Increasingly home speaker companies that make outdoor speakers are borrowing a technology from the commercial A/V market called 70-volt/100-volt audio.
Utilized in the commercial A/V market to ensure signal reliability, 70-volt/100-volt speaker systems employ transformers that support the use of multiple outdoor speakers and long speaker cable runs without affecting system performance.
Today the growing popularity of outdoor speakers is driving the consumer audio industry’s use of 70-volt/100-volt speaker systems to allow professional integrators to strategically place outdoor speakers throughout a property to create evenly dispersed sound.
Homeowners can find their favorite speaker companies offering 70-volt/100-volt solutions, including brands such as Paradigm, Monitor Audio, Terra Speakers, Origin Acoustics, JBL, and many others.
So here’s a brief explanation from Terra Speakers on how they work and where you might consider using them.
What’s a 70 volt distributed audio system?
Amplifiers designed to drive typical, low impedance speakers (4, 6 or 8 Ohms) are constant current devices. The current delivered depends upon the impedance of the speaker load, but in order to make the system work properly with lots of speakers connected, you have to use series or series/parallel wiring arrangements and devices that maintain at least a minimum impedance load. If you don’t and the impedance drops too low, the amplifier will eventually overheat and (hopefully) protect itself, or worse.
However, if you choose an amplifier designed to drive a 70 volt line (or put a transformer on the output of a low impedance amplifier) and attach a matching transformer to each speaker, you create a constant voltage system that’s isolated from the combined speaker load impedance. In other words, you’ve eliminated impedance matching concerns. All you’ve have to do is ensure the amp can deliver the wattage needed to drive the connected speakers.
Here are some tips:
- AmplifiersIf you’re not already using an amplifier that has 70 volt outputs (like a Crown CDi 1000), you’re going to have to either get one or use a standard low impedance amplifier and purchase and install a transformer at the amplifier’s speaker outputs. These types of transformers have wattage ratings, so be sure you get one that can handle the total wattage you’re intending to distribute to all the speakers. However, it’s recommended that you simply use a 70 volt amp for ease of system design and installation.
- Watts, Watts, WattsYou no longer have to be concerned about impedance matching, but you do have to calculate the system’s wattage requirements. Each speaker in the system will typically have its own 70 volt to low impedance step down transformer. And each step down transformer will have several “taps” for connecting to the main 70 volt trunk line from the amplifier. The taps are marked in watts and which one you choose determines how loudly that particular speaker will play (and how many watts it’s fed), relative to the others in the system.
In order to determine the system’s total wattage you’ll need to add up all the watts, based upon the taps you’ve chosen for each speaker and the watts it will draw. Then you have to be sure that both the amplifier and the step up transformer you’ve installed at the amp (if you’ve used one) can deliver that amount of power.
The minimum required amplifier power is the number of speakers multiplied by the tap value. For example, using 6 speakers set to a tap value of 16W would require about 100W of power (6 x 16 = 96). However, it’s recommended that you use an amplifier with 20% more power than the minimum required; in our above example, about 120W. The formula for this equation would look something like this:
(tap value) x (number of speakers) + (20% – headroom) = total power required
So how do I decide which tap to use?
Let’s assume that you have step down transformers with connection taps rated at 4, 8, 16, and 32 watts. Note too that these are multiples of each other. Each higher number tap will deliver higher power to that speaker and in turn that speaker will play louder. So, if you’ve got a space that needs more acoustic power, simply choose a higher rated tap and bask in the glow of more. Or vice versa. If necessary, you can simply connect a speaker to the different taps in order to experiment with how much difference each tap appears to make using a particular model speaker.
Here are 5 70-volt outdoor speakers worth looking at:
Terra Speakers LS.10 Halo
The LS.10 is an integral part of the LuminSound series. It stands 10inches tall and contains a 5.25-inch co-axial driver in a totally weather tight enclosure. The driver is mounted at a 35 degree up tilt to ensure proper sound coverage even though the LS.10 will most often be mounted at ground level. Available in Black or Green, the LS.10 will visually blend well within landscaping and in combination LS.32/LS.10 systems.
Terra offers a Crown CDi 1000 DSP-capable amplifier for the LS.10 system so that all you will need to add is source equipment for a complete outdoor sound system.
JBL Professional Control 80 Series Landscape Speakers
The weather-resistant Control 80 Series Landscape speakers from JBL Professional provide 360-degree coverage. Designed to be mounted on or in the ground, the speaker is unobtrusive and easily blends in with its surroundings. A tough polyethylene enclosure resists abuse from lawn care equipment and the elements, and the enclosure color extends throughout the material so the speaker will maintain color even when scraped or scratched.
Origin Acoustics Seasons LS44
Sound that fills the entire exterior of a home can be achieved through multiple speakers that virtually disappear into the landscape. Several mounting options for the Origin Acoustics Seasons LS44, like spikes driven into the ground, produce full range musical coverage. Three sizes of subwoofers can be buried under the surface to support the lowest frequencies. The resulting effect is earthshaking bass and pristine high frequencies filling the environment with sound usually confined to indoor spaces.
Paradigm Garden Oasis System
The scalable outdoor audio system from Paradigm includes 4-inch and 6-inch satellite speakers, plus 10-inch and 12-inch subwoofers. Each satellite speaker can be switched between 8 ohm, 70-volt and 100-volt options. “Quick Connect” mounting and aiming options offer the flexibility to mount the speakers on the ground, on a deck rail, in a tree, or under an eave. The shell of each speaker has been engineered to withstand extreme temperatures, and with high UVB resistance will keep it from crackling over time.
Monitor Audio Climate Garden System
The Monitor Audio Climate Garden System comprises the Climate CLG140 satellite speaker and the CLG-W12 subwoofer ‘daisy-chained’ together in 70/100V line arrays of up to 12 satellites per subwoofer, expandable with additional satellite and subwoofer sets according to garden area.
Its super-discreet all-weather satellite / subwoofer design has been engineered for ground level installation among shrubs and trees to deliver a luxury blend of unobtrusive aesthetics and natural full-range audio in gardens of any size.