest misconception.

5.1 #27 · Myth: buy an amp with 2–3× the speaker's rating "for headroom" → Only safe if the gains can never clip it; "3× RMS" is nonsense.

Setting treble gains with a −10 dB tone tells a 300 W amp to try for 3,000 W. The volume control, used with care ("carefully monitored", as pro audio says), is the real protection, and a warranty covers defects, not damage. [RARE] [Conflict: in 2015 he called −10 dB/multitone gain setting (JBL's EZ gain) legitimate; the later warning targets maxing treble gains with such tracks.] Sources: OFCAP 19 @27:00 · DIYMA 2021-09-20 · DIYMA 2021-07-10

In plain English: Many people buy an amp with 2 to 3 times the speaker's rating "for headroom" (spare power). He says that is safe only if the gains are set so the amp can never be clipped, and "3× RMS" is nonsense. His example: setting the treble gains with a test tone recorded at −10 dB tells a 300 W amp to try for 3,000 W, because full-level music is 10 dB louder than the tone, and 10 dB more means ten times the power. The real protection is the volume control, used with care ("carefully monitored", as pro audio says). And a warranty covers defects, not damage. The Conflict tag notes that in 2015 he called gain setting with −10 dB or multitone tracks (JBL's EZ gain) legitimate; his later warning is aimed at maxing out treble gains with such tracks.

5.1 #28 · Myth: tweeters need 100–150 W channels → With music a tweeter gets a watt or two.

Music's energy falls about 3 dB per octave like pink noise: calibrate an amp to 20 W and the band near 2.5 kHz gets about 0.16 W, so a 200 W amp at full output can cook a passive tweeter without clipping. His 24-channel car ran 30 W channels plus 800 W on subs. [RARE] Sources: Audiofrog blog Dec 2020 · DIYMA 2020-10-14 · OFCAP 19 @11:00

In plain English: Many people believe tweeters need 100 to 150 W amp channels. He says that with music a tweeter gets a watt or two. Pink noise is a standard test hiss whose level at any single frequency falls 3 dB (half the power) for each octave you go up, and he says music's energy falls in about the same way. So if you calibrate an amp to 20 W, the band near 2.5 kHz gets only about 0.16 W. The flip side: a 200 W amp at full output can cook a passive tweeter without ever clipping. In his worked example, the tweeter in a "20 W" passive speaker handles about 0.2 W, and a 200 W amp at full output feeds it about ten times that. His own 24-channel car ran 30 W channels, plus 800 W on the subs.

5.1 #29 · Myth: passive crossovers waste lots of power, and active amplification is a band-aid for bad speakers → Both wrong.

Passive loss is only the coils' series resistance (like asking what power an EQ cut "wastes": 6 dB is 75%); active crossovers just remove passive level-matching trade-offs. [RARE] Sources: DIYMA 2018-03-31 · DIYMA 2013-11-28

In plain English: A passive crossover is a set of coils and capacitors between the amp and the speakers that splits the frequencies. An active crossover splits them before the amps, usually in a DSP, with one amp channel per speaker. Many people believe passive crossovers waste lots of power, and that going active is a band-aid for bad speakers. He says both are wrong. The only real loss in a passive crossover is the series resistance of its coils. He compares the question to asking how much power an EQ cut "wastes": a 6 dB cut means 75% less power at that frequency, even in a preamp EQ before the amp. Cutting is what a filter is for, and designers allow for the coils' resistance when they design the crossover. Active crossovers just remove the trade-offs a passive network makes to match the levels of the different drivers.

Speakers and drivers

5.1 #30 · Myth: speakers must "break in" → Only the spider loosens, and that matters mainly for subwoofers.

Resin in the spider cracks, changing behaviour at and below resonance; mids, midbass and tweeters crossed above resonance barely change ("a nothingburger" for tweeters), and he re-measured a car three years on within 0.5 dB. Big changes signal a design flaw; liking a system more over time means you got used to it. [RARE] Sources: DIYMA 2017-07-28 · DIYMA 2021-05-07 · DIYMA 2015-05-30

In plain English: Many people believe new speakers must "break in", playing for hours before they sound right. He says only the spider loosens, and that matters mainly for subwoofers. The spider is the springy fabric ring behind the cone that keeps it centred. Resin in it cracks as it flexes, which changes the speaker's behaviour at and below its resonance (the note it naturally vibrates at). Mids, midbass and tweeters are crossed over above their resonance, so they barely change; for tweeters he calls it "a nothingburger". He re-measured a car three years on and it was within 0.5 dB. He says big changes signal a design flaw, and liking a system more over time means you got used to it.

5.1 #31 · Myth: cone material gives a speaker its "sound" → Only stiffness, mass and damping matter, and an unsmoothed response graph shows whether they worked.

"The right tone" is frequency-response management; renamed paper and exotic materials are marketing (to a seaweed-cone pitch he asked for MDMA cones for house music). He ranks it the second-biggest boondoggle after directional cables. [RARE] Sources: DIYMA 2015-12-23 · DIYMA 2021-09-14 · BusinessWorld 2024

In plain English: Many people believe the cone material, such as paper, metal or something exotic, gives a speaker its "sound". He says only stiffness, mass and damping (how well the cone soaks up its own vibrations) matter, and an unsmoothed frequency-response graph, one not averaged to hide the bumps, shows whether the designer got them right. To him, "the right tone" is frequency-response management. Renamed paper and exotic materials are marketing; when someone pitched him a seaweed cone, he joked by asking for MDMA cones for house music. He ranks cone material as the second-biggest boondoggle (a costly waste) after directional cables.

5.1 #32 · Myth: a deeper cone has more effective area → It doesn't;

displaced air depends on diameter (plus about a third to half the surround), not cone surface. [RARE] Source: DIYMA 2021-09-16

In plain English: Many people believe a deeper cone has more effective area, so it moves more air. He says it doesn't. The air a speaker displaces depends on its diameter, counting the cone plus about a third to half of the surround (the flexible rubber or foam ring at the edge), not on the cone's surface area.

5.1 #33 · Myth: phase plugs improve dispersion → They are "just plugs".

Without a dust cap the cone's centre resonates like a bottle and the plug fills it; on a 6.5" it can lower a cone-mode peak but costs midband sensitivity. Sources: DIYMA 2015-10-09 · DIYMA 2021-12-04

In plain English: A phase plug is the fixed, bullet-shaped piece in the centre of some speakers, where a dust cap (the small dome over the centre) would normally sit. Many people believe phase plugs improve dispersion, meaning how widely the sound spreads. He says they are "just plugs". Without a dust cap, the open centre of the cone resonates like a bottle, and the plug fills that space. On a 6.5-inch speaker it can lower a peak caused by a cone mode (a frequency where the cone flexes instead of moving as one piece), but it costs midband sensitivity (loudness for a given power in the middle frequencies).

5.1 #34 · Myth: billet baskets and "non-ringing" frames sound better → The basket contributes very little;

big vents under the spider matter, and CNC machining is a low-volume cost and perceived-value choice. Source: DIYMA 2015-09-27

In plain English: The basket is the metal or plastic frame that holds a speaker's parts together. Some brands sell CNC-machined "billet" baskets, carved from a solid block of metal, or "non-ringing" frames as better-sounding. He says the basket contributes very little. What matters is big vents under the spider: air forced through small holes there makes mechanical noise. He says CNC machining is a choice driven by low production volume and by perceived value; in the same post he put the tooling for a cast 6-inch basket at about $5,000 to $20,000, a cost machining avoids.

5.1 #35 · Myth: hand-built, "bespoke" or "individually matched" drivers beat "build house" products → Consistent production wins.

Audiofrog tests 100% of units at end of line; "matched pairs" often signal a high-variance process; replicating a qualified design within tolerance is manufacturing wherever it happens, so "artisan" Europe vs "built not bought" USA is a double standard. [RARE] Sources: DIYMA 2013-11-28 · DIYMA 2015-05-31 · DIYMA 2021-06-29

In plain English: Many people believe hand-built, "bespoke" or "individually matched" drivers beat "build house" products (speakers from big factories that make drivers for many brands). He says consistent production wins. Audiofrog tests 100% of its units at the end of the production line. "Matched pairs" are often a sign of a high-variance process: you only need to hunt for matching pairs when units differ a lot. Copying a proven (qualified) design within tolerance, over and over, is manufacturing wherever it happens. So he mocks the double standard where a small European assembly line is called "artisan" and a US one "built not bought", while a factory elsewhere gets the "build house" label.

5.1 #36 · Myth: "Made in Germany/USA" means quality and "made in China" means cheap labour → Quality is a specification, a test spec and verification.

He has built products in about a dozen countries, each with great and poor factories, and labour is a small cost for line-built car audio. Audiofrog builds in China because only two factories would build to its reliability spec, and the chosen Tier-1 auto supplier cost more than any other. [RARE] Sources: DIYMA 2016-03-10 · DIYMA 2021-01-14 · DIYMA 2020-12-25

In plain English: Many people believe "Made in Germany" or "Made in USA" means quality, and "made in China" means cheap labour. He says quality is a specification, a test specification, and verification, meaning checking that products really meet them. He has built products in about a dozen countries, and each had both great and poor factories. Labour is a small part of the cost of car audio built on a production line. Audiofrog builds in China because only two factories would build to its reliability spec, and the one it chose, a Tier-1 auto supplier (a company that supplies parts directly to carmakers), cost more than any other.

5.1 #37 · Myth: same factory means same driver, so buy "direct" on Alibaba → It depends what the brand contributed.

Some brands only change the logo; others own tooling and specs, and small invisible changes shift performance a lot. Many brands hide country of origin (Dynaudio has been owned by China's GoerTek since 2014). [RARE] Sources: DIYMA 2022-03-29 · DIYMA 2022-03-31

In plain English: Many people believe that if two brands' drivers come out of the same factory they are the same driver, so you can skip the brand and buy "direct" on Alibaba. He says it depends on what the brand contributed. Some brands only change the logo. Others own the tooling (the moulds and dies that shape the parts) and the specifications, and small changes you can't see can shift performance a lot. He adds that many brands hide their country of origin; for example, Dynaudio has been owned by China's GoerTek since 2014.

5.1 #38 · Myth: cone treatments such as EnABL help → In the posted data the untreated driver measured better every time.

Source: DIYMA 2015-10-27

In plain English: EnABL is a treatment in which a pattern is painted onto a speaker's cone, with claims that it improves the sound. Many people believe treatments like this help. He says that in the test data that had been posted, the untreated driver measured better every time. In the same post he argued the pattern isn't random enough to change the cone's modes (the ways a cone flexes).

The full series

Download the complete guide as one PDF (351 pages, every point with its explanation).