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Product Spotlight: Sony Mobile ES XAV-9000ES Car AV Receiver

Sony XAV-9000ES

If you’ve visited the BestCarAudio.com website, you’ll know we’re big fans of Sony’s Mobile ES product line. Not only have the products we’ve reviewed performed exceptionally well in the lab, but our team members who also work on the retail side of the mobile enhancement industry love their value and reliability. It’s been a few months since anything new has joined the line. In May 2023, Sony announced the release of a second flagship multimedia receiver called the XAV-9000ES. Let’s check it out!

What Is the Sony Mobile ES XAV-9000ES?

If you’ve read our Test Drive Review of the XAV-9500ES, you know it’s a single-DIN radio with a 10.1-inch floating-face display that mounts to the front of the chassis and hovers (securely) in front of your dash. When it comes to installation, that design opens up many options. That said, not everyone wants a large display or has a vehicle that can accommodate one. As such, Sony has created the XAV-9000ES as a double-DIN solution that’s modeled after radios like the XAV-AX4000 and XAV-AX6000. The radio continues to use the anti-resonant, dual-layer design single-DIN chassis but features a 6.75-inch capacitive touchscreen with a 1280-by-720-pixel ultra-bright display. In addition, the touchscreen includes a special anti-glare coating that cuts down on reflections that would otherwise make the radio challenging to see in bright sunlight. If you’re after a benchmark-quality radio that fits a conventional double-DIN opening, Sony says, “You’re welcome.”

Sony XAV-9000ES
The high-resolution touchscreen on the XAV-9000ES features an anti-glare coating and a bright display.

At the bottom of the radio display is a row of buttons, similar to what you’d find on the XAV-AX6000. These mechanical buttons make it easy and intuitive to adjust the volume, change tracks or stations or activate the voice recognition feature of Android Auto or Apple CarPlay without looking at the radio, and the center button is programmable to mute the sound or change sources. The onscreen menu system is similar to that of the XAV-9500ES, remaining intuitive and easy to use. The five source or function icons across the lower part of the screen can be easily modified to display the options you use most frequently, and the icons can be arranged in the All Apps drawer.

CarPlay and Android Auto operate wirelessly using integrated Wi-Fi, so your phone will automatically connect after you start the vehicle. The radio has a USB-C connector on the back to charge your smartphone. Alternatively, you can connect a USB memory stick to play audio or video files.

Sony XAV-9000ES
The single-DIN chassis leaves lots of room for wiring and interfaces in the dash of your car or truck.

Audio Source Options

Aside from supporting all the popular digital media formats, the XAV-9000ES includes an AM/FM tuner with RDS support. You can pair a digital media player, laptop or desktop computer using Bluetooth to stream audio. The Sony radio supports the LDAC Bluetooth transmission protocol, so wireless audio from your compatible smartphone will sound the best it can. Finally, your installer can upgrade the radio with a SiriusXM SXV300 satellite radio tuner so that you can enjoy genre-specific programming almost anywhere in North America.

Sony XAV-9000ES
The XAV-9000ES includes Bluetooth LDAC support, so wireless audio streaming from your smartphone or a media player sounds the best it can.

Radio Design and Audio Performance Features

Sony worked hard when creating the XAV-9500ES to come up with a solution that sounds amazing. If you look at how many auto sound competitors use that unit, you can appreciate that their efforts were worthwhile. We haven’t tested a better source unit in the lab, so that says a lot! The XAV-9000ES is no different in terms of its lofty goals. It uses an ESS ES9080Q digital-to-analog converter to output high-resolution WAV, FLAC, ALAC or DSD audio files with the smoothest sound and nearly imperceptible distortion.

At the heart of the XAV-9000ES is an Analog Devices 192-kHz, 24-bit digital signal processor. This potent processor gives your installer their choice of front, rear and subwoofer or three-way high, mid and low crossover configuration options. The radio has a 14-band global equalizer and eight bands of parametric equalization on each of the six output channels. There’s also a menu to set signal delays to each of the six 5.0-volt preamp outputs and the four channels fed by the built-in 20-watt-per-channel Class A/B amplifier to optimize the soundstage.

Sony XAV-9000ES
The XAV-9000ES includes an eight-band parametric equalizer that will allow your installer to optimize the performance of your sound system.

The radio is compatible with the iDatalink Maestro RR and RR2 modules to communicate with your vehicle’s computers. Depending on your vehicle, the RR or RR2 will provide access to climate control settings, parking sensors, tire pressure and door status information. The RR and RR2 also include steering wheel radio button control connectivity to make using the radio easier. If the RR or RR2 doesn’t support your vehicle, the Maestro SW will provide steering wheel control connectivity. Your local authorized Sony Mobile ES dealer can explain all the features supported by the Maestro interface for your vehicle.

Sony XAV-9000ES
Support for the Maestro RR and RR2 allows the XAV-9000ES to communicate with the computers in your vehicle.

The XAV-9000ES retains the triple camera inputs with dedicated triggers included with the XAV-9500ES. You can use these additional camera inputs for blind spot monitoring cameras or a forward-facing parking camera, and they can be independently triggered for custom control integration.

Sony XAV-9000ES
The three camera inputs have dedicated triggers for custom control integration.

Experience the XAV-9000ES at an Authorized Sony Mobile ES Retailer Today!

If you’re shopping for a truly high-end multimedia receiver for your car, truck or SUV, drop by a local authorized Sony Mobile ES retailer and check out the XAV-9000ES. Be sure to bring along your phone to hear just how great the radio sounds and experience the lightning-fast and intuitive interface. For more information on this radio or any Mobile ES products, visit the Sony Mobile ES website.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, PRODUCTS, RESOURCE LIBRARY Tagged With: Sony Mobile ES

Differential Inputs are Your Friend

Differential InputsIn the 80s and 90s, it seemed like car audio installers were often having to resolve noise issues after installing a system that included an amplifier or signal processor. In many cases, the problem was called a ground loop. However, in some cases, the noise was present because one of the signal cables passed by a source of noise. The only solution was to reroute the wire. No matter what the problem was, or what cure was applied to resolve the problem, ultimately it wasted time and frustrated installers.

Noise problems are not as common these days. They do crop up from time to time, but certainly not with the same frequency as before. One simple technology that has helped to reduce noise issues is the inclusion of differential inputs of modern amplifiers and processors. In this article, we will explain what differential inputs are, how they work, and what benefits they offer.

Amplifier Input Circuitry – Single Ended Inputs

The RCA input connections on your amplifier have a relatively easy life. They do not need to pass any significant amount of current. They do not get connected and disconnect very often. They just sit there and do their thing.

Behind the connections, where the circuitry of the amplifier starts to do its job, there are two circuit designs commonly used. The aforementioned differential input, and single ended inputs.

In a single ended input design, the shield of the RCA cable is connected to ground through a resistor. This resistor is often around 1000 Ohms. The center pin of the RCA cable, which contains our audio signal, is connected to the preamp stage of the amplifier. The preamp stage includes the sensitivity control, crossovers and so forth.

The image below shows an RCA with a sine wave and noise on both the shield and the signal conductor.

Differential Inputs

When we feed the signal shown above into an amplifier with single-ended inputs, the noise on the ground wire is ignored, and the sine wave and noise on the signal wire are amplified. The unfortunate and unwanted result is below:

Differential Inputs

Amplifier Input Circuitry – Differential Inputs

In a device with a differential input design, the shield of the RCA cable is completely isolated from the chassis. Before the audio signal passes to the preamp stage of the amplifier, it goes through an op-amp. An op-amp (or operational amplifier) is a small IC that has two inputs and a single output. One input is labeled as +, and the other as -. When we put a signal on the + input, it is passed to the output of the device with little to no change. When we put a signal on the – input, the polarity of the signal is inverted and sent to the output. In a differential input configuration, the – input of the op-amp is also connected to the shield of the RCA.

If we have an audio signal on the + input, and nothing on the – connection, the audio signal is passed through to the output of the op-amp, then on to the pre-amp stage of our amplifier.

The image below shows an RCA with noise on the shield and the signal conductors.

Differential Inputs

If we have noise induced on the shield and signal conductor of the RCA, then the noise signal on the shield is inverted and passed to the output. The inverted noise signal adds to the non-inverted signal and cancels out.

Differential Inputs

We call the system a differential input because it is looking for the difference between the shield and the signal conductors. More accurately, it subtracts any signal that is common to both conductors from the output signal.

How does Noise get into the System?

When our interconnect cables run through the vehicle, they come close to all sorts of electrical noise devices. High-current wiring, computers, sensors, electric motors and even the alternator can produce radiated noise in the form of a pulsing magnetic field. When a conductor passes through this field, a current will be imposed on the wire.

When this imposed current (or signal) reaches our amplifier, it gets amplified. If the noise is a high-frequency buzz, then that buzz is amplified, and we hear it through our speakers. Yuck!

Another source of noise is a ground loop. In a ground loop, current is flowing on the shield of our interconnect to equalize the ground potential between two devices.

Differential InputsLet’s look at an example. Perhaps someone has installed a radio in the dash of a truck and grounded that radio to the dash support. In some cases, that dash support is isolated from the truck chassis with big rubber bushings. When we connect the RCA cables from our radio to an amplifier in the trunk that has single-ended inputs, the radio seeks an improved ground location through the RCA shield. The resistor in the amp prevents massive amounts of current from flowing, but there is often enough to induce noise in the signal conductor.

A quick test for a ground loop is to pull the RCA out of the amp until only the center pin is touching. If the noise goes away, you have a ground loop. A remedy is to install a ground loop isolator. A ground loop isolator is a device with a transformer in it. The audio signal is transferred through the magnetic interaction of the transformer windings. There is no direct electrical connection between the input and output cables. With no electrical connection present, current cannot flow. The drawback of a ground loop isolator is that it can detrimentally affect the frequency response of the signal passing through it.

Do the Interconnects Matter?

For differential inputs to work, we need the noise signal to be equal on both the signal and shield conductors of our RCA cables. In a coaxial cable design, the shield can block noise from getting to the center conductor. If you use coaxial interconnects with differential inputs, the noise on both conductors is not equal and can induce noise into the signal path.

Differential Inputs

The easiest way to ensure that any induced noise is equal on both conductors is to use a twisted pair interconnect. In a twisted pair configuration, both conductors have the same effective amount of shielding and subsequently, the same amount of noise.

Differential Inputs

Differential Inputs are Your Friend

The next time you are shopping for an amplifier or signal processor for your car, remember that one of the questions you should be asking is if it has differential inputs. While you can certainly build a great sounding audio system around an amp with single-ended inputs, there is no point of taking the risk of having noise or installation headaches. Your local mobile electronics specialist retailer would be happy to assist you in finding an amp or processor with differential inputs.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Product Spotlight: iDatalink Maestro AR Multi-Amp Upgrades

Maestro AR

Several years ago, iDatalink, the company known for its class-leading remote car starter interfaces, launched an amplifier integration solution called the Maestro AR. The AR (which is short for amplifier replacement) was designed to interpret the CAN bus commands intended for a factory amplifier into something a third-party digital signal processor can understand. While DSP-equipped products from several companies work with the Maestro AR, iDatalink took advantage of a feature in the ARC Audio PRO Series line of processors to develop a unique solution. Multiple AR units can be installed in a single vehicle to control multiple digital signal processors or DSP-equipped amplifiers at the same time. Let’s examine how these upgrades work and why you’d want this solution in your vehicle.

How Does the Maestro AR Work?

In most vehicles with CAN bus-controlled factory-installed amplifiers, the radio’s audio output is a fixed-amplitude (volume) stereo signal. To be clear, the analog audio signal from the source unit, be it the FM radio, Bluetooth streaming or playback of a digital audio file, does not change level with the volume control on the radio. This limitation means that if your installer connects an amp to this signal, it will always be at full volume, no matter where the volume on the radio is set. In some vehicles, there is also a digital audio signal connection between the source unit and the amplifier. The Maestro AR will convert these to an analog signal.

Along with the audio signal coming from the radio are commands that travel along the CAN bus. These commands include volume adjustments, signal routing changes for Bluetooth hands-free calling, warning chimes and tone controls and adjustments to features like bass, midrange and treble tone controls, surround sound modes or speed-compensated volume adjustment. In many vehicles, a second analog signal from the radio caries navigation prompts and hands-free Bluetooth call audio.

The digital signal processor in the factory-installed amplifier routes the stereo audio signal to the various speakers in the vehicle after applying whatever filtering, equalization or up-mixing the manufacturer requested. The Maestro AR interprets commands on the CAN bus network and feeds them to the third-party DSP to ensure that warning prompts and Bluetooth signals are mixed into the system and routed as needed. Finally, and most importantly, the digital messages on the CAN bus control the output level of the third-party DSP in the amplifier to act as the master volume control.

Maestro AR
The radio in the dash of many vehicles sends digital commands to a DSP-equipped amplifier to process the stereo audio signal.

In the above diagram, you can see three connections from the source unit to the amplifier. Those are the fixed-level audio, the analog Bluetooth/prompt signal and the CAN network connection.

In a vehicle that uses the Maestro AR, those control commands go to a third-party DSP from companies like ARC Audio, Audison or Rockford Fosgate. These processors can then replicate the majority of the functions of the DSP in the factory amplifier to give you complete control over your audio system.

In a typical upgrade, your installer would program the Maestro AR interface for your vehicle’s year, make, model and trim level, then connect it to the wiring in the car with a T-harness that’s also available from iDatalink. All third-party partner DSP companies require the technician working on your vehicle to install a brand-specific adapter harness to work with the Maestro T-harness.

For this article, we’ll talk about an upgrade that uses ARC Audio DSP-equipped amplifiers. This ARC Audio DSP installation requires an input adapter harness called the IDATA-OEM, which would be available from your ARC Audio retailer. The IDATA-OEM harness connects to the iDatalink T-harness and the analog RCA inputs on any ARC Audio amplifier or DSP that uses the PS8-Pro platform (PS8 Pro, IPS8.8, PS8-50, Blackbird or PSM Pro). The T-harness includes speaker wires that your installer would connect to the output of the new amplifier to make it easy to feed audio signals to the speakers. Finally, your installer would configure the DSP’s output channel assignments (front left, front right, rear left, rear right, center and subwoofer), crossovers, equalization and, if applicable, delays for each speaker to make the new system sound great.

Maestro AR
An example of an audio system that includes a Maestro-AR compatible DSP-equipped amplifier.

ARC Audio Multiple Amplifier Systems

Many years ago, ARC Audio added a feature to its PS8-Pro and newer digital signal processors that allows several processors to be connected simultaneously to a computer via unique and individualized electronic product IDs for every signal processor made. The installer can label each processor, and the technician setting up the system can select which processor (or DSP-equipped amplifier) they want to adjust from a pull-down menu. While the product development team at ARC Audio was working with iDatalink on Maestro compatibility, the two companies realized they could use this feature to allow multiple AR modules to work together simultaneously to control multiple stand-alone DSPs or DSP-equipped amplifiers.

Maestro AR
The PS8-Pro and new DNA software allow your installer to connect to multiple DSPs simultaneously.

Why would someone want multiple amplifiers in their car’s audio system? We’ll use the example of Fred Lynch’s Ford Flex. Fred works at ARC Audio, and one of his many duties is to oversee international sales. He recently drove his Flex from Modesto, California, to Toronto to be displayed and auditioned at the CMA Expo in March 2023. The audio system in the Ford Flex has three ARC Audio Blackbird 12-channel DSP amplifiers and an additional ARC 1000.2 amp that powers a trio of A-Series shallow-mount subwoofers. In addition, three Maestro AR processors in the vehicle individually control each of the system’s three DSPs.

Fred built the sound system in his Flex to demonstrate the capabilities of ARC Audio’s amplifiers, processors, speakers and subwoofers in an OEM application with all OEM controls and features retained. Most importantly to his family, no storage space was lost. As such, he optimized the system with as much power as possible. He’s also upgraded the vehicle with a three-way front stage with 8-inch woofers in the doors and RS-3.0 3-inch midrange speakers, and RS 1.0 tweeters in the A-pillars. He also bi-amped the rear ARC-Series, coaxial speakers in the mid doors and rear D-Pillar speakers! The center channel midrange and tweeter are also filtered actively. A pair of preamp DSP outputs on one of the Blackbird amplifiers provides the signal to the ARC 1000.2 subwoofer amplifier.

Bonus Features of Maestro Integration

We mentioned earlier that the AR interface sends more than just volume control commands from the factory radio to the amplifiers or signal processors. The ARC Audio DNA software allows your installer to set up a dedicated equalizer band that works with the midrange control and a high-shelf filter that responds to the treble tone controls on the radio. The bass EQ control on the radio can be configured to adjust a single-band EQ, a shelf filter or the remote level control for the subwoofer output.

Finally, the Surround Mode control on the factory radio allows for selecting from several DSP configuration presets. It’s worth noting that the number of presets is limited by the interface on each vehicle’s radio. In Fred’s Flex, he has a configuration with just the front-stage speakers only. The second preset adds the subwoofers. The third preset adds the side and rear speakers. This third preset configuration added space and size to the experience without degrading the tightly focused front stage. The fourth preset changes from a sound-quality-oriented configuration to something more popular with enthusiasts who like a lot of bass by raising several crossover points so the system can safely use the amplifiers’ prodigious power. Toggling the “speed-compensated volume” selection from off to Low to Medium or High switches the presets on all three amplifier DSPs simultaneously.

Another unique feature of the Maestro AR system when using the ARC Audio Pro-Series DSP-equipped product is that installers can reconfigure the volume structure and incremental step level on the factory volume knob. For example, many factory-installed audio systems have issues where the volume control’s first step results in sound that can be too loud to converse with the person in the seat next to you. Another common problem is that the system reaches its maximum output capabilities using half of the volume steps on the factory radio. With AR and an ARC Audio processor, your installer can redefine the volume steps so the volume control works like a factory system with the range and incremental steps you expect.

Maestro AR
Commands from the midrange and treble controls on the factory-installed radio adjust the midrange and treble tone controls as configured by the ARC Audio DNA software.
Maestro AR
ARC Audio’s DNA software allows your installer to set minimum and maximum volume levels to ensure that the system doesn’t distort.

Why Use the Maestro AR?

Any audio system upgrade ideally aims to deliver improved sound quality, extended frequency response and output capability while maintaining the system’s ease of use. Upgrading the system with better speakers, subwoofers, high-power amplifiers and client-specific system calibration while retaining the intuitive control and appearance of the factory radio using the iDatalink Maestro AR ensures that the results are going to be predictable and reliable. Furthermore, this solution eliminates the need for the installer to attempt to recombine filtered, equalized and delayed signals; worry about Bluetooth hands-free calling echoes; or add an external volume control. In short, everything works intuitively and sounds excellent.

So if you have a Ford, Chrysler, Dodge, Jeep, Ram, Toyota, Lexus, Subaru, Volkswagen or Mitsubishi, or a Harley-Davidson motorcycle, visit a local authorized vehicle iDatalink Maestro Retailer and ask about an audio system upgrade that uses the iDatalink Maestro AR interface. As a bit of teaser, we have it on good authority that iDatalink is working on an interface solution for vehicles that use A2B communication, digital over the copper (as is found in many Hyundai and Kia vehicles), along with MOST 50- and MOST 125-equipped vehicles. With the Maestro AR solutions, owners of these vehicles will be able to upgrade the sound systems with premium signal processing, amplification and speakers, ensuring that music enthusiasts can continue to have audio systems that are enjoyable and easy to use.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, PRODUCTS, RESOURCE LIBRARY Tagged With: ARC Audio, iDatalink

Bench Battle: Headunit Features vs. Performance

Headunit FeaturesAwhile ago, a client asked us what you get when you buy a “better” headunit. The usual answer is that you get more features and improved functionality. Those of us with a drive for the ultimate in sound quality and realism from our mobile electronics systems choose products in hopes of them receiving improved sound quality. Beyond frequency response and noise, what else makes one radio sound better than another?

We invited two head unit specimens to the Best Car Audio test bench for a little head-to-head battle. The first subject is a modern multimedia station that is equipped with navigation, smartphone integration and the general Bluetooth goodness. The challenger is a veteran, but premium, CD receiver. It has never heard of MP3 files, doesn’t understand the concept of satellite radio and thinks Bluetooth is the result of eating blueberry pie. However, in its day, it was one of the best. We do not need to mention names here, but we will call this the bench battle of features versus performance.

The Equalizer – Premium Test Equipment

Measuring the frequency response of a car audio product is relatively easy if you can feed a known signal into the device. When it comes to measuring a signal source, that is responsible for generating the signal, so all we can do is measure the output. We have a high-end digital interface on our bench. It offers a flat frequency response from 5 Hz to 92 kHz with a tolerance of 1 dB. The signal to noise ratio is an amazing 116 dBA and distortion is specified at less than 0.00032%. These specifications exceed those of both source units we are going to test.

Frequency Response Measurement

Testing the frequency response of a source unit requires some trickery. We have developed a reliable method that has proven itself time after time. The image below shows the frequency response of the reference signal. It has a slight incline in the high-frequency region, but everything is within a tolerance of about 1 dB. We converted this 192 kHz, 24-bit test track down to the CD standard of 44.1 kHz and 16 bit. Response to 22.05 kHz remains ruler-flat.

Headunit Features
Reference White Noise Signal

Frequency Response Results

Before we get into the results, we want to explain how to use the measurement graphs. The test track uses random noise as part of the test procedure. We process that after the test is complete. What you want to observe is the trend of the charts. A small peak or valley is not an anomaly in this scenario. Average the curve in your mind to see the overall trend.

The CD receiver: We played our test track from a standard CD audio file to make sure both source units were given the same information. The frequency response of the unit showed a typical response. The high-frequency filter kicks in around 17 kHz, which is normal for consumer products.

The DVD receiver: We played the same CD in the DVD receiver to see how it responded. The manufacturer of the DVD receiver has included a 2 dB boost on the top end that starts at 7 kHz and peaks at just over 2 dB at 15 kHz. The high-frequency filter response is similar to that of the CD player.

The high-frequency boost is not a big deal in terms of how a system sounds. Most of us have some high-frequency attenuation in our hearing, so this helps put some of the sizzle and air back into our music. It would be worth checking whether the source unit output clips when a 0 dB 15 kHz tone is played. This article is not a product review, so we will save that for someone else to tackle.

Headunit Features
Frequency Response Comparison

Bring the Noise

Our next challenge for the new versus old shootout is a little more technical: We wanted to see how each unit performed regarding background noise. This test is often reserved for lab environments, but can quantify the effort put into the component selection and system design.

For this test, we used a 1 kHz test tone recorded at -90 dB relative to full scale. Because the two source units have different pre-amp capabilities, we adjusted them so the output of the 1 kHz tone was equal in amplitude. This would best depict the noise imposed on the signal.

Headunit Features
1khz Noise Test

The CD receiver: We can see that the background noise relative to the signal is very quiet. There is a little bump at 60 Hz that was created by the power supply on our test bench. Otherwise, the test was impressive.

The DVD receiver: The background noise relative to the 1 kHz is 10 to 15 dB louder than that of the CD receiver at higher frequencies. There are also some spurious harmonic distortions in the output signal, mostly above 1 kHz. The large bump in noise in the low-frequency region could be caused by our 60 Hz 120 volt power supply causing some harmonics. The bandwidth is really wide, so it is hard to determine for sure.

A Distorted Perspective

We decided to repeat the test with a full-amplitude 1 kHz sine wave to see what harmonic content would be created at higher internal levels. The limits of the FFT analysis in our software starts to show up here. The flat horizontal line on the left of the chart and the angled line on the right are due to the analysis software and don’t represent noise.

Headunit Features
1kHz Noise Test 0dB

The CD receiver: We noted two small harmonics at 14,750 and 165,000 Hz, with a slight harmonic at 12,000 Hz. Otherwise, the signal was very pure.

The DVD receiver: Harmonic distortion was clearly present at 1 kHz intervals starting at 2 kHz. It is worth noting that the first resonance is 45 dB quieter than the reference signal. If you were just playing the test tone, you might be able to hear it, but only just barely.

The Grand Finale – Intermodulation Distortion

Testing for intermodulation distortion is, well, mean. Out intermodulation distortion test is comprised of a CD test tone with 19 and 20 kHz sine waves played simultaneously. The spectral response of the test track can be seen below.

Headunit Features
Intermodulation Reference

The CD receiver: When you are looking at an intermodulation comparison test, you are looking for frequency content that wasn’t in the original file. In the case of the CD receiver, we can see a very small bump at 1 kHz. This is significant because it is the difference between 19 kHz and 20 kHz. This would be considered an excellent result. A few other spikes show up at 3,500, 4,500 and 9,500 Hz, but they are still quite low – peaking at -93 dB relative to the test signal level of –15 dB.

The DVD receiver: We cannot really explain what happened here. There is 1 kHz content only 20 dB down from the 19k Hz and 20 kHz tones. Then harmonics upon harmonics of this up to 21 kHz. This test shows why some source units sound accurate and pure, while others do not.

Headunit Features
Intermodulation Comparison

Are Headunit Features Worth the Trade-off?

A few months ago, we published an article about harmonic distortion. That served to establish the basic understanding of how distortion creates content that wasn’t present in an original audio file. Our intent in this comparison is not to put down the modern DVD receiver, but to show what happens when manufacturers forego the bells and whistles and simply focus on all-out performance.

The same tests that apply to these source units are also common in amplifiers and speakers. We will subject an amplifier to the same mean and nasty tests in the coming months.

Don’t ever let price, perception or age dictate how you think a product sounds. Work with your mobile electronics specialist retailer to listen and compare for yourself. You will be amazed at what you hear.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Custom Vented Enclosures-More Bang for Your Buck

Custom Vented EnclosuresWe all know that the performance of different makes and models of speakers and subwoofers has a dramatic difference in how they sound. When it comes to the installation of subwoofers, the choice of enclosure plays a huge role in the sound of the subwoofer system. In this article, we look at some of the benefits of custom vented enclosures and solutions available.

The Factors that Determine Performance.

Custom Vented EnclosuresThree criteria have the most effect on performance: air volume, tuning frequency (for bass reflex enclosures) and construction. Every subwoofer has its electro-mechanical characteristics. Subsequently, each subwoofer needs its very own enclosure design. With that said, some relatively standard designs offer good performance across a wide variety of speakers.

The difference between having an enclosure that “works” and one that sounds amazing is all in the design. Have your mobile electronics retailer confirm that the air volume and tuning frequency match your application before you purchase. (We will explain that happens when the air volume or tuning frequencies are “off” in another article.)

Wait, Why Vented Enclosures?

While there are benefits and drawbacks to each type of enclosure, a vented (bass reflex) enclosure will offer excellent efficiency and low-frequency extension for most people. These enclosure characteristics reduce the amount of power we need to send to the woofer, and therefore reduce the chances of overpowering and damaging the woofer.

Off-the-shelf Enclosures

Many car audio retailers offer subwoofer enclosures that have been mass-produced. These enclosures vary dramatically in construction quality and design. Some companies tune their enclosures relatively high to increase efficiency at higher frequencies while sacrificing low-frequency output and power handling. The materials used to build these enclosures also vary in quality.

Almost all of these off-the-shelf enclosures are made of MDF. That said, the density of the material varies a great deal. Some MDF is very soft in the middle, offering less resistance to panel deformation. Enclosures made of this soft-center MDF are also prone to having the mounting hardware strip when your installer goes to mount the subwoofer.

These days, efficient use of space is increasingly important for auto sound enthusiasts. An off-the-shelf enclosure may not maximize the available space in the storage area of your vehicle. Enclosure manufacturers try to balance the dimensions of the enclosure against the airspace requirements of the intended driver and the space available in the average vehicle.

Construction Methods

Many enclosure manufacturers claim to use a rabbet joint where two panels meet. Unlike a butt joint, a stepped rabbet joint will increase the surface area of the connection by about 50%. Enclosure assembly typically makes use of a generous amount of glue. Once glued, the panels are held together with brad nails to allow the glue to set up. The additional surface area provided by the rabbet connection results in a stronger joint and a reduced chance of air leaking.

Vent Considerations

If a vent (or port) is designed and constructed properly, a vented enclosure can produce less distortion than a sealed (acoustic suspension) enclosure. To reduce distortion and meet these goals, the vent must have adequate surface area and be designed in a way that the air entering and exiting the vent will couple well with the air in the listening environment. Several subwoofer manufacturers design and construct their enclosures. These stand out from the crowd as having excellent vent designs.

Custom Vented Enclosures

Enclosures with no radius or taper on the vent end are more prone to noise. This sharp edge on the vent can create chuffing or other noises as air rushes over its edges. For a 3-inch or larger vent, a simple 3/4”-inch radius on the vent edge is just barely enough to be beneficial. A much larger radius offers more benefit in allowing the air inside the vent to decelerate properly.

Your Enclosure May Need Bracing

Custom Vented EnclosuresIf you are looking for the best possible performance from your subwoofer system, then every effort possible should be made to ensure that each panel of the enclosure is as rigid as possible. One way to add strength to an enclosure is for the manufacturer to install bracing. Bracing connects opposite panels to each other to reduce flexing. Panel vibrations can, in extreme cases, cause glue joints to fail.

Application-specific Subwoofer Enclosures

Custom Vented Enclosures
This enclosure provides a creative solution to adding bass, replacing the bottom half of a center console with an enclosure.

We have talked about some of the benefits and some of the drawbacks of an off-the-shelf subwoofer enclosure. The alternative is to have your mobile electronics retailer design and construct an enclosure to fit your vehicle. Maximizing usable storage space can be achieved by having your fabricator fit the enclosure snugly to the sides of the vehicle. Many vehicle-specific enclosures combine different construction techniques. Flat panels, fiberglass, stacked-panel fabrication and more can allow an installer to make amazing use of every cubic inch of your storage space.

Maximize Bass Custom Vented Enclosures

One of the first and most beneficial additions than can be made to a factory audio system is a subwoofer system. When it is time to take that first step, visit your local mobile electronics retailer. They will be happy to show you what is available for your vehicle, and what they can create. We know that no matter what you choose, you will be pleased with the dramatic results.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

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