Just as the invention of the transistor eliminated the need for vacuum tubes, advances in technology allow us to create new and unique entertainment solutions with more and more features. We thought it would be fun to take a quick look at a few important car audio technologies throughout history.

Transistors

The first car radios used vacuum tubes as integral parts of their tuner and amplifier circuitry. Tubes required high-voltage power supplies and consumed a lot of power. They produce a lot of heat and are fragile. The result was finicky products with limited performance. The first transistor was theorized in 1926 but wasn’t built for the first time until 1947. It wasn’t until 1955 that we saw Chrysler and Philco announce the first automotive transistor radio – the Mopar model 914HR.

The transistor is considered one of the greatest inventions of the 20^th century. Transistors improved the efficiency and reliability of electronics components and led to the creation of microchips and ultimately computers. The Apple A11 Bionic CPU, found in the iPhone 8, 8 Plus and iPhone X, has 4.3 million transistors built into it. The Microsoft Xbox One main CPU has more than 7 million transistors inside. More impressively, a 128 gigabyte stick of DRAM memory has more than 137 quadrillion transistors!

Broadcast Radio

Radio was truly the technology that drove car audio systems. The first radio broadcasts were weekly special events that included concerts in 1914 and daily news broadcasts in 1916. On May 20, 1920, XWA – the experimental station of the Canadian Marconi Co. – began regular broadcasts in Montreal. XWA claims status as the first commercial broadcaster in the world. These were all AM (amplitude modulation) stations. FM (frequency modulation) radio was patented in 1933, but it wasn’t until the late ’30s that FM broadcasts became popular. The broadcast of a stereo FM signal was first considered by the FCC in the late 1950s, and a standard was approved in 1961.

The Compact Cassette and 8-Track Tape

Reel-to-reel recording on magnetic tapes was popular in the 1940s but wasn’t suitable for use in mobile applications. The 8-track was preceded by the Stereo-Pak 4-track cartridge in 1962. The endless-loop cartridge could store both sides of a vinyl album. The 8-track, known originally as the Lear Jet Stereo 8 Track Cartridge, was launched by Bill Lear in 1963. In 1965, Ford offered factory and dealer-installed 8-track options on its Mustang and Thunderbird and on several high-end Lincoln vehicles.

Call it a tape or a cassette, the first compact cassette (as we know it) was introduced by the Phillips Corp. in 1963 as a storage medium for dictation machines. Widespread use of the compact cassette in the mid-’70s and the introduction of chromium dioxide (CrO2) as a premium recording medium and Dolby B noise reduction spelled the end of the 8-track.

Digital Audio

Most people don’t realize that digital audio (known then as pulse code modulation) was invented in 1937 in Britain and was used in telecommunications. In the late ’60s, Denon pioneered commercial digital recording. The BBC used digital audio transmissions to link its broadcast center to its transmitter in 1972. Sony and Mitsubishi drove the consumer popularization of digital audio in the early ’80s and brought about acceptance by major record companies. The first compact disc was released in 1982 using the Red Book Compact Disc Digital Audio (CD-DA) standard that is still in use today. The first OEM-installed CD players were in the 1987 Lincoln Town Car.

Class D Amplifiers

The benefit of Class D amplifiers is their efficiency and low-to-moderate power levels. Class D amps use high-frequency pulse-width modulation waveforms to switch MOSFETs (metal-oxide-semiconductor field-effect transistors) on and off very quickly to amplify signals. Filter networks on the output of the circuits remove high-frequency noise so that only the audio signal is left to drive our speakers. Class D amplifiers allow manufacturers to produce much more powerful amplifiers that take up very little space. These amplifiers consume less current than their Class AB counterparts.

Computerized Source Units

Around 1980, we saw the first digitally tuned car radios. Mechanical tuning knobs and presets were replaced with vacuum fluorescent displays and electronic buttons. This would lead to computerized source units that included electronically controlled cassette players and equalizers with spectrum displays around 1982. By the late ’80s, with the growing popularity of CD players, having a microcontroller built into a car radio was commonplace.

Around 1992, companies like Alpine and Clarion were selling in-vehicle navigation systems that included LCD screens, and by 1993, digital communication solutions were available to transmit computer information to vehicles. In 1998, Clarion launched the AutoPC in conjunction with Microsoft to become the first in-vehicle computer. Modern multimedia receivers now run embedded versions of Windows and Linux operating systems.

The Apple iPod

The Apple iPod was introduced in the fall of 2001. The original compact digital media players were only compatible with computers running the Apple Macintosh operating system and as such, sales were limited. In 2003, the iPod 3G was launched with a standard USB port instead of Firewire, making it compatible with Windows-based PCs as well. By June 2003, Apple had sold 1 million iPods.

In June 2005, BMW announced that an iPod adapter would be available for the 3 Series, the Z4 Roadster, the X3 and X5 and the Mini Cooper, and was backward compatible to many 2002 models.

By 2005, the iPod was a popular solution for carrying thousands of songs, and Clarion launched its VRX745VD – a single-DIN multimedia receiver with a dedicated iPod interface. The iPod quickly replaced the CD changer as a means of storing a large number of songs in vehicles.

Bluetooth

Though incorrectly perceived as a hands-free and audio streaming technology, Bluetooth was created in 1994 as an alternative to RS-232 wired communication. Within the Bluetooth communication standards are dozens of profiles, including fax, cordless telephony, printing, file transfer, dial-up networking and of course, the hands-free and audio distribution profiles that we know and love! In 2002, the Audi R8 was the first to apply Bluetooth technology in a car. DaimlerChrysler, Acura and BMW joined in 2003.

Apple CarPlay and Android Auto

Since the very first car radios were built, people were concerned about them being a distraction. Turning the tuner knob to find a local station meant you weren’t focused on the road in front of you. In the late ’90s, we saw drivers with headsets and earpieces making phone calls while they drove. Adding a headset was a common purchase with a new phone. In the mid-2000s, Bluetooth communication replaced wired hands-free connections.

Data distractions took off in the late ’90s and early 2000s with the Blackberry. When smartphone technology took off in the 2000s, so did text messaging. We now had lots of ways to distract us from our driving duties.

Apple realized that the smartphone was as much of a problem as it was a solution in the early 2010s. In 2013, Siri Eyes Free was offered as a dealer-installed accessory for several Honda and Acura vehicles. In 2014, the Ferrari FF became the first new vehicle to come equipped with Apple CarPlay.

CarPlay is a software application that runs on the multimedia source unit in the vehicle and uses the Siri voice recognition engine built into the iPhone to allow voice commands to be executed. You can send a text message, make a phone call or choose the music you want by simply asking. Turn-by-turn navigation is also included.

The Open Automotive Alliance announced in 2014 that it would introduce a competing technology for Android-based smartphones called Android Auto. The 2015 Hyundai Sonata was the first OEM implementation of Android Auto. Few car audio technologies have rivaled the importance of CarPlay and Android Auto.

Technology for Safety and Entertainment

There have been hundreds, if not thousands, of milestones throughout the 100-plus years of automotive technology advances. These innovations are just a sampling of the way mobile electronics have evolved and changed. If you are looking for the latest and greatest car audio technologies, or simply want to improve the performance of your entertainment system, visit your local mobile electronics specialist retailer.

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.

(ipod photo:KAMiKAZOW [CC BY or CC BY 3.0-2.5-2.0-1.0 (https://creativecommons.org/licenses/by/3.0-2.5-2.0-1.0)], from Wikimedia Commons)

In our Bang for your Buck series, we talk about product features and component designs that offer increased value and performance. We’ve discussed source units and speakers, and now it’s time to take a deep look into amplifiers and what separates one amplifier from another.

Years ago, a prominent mobile audio enthusiast claimed that all amplifiers sound the same under strict test conditions. He even backed up the statement by offering a large cash reward to anyone who could pick one amp 10 times out of 10 under controlled listening tests. While there is value in his claim and it would be very hard to determine the difference between two amplifiers in blind testing 10 out of 10 times, that doesn’t mean that all amplifiers are the same. In fact, there are some big differences.

This articles focuses on two widely different areas of performance that many manufacturers refuse to discuss in detail: distortion and noise.

Is Power Important?

Does the ability of one amplifier to make more power than another determine its quality or performance capabilities? Well, if the less-powerful amplifier is driven into distortion, then certainly the more-powerful amplifier will sound better. While they’re operating within their rated power ranges, though, does maximum power matter? Not so much.

What’s this Damping Factor Thing?

For decades, manufacturers of high-end amplifiers have provided damping factory specifications. This number is a ratio of the output impedance of the amplifier to a specified load impedance. The story goes that an amplifier with a higher number would produce a tighter, more-controlled sound because the low impedance of the amp would short the back-EMF signal from the speaker.

Depending on your version of physics, the damping factor can be a large number, or a very small one – making it potentially relevant or a complete red herring.

For solid-state amplifiers, the damping factor or output impedance ratio is high enough that the load impedance has very little effect on the resulting frequency response of the system. For tube amplifiers with impedance-matching transformers, this isn’t always the case. Worrying about, or even considering, the damping factor is way down the list of concerns.

Background Noise

We’ve talked about signal to noise ratio in detail in our discussion of head units. It’s a big deal in a discussion of amplifiers and will rear its head again when we talk about signal processors.

Any electronic device creates unwanted noise when a signal passes through it. Even something as simple as a resistor creates a small amount of noise. In this example, it’s likely too small to be audible – but it’s there. In a complex circuit with gain (an increase in signal amplitude), creating unwanted noise is a common byproduct of questionable design.

How does noise manifest itself in an amplifier? It’s the background hiss you hear from your speakers when no music is playing. Ideally, you don’t want any noise adding content to your music.

If you have those really efficient PA speakers, then choosing amplifiers with excellent noise specifications is crucial. The speakers themselves offer 5 to 10 dB more output for a given input signal, so any noise that is present will be 5 to 10 dB louder.

Signal to Noise Ratio Specification

We’ve covered this before, but we are going to do it again now because it’s important. There are two ways manufacturers publish SNR or S/N Ratio specs: either rated to a specific output level (1 watt into 4 ohms) or relative to the maximum power production capabilities of the amplifier. You can’t compare the two directly, but you can estimate.

Let’s look at two full-range amplifiers. In this example, we’ll use a pair of similarly rated four-channel amplifiers. Amplifier A has a S/N Ratio published at -104 dB and amplifier B amplifier rated at -88 dB. Assuming the numbers are published using the same standard, amplifier A produces 16 dB less noise than amplifier B. Unfortunately, in this example, the -104 specification of amplifier A is published related to its rated power, while amp B is relative to 1 watt of output. Using the same specifications, amp A produces -84 dB of noise, 4 dB more than amp B.

Distortion Considerations

Distortion is, in the simplest of terms, the addition of unwanted information to a signal. Just as with noise, all electronic devices add some amount of distortion to signals as the signals pass through. In most cases, unless something has gone very wrong, the original signal passes through the device unchanged. Distortion is generated by the addition of unwanted information.

Harmonic distortion is the addition of multiple instances of the original signal. Many high-end home amplifiers are tested using a 50 Hz tone at rated power. Analysis of the resulting spectral content shows just how much unwanted information is produced.

The image above shows amazing performance from a very high-end solid-state home amplifier. As you can see, there is a little bit of 150 and 175 Hz content, but it is at almost -120 dB below the stimulus signal.

In this example, we can see the harmonics created in a high-end home audio Class D amplifier. A 100 Hz signal is present at a level of -85 dB and a 250 Hz signal is present at a level of -90 dB.

To really highlight the potential for unwanted behavior, we have included the spectral content of a high-end vacuum tube amplifier. You can see that there is spectral content at 100 Hz at a level of -42 dB, 150Hz content at -54 dB and 200 Hz content at -67 dB. This distortion would be audible during listening.

Intermodulation Distortion

Another kind of distortion is created when two signals passing through an amplifier interact with one another to produce distortion that is the difference between the two signals. The industry standard test for intermodulation distortion is to play a test signal that contains two sine waves – one at 19 kHz and a second at 20 kHz. Two things will happen when distortion is produced using these stimulae: Content will be created on either side of these tones and at a difference between them, i.e., at 1 kHz.

This graph shows a high-end home amp with excellent IMD behavior. The two side-bands are at -119 dB and would be completely inaudible.

This graph shows the same Class D as in the discussion of harmonic distortion. It is easy to see that the test stimulae created a significant amount of information. The peak is at -78 dB, so it’s not a complete disaster.

Shopping for a Car Audio Amplifier

Since nobody in the mobile electronics industry seems willing to submit their products for this level of scrutiny, how does one go about picking an amplifier that offers exceptional performance? The only way is through extensive listening. A handful of amplifiers on the market offer exceptional performance, and not all of them are expensive. At the same time, some very expensive amplifiers perform poorly.

If you want to find the best, then see if you can borrow that amp in question from a friend and put it into a reference system. If your music suddenly sounds warmer, that’s a sign that there is additional harmonic content. It is “nice” to listen to in some cases, but it is certainly not accurate.

Once you have developed a strong reference for accuracy, you will be able to pick out amplifiers that offer excellent performance. Your local mobile electronics retailer should have a demo vehicle that you can audition. Happy shopping!

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.

Shopping for a new car audio amplifier is tricky. There are thousands of amplifiers available from at least a hundred car audio companies. Picking the right amp for your system requires balancing an expectation of performance with the cost and features of the amp in question. In this issue of Bang for Your Buck, we are going to talk about car audio amplifier features that will make your audio system sound better and more enjoyable while maximizing your investment.

Amplifier Channels

Decades ago, you could choose from two- or four-channel amplifiers to power your audio system. Most people used a four-channel amp for the front and rear speakers and a high-power stereo amp bridged to drive a subwoofer or two. The rise in popularity of class D monoblock amplifiers in the ’90s replaced the big stereo amp on the subs with something more efficient, and often more powerful.

No matter how you divvy up the work, you are going to need multiple amplifier channels. Let’s look at two amplifier options for a starting point. A four-channel amplifier is extremely flexible. It can power your front and rear speakers, a set of components and a subwoofer or be dedicated to a set of components using active filters instead of passive networks. It’s rare that a high-quality four-channel amp can’t remain an important part of your system.

Another alternative for an amplifier is a five-channel model. In most cases, these amplifiers provide between 50 and 100 watts of power from the four main channels and 300 to 600 watts from the subwoofer channel. A significant advantage of these amplifiers is that they are housed in a single chassis. This design reduces the need for power and ground distribution blocks and simplifies installation.

Built-in Crossovers

When you are starting out on an audio system upgrade, you will want to take a close look at the crossovers built into the amplifier you are looking at. Assuming you go with a four channel amp, each channel pair will likely include crossovers that can be configured in a high- or low-pass mode. This crossover design makes the amp suitable to drive speakers or a subwoofer. If you plan on using the amp to drive a set of components in an active configuration (something that you should aspire to), then look for crossovers that can reach higher frequencies – in the 4 to 5 kHz range. If you are planning on using a digital signal processor to handle crossovers (another wise aspiration), then the crossover frequencies matter less.

Vehicle Integration Features

Upgrading a modern factory sound system can be tricky. In many applications, the source unit can’t be replaced. This means we need to connect to the radio or the amplifier. If you are planning on keeping your factory source unit in the system, then you will want to choose an amplifier that provides OEM integration features. First and foremost, the amplifier needs to be able to accept a speaker-level signal. Some amplifiers have dedicated connections for high-voltage signals. Other designs allow you to connect the factory speaker wires to the RCA inputs, then press a button to reduce the voltage to something that the amp can handle. A third popular option is amplifiers that include an RCA adapter that has circuitry built into it that reduces voltage.

The second feature you are going to want to look for is remote turn-on detection. Different companies have different names for this feature. In a nutshell, you want the amplifier to turn on when the factory stereo turns on. Amplifiers with automatic remote turn-on detection monitor the input connection for an audio signal or the presence of a DC voltage generated by BTL-type amplifiers in head units.

Remote Level Controls

If you are going to use the amp you have chosen to drive a subwoofer, then choose something that includes or has the provision for a remote level control. A remote level control is typically a small metal or plastic box with a knob sticking out of it. You can turn this knob up or down to increase or decrease the level of the subwoofer relative to the rest of the speakers in your car.

The best designs are attenuators. This means that at the maximum position, the amp behaves as though the knob isn’t connected. You can turn down the bass level by turning the knob counterclockwise. The reason this design is best lies in the process of how systems are tuned.

Ideally, try to avoid bass boost controls. If you want more bass, then you should want more of ALL your bass, not just those frequencies around 50Hz. Deep bass (below 30Hz) is a lot of fun!

Amplifier Power

Here’s another tricky subject that requires balancing a lot criteria. First, you can never have too much power available. With that said, depending on your speakers, you may have more power than you’ll ever be able to use. In almost every case, maximum amplifier power determines the size of the amplifier, and vice versa. A 1,500-watt subwoofer amplifier that will operate reliably on a hot summer day isn’t going to fit in the palm of your hand. If you are hoping to upgrade your audio system while keeping the equipment out of sight, then you will need to choose an amplifier that will fit under a seat or in a storage compartment.

In terms of speaker longevity, choose an amplifier that is rated at the same (real) power ratings as your speakers. If the system is set up properly, you shouldn’t have any reliability problems.

Amplifier Installation Accessories

The second-to-last step in choosing an amplifier for your vehicle is to choose the right installation accessories for it. No, we aren’t talking about chrome shrouds or lighting kits. Your choice of power wire can have a dramatic effect on the performance and reliability of your amplifier. It might sound like a sales pitch, but don’t be stingy with the wiring you choose. A $40 amp kit with 1,000-watts printed on the package may look like a deal, but do you think it will supply power to your amp the same way a $100 kit will?

Think of your power wire like the tires on your car. Inexpensive skinny tires work fine when you are cruising through town on the way to get the groceries. When it’s time to crank up the excitement, these tires fail to provide premium performance. A high-quality tire simply sticks to the road better, and in many cases, lasts longer. Power wire is the same.

Quality Installation and Configuration

Last and certainly not least is your choice of who will install your amplifier. Cars and trucks aren’t as simple as they used to be. Composite construction, aluminum, high-strength adhesives, computer data networks and BCM-controlled charging systems require that someone with extensive experience work on your vehicle. Assuming that your new car or truck is like every other vehicle they have worked on is a recipe for disaster.

A properly trained and qualified installation technician understands how to mount equipment safely and reliably. They understand the proper process to make electrical connections so that they are efficient and safe. Finally, they have a tried-and-true process that ensures every amplifier is configured to provide maximum performance and reliability. Choose whom you let work on your car very carefully.

Local Help With Car Audio Amplifier Features

When it comes time to upgrade your stereo system, drop into your local mobile enhancement retailer and ask about the latest car audio amplifier features. They will work with you to choose a solution that includes the features you want and provides the performance you desire.

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.

We recently talked about the difference between good and great speakers. In a nutshell, when you choose great speakers, you get more power handling, the potential for more output and dramatically improved clarity, thanks to a reduction in distortion. In this issue of Bang for Your Buck, we are going to look at two car audio speaker technologies that reduce distortion. This article will be a true behind-the-scenes look at how speakers work.

Current Flow and Magnetic Fields

According to Lenz’s law, when current flows through a conductor, a magnetic field is created around the conductor. At the same time, when we move a conductor through a magnetic field, a current is created in the conductor.

The diagram above shows a conductor (in grey) with a current flowing through it. The green lines show the direction of the magnetic field around the conductor.

In a speaker, the voice coil is a coil of wire wrapped around a bobbin or former. Current from our amplifier flows through this conductor and sets up a magnetic field around the voice coil. We use this property to move the speaker in and out of the basket. When the polarity of the magnetic field is the same as that of the fixed magnet, the similar magnetic fields repel each other, and the speaker moves forward. When the polarity of the magnetic field reverses, the speaker is attracted to the magnetic field and the speaker moves rearwards.

Unfortunately, when it comes to dealing with alternating current, the behavior of magnetic fields can work against you. When the polarity of the current reverses, it has to fight against the magnetic field it created. You can think of it as momentum. If marbles are rolling across the floor, it takes energy to make them change direction. This opposition to the change in the flow of current is called inductance. The electrical momentum resists the desire to set up a new magnetic field of the opposite polarity.

Managing Voice Coil Inductance

The amount of inductance in a speaker voice coil is determined by several factors. The size of the voice coil conductor, the geometry of the conductor, the number of layers in the voice coil and the proximity of the voice coil to the top plate and the pole piece – just to name a few.

So, how does inductance cause distortion in a speaker? As you can see in the diagram above when the voice coil winding (in red) is at rest, it is centered on the top plate (in green). As the cone moves down, more of the voice coil is beside the magnet (in blue) and the pole piece (in pink). Conversely, as the come moves outward, less of the cone is near the pole. In a conventional speaker design, the changes in proximity to the steel pole piece cause changes in inductance. As the inductance decreases, there is less opposition to the flow of high-frequency current and an increase in high-frequency performance. Changes in performance based on the position of the speaker cone result in distortion.

The image above shows the inductance of a voice coil relative to its position in the speaker. The red curve is the inductance graph of a conventional speaker. The blue curve is the inductance graph of a speaker that includes an aluminum shorting ring at the bottom of the T-yoke. As you can see in the image above, without the shorting ring, the speaker has dramatically different inductive characteristics depending on the position of the cone.The graph above shows the frequency response of a speaker without a shorting ring (in red) and that of a very similar speaker with a shorting ring (in blue). As is clearly evident, the inclusion of a shorting ring dramatically improves the high-frequency performance of a speaker. Further improvements in linearity can be achieved by including a copper cap on top of the T-yoke.

When you are shopping for great speakers, look for inductance-reducing caps on all speakers (subwoofers, midrange drivers and tweeters), and in larger speakers (subwoofers and midrange drivers) where the room is available in the motor assembly, look for the presence of a shorting ring.

Comparing Inductance Numbers

If we can’t determine whether a speaker has a design that mitigates changes in inductive characteristics, can we simply look at the specifications? They most certainly do provide a hint. A 6.5-inch woofer without a cap or shorting ring may have an inductance of 0.7 to 1.1 mH (millihenries), whereas a speaker with these technologies will be closer to 0.1 or 0.2mH. In terms of how they sound, all other design criteria being equal, the driver with the lower inductance will have better high-frequency performance and produce less distortion.

Speaker Suspension Nonlinearities

The purpose of the spider (also known as a damper) is to keep the voice coil laterally centered in the air gap between the top plate and the pole piece and to help return the cone to the resting position when the audio signal is removed.

Picking the perfect damper stiffness (compliance) for a given cone mass and desired resonant frequency is one of the biggest balancing acts involved in designing a speaker. If the spider is too stiff, the resonant frequency of the speaker may be too high for the desired application and its efficiency may suffer.

A variety of materials are available, as well as different sizes and different geometries. A spider is a spring. Some spiders are designed for linear compliance and some are progressive. More importantly, because of variances in voice coil winding height and basket design, some spiders include an offset mounting lip. This is called a cupped spider. This cup or spacer allows the spider to attach to the voice coil former above the winding, then connect to the chassis while keeping the voice coil vertically centered in the magnetic gap.

The above graph shows the suspension compliance of two different 6.5-inch diameter speakers based on the position of the cone. The graph in red shows the compliance of a speaker that uses a cupped spider. You can see that at 6.5mm of inward travel, the suspension is 25 percent stiffer than at 6.5mm of outward travel. The blue graph shows a similarly sized speaker with a flat spider. Though the overall compliance is different, the behavior in the forward and rearward directions is nearly identical.

What To Look For in a Spider

Ultimately, we want the spider to exert the same amount of force on the cone and voice coil as it moves forward or backward from the rest position. The amount of force should not change based on the direction of cone travel. Imagine the distortion created by a speaker playing a sine wave where the cone doesn’t move as far rearward for a given amount of current as it moves forward. As such, try to avoid speakers that use cupped spiders.

Hear Different Car Audio Speaker Technologies In Person

The next time you head to your local mobile enhancement retailer to listen to new speakers, choose two wildly different price points and listen to the same portion of a song on each speaker. Listen to them at a reasonably loud volume level, and position yourself across the room. Switch back and forth until you determine the differences.

Then, add a third speaker option, priced and featured somewhere in the middle. Make the same comparison with this new speaker and the expensive speakers. Once you have listened to the speakers, ask to look at a sample of each and see if you can correlate some of the design characteristics we have discussed with their performance. It’s not only a great way to audition products but to learn about what makes one car audio speaker technology or design better than another.

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.