Adcom Speaker Selector Systems
Now with Adcom's GFS-3 and GFS-6 speaker selectors you can fill your home with sound at the push of a button Both selectors offer the security of Adcom's unique Minimum Impedance Protection-a design that fully protects your amplifier from almost any problem it might encounter when asked to simultaneously drive multiple speakers. And Minimum Impedance Protection does so without compromising the basic performance of your sound system! How very like Adcom. And how very unlike the competition.
Of course, the inspiration for this innovation comes from Adcom's long experienceand substantial success in producing high performance, high fidelity power amplifiers. Part of the knowledge gained over the years is an intimate familiarity with the demands loudspeakers place on any amplifier and the magnified demands created by a multiplicity of speakers. Our design goal quickly became not to just deliver sound to multiple speakers but to maintain the signal's sound quality as more speakers are added.
Adcom's user-selectable Minimum Impedance Protection circuit on both GFS-3 and GFS-6 Speaker Selectors insures accurate and musically pleasing sound regardless of how many pairs of speakers you may want to drive simultaneously. This "security system" inserts massive protective resistors between your amplifier and speakers to insure that the load impedance is always within your amplifier's safe operating range. This low-impedance protection enables your amplifier to drive several speaker systems simultaneously without activating the amplifier's protection circuits or causing amplifier shut-down.
In addition to Minimum Impedance Protection, both the GFS-3 and GFS-6 feature wide-contact, heavy-duty switches capable of handling the full output of even a 200 watt per channel amplifier. High-quality circuit boards with wide signal traces contribute to minimal power loss. Each speaker selector is easy to connect with twist-lock input and output terminals which insure positive contact with both speaker and amplifier cables and prevent accidental disconnection.
Both the GFS-3 and GFS-6 Speaker Selectors should be wired between your amplifier's outputs and your loudspeakers. (See the illustration.) The GFS-3 accommodates up to three pairs of speakers while the GFS-6 will permit you to use up to six pairs.
Expand the versatility of your audio system with Adcom Speaker Selectors and you'll hear a difference. It's in the details.
Why you need minimum impedance protection
Amplifiers are designed to operate efficiently into a certain resistance or "load". Loudspeakers usually present a reasonably high resistance (4 to 8 ohms) when they are measured on a test bench at mid-frequencies and are consequently easy for most amplifiers to drive. However, many loudspeakers are much more difficult to control in real-world use as their impedance or load drops substantially-sometimes to even lower than 2 ohms. Under these conditions, an amplifier must supply large amount of current to the loudspeakers to maintain effective control. Although Adcom amplifiers excel under these difficult conditions, most competitive amplifiers do not and produce audible signs of distress as their internal protective circuitry either reduces power output (and increases distortion) or simply shuts the amplifier down completely.
Multiple speakers compound the problem even further by decreasing the load seen by the amplifier. If one speaker presents an 8 ohm load, two speakers connected in parallel (the sonically desirable method) will combine for a 4 ohm load. Add another speaker and the load drops to almost 2 ohms. Here, audible and distinctly unpleasant distortion will probably intrude on the music regardless of playback volume. That's a situation you need to avoid and Minimum Impedance Protection is one detail of both the GFS-3 and GFS-6 you'll benefit from time and time again.
The GFS 4 is truly an audiophile grade loudspeaker switching system. It is designed to be the best product of its type regardless of price. Both in design and construction the GFS-4 exemplifies the attention to details that distinguishes all Adcom products.
The first design goal for the GFS-4 was that it not influence the musical signal at all. Extensive analysis, both theoretical and through demanding listening tests, preceded all parts selection. Connectors are the same heavy-duty, gold-plated solid brass, 5-way binding posts usually found only on the finest quality instrumentation grade equipment. Extremely low internal resistance, less than 0.001 ohms and well below even the contact resistance of the amplifier output connectors, contributes to minimum power loss as does a glass-fiber-epoxy (NEMA FR-4 grade) circuit board with wide signal traces. The critical internal wiring is heavy stranded cable (12AWG) made of Oxygen Free Copper to insure signal integrity while massive nickel-plated-copper ground buss-bars insure the lowest connection resistance between grounds.
Designed to be wired between your amplifier and up to four pairs of loudspeakers, the GFS-4 will not degrade the damping factor of any amplifier. All measurable signal parameters are the same at its output as at its input. This allows easy comparisons between the finest speakers or simply the finest sound quality in many rooms. Simply press the appropriate front panel button for speaker selection.
Adcom wants you to enjoy your fine audio system to its maximum potential. The GFS-4 provides you with the capability to easily and safely fill your living or working spaces with music. Now you can listen to all the details. Even the small ones.
Adcom Speaker Selector Specifications
Adcom GFS-3 Dimensions
Adcom GFS-4 Dimensions
Adcom GFS-6 Dimensions
All Specifications subject to change without notice.