Audio CalculatorsA collection of convenient, easy-to-use audio calculation tools from Extron

XTRA™ Series Energy Usageand Thermal Dissipation

Enter the type and quantity of XTRA Series amplifiers required for your project. This tool will calculate the total input power, heat load and the required cooling.

To calculate the number of ceiling speakers required for your project, enter the room dimensions, Extron ceiling speaker model, anticipated type of playback content, and allowable variance in sound level between speakers. Results can be viewed and printed by selecting the VIEW/PRINT COVERAGE MAP button in the Results section. The Ceiling Speaker Calculator also determines the amplifier power necessary to drive the speakers.

For best performance, use Google Chrome, Mozilla Firefox, or Microsoft Internet Explorer Version 9 or later.

These are a series of audio calculators that sound system designers, engineers, and technicians frequently need to access, such as determining amplifier power requirements, converting between dBu and dBV or volts, or estimating the loss in sound pressure level with an increase in distance. All of the easy-to-use calculation tools are accessible right here by clicking on any of them above.

What It Is

Extron XTRA Series amplifiers are highly efficient Class D amplifiers that draw less power than conventional amplifiers. As ENERGY STAR qualified amplifiers, they also automatically enter a very low power "sleep" mode after 25 minutes in which no signal is present at the input. System designers frequently want to know the energy usage of a rack of amplifiers, as well as how much cooling will be required. Since amplifiers generate significant waste heat, this is a key factor.

This audio tool calculates the total input power draw, thermal dissipation or waste heat, and the required cooling for a collection of amplifiers. Up to four types of Extron XTRA™ series of amplifiers can be selected. Select the line voltage for the region in which the amplifier will be used, select the type and quantity of amplifiers, select the desired speaker impedance for amplifiers with low impedance outputs, and then press Calculate.

Essential Formulas

Power Draw and Thermal Dissipation figures at 1/8^{th} power output are taken from the XTRA Series amplifier product specifications found at www.extron.com.

Cooling Required follows the industry practice of measuring air conditioning cooling capacity in tons. The required capacity is calculated by dividing the BTU/hr heat load by 12,000.

Annual Calculation assumes amplifiers are operating for 2,080 hours at 1/8th power, and 6,680 hours in standby mode.

For more information, see the white paper at www.extron.com/xtrapaper. Please see the XTRA Series User Guide for proper amplifier spacing requirements.

What It Is

Sound system designers frequently want to know much amplifier power will be needed to deliver adequate sound pressure levels for the application. This can be determined based on the desired listener distance from the speaker, the desired sound pressure level of the audio at this distance, and the loudspeaker's published sensitivity rating to provide the reference acoustical output at 1 watt at 1 meter. For Extron speakers, use the dropdown box and select the desired Extron speaker to automatically load its sensitivity into the calculator field. Additional headroom should be added for the amplifier, for example, 10 dB, to account for variability in program audio levels.

This audio tool calculates the acoustical attenuation from the reference location of 1 meter (3.28 feet) to the listener, and then applies this, together with the sensitivity rating and amplifier headroom, to determine the necessary output power from the amplifier.

Essential Formulas

APR = 10^{((LP + H – LS + 20 log (D2/ DR))/10)}

Where:

APR = amplifier required power

L_{P} = required SPL at listener

H = desired amplifier headroom

L_{S} = loudspeaker sensitivity at 1 watt and 1 meter

D_{2} = distance to farthest listener

D_{R} = 1 meter or 3.28 feet reference distance

What It Is

Volts, dBV, and dBu are three units describing voltage levels that are used interchangeably in professional audio based on the point of reference. This audio tools provides a quick and convenient means to convert between them. dBV refers to a voltage magnitude referenced to 1 volt, while dBu is referenced to 0.775 volts.

Essential Formulas

dBV = dBu - 2.21

Volts = 10^{(dBu / 20)} x 0.775

dBu = dBV + 2.21

Volts = 10^{(dBV/20)}

dBu = 20 log (Volts/0.775)

dBV = 20 log (Volts)

What It Is

Sound pressure level - SPL decreases 6.02 dB as a listener's distance doubles from the sound source. This number is commonly rounded down to 6 dB. The opposite is true as the listener halves the distance to the source, so that the SPL decreases or increases by 6 dB with every distance doubling or halving, respectively. The Inverse Square Law is used to calculate the change in SPL with distance, and is useful in predicting the sound pressure level a listener will experience as speaker placement and sound levels are considered.

Essential Formulas

L_{N} = L_{R} - 20 log (D_{N}/D_{R})

D_{R} = reference distance

D_{N} = new distance

L_{R} = SPL at reference distance

L_{N} = SPL at new distance

What It Is

Ohm's Law describes the relationships that exist between voltage, current, and resistance. Quantities of these properties are expressed in volts (V); amperes, "amps" (A); and ohms (Ω) respectively. The product of voltage and current is the applied power and is expressed in watts (W).

Essential Formulas

E = IxR

W = ExI

What It Is

A change in power, from P_{1} to P_{2} can be expressed as a ratio in decibels with the equation dB = 10*log(P_{2}/ P_{1}) . A doubling in the power level translates to a power ratio of 3 dB. Similarly, halving the power equals a -3 dB power ratio.

Essential Formulas

dB = 10 log (P_{2}/P_{1})

What It Is

A change in voltage, from V_{1} to V_{2} can be expressed as a ratio in decibels with the equation R_{V} = 20*log(V_{2}/ V_{1}). A doubling in the voltage level translates to a power ratio of 6 dB. Similarly, halving the power equals a -6 dB voltage ratio. This calculator can also be used to express differences between two distances or pressures.

Essential Formulas

dB = 20 log (V_{2}/ V_{1})

What It Is

Sound system designers and sales engineers need to know how many ceiling speakers are required for proper coverage in a given application. Each environment is different based on the room dimensions and ambient noise. Consideration must be given to the listener height, audio program content, desired SPL - sound pressure level, and how much the client will tolerate sound pressure level variances throughout the space. Since speakers are often tailored for specific applications, their design and performance play a major role in determining quantities and positioning.

This audio tool utilizes a database of speaker coverage angle values for Extron ceiling speakers, based on the type of audio content and amount of SPL attenuation. Speaker performance data for traditional polar plots were normalized and then linearized onto a horizontal plane to calculate sound pressure levels for standing or seated listeners. This tool also provides power recommendations and transformer tap settings based on speaker sensitivity data and desired SPLs.

Where:
R_{C} = Radius at coverage angle and listening plane
H_{C} = Ceiling height
H_{L} = Listener height
A = Coverage angle at isobar
D_{C} = Distance from speaker at coverage angle and listening plane
ΔL_{A} = Distance loss for listener on-axis (inverse square law)
D_{R} = 1 meter or 3.28 feet reference distance
ΔL_{E} = Distance loss for listener at isobar
L_{MINREF} = Minimum target level on-axis at reference distance
L_{MIN} = Minimum needed level for listener at isobar
Isobar = Boundary with a specified SPL attenuation
L_{MAXREF} = Maximum target level on-axis at reference distance
L_{MAX} = Maximum target level for listener on-axis