In 1991, Kevin Knoll, P. E. a life-long stereo enthusiast and designer began hosting customer/dealer/distributor focus sessions on the subject of multichannel amplifiers and controllers. During these events, it became very apparent that there was as urgent need for no-frills, super dependable 8 and 12 channel multichannel amplifiers. Class AB was an easy selection because of its superior sound quality over every other class but class A. Inefficient class A designs were never really considered due to their horrible impact on the environment as well as their crazy expensive manufacturing and operating costs.
A multichannel amplifier is defined as a device that houses multiple amplifiers such as 3, 4 or 6 stereo amps or as many as 12 individual amps in one box. These are primarily used in commercial and larger residential installations where multiple rooms or zones need individual control over the music playback system. About 60,000 multichannel amplifiers have been sold by Knoll since 1992. Kevin Knoll is now working with Hafler to substantially upgrade the legacy Knoll multichannel amps and is introducing many refinements unique to Hafler.
Dependability in an amplifier - especially a multichannel amplifier - is probably the most important requirement. From the very beginning, these multichannel amps were designed with bullet-proof dependability by making sure that all of the safe operating area (SOA) parameters were not only in the safety zone but not even close to the edge. Over the years, these amplifiers have enjoyed the lowest number of returns of any of the major selling brands. We recently had a return of a 12 channel amplifier used in an orange grove in the Orlando Florida area where it was playing classical music 24/7 to the orange trees! This amp was in use since our first year of production in 1992 (24 years so far). The amplifier was working but was making a cracking noise on all channels. We replaced the capacitors in the amp and sent it back to a very satisfied customer!
In a more complex installation such as that requiring one or more multichannel amps, it is imperative that the installer establishes the signal flow and sets the gain structure for each of the audio amplifiers. The installer does not want the operator fiddling with the system, thus triggering an expensive service call. Ideally, the amps should be ‘set and forget’ unless something major is changed in the system. One of the many features incorporated in these amplifiers are the rear-mounted controls. These are purposely out of view of the owner-operator to save them from harm’s way!
Initially the amps had 5-way binding posts to connect the speakers. Dealer and installer focus groups did not like these because it takes time to install 16-24 speaker wires and when the amp gets pushed into its permanent operating position, sometimes one or more wires would pop off. Overwhelmingly the request for detachable Euroblock (Phoenix® style) connectors were asked for and we revised the design. Hafler is going one step further by offering an optional tie-down bar, completely eliminating unintentional wire detachments!
There are a number of other refinements in the Hafler CI Series: Dual mains voltage with a 115V ~230V switch allows the same inventory to be used in jurisdictions around the globe. To aid during setup, rear mounted LEDs plus a handy 3.5mm input allows the installer to locally source and monitor signals during the installation process. This is augmented with both signal presence and peak LEDs for each channel on the front panel.
Probably the biggest added feature by Hafler is the energy saving ECOSYSTEM™. After playing, the amplifier automatically turns itself off in a minute or so without any speaker ‘clicking’ noise. This saves energy and of course money. ECOSYSTEM will pay for itself in energy savings in a few years in both amplifier energy reductions and the associated costs to air condition the generated heat out of the room. When required to amplify sound, the amp turns itself on in about 10ms (1/100 of a second) without missing a beat. REMARKABLE! With the ECOSYSTEM now added to the Hafler amplifiers, old fashioned trigger on and off is not required. Individual channel triggering is now completely automatic with one, many or all amplifier channels at any time in any order!
Finally, the Hafler CI series amplifiers feature an expansion port called an Omniport™. This changeable rear port allows various modules to be added to the amplifiers to provide the installer with greater flexibility and future-proofing. Modules include Jensen transformer isolated balanced inputs, Euroblock connectivity and Dante™ digital networking capabilities over Ethernet.