Alpine 7909
Features Detailed
Higher Quality Electronics
Electronic components come in different grades, expressed in Standards.
Dual Burr-Brown 18-Bit DAC’s
Precision 18-bit digital-to-analog converters with ultra-low distortion over a very wide frequency range. The Dual Burr-Brown 18-Bit DAC’s feature a very low noise and fast settling current output.
In factories CD´s are recorded at 16 bit/44.1 khz, the Alpine 7909 having Dual Burr-Brown 18-Bit DAC’s is able to play more frequencies than a factory recorded CD. And a 1 bit stereo would not be even close to play all the frequencies that a factory recorded CD has and it would be far from sounding like a real professional concert.
Bit depth is a series of levels, that audio energy can be divided at any given moment in time. With 16 bit audio, there are 65,536 possible levels. With every bit of greater resolution, the number of levels double. When reaching 18 bit we have 262 144 levels on a piece of audio frozen in a single moment of time. 1 bit has ONLY 2 levels, 99.999999% of the CD players have only 1 bit.
The picture below shows 4 bit audio that gives you only 16 levels:
Sample rate is the number of samples of audio carried per second, measured in Hz or kHz (one kHz being 1000 Hz). 44100 samples per second can be expressed as either 44100 Hz, or 44.1 kHz.
Bandwidth is the difference between the highest and lowest frequencies carried in an audio stream. The sample rate determines the maximum audio frequency that can be reproduced. Theoretically the maximum frequency that can be represented is half the sample rate (known as the Nyquist frequency).
Sample rate will capture frequencies at half of its amount. A sample rate of 44.1Hz will accurately represent frequencies up to 22kHz. Humans with great hearing can hear up to 20kHz.
Higher sample rates of 48 kHz, 88.2 Khz, 96 kHz and even 192 kHz are available in music and audio production software
The disadvantages of working at sample rates over 44.1 kHz
a. The human ear can only process up to 20 khz, 44.1 khz recording equals to 22 khz, 48 khz = 44 khz, 96 khz = 48 khz
b. When sample rates double, so do the file sizes on your drive
In order to enjoy the full 18 bit of the Alpine 7909 the songs have to be recorded in a professional studio with an 18 bit CD recorder, all the instruments played have to be high performance quality, if the instruments are top of the line, even better, the singer or singers have to be at the studio, if you record from a 16 bit CD in the 18 bit CD recorder, you cannot get the 18 bits, you will get the same 16 bits only.
What does it mean? It means that when you are listening to a 16 bit Factory recorded CD, played with the Alpine 7909 that has Dual Burr-Brown 18-Bit DAC’s you will hear each instrument in a different part of the space and completely separated from the other instruments, not like other stereos that you hear all instruments in one speaker on every single speaker. Each instrument will sound like you are listening to a real one and it will not sound like a car stereo, but like a real concert. But of course you have to keep in mind that you need top of the line amplifiers for 8 speakers, 1 top of the line amplifier for the swbwoofers, top of the line crossovers, 8 top of the line speakers and 2 top of te line subwoofers and the crossovers with the right frequency output to each speaker.
See the picture below to see the difference between Bith Depth and Sample Rate:
8 Times Oversampling Digital Filter
Oversampling means generating more samples from a waveform that has already been digitally recorded.
Compared to analog filtering, digital filtering can provide higher overall system performance and reduce circuit complexity. The use of digital filtering (as opposed to analog filtering) can provide higher overall system performance while simultaneously reducing circuit complexity. Oversampling is the technique of sampling a signal at a higher rate than would be required to just preserve the desired signal frequencies. It is typically referred to as a multiple of the desired sampling here being 8x oversampling. The oversampled signal is then sent through a digital filter before being downsampled to the desired sample rate. There are some significant advantages to oversampling a signal. For the antialiasing application, oversampling allows the lowpass filtering operation to be split between the analog domain and the digital domain. This split allows better filtering performance while simultaneously reducing the complexity and performance requirements of the analog filter and ADC.
With 8X oversampling, we have a very gentle filter getting 158 KHz.
The higher the degree of oversampling, the more effectively that a digital filter can suppress the interference signals, and the simpler the analogue output filter can be. Which in turn benefits the final reproduction quality.
10V+/- DC to DC converter
Conventional car audio system power supply ICs, although generally easy to design, are often centered around a linear regulator which suffers from poor efficiency, reducing the operating efficiency of the entire system. In response, the 10V+/- DC to DC converter provides much greater efficiency, enabling support for the latest high-performance Alpine 7909.
Max line output of 4.5V
99.99 + % of the car decks have 1 Volt Pre-out or less.
A Higher Pre-out voltage does two things for you:
1) Less susceptible to external noise (alternator, ignition coil, etc.) in the signal path as it´s connected through RCA cables to amplifiers.
2) Lower gain setting on amplifier as the original signal has a greater amplitude. This allows the amplifier to operate with much less distortion ending in better sound quality. With 4.5 Volt Pre-out you can listen a soft passage of classical music at rock concert levels and you won´t listen the “sssss” on the back of the song, quiet moments will be COMPLETELY QUIET and you would listen just pure, crisp music.
Tone & Balance circuit bypass
It uses a balance potentiometer and a tone potentiometer, the sound travels as is and not being distorted by electronic circuits delivering the cleanest and crisper sound.
External DC filter
Your alternator generates noise on the power line. Alpine 7909 is a better car CD-radio and has internal filters for the power supply (a big choke and some caps).
Alternators ALWAYS generate noise (since the output is rectified AC), and creates even more noise if you have a bad (since the battery acts as a big capacitor to smooth out the output from the alternator). Alpine 7909 filters the power unlike the other car CD-Radiostereos.
The Alpine 7909 External DC filter uses passive or active components, offer resistance to the specific offending frequency components to suppress them. For example odd harmonics/interference riding on the AC main power line must be removed for the safe reliable operation of electronic devices. The Alpine 7909 targets the offending frequency component and not the fundamental i.e. 50 Hz.
External DC filter: Unfiltered DC is pulsating. The Alpine 7909 External DC Filter makes it pure DC:
External DC filter sends the noise current safely to ground and passes only clean DC to the The Alpine 7909 unit.
CDS “Black Out” feature
Allows the display to be shut off to minimise interferance for a cleaner audio signal.
Copper Plated Chassis Bottom
One of the main benefits is radiated noise isolation. Copper it´s used where a high level of conductivity is required.
Copper-plated chassis and back panel for lowest impedance grounding, copper-plated chassis makes the bass tighter, offers increased transparency, and removes a ‘dark overhang’ that was clearly audible when compared against the same circuitry in a chassis of more conventional material.
High Quality RCA Connectors
CD Straight Technology
Fiber Optic
The six crystal buttons on the right of the Alpine 7909 have each a fiber optic, each button has a second function, when the secondary function of the button is on, the fiber optic lights up Bright RED while the button stills lighted up green.
Vacuum Display
Manages high level of brightness with clear contrast, the display it´s bright and performs well in all light conditions including full sunlight. Has excellent readability with a wide viewing angle which let you see the information on the display from any angle. This is very important as 99+ % of car stereo displays cannot be seen inside the car when the sunlight is bright.