Standalone Intercoms

In a glutted field with few standouts, PSEngineering, NAT and DRE are top picks.

Not long ago, instructors screamed across the cockpit at their struggling students and this was deemed more or less normal. Not anymore.

A cockpit intercom of some kind is an absolute must. For airplanes without intercoms, a portable adds an inexpensive touch of civilization to the cabin but with all the wires and plugs, portable push-to-talk switches and power cords cluttering the cockpit, why bother?

A panel-mount intercom is the way to go, with permanent PTT switches, preferably for both yokes. Virtually all of the late-generation audio panels on the market have built-in intercoms but not everyone wants to go that upgrade route. So in this article, we’ll take a look at the standalone intercom options, of which there are quite a few to pick from. In fact, the market is so glutted with these things that picking one out of the herd is a chore.

Hold On There
Before you invest obscene sums of money on autopilot upgrades and gee-whiz GPS, make sure the audio system is up to snuff. These days, the integration of several components can make up the entire audio system-the audio panel, intercom, entertainment source and, in some cases, active noise canceling interface modules.

Question 1: How will a new intercom tie into what already exists? Will the audio panel and intercom play together okay? If you need to wire all four places, how will the cost of that compare to biting the bullet and going with an integrated audio panel/intercom rather than a standalone?

Aesthetics is a major concern in custom audio installations. The jacks should be installed in convenient locations where they arent susceptible to damage. Common sense rules. We cringe when we see jacks flush mounted on an aircraft floor, inviting dirt to find its way into the hardware.

Mic and phone jacks that are improperly mounted into interior side panels can short and cause intermittence and expensive troubleshooting. Many jack enclosures are as attractive as they are rugged and worth the minor additional expense.

The advance of intercom technology has ushered in a few new gimmicks. Stereo sound-oh sure, left and right channel separation-has found its way into the small aircraft thanks to the ICS.

But don’t expect to be dazzled with amazing acoustics, given the level of noise in the average GA airplane. Between the wiring, the headsets and the din, few airplanes weve flown would allow the educated listener to distinguish between Lee Rittenours Fender in the left ear and Larry Carltons in the right. If your shop has qualified you as a candidate for an intercom-only upgrade-and you agree-the next thing to ask about is how many seats you want wired. Most modern intercoms will support four to six seats.

If you fly an aircraft with six passenger seats, you might really fly with only four or five filled, for performance and load carrying reasons. If you never use all the seats, why wire the stations? On the other hand, in a four-place airplane, spending the extra bucks for a six-seat model is wasted money. One important feature to look for in any intercom is independent volume and squelch control for pilot and copilot. There’s nothing more annoying than being a helpless rightseat occupant without a volume control when the pilot has the radio cranked up to the threshold of pain.

This difference in volume level may be related to differences in headsets or personal hearing disabilities and preferences. Also, the squelch settings may need to be different for pilot and copilot. Females on the ICS station may need more squelch triggering than a male and the presence of independent squelch controls helps. In most units that have independent controls, the copilots volume and squelch also controls rearseat stations.

One popular intercom feature is pilot isolation, which allows the pilot to cut out audio from the chattering passengers so he can hear ATC. The crew mode found on many intercoms is also useful but could be overkill for some applications. If you have a twin or heavy single that you use for charter or hauling around business associates, the crew mode is handy. This is an option on some systems so be sure to specify you want it wired during installation.

A related issue here: don’t assume that the shop will interface the system for music input. While many intercom systems allow for music input, make sure the one you have in mind allows for it and that the shop knows you want it wired.

Physical size of the box itself may matter. The panels that come through our shop are loaded with all kinds of gear and the space required for even the smallest intercom may be tough to find.

The intercom is generally thought of as a set-and-forget box so mounting it on the copilot panel or down low on the panel shouldnt be a problem. But in some panels- an older Mooney, for example-you could be looking at major rework to accommodate even the smallest intercom. If this is the case, see the sidebar on the argument for an integrated audio/ICS.

As far back as we can remember, Sigtronics has been a popular player in aircraft intercom. The SPA400 was a small no-frills intercom system, of which we see plenty, especially in older airplanes that havent been upgrades. The current production SPA-4S is a four-seat capable ICS with input for stereo music. Again, no frills; it takes over where the SPA400 left off but adds the music input. Its market is sport aircraft that might be tight on panel space. There’s no pilot isolation, no independent volume and squelch, just a basic low-cost intercom that might be a good choice for a Citabria or Decathlon, for example.

The higher-end Sigtronics product is the SCI-4 (or SCI-6 for six-seat interface). These systems offer dual volume and squelch control, music input and pilot isolation, crew isolation and an interesting squelch setting feature. Squelch indicator lights help in fine tuning squelch thresholds for pilot, copilot and passengers, something that might come in handy.

The SCI series is quite small and designed as an easy upgrade for the SPA400. If you want dual music inputs for front and rear, the SCI-S4 (or SCI-S6 for six-place) is the unit of choice.

Sigtronics certainly has the experience and proven reliability in aircraft audio. That said, we don’t necessarily agree with Sigtronics claim that due to the superb engineering, there’s no need for shielded cable. Shielded cable is a must in any intercom installation, in our view, and weve chased enough snaps, crackles and pops to know.

Any imperfection in the aircraft charging, electrical system and other on board equipment (strobe and beacon power supplies, for example) can show up in the intercom system. In fact, if you have an intercom installed you could hear these imperfections for the first time.

The five-year warranty on Sigtronics is impressive, even though repair incidence and costs on intercoms are both relatively low.

PS Engineering
These guys are the founding fathers of modern intercom systems. The PM1000 intercom is probably the most popular full-featured intercom in the field. This unit set the standard for panel-mount ICS, with pilot isolation, crew isolation, dual volume and squelch control and dual music input. The PM1000 evolved into the PM1000 II, with TSO approval, many improvements and a ton of options.

Supporting up to four seats, the PM1000 II is available in different flavors for aircraft with high noise levels-warbirds and helicopters, for instance. Separate pilot and copilot transmit capability is a function that can come in handy in a training environment.

The only voice heard during transmission is the one keying the push to talk switch. In other words, if the pilot is transmitting and the student or passenger starts speaking, only the pilot (the one keying) is heard at the other end of the transmitter.

A red light illuminates on the front panel indicating when a transmitter is keyed, which is helpful in detecting a stuck mic. The light turns green when the ICS is on, serving as a power indicator. The PM series is also available in a horizontal or vertical-mounting configuration.

If its stereo sound you want, the PM3000 series is the box of choice. The PM3000, however, doesnt have independent volume and squelch. The PM3000 is also capable of supporting six-seats, with dual music input.

With all the PM series of intercoms, you have the option of getting the digital readback recorder, a continuous loop handy for playback of IFR clearances. It works we’ll and doesnt waste storage space by recording dead air.

Worth a brief mention is the PM501, a basic no-frills four-seat intercom, which has been a popular low-cost install in training airplanes. Like the rest of the PS product line, its audio quality is quite good.

David Clark
The six-seat capable David Clark DC-Com Model 500 is a high-end intercom with more features and functions than the average small aircraft needs. There are independent volume and squelch controls for pilot and copilot. The unit is fairly large in size (1.7 inches high) so its not the best option for tight panels. Like the PS products, it can be mounted vertically or horizontally. We like the music-input jack mounted in the face of the unit, eliminating the need for a remote minijack.

The com 1, com 2, com 3 selector switch on the unit is an interesting although sometimes confusing feature. When in the com 1 position, the pilot and copilot can transmit and receive on the primary com radio. When the com 2 position is selected, the pilot transmits and receives on com radio 1 while the co-pilot can transmit and receive on com 2. In the com 3 position, pilot and co-pilot transmit and receive on com 2. Got that?

The system is true stereo capable but during installation, internal wiring jumpers must be configured for stereo.

Not a big deal, but a detail for the installing shop. There’s a crew mode that, in our view, is a must for this system, since its the perfect candidate for higher-end aircraft and helicopters. Like all of the David Clark product line, this system is rugged and with a definite high quality feel, with crisp audio and precise squelch operation.

The industry standard in helicopter audio control switching and related equipment, NAT (Northern Airborne Technologies) sets the standard in ruggedness and high-quality feel.

For general aviation aircraft with high-end quality, the NAT AA80 series is full featured (with many variations) with independent pilot and copilot volume and squelch, pilot and crew isolation and music input.

The flexible mounting options of this series makes it a convenient choice for most panels. There’s a horizontal and vertical mount, through-panel mount or standard clock cutout mount. The AA85 series takes entertainment control to a higher level with crew music muting, passenger music muting and music volume controls. These features may be desirable for some but might be overkill for anyone looking for basic music input capabilities.

In any case, any of the NAT products will serve we’ll with high quality and exceptional sounding audio for intercom that don’t cost a lot of money.

DRE Communications
An interesting unit that probably doesnt get the marketing attention it deserves is the Symphony 468, by DRE Communications. This box, which resembles an audio panel with its touch button controls, has a high-end look and some nice features.

More common in mucho-seat airplanes (some will handle up to eight seats) it offers fantastic audio, even concert hall quality music if used with the companys matched headsets. And the pilot can select which music source is muted when ATC radio activity is active; this sing- along mode is a must-have feature in corporate jets and such.

What we like most about this system is its liberal interface with stereo or mono headsets. With most other systems, the installation of stereo phone jacks is required for headsets operating in stereo mode only. The other alternative is to install a stereo/mono selector switch on the panel-not a great idea in our view as this could be a future failure point.

The remote operating mode switch-which can be mounted on the control yoke-can come in handy for selecting the numerous functions such as the music input and isolation. A stuck mic alarm lets you know when youre inadvertently leaning on the PTT. This system can be had with an airborne phone and clearance recorder option.

But if you don’t have a Cheyenne or multi-seat Caravan to put the Symphony 468 in, consider the DRE-244e six-place capable system, which uses similar logic. We reviewed the DRE-404 portable unit shortly after it appeared and found it to be a winner. The model 244 panel mount can also be interfaced via a remote mode selector switch and has stuck mic alert, sing-along mode and pilot isolate. No independent volume and squelch, however.

Flightcom, Softcomm
Two other lines are worth mentioning: Flightcom and Softcomm. Space-challenged panels might benefit from the Flightcom ICS. Some have even complained that the unit is too small.

The model 403d is a stereo six-place with a 32-second readback recorder mounted in a separate control head, so in this configuration, it isn’t the smallest. No independent volume and squelch is provided but just basic pilot isolation. The mono only, four-place model 403mc is perhaps one of the smallest out there, requiring just 2.5 inches of depth behind the panel. These specs might not seem important but in some airplanes, a box this small may be the only option, due to space. Selectable auto muting allows the pilot to configure the music input mute: ATC radio can be set to mute intercom, music or both.

In the business for many years making headsets and portable intercoms, SoftComm recently ventured into the panel-mount intercom market with what appears to be a carry over from the portable.

The ATC series is available in mono or stereo and two-, four-place and six-place versions. They ship with a pre-tested wiring harness and jacks and have 9-volt battery backup feature thats intriguing but of limited value, in our view. If you suffer an electrical failure, the least of your worries is talking on the intercom.

Softcomm says installation is 2.5 hours for the two-place version but were skeptical of that. Every installation is different and a customer with a wiring mess behind the panel may be shocked when told itll take 10 hours to install the intercom.

Our research revealed something interesting about this market: Despite the fact that its on the wane due to encroachment by integrated ICS offerings, there are so many choices that its all but impossible to pick a standout winner.

Our advice is to list the features you think are important-see the chart on page 9-then shop price, asking your shop for an estimate on installation. In terms of raw performance, these intercoms are very close in capability.

That said, we lean toward picks from PS Engineering and NAT, simply because both companies have been in the intercom field awhile and tend to remain at the cutting edge in audio circuitry. Both also provide good technical support during installation, which is always welcome in a busy shop. DREs offerings-especially the 244E-are quite impressive as we’ll but the Symphony 468 is too pricey in this crowd, except for high-end aircraft and serious stereophiles.

We don’t mean to diminish offerings from, Flightcom, SoftComm, David Clark or Sigtronics, all of whom make excellent intercoms. But at some point, you have to make a decision and ours would start with PS, NAT and DRE, in that order.

Also With This Article
Click here to view “Why A Standalone Makes Sense.”
Click here to view the Checklist.
Click here to view Addresses.
Click here to view Intercoms Compared.

-By Larry Anglisano

Larry Anglisano is an Aviation Consumer avionics editor and a consultant for Exxel Avionics in Hartford, Connecticut.