Modern aircraft audio systems are self-contained control boxes and can handle nearly every aspect of cockpit and cabin communications. They command the radios in the avionics stack, provide seat-to-seat intercom function and even offer high-fidelity music and telephone capability. But for basic aircraft, like the many LSAs and older tailwheel tandems on the ramps, a basic standalone intercom might get the job done for a lower cost while still providing high-quality audio and a decent level of functionality. These systems don’t control the radios, so if you have a couple of coms and navs in the stack, you’ll need an audio switching panel. Heres a review of available intercoms and as you’ll see, not all units and installations are created equal.
Get Sound Wiring
Installation costs should be pretty close among all the systems, except that a pre-fabricated wiring harness could save a few hundred dollars. Still, invoices that top two grand arent uncommon for two-seat jobs. Four-seaters cost more due to removing interior to route new wiring.
Using old and existing non-shielded wiring is a sure way to induce unwanted noise into the audio so every new intercom installation should include new wiring. Its just too critical an area to skimp on.
Electrical noise can be tough to avoid and it isn’t always the fault of the installer. Weak charging systems, alternator whine, faulty strobe light power supplies and even a single bad cell in the aircraft battery can induce noise. Entertainment input circuits are also common noise culprits. The older Garmin GPS396 XM Radio interface is known to require a ground loop isolator.
A few other key points: Put the microphone and headphone jacks in sidewalls, not the floor where dirt and debris can fall in, and passengers can step on the plugs. Place those jacks so the headphone plugs are recessed into the housing rather than sticking out at a 90-degree angle. Wed avoid drilling yokes that don’t already have push-to-talk switches. Get a high-quality switch that straps on.
PS Engineering
The hugely popular PM1000-series intercom put PS-Engineering on the map years ago and the TSOd PM1000II four-place intercom remains in the lineup. This unit has nearly all of the smart yet basic functions one could want in a stand-alone intercom including pilot isolate mode, independent volume and squelch controls for pilot and copilot, entertainment input and optional crew isolation, which isolates the front seats from the rear passengers.
If you want stereo sound you’ll need to step up to the PM3000 series, which is a six-seat model. It doesnt have the independent volume and squelch control that we like in the PM1000-series but it does have the same high-quality audio.
Spun off from the PM1000 is the PM1200 for high-noise cockpits. Weve used the PM1200 in an open-cockpit warbird and find it to be a flawless performer. It can be wired for voice activation or push-to-talk.
Flightcom
Well known for their Denali line of ANR headsets, Flightcom also makes intercom systems. In fact, the company has roots in intercom design after the founder struggled to hear his flight instructor while taking lessons during the 1980s. His portable design won our Product of the Year back in 1986. The modern no-frills units are designed for utility on a budget, and have a generous two-year warranty.
The model 403 stereo intercom can be interfaced for six seats and has pilot isolation and entertainment input. One feature we like a lot is the mono/stereo selection switch at each intercom station. This means installers can use stereo jacks all around but users wont need to worry about plugging in a mono headset that doesnt have a mono/stereo switch. The systems sell for $269.
The Flightcom model 403LSA is a two-place stereo and voice-activated intercom based on the same platform as Flightcoms flagship model 403 but pitched at LSAs. It has auxiliary music input with auto-muting and, for tight panels, there’s an optional faceplate for mounting in a 2.25-inch instrument hole. An optional 15-foot prewired harness simplifies the connection. The 403LSA was recently marked down to $199.
The model 403MC is marketed toward space-limited panels and owners on a budget with its $179 price. It could be the smallest intercom on the market measuring 2.6 by 2.3 by 1 inch high with the ability to mount vertical or horizontal in the panel. There are no bells and whistles, but it has pilot isolation, auxiliary input and failsafe circuitry design.
Sigtronics
Sigtronics has achieved success with the four-place SPA-400 and six-place SPA-600 intercom systems that date back to the early 1970s. There are a ton of these basic units still in service and you can buy them new. The SPA-400N/600N models are designed for high-noise cockpits.
SPA owners complain that there’s no entertainment input. But now they can add stereo capability (and crew isolation) to an existing SPA-400/600 intercom installation with the RES-401/601. The RES is an add-on system that wont require a major rewire of the old intercom, accepts input from nearly any remote device (iPod, MP3, etc.) and provides muting when a com radio is transmitting or receiving, or when the ICS squelch is opened. There’s also a karaoke mode for passengers.
The new two-place Sport 200 and Sport 200 S (stereo) intercoms are designed specifically for LSAs, ultralight and helicopters. Aimed at high-noise environments, the company claims theyre tested at ambient noise levels of up to 120 decibels. They can be used in either voice activation mode or push-to-talk intercom mode. These units are small, requiring 2.5-inches wide by one inch of vertical panel space.
The SAS-440 and six-seat SAS-640 are four- and six-place models that have a one-touch button to set the squelch threshold for a given environment, pilot isolation and multiple mounting schemes.
The SCI-series intercoms offer dual volume and squelch control and are a drop-in upgrade to an existing SPA400 or SPA600. The four-place SCI-4 and six-place SCI-6 offer dual volume and squelch control and three modes of operation: all, pilot isolate and crew isolate.
Sigtronics supports their claim that their units are RFI and EMI immune, even saying shielded wiring isn’t needed. Were skeptics on that, but applaud the company for designing intercoms to battle the sources of audio noise. We also like their five-year warranty on parts and labor.
NAT, GCA and DC
Northern Airborne Technologies (NAT) in Canada has perfected audio control for helicopter, special mission and airborne law enforcement applications. The AA-80 series intercom for general aviation applications is built to the same higher standard.
The unit comes with dual volume and squelch control plus entertainment input circuits The controls on NATs general aviation products are as rugged as they are in NATs higher-end products and are offered in various configurations and mounting schemes.
Weve found NAT audio quality to be excellent and reliable with squelch circuits that open and close nearly perfectly. We havent seen many NAT intercom failures, either. This always bodes well, in our view. We wouldnt have any problem putting a NAT audio product in our aircraft based on quality and performance alone. However, at $931 for the mono system and $955 for the stereo system, were not surprised that they arent big sellers in the GA market.
The $139 GCA-400A from Gulf Coast Avionics is a budget intercom that supports four seats and has pilot isolation and entertainment input. The unit can be mounted vertical or horizontal and comes with mic and phone jacks. Like the Sigtronics SCS, the folks at Gulf Coast warranty the GCA-400A for five years. Weve found the service at Gulf Coast to be exceptional.
David Clarks Isocom has been around for a long time and still remains in the headset-makers product line. Its bare-bones and is popular for yanking out of the panel to make room for something more modern. It doesnt have entertainment input or crew isolation. About the only thing we admire about the Isocom is its longevity (which usually says something positive about a product) and its ability to mount in a two-inch instrument cutout.
Conclusion
Before deciding on a standalone intercom, price a full audio panel installation, such as Garmins GMA 340 or the PS Engineering PMA8000 series. The additional capability of a full-up audio console may mean a better value-especially if advanced entertainment is part of your plan. These sophisticated audio controllers also offer room to grow if you add more radios or entertainment sources to the aircraft.
Keep in mind, however, that the radios in the main stack need to be interfaced, which will complicate the installation and add to the cost. But for aircraft that have original audio wiring left over from the 70s, this is likely the best plan. But for others with otherwise good audio wiring, a standalone intercom upgrade might be a good value.
