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Introductions
Rodney Rupp
Sales Application Engineer– Harman Professional
© 2013 HARMAN. All rights reserved. 1
The Gear – What’s The Difference?
Quality / Dependability Issues • 24/7 Usage
Warranty Concerns • Is Commercial Use Covered?
Performance Depth • Volume requirements / Paging Headroom
• System Functionality / Use of Microphones
Efficiency in Design • Low Z (8 ohm) vs. Hi Z (70 volt)
© 2013 HARMAN. All rights reserved. 3
Lets Look at the Low Impedance Way
Low Impedance means WHAT? • This refers to 8/4/2 Ohm Means of Connecting Speakers
– Conventional Home Stereo
• Requires Load Balancing if several speakers are needed
– Either additional Hardware required or Complex Series Parallel Connections
• Requires Large Gauge Conductors; copper is expensive!!
– Copper Costs UP 4X in just last 10 years
• Requires More of this High-cost Wire for Load Balancing
– More Home Runs
4 © 2013 HARMAN. All rights reserved.
Power Drawing
70/100V
(Amplifier)
Speaker Wire
Speaker
Transformer
Speaker
5 © 2013 HARMAN. All rights reserved.
There Must Be A Better Way…
Constant Voltage Speaker Systems • 25V Systems
– Used primarily in schools K-12
– Class 2 Wiring in the USA and no conduit required in most cases (Open cable is acceptable in most localities; check local standards adopted)
– Less loss and easier applications over 8 Ohm Series Parallel
• 70V Systems
– Used in many applications from Life Safety, Industrial, Medical, Stadiums, Education, Clubs, Themed Entertainment
– Class 2 Wiring in the USA and no conduit required in most cases (Open cable is acceptable in most localities; check local standards adopted)
– Less loss than 25V, as it is higher voltage
• 100V Systems
– Used in similar applications as 70V; more prevalent outside the USA
– Less loss than 70V, as it is higher voltage
– Must be in conduit in USA; voltage exceeds Class 2 Standards
6 © 2013 HARMAN. All rights reserved.
Constant Voltage Speaker Systems
Advantages
High Z Systems - 70V Systems; 100V Systems
• Multiple loudspeakers: Many loudspeakers can be driven by a single
amplifier without complex series/parallel connection schemes.
• Multiple power levels: Different sound-pressure-level targets can be
achieved at different listening areas while still using a single amplifier.
• Less expensive: Since the voltage of the signal has been stepped up
and the current is relatively low, lighter, less-expensive cable can be used
without incurring additional loss. Where a typical 8 ohm speaker system
might require 12 gauge cable, a 70 volt system could use 18 gauge or
smaller cable.
• System expansion: A 70 volt system can be expanded easily.
• Easy volume adjustment: A passive volume control may be installed to
give the user easy, level control over a single loudspeaker or a multiple-
speaker zone.
7 © 2013 HARMAN. All rights reserved.
Constant Voltage Speaker Systems
Disadvantages
25V Systems; 70V Systems; 100V Systems
• Distortion: Overdriven transformers can add distortion. Additionally, low-
cost transformers are prone to distortion at higher power levels. However,
distortion can be present in all types of systems. Proper engineering will
avoid these complications.
• Insertion loss: The transformers themselves commonly reduce total
power applied to the loudspeakers by 10-20%. At 1 watt tap, this
represents 1.1 to 1.2 watts.
• More expensive: Some local building and electrical codes may require
70 and 100 volt cabling to be carried within conduit, increasing the overall
project cost.
• Difficult troubleshooting: Since constant voltage systems tend to have
many speakers, locating the defect is sometimes difficult. If there is a
short circuit half way to the end of the circuit, sound can still be present in
the first half and it may not be obvious where the issue is.
8 © 2013 HARMAN. All rights reserved.
Which makes more sense? • Residential you can control or anticipate where the listener
will sit.
– We can expect that the stereo or surround image will benefit
the listener
• Commercial there is no control or anticipated location of
the listener.
– We would not want the user sitting under a speaker to only
hear one channel of content?
Therefore Home theatre = Stereo or Surround
Commercial Systems = Mono
© 2013 HARMAN. All rights reserved. 9
Restaurant & Bar
Floor Plan 6 Speakers Bar
4 Speakers Host
14 Speakers Seating
3 Zones
© 2013 HARMAN. All rights reserved. 13
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Restaurant & Bar
Low Z Method (Series Parallel) Series Parallel Network at Equipment Location
½ hr per speaker
8 hrs per 1000’ wire
¼ hr per termination@Rack
Approx 950’ cable required
Complexity = HIGH
© 2013 HARMAN. All rights reserved. 14
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Restaurant & Bar
High Z 70Volt Method All Speakers in each Zone in Parallel
½ hr per speaker
8 hrs per 1000’ wire
¼ hr per termination @ Rack
Approx 450’ cable required
Complexity = LOW
© 2013 HARMAN. All rights reserved. 15
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Restaurant & Bar
Which one looks easier?
Which one Saves you Install Time?
Which One saves you Cable?
Which one allows you to use smaller cable?
Which one puts more money in your pocket?
Do you Like More Money?
© 2013 HARMAN. All rights reserved. 16
Residential Home
© 2013 HARMAN. All rights reserved. 17
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Floor Plan 9 Speakers
1 Zone
Residential Home
© 2013 HARMAN. All rights reserved. 18
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Low Z Method
Look at all this Cable!!
Small Doctors Office
© 2013 HARMAN. All rights reserved. 20
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Floor Plan
1 Speaker and Volume Control per
Room
9 Speakers in Hallways for Sound
Control
Small Doctors Office
© 2013 HARMAN. All rights reserved. 21
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Low Z Method
Small Doctors Office
© 2013 HARMAN. All rights reserved. 22
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High Z 70 Volt Method
Residential Home
Which one looks easier?
Which one Saves you Install Time?
Which One saves you Cable?
Which one allows you to use smaller cable?
Which one puts more money in your pocket?
Do you Like More Money?
© 2013 HARMAN. All rights reserved. 23
Typical 70 Volt System Calculations
Control 29AV-1 Nominal Sensitivity 90db 1w1m
90db@ 3.3’
90 – 6db at 6.6’ = 84db
84 – 6db at 13.2’ = 78db So we have 78db @ 1 watt
Sports Bar and Grill Application = 90db SPL Goal
Ceilings at open to deck at 16’
Patrons are seated
16’ minus 3’ on average for seated patrons = 13’
13’ minus 2’ for speakers mounted at bottom of Ceiling structure = 11’ . Therefore we need our 90db Goal at 11’
© 2013 HARMAN. All rights reserved. 27
So now we need to calculate TAP for the speaker to hit our 90db Goal
Typical 70 Volt System Calculations
78db @ 1watt
78 + 3 = 81db @ 2watts
16 watts
81 + 3 = 84db @ 4 watts
84 + 3 = 87db @ 8 watts
87 + 3 = 90db @ 16 watts
So what is our tap to be set at?????
Typical 70 Volt System
You have a 500 watt per channel, 70volt amplifier • Crown CDI-1000
You have 44 speakers adjusted to 14 watts each • JBL Control 29AV Speaker (Sensitivity :90 dB (35Hz – 20kHz),1W, 1M)
• 44 Speakers X 14 watts each Divided into 2 zones = 308 watt load per
circuit
192 watts of reserve power (Future growth and
Headroom)
At 14 watts you could potentially use 64 speakers!
IT’S AUDIO BY THE ACRE!
Designing a System - Density Options - Square
Edge to Edge Minimum Overlap Full Overlap
Ceiling Speaker Coverage
Ceiling Speaker Coverage
© 2013 HARMAN. All rights reserved. 30
Square or Symmetrical Used to keep the ceiling
Looking Symmetrical.
Hexagonal or Alternating Can Save Some Money 14 vs 16 Speakers
Designing Commercial Systems for
Maximum Performance & Profit
Key Takeaways…
Specify commercial gear in appropriate applications…
Know when a 70 volt solution makes the most sense…
Understand and communicate the cost efficiencies and
profit opportunities that come into play…
Know the basics of calculating a Tap…
Understand speaker coverage density and turn it into an
opportunity…
Use the resources available to you from Harman…
© 2013 HARMAN. All rights reserved. 31
Troubleshooting
Why can’t I use my Ohm Meter? • Ohm Meter uses DC Voltage and on a coil will only
indicate the resistance of the actual wire, but not the
Impedance of the coil.
• Looks more like a short, as a “length of wire” and Not
As a COIL.
How do we check coils? • Impedance Bridge checks coils for Impedance at a
given frequency. (1Khz Typical)
If we are going to do the job, we need to
have the right tools!!
32 © 2013 HARMAN. All rights reserved.
Troubleshooting
Use the Bridge to check your entire load and use the
equation we learned earlier. E = Voltage Squared Divided
by Impedance • Lets say the Bridge reading states 125 Ohms
• 70.7 X 70.7 = 4998.49 (5000)
• 4998.49 divided by 125 = 40 watts on this speaker line
• Benefit is this checks both the wire/transformers/speakers and is the
actual wattage the amp will be loaded to.
• This takes the guesswork out of it!!
Note: Document your Bridge readings on your job documents so later, when
you get called back, you can look for the same reading. If it is not, then you
have an issue on speaker load.
33 © 2013 HARMAN. All rights reserved.
Troubleshooting
Shorts – How do I find the needle in the haystack? • Listen to the system and walk the system.
• IF it works but is much lower than expected, walk the speakers and listen
for a drop. Walk back a few speakers and split your circuit here.
• Take Bridge reading at this point on the open (not connected to amp) part
of the circuit. Does it represent what the load should be? Adding up Taps,
then using the Bridge reading. Are they approximately correct?
• Keep halving your speaker circuit, checking both ways without connection
to amp to find the short.
© 2013 HARMAN. All rights reserved. 34
Troubleshooting
Other cool tools for 70V and audio systems
in general • Music Supply Company TS-1A Audio Test Set
• Use it as a speaker, mic, check output line level, etc.…
• Best tool on the planet for checking audio systems
© 2013 HARMAN. All rights reserved. 35
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