Conclusion -

Using the guidlines presented in this paper to select the proper type of audio cable for a project will optimize system performance and in most cases reduce the overall cabling expense. The chart below lists some common audio cable applications and expamples of recommended product types.

Example Application Chart

Application: Speaker

Permanent Install:
SSC-122SSA105 12 AWG stranded BC twisted pair and PVC jacket

Portable:
Gepco GSC132 13AWG stranded BC twisted pair and TPE all weather jacket

Patching:
Gepco GSC122OFC 12AWG stranded OFC BC w/ transparent PVC jacket

Application: Instrument

Permanent Install:
N/A

Portable:
Gepco GLC20 20AWG stranded TC w/ 95% BC braid and semi-conductive PVC tape and flexible matte PVC jacket

Patching:
Gepco GLC20 20AWG stranded TC w/ 95% BC braid and semi-conductive PVC tape and flexible matte PVC jacket

Application: Mic/Line

Permanent Install:
Gepco 61801EZ 22AWG stranded TC twisted pair w/ 100% foil shield and PVC jacket

Portable:
Gepco M1042 20AWG stranded TC w/ 95% TC braid and TPE all weather jacket

Patching:
Gepco XB401 24AWG stranded OFC BC w/ 95% TC braid and flexible matte PVC jacket

Application: Digital Audio S/PDIF

Permanent Install:
Gepco VPM2000 20AWG Solid BC w/ 95% TC braid and 100% foil Shield and PVC jacket

Portable:
Gepco VE61859M 22AWG stranded BC w/ 95% BC braid and flexible matte PVC jacket

Patching:
Gepco VE61859M 22AWG stranded BC w/ 95% BC braid and flexible matte PVC jacket

Application: Digital Audio AES/EBU

Permanent Install:
Gepco 5596EZ 24AWG Stranded OFC BC w/ 100% foil shield and PVC jacket

Portable:
Gepco 5596M 24AWG Stranded OFC BC w/ 95% OFC BC braid and flexible matte PVC jacket

Patching:
Gepco 5596M 24AWG Stranded OFC BC w/ 95% OFC BC braid and flexible matte PVC jacket

Definitions

Wire : metal in the form of a usually very flexible thread or slender rod

Cable : an assembly of electrical conductors insulated from each other but laid up together usually by being twisted around a central core.

Conductor : a material or object that permits an electric current to flow easily

Insulator : a material that is a poor conductor (as of electricity or heat)

Current : a flow of electric charge; also: the rate of such flow

Inductance : a : a property of an electric circuit by which an electromotive force is induced in it by a variation of current either in the circuit itself or in a neighboring circuit b: the measure of this property that is equal to the ratio of the induced electromotive force to the rate of change of the inducing current

Capacitance : a : the property of an electric nonconductor that permits the storage of energy as a result of the separation of charge that occurs when opposite surfaces of the nonconductor are maintained at a difference of potential b: the measure of this property that is equal to the ratio of the charge on either surface to the potential difference between the surfaces.

Balanced Line : a : an audio transmission line where the signal is applied differentially between two conductors, each of which has equal impedances to ground or common.

Impedance : a : the apparent opposition in an electrical circuit to the flow of an alternating current that is analogous to the actual electrical resistance to a direct current and that is the ratio of effective electromotive force to the effective current

That's all for the moment, folks. Thank for reading & visiting. Would like to wish "Gong Xi Fatt Choy" for those who celebrate Chinese New Year & Prosperity year ahead.

The Fins

Choosing the Right Audio Cable

One of the most common types of cabling in professional audio systems is a shielded twisted pair. Generally used for mic and line level analog audio it can also be used for AES EBU digital audio. When using a shielded twisted pair for analog mic/line level signals, there are a couple factors to take into consideration, both of which relate to the cables flexibility and durability. We can break this down by the cables intended use. Generally for permanent installations the cable should utilize a foil shield with a UL listed jacket. These cables tend to be less flexible because of the materials utilized to make the jackets. Also, the foil shield offers a more cost effective cable. For portable or live use, the cable should utilize a braided shield, which offers a longer flex life. However, the jacket choice depends on the environment the cable will be used in. If the cable will be used outside it must have a jacket resistant to sunlight and water. This will make the cable less flexible. If the cable will be used for AES EBU signals the most important factor, yet again, is characteristic impedance. These cables should have 110 Ohm characteristic impedance.

A shielded quad conductor is generally used for microphone level signals where external interference is likely to be a problem. When terminated the conductors that are diagonally opposite are connected together. This is done to reduce EMI coupling by making the effective center of each conductor pair the center of the cable. This gives the cable a higher capacitance. Although the number of conductors and their physical relationship improves the cables EMI rejection, it does not make it useful for long runs. The most important aspect of this cable should be its shield. Since these cables are generally used for portable or patching purposes they must be flexible and utilize a braided shield for a long flex life.

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Cable Configuration -

Cable configuration is also a determining factor of function. The major types of cable configurations to be analyzed are a pair of parallel conductors, a twisted pair of conductors, a shielded single conductor, a shielded twisted pair of conductors, and a shielded quad conductor.

A parallel pair of conductors is generally used for a balanced signal with no ground (i.e. speaker cable). However, it can be used for an unbalanced signal with a ground and is generally used when the benefits of twisting are irrelevant such as AC power wiring. In the case of loud speaker cabling the most critical factor is the conductor size. It is important to use the appropriate size to minimize losses over length of run so the amplifier may still apply its control over a loud speaker’s driver. The primary factor is the total impedance presented to the amplifier by the speaker. This value is derived from the number of speakers their impedance and the cables direct current resistance described in Ohms/Mft. However, in most applications only one speaker is connected to one channel of an amplifier. This simplifies the equation and we can now use a general rule of thumb: the longer the cable the higher the resistance; in addition, the thicker the wire the lower the resistance.

Load Z Length of Run
<100’>100’

16 Ohms 16AWG 14AWG
8 Ohms 14AWG 12AWG
4 Ohms 12AWG 10AWG

As a simple reference the table to the left can be used to determine the wire gage necessary. If multiple speakers are connected to a single amp channel the effective load must be calculated first. Formulas for calculating the resistance of serial and parallel loads can be found in most basic electronic texts. However, in the case of high impedance loudspeaker systems or 70V systems wire gage is the key design consideration. For a 70V system, wire gages as small as 18AWG can be used to connect multiple speakers. This is due to transformers wired in parallel across the amplifiers output and an amplifier that provides a constant output voltage is used. A twisted pair of conductors offers the same functionality of a parallel pair with the additional benefit of common mode rejection. This makes the cable less susceptible to electro magnetic noise by reducing the loop area of the cable. When a signal is applied differentially between the two conductors it creates what is known as a common mode signal. Due to the signals equal yet opposite position relative to ground, the common mode signal will be attenuated.

Shielded single conductors (known as coaxial cables) can be used for a wide variety of signal types ranging from analog audio to digital video. The physical characteristics are crucial when choosing a single shielded conductor for video or digital audio. However, less demanding when used for instrument level or analog unbalanced audio. In the case of digital audio the characteristic impedance is the determining factor. If a cable is terminated at its characteristic impedance electronically it will appear infinitely long, consequently reducing signal reflections. The characteristic impedance of a analog audio to digital video. The physical characteristics are crucial when choosing a single shielded conductor for video or digital audio. However, less demanding when used for instrument level or analog unbalanced audio. In the case of digital audio the characteristic impedance is the determining factor. If a cable is terminated at its characteristic impedance electronically it will appear infinitely long, consequently reducing signal reflections. The characteristic impedance of a cable is determined by the relationship of the center conductor to the shield and the dielectric that separates them. For example, the characteristic impedance of an unbalanced digital audio cable (S/PDIF format) should be 75Ohms. In the case of unbalanced analog audio the cables shielding is important. These cables are generally used for instrument level signals as well as line level audio signals. Given that a single conductor offers no common mode rejection to electromagnetic coupling, the shield plays an important role of protecting the cable from EMI. However, this is not to say that shielding is unimportant for digital audio. In the case of instrument cabling, a semi conductive PVC tape is utilized as well as a shield to minimize handling noise.

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I came across these theory of...

Choosing the Right Audio Cable...

Determining what cable to use for different aspects of a system can sometimes be challenging. However, there are a few rules of thumb to follow when choosing what cable to use. First and foremost, cost does not determine quality. A lower cost cable may actually be more suitable for a given signal type and usage than a more expensive cable of the same type. In addition, there are many key distinctions among similar looking cables.

> The number of conductors
> The size and construction
> The geometry between pairs
> Shielding
> Insulation
> Jacketing

All of these parameters combined help determine the cables intended use. Because there are many different cable types, this article is limited to low voltage audio cables. Future articles will cover video and data cable selection criteria.

Number of Conductors -

When determining how many conductors are necessary, you are limited to either unbalanced or balanced. With an unbalanced connection at least a single conductor and a ground is required and with a balanced connection at least two conductors with or without a ground conductor is required. If interfacing between balanced and unbalanced, you require at least two conductors. However, complexity arises when mixed formats must be connected. With balanced and unbalanced terminals, there are numerous likely interconnection schemes. Ground loops and shorted outputs are possible problems.

Gage -

There are two major considerations for gage. First, is the conductor large enough to carry the necessary amount of current without overheating? Second, does the conductor offer an adequately low resistance over length so that losses are acceptable.

Conductor Construction -

The construction of the conductor relates to the cables flexibility as well as ease of termination. A solid center conductor is less flexible and more susceptible to stress over time. Cables with solid center conductors are better suited for permanent installation where the cable would remain in a raceway. This would limit the cables movement and reduce stress from flexing. A stranded center conductor is more flexible than a solid center conductor and offers a longer flex life. Cables using stranded center conductors are more appropriate for portable use, so the cable may be flexed often.

Insulation -

Not only is insulation a flame retardant, it protects the inner conductors from abrasion. However, its most crucial function is separation and symmetry. The spacing of the conductors determined by the insulation is known as the dielectric constant. It is the dielectric constant that determines the capacitance between signal carrying conductors as well as the shield. These capacitances combined with the natural resistive properties of the conductor(s) constitute a low pass filter. This means the larger the capacitance per foot, with a longer cable, the more high end roll off experienced. The shorter the run the less critical it becomes for analog audio. However, for runs over 100 feet a low capacitance cable should be used.

Shielding -

There are three main types of shields used in cable construction: braided, spiral, and foil. A braided shield offers the best structural integrity. They are flexible and have a long flex life. Braided shields are usually specified with a coverage area; however, this does not denote the amount of attenuation the braid offers, rather the physical coverage area of the braid. The number of strands, the grouping of those strands, the number of crossovers per inch, and the angle determine the braided shields effectiveness. In addition, a braided shield offers a lower resistance path to ground. This makes cables with a braided shield more appropriate for portable use. A foil shield can achieve 100% coverage and minimizes electromagnetic interference, particularly radio frequency interference. Again, the 100% is related to physical coverage and does not mean faultless EMI shielding. Foil shields are also more flexible than braided shields. However, the flex life for a foil shield is shorter than a braided shield. This makes foil shielded cable more suitable for permanent installation. Foil shields are usually combined with a bare drain wire to lower resistance and provide a simple termination point for the shield. A spiral shield has great flexibility and is easily terminated. However, over time flexing the spiral can spread it and cause a gap in the shielding. This leads to a short flex life, which makes a cable with a spiral shield appropriate for permanent installation.

Jacketing -

The jacket of a cable serves as a bundle and physically protects the inner conductors. This makes the criteria for materials used unique. In certain cases, the jacket material may be required to meet standards set by a governing body such as underwriter’s laboratory (UL). In this case, ratings are assigned to the jacket material which relate to its flammability. Cables with a UL rating of CMP, CL3P, and CL2P are considered to be plenum rated. This means that the cable is suitable for use in a plenum, which is an environmental air space or duct. Cables that have a UL rating of CMR, CL3R, and CL2R are considered suitable for riser use. This means that the cable is can be used in vertical riser shafts from floor to floor in a building. A cable with a rating of CM is considered suitable for general use. This means a cable is suitable for general purpose use, with the exception of risers and plenums. Each rating utilizes different mixtures of materials to craft the jacket. Plenum cables tend to be the least flexible, riser rated cable are flexible, but tend to have a memory, and general cables tend to be the more flexible. One of the most commonly used types of jacket material is PVC or polyvinylchloride. PVC is available in numerous blends customized to many applications. It resists most solvents, oil, flame, and sunlight. Although, standards like these have been set you must consult your local authority to determine the appropriate cable rating for the job.

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Three types of power supplies commonly used in Audio

Batteries...
Either “one time use” or rechargeable

Batteries, especially the rechargeable type, are pretty much an ideal power source for audio components if they are correctly sized. A battery is a reliable source of clean, quiet power. That is if the battery is large enough to power the component for a reasonable time without significant discharge. One problem is that the impedance of a battery increases as it discharges, the higher the impedance the faster the rise in voltage ripple. If the frequency of the voltage ripple is in the audio range then this can cause undesirable noise to be heard from the component.

Another obvious con for battery powered systems is the constant requirement for either replacement or recharging.

Wall Wart power supplies...
This is the little black box supplied with your Firestone Audio Component (FAC)

The standard wall wart power supply is a non linear, unregulated power supply; these are the simplest and least expensive solution for powering your Firestone product.

With the wall wart you have 120VAC going in and 24VDC coming out (assuming a stable 120VAC source). It includes a rectifier to convert the AC power to DC and a smoothing circuit to help tame the pulsating DC. Unfortunately there is still a significant amount of ripple on the DC side and the small space available in most wall warts limits the amount of filtering that can be used to reduce the ripple. The result is degradation in the DC power and a corresponding degradation in audio quality.

Another problem with an unregulated power supply is that the output voltage will rise and fall with changes to the input voltage. Any variation on the AC input side will be directly translated into DC variation on the output side. If your AC wall power has hash, surges, spikes, brown outs or some other ugliness; this will appear on the DC side as well and degrade the audio quality. These DC artifacts are known as noise and ripple. Fortunately your FAC is equipped with ”power regulation” and “low pass filter” circuits to help minimize the bad effects of this.

Last but not least is the low power output capability of the wall wart. Electronics that are “power challenged” tend to sound thin or flat at frequency extremes and don’t have the oomph to follow the peaks and large dynamic swings in the music. The FAC’s as with any audio component will draw considerably more current during intense passages in the music; this is when the wall wart may not have the jam to follow along.

Linear, Regulated Power Supplies...
This is the SUPPLIER Power Supply upgrade.

To help deal with the AC voltage variation and other assorted nastiness from the wall power, the Firestone engineers designed the SUPPLIER power supply. The SUPPLIER is a linear, regulated power supply so this means the DC output voltage is largely independent of the AC input voltage. It is designed to output a stable 24 VDC despite variances to the AC input voltage. Is it perfect? Of course not, but it’s a major improvement over the relatively large voltage swings seen at the DC output of a wall wart.

The Supplier also has vastly superior filtering for both DC ripple and noise. This is where you’ll experience a majority of the increase in sound quality; tighter bass, clearer highs and a better defined midrange. To my ear the biggest improvement is in the dynamic contrasts, dynamics are noticeably improved. Also, if your system can reveal it you’ll experience an increase in the magical, low level detail as the line noise and hash present with the wall wart are filtered away by the Supplier.

The SUPPLIER also has much higher power output and superior reserve power compared to the wall wart. Its high current output effortlessly follows the music regardless of dynamics and helps your FAC deliver the very best from the music.

So is it really worth the EXTRA COST?
YES, with one exception. If you are using the Fubar II with a low resolution system then the improvements may not be as apparent. I personally can detect the addition of the Supplier 100% of the time in my system in an A - B - A test; all I have to do is listen to the low level detail in the music.

Chao...

SUPPLIER Power Supply...Is It Really Worth the Extra Cost?

This is a great question and one we get quite often get. Many people just can’t understand how a power supply from TNB can help improve the sound of an audio component.

Before we talk specifically about the SUPPLIER Power Supply Upgrade lets talk a little about power supplies in general. If you look at the history of Hi-Fi one can see the continued progression of bigger, better and cleaner power supplies being added to high-end components. If you examine any high-end component you’ll find that clearly half the cost or more is in the power supply section. One could argue that improvements in electricity are the source of all improvement in Audio.

If you could order up the ideal power supply it would be one that provides unlimited current while the voltage remains perfectly constant. Nice in theory but not practical in the real world as every type of power supply has limitations that stray from this ideal. As with most any audio component, to power their circuits. They require a clean, free from any contamination, stable 240 volts AC to sound their best.

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