Welcome to Istorya Mobile Audio Enthusiast
A Car Audio Enthusiasts
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Recommended Cable Size by Power and Distance
Recommended Power and Ground Cable Sizes
UPdated chart please click link
Interactive Frequency Chart - Independent Recording Network
My chart above shows the approximate frequency ranges of various musical instruments and the human voice. The black boxes represent their fundamental frequencies and the yellow boxes represent their harmonic frequencies. It's much easier to understand and enhance the instruments you want to hear when you know what frequencies they cover.
Bass
(Approximately 20hz-140hz)
There is little musical material with fundamental frequencies below 60hz. What is normally perceived as low bass material is actually in the 60hz-140hz range. Only a few instruments actually reach this range such as the organ, contrabassoon and string bass.
The 60hz-90hz range is where we notice the greatest perceptible changes in "bass response." Try a test tone and see just how well you hear 20hz or even 32hz, compared with the same volume of 60hz or 90hz.
Mid-Bass
(Approximately 140hz-400hz)
Mid bass has lots of instruments included in its frequency range. Cello (my instrument), Bassoon, French Horn (Freedom Horn this year) and yes Male Voice are all here. This is where most 'bass' controls really muck up your music. Overemphasizing the mid-bass range gives the music a muddy, or "boomy" quality. If the mid-bass region is underemphasized, the music sounds hollow and thin.
Midrange
(Approximately 400hz-2.6khz)
Since our ears are most sensitive to midrange frequencies, midrange has the greatest effect on the overall sound of your stereo system. Actually there is controversy among engineers and audiophiles as to what the proper balance should be in this range. Some settings are best suited to particular types of music.
The "proper" settings are the ones most pleasing to you the listener. I won't list instruments here because virtually all instruments have fundamentals found here in the midrange with the exception of Contra Bassoons, Bass Tuba and a very few others.
Upper Midrange
(Approximately 2.6khz-5.2khz)
Except for the pipe organ and piano, not many instruments have fundamental frequencies this high. Well, I guess the violin does touch into the range. But, it's really amazing just how little fundamental frequency material actually starts above what we consider midrange.
Speaker designers often boost output in this range to affect the quality or "presence" of the music. Too much energy, on the other hand, sounds overbearingly harsh and strident. A good balance between this frequency range and the midrange frequencies gives the most pleasing sound.
High End
(Approximately 5.2khz-20khz - Two Regions)
The region from about 5.2khz up to about 12khz is normally perceived to be the high-frequency range. (The dreaded treble control.) Only the pipe organ actually contributes any fundamental frequencies in this spectrum (as well as a few others such as the flute), but this is where the harmonics really enhance your musical enjoyment. It's this range that affects the brilliance of music. Overemphasizing these frequencies gives an unpleasant, harsh and even piercing quality to your music.
The final region, the super high frequencies, from about 12khz-20khz, actually contains very little musical material despite all the editorial coverage it receives. However, many very soft 2nd and 3rd order harmonics do reach into this area.
Plus, most adults can hear only subtle differences when adjustments are made in the 14khz-20khz range. It's important to remember that adults, (mainly men) simply can't hear much above 15-16,000hz after the age of 50. So, this area primarily adds a little more dimension to your sound.
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Terms to Know about Car Audio: Aspects of Sound Quality
Listening to audiophiles go on about the sound quality of their audio systems — from their woofers to their tweeters — can sound a lot like oenophiles going on and on about the qualities of wine. To understand such talk, start by understanding the four basics of sound quality:
* Clarity
* Dynamic range
* Frequency response
* Tonal balance
Clarity
Clarity is the ability of a system to produce the original signal as intended, without distortion. Distortion can be caused by numerous things — from a head unit that's not level-matched with an amplifier to an amplifier that's clipping, or being overdriven and sending a distorted signal to the speakers. And distortion can come from any component in a system.
A good test is to listen to cymbals, which can have a brassy and off-putting sound when distorted. High-pitched female vocals are also difficult to reproduce and can reveal distortion rather easily.
Achieving clarity and therefore avoiding distortion is all about proper system design and tuning. It's making sure components are of sufficient quality and compatible with one another and that signal levels are well matched between electronics. It also involves using a component as it was intended and not pushing it past its design limits.
Dynamic range
Dynamic range refers to the ability of a system to reproduce loud and soft passages in music with the same level of detail. When you're at a live concert, a singer may wail and then whisper or a drummer may hit a drum head with brute force and then back off a bit. Each extreme is an important part of the performance.
If the performance is recorded and reproduced by an audio system, the loud and soft parts should be delivered with the same detail and accuracy. But often a system tends to suppress soft parts and emphasize loud ones, meaning you lose the subtleties of the performance.
A related concept is linearity, which refers to a system's tendency to lose detail when the volume is turned down. A system has great linearity if it can retain the same detail at a low volume that it does when it's cranked up.
Frequency response
Every sound you hear, from the low rumble of thunder to the high-pitch wail of a siren, is caused by vibrations in the air that occur at certain frequencies. These vibrations are measured in hertz (Hz), which refers to the number of times per second these vibrations occur.
Humans can hear frequencies roughly from 20 to 20,000 Hz. A car audio system's frequency response represents how much of the audible frequency spectrum it can reproduce. The frequency response of a car audio system can be measured by an instrument known as a real-time analyzer (RTA), which consists of a microphone attached to a processor with a display that has a graph that shows a system's response.
Tonal balance
An ideal car audio system uniformly reproduces the entire audible frequency spectrum from 20 to 20,000 Hz. But no system — at least while playing music — is perfect. Music is dynamic; some parts are loud and some are soft, so a system will naturally have dips and peaks in its frequency response.
Although a system can have these peaks and dips in frequency response, it needs to have good tonal balance — a relatively equal amount of sonic energy across the frequency range — to sound good. Subsequently, system designers and tuners often measure frequency response to gauge which frequencies may need to be boosted or cut as opposed to trying to achieve a flat frequency response. This can be done with an equalizer, although it's best that the system is designed in such a way that it has good tonal balance to begin with.
Taken from Drew's Frequencies
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Other links: for Istorya Mobile Audio Enthusiasts Sports And Recreation
https://www.istorya.net/forums/index....tml#msg3049712
Important Faqs
By Niel aka. blade4683
1. car's electrical system
* using a 100A alt is not enough. you have to know at what engine rpm the alt is giving out 100A otherwise your system is getting much less (this is why some people adjust their engine's choke to increase the engine rpm at idle... to keep the alt's rotor rotating at the desired rpm for the desired output current)
* even if he's using a kinetik battery (or 2), if the alt is still stock, the kinetiks will have a shorter-than-expected life
* to power his entire system (assuming 1200wrms, 1-1000wrms for sub and 1-200wrms for front seps), his electrical system needs to produce 83.3A at 14.4v, or 86.96A at 13.8v (note higher current at lower voltages)... and that's assuming nothing but his sound system is on.
* at power output in the kilowatt range, no amount of capacitance (by using stiffening caps) will substitute for an aftermarket alternator built to do the job
* this is also why some inexperienced users often blow their "main" and amp fuses... to keep up with the high power drawn by amp(s), current flow increases to keep up with sagging voltages.
2. amp's efficiency (by virtue of its type/class)
* class AB amps are about 60% efficient, while class D amps are much more efficient at up to 80+%
* even if the electrical system is giving 1000w of power, see how much of it drives the speaker and how much is converted to heat...
* to have an amp that produces 1000wrms at its speaker terminals, the manufacturers need to engineer the amp to compensate for these losses. so if indeed the amp powering the sub really gives out a true 1000wrms, it will actually demand more power at its input.
3. amp's actual output power
* in fairness, some amps are also underrated. one can refer to what they call an amp's "birthsheet" to see how much power is actually produced by the amp (take note though, at what operating voltage the amps are running at)
* my dls ca-10 is advertised to produce 1000wrms, but benchtests results reported by users in other forums report this amp can put out up to 1300wrms to 1ohm at 14.4v. unfortunately my electrical system can only give it up to 14.1v.
4. amp's power supply type (regulated or unregulated)
* for amps with a regulated psu, they can keep rated power at its output over a wider range of input power, while for amps with unregulated psu's, output power is dependent on how much input power it gets from the car's electrical system.
5. sub's sensitivity
* this is a figure that gives one an idea how "easy" or "difficult" it is to move the sub's cone (i.e. produce sound). higher figures mean sub will be relatively easy to drive
6. sub's true power rating
* for this discussion and for simplicity sake, lets just say all dd subs are underrated by 200w. given this, wouldn't this mean that to run the sub at max power, the amp has to provide and additional 200w above the sub's rated power?
7. amp's protection circuits
* any decent amp will have a protection circuit to protect it from excess heat or from drawing too much power (in addition to the installed fuses, as fuses take more time before they blow). running the amp cooler will mean lesser to no instances this protection circuit is triggered, meaning lesser amp cut-offs when showing off your system or when enjoying music at high volume
* note that some manufacturers tend to keep their amps running on the safer side of things, and end up engineering their amps with lower-than-necessary thresholds for their protection circuits (i.e. protection circuits kicking in even "sooner" than expected)
setting an amp's gains is another story... the above presumes amp's gains are reasonably set (meaning at no instance will the amp be clipping during operation).
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HOW TO SET GAINS
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The ADD version -
1. Play a typically loud music CD in your headunit. Set volume to 75%. Wear ear protection.
2. Starting with the amp gains at their lowest setting, slowly raise one gain at a time until you hear clipping from the corresponding speaker. This will sound like audible distortion.
3. Once you've found the clipping point, back the gain down until you no longer hear the distortion.
4. Repeat for any addt'l gains on the amp/amps.
5. Your new maximum volume setting on the headunit is 75%, never exceed that for happy, healthy speaker life.
(This is the quick & dirty method, it'll get you 80% to proper settings. Read on for the other 20%.)
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How to do things right -
What's gain?
Also known as input sensitivity, gains are the small, typically recessed "volume knobs" on most equipment between the speakers & the headunit. All amps have them, also many EQ's, line output converters, some crossovers.
What's it for?
The idea is to properly match the output from different pieces of gear so that each communicates the cleanest signal to the other, resulting in maximum performance and minimal noise & risk of damage.
Know your enemy - Clipping.
Clipping is the tech term for the distortion that occurs when an amplifier is pushed beyond it's capabilities. In simple terms it sounds like significant distortion of the musical peaks. So for instance a big drum strike will sound muddy or distorted when turned up, but remains clear at a lower volume. That's clipping. What's happening is the amp momentarily runs out of power.
To properly understand this w/o an engineering degree you need to know the difference between constant power (RMS) and peak power. Constant power, very simply, is the amount of juice your amp can produce consistantly. Since there are some standards for measuring this it is one of the few benchmarks we have for amplifiers. But since sound waves are exactly that - waves, with peaks & valleys - understand that an amp's output is never constant, it has to increase & decrease with the music signal.
The amp's "reserve power" is what it uses to deal with the peaks in the music. This is called peak power, or my favorite, headroom. Headroom is typically about twice the RMS power of an amp, but can only be sustained for a few milliseconds before the amp gets totally winded.
So a good way to think of this is a 10 yr old jumping on a bed - that's the music signal. The bed is the amp's RMS power, the ceiling above is the headroom limit. If the kid jumps too high he whacks his head - that's clipping. Do it a couple times & he'll survive. Do it repeatedly & there WILL be permanant damage. This is the single biggest speaker killer out there.
So the object of the game is to adjust the bed height (by using the gains) to the right height so the kid can jump around like a caffeinated monkey without ever whacking into the ceiling. So setting the gains properly allows you to get the amp's maximum output without overtaxing the equipment. With me so far?
A few other basics -
To do this properly you'll need a few things:
Ear protection. Stuff some cotton in your ears if you don't have anything better.
A test CD with a sine wave set to 0db, a 50-80hz stereo tone is ideal. This is important - it's far more accurate than using a music CD. You can purchase these at most any guitar or pro music stores, Amazon, or download a program to make your own. Making your own isn't recommended since there are a lot of variables in computers that can affect the final product.
If you have a crossover, you'll need test tones within the frequency range for each amp. For instance if you have a dedicated sub amp crossed over at 80hz, get a 60hz test tone. For your mains, work with a 120hz tone. If you have a 3-way or more crossover, adjust appropriately, just be sure the test frequency is within the bounds of the speaker range. Test each frequency seperately.
Fader, tone controls, loudness/expansion, etc.
Ideally you'll have the sound from your headunit/EQ completely flat on a normal basis. If so, be sure everything's this way before you test. However, if you KNOW you'll have the bass boost activated, some sort of expansion, or the tone controls preset in some way then go ahead & set them before you test.
Otherwise it's best to have everything flat. If you choose to adjust the tone controls later & leave them that way you can always repeat the process. Regardless, be sure the fader & balance are zeroed out.
Dedicated sub volume controls
A lot of amps have outboard sub volume knobs & headunits frequently have dedicated internal sub volume adjustments. If you plan on using these they should be maxed before setting your gains. If you're not going to use them, best to de-activate them.
Set all amp gains to their lowest point before starting. Usually full counter-clockwise.
Input sensitivity switches
If your amp has a selector switch for different input sensitivities, start by setting it to the highest setting. These are typically expressed in voltages, for example .2-1v, 1-3v, 3-8v. Start with the higher numbers (ex. 3-8v) (lowest sensitivity). If you can't get the amp to clip at those settings, try the next one down until you find the clipping point. You can disregard generally what the markings themselves say since there's no real standard for measuring that stuff. Never trust your system's well-being to those voltage numbers, they're just a guideline best ignored.
Work with one gain at a time.
For example, if you have a L&R gain for your front speakers, you'll be working with each side seperately. If multiple amps, unplug all but the amp you're working with. If a 4+ channel amp, typically you'll have only a single L & R gain, so treat it like a 2 channel. If it has more gains, isolate each & adjust seperately.
Play your test tone thru the headunit. Adjust your headunit volume to 75% of max.
This doesn't need to be precise, just be sure you know where this setting is b/c it's now the HIGHEST you'll ever turn up the volume on the headunit.
(But the amps go to 11...! You're using 75% volume because some CD's will be louder than others. Also b/c there's a small amp in the headunit that will clip if pushed too far. Trust me on this one.)
Now turn up the gain you're working with until you hear the tone quality change - it'll be a distinct change in the tone, there will be distortion. This is where your amp clips. Now turn the gain back down to just below where that distortion occurs. That gain's now set. Repeat for all other gains. Repeat for all other amps.
Final tweaking -
Have an EQ? Want to use the "loudness" button? Want to adjust the bass/mid/treble controls? If you're making minor tweaks (+/-1) there's no real need to worry about gains. If you're talking about bigger changes (+4/-3, etc) you may want to run the tones again to be sure you're still set right.
Also now that the gains are properly set you can adjust them DOWN to balance your system. Need more front volume but don't have a fader? Turn down the rear gains. Sub underpowered? Turn down the mains. The important thing is to never turn them UP from where they are, just down.
A few other notes -
Can't I just use an O-scope or DMM to set gains?
Sure, IF you know the exact output (rarely the rated output) of your amp and you're a freakin' genius with your toys. Generally more accurate & far easier to use your ears.
What about the gains on the EQ/X-over/line-output converter?
Ooh, good question. The general idea here is to follow the same process but use the gains that are the furthest UPSTREAM (I.E. closest to the headunit) and set all the others to their lowest setting. This will send the hottest signal possible thru all the components. Just remember that anywhere the signal splits you'll have to set them there also. For example, if you have a LOC & an outboard crossover you'll need to set gains on both, starting with the LOC. This can get tricky. Let your ears guide you.
What if my headunit says "9v output" and the amp only says "5v input?"
Eh, doesn't really matter. Again, there isn't really any set standard for measuring this stuff & it's usually just marketing. Also remember that music is a wave, not a line, so that rated output is usually a max, not a constant. Just set everything according to the above process, nothing changes.
Originally Posted by alvingo
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