Klein + Hummel O 500 C Digital, active Studio Monitor

New directions in monitor technology
Living in the digital studio age requires fresh thinking in monitor technology if we hope to make real progress in how sonic experiences are reproduced. KLEIN + HUMMEL, in its constant striving to produce a perfect transducer, has developed a comprehensive and innovative approach to the design of large studio monitors. This approach integrates the latest DSP technology and sets completely new standards for absolutely uncolored, accurate audio reproduction.

Integrated digital controller with the latest FIR Filter technology
The O 500 C is one of a new class of large reference monitors that employ an integrated digital controller. Utilizing active FIR filters, this monitor delivers an entirely new dimension in playback quality. Digital signal processing combined with Finite Impulse Response (FIR) filters make it possible to control the amplitude response and the phase response independently of each other. As a result, not only can the crossover be made to function as a linear phase filter, but the most detailed and thorough equalization of the three individual drivers can also be achieved. This combination offers unique advantages in the design and construction of monitors that are simply not possible with analog technology:

• Taking into consideration their acoustic center, you can arrange the individual drivers in the baffle in whatever way you like, and as long as you design independent and uncompromising waveguides, you can hope to achieve a perfect dispersion pattern.
  
• Amplitude response can be so precisely corrected that it is possible to achieve absolutely linear frequency response from 27 Hz to 20 KHz.
  
• The phase response of the system can be made to be completely linear, thereby avoiding the discrepancies in time coherence common to analog systems.
  
• Each monitor can be precisely tuned to specification, which virtually eliminates response deviations between the two monitors in a pair and insures an extra-ordinarily precise stereo image.
  
• Due to the nearly ideal slope in the crossover region, the overlap in frequency spectrum between any two drivers is extremely narrow, actually only a few Hertz. As a result, vertical directivity remains optimal in this region, even off-axis.
  
• The FIR-controller simultaneously manages the crossover, equalization, and limiter functions as well as the complete protection of the power amplifiers. The limiters monitor transient peaks as well as continuous power output of the individual drivers and preemptively regulate power amplifier overloading. As a result, the kinds of distortion experienced with analog limiters is avoided.
  
• The O 500 C can be fine-tuned to compensate for the acoustic peculiarities or deficiencies of a given studio, and thereby significantly improve listening conditions.
  
• The controller can bring about substantial improvements in the rise-time and decay time of the loud-speaker membranes, thereby im-proving acoustic phase response and time coherence.
  
• The monitor offers digital and analog inputs as well as a MIDI and an RS232 interface. Using the MIDI interface you can recall all setups and all parameters that can be set using the software.
  
• As an option, you can recall different equalization setups for different purposes, such as for classical recordings, pop, or drama.
  
• All user-specific parameters can be saved to a plug-in memory module, allowing for the quick and easy transfer of data to another studio monitor of the same type in the event your monitor needs to be serviced or swapped out.
  
• There is an additional output for connecting an active subwoofer; if you make use of this output, the digital controller of the O 500 C will assume the crossover, equalization, and phase correction functions for both units.
  

As a result of this new technology, you can experience sound, space and time reproduced with an accuracy like you have never known. Until now.

Extended sweet spot and precise spatial imaging
Thanks to a new material called LRIM (Low Resonance Integral Moulding), it is now possible to integrate the waveguide that is required for optimal dispersion directly into the loudspeaker baffle. By employing the right combination of computer algorithms and optimized drivers for the high and midrange frequencies, it is possible to achieve a tightly controlled sound dispersion pattern that is well matched to the bass driver. This specific dispersion pattern creates an extended listening area without introducing distortion, which in turn means more freedom of movement for the sound engineer at the mixing console. At the same time, in the vertical plane the dispersion angle has been made narrower so as to significantly reduce the amount of surface reflections that might interfere with the direct sound (comb-filter effect).

The end result is an absence of coloration at the listening position and an extraordinary spatial image, i.e. a precise stereo soundstage with clear focus and depth.

Option: FIR-based room-compensation
Although the 0 500 C is factory equipped with a fairly versatile room-compensation capability, this may not always be sufficient to compensate for acoustic deficiencies in the studio.

The integral FIR-based controller offers the unique possibility of very finely tuning the monitors to the listening room and to their specific location within the room. Depending on measurements taken of the room acoustics, the frequency and phase of the FIR filters can be adjusted to the specific room in such a way that optimal listening conditions will prevail at the mixing position.

First, third-octave measurements are taken from very many points in the listening area, then averaged. The resulting curve reflects both the speaker`s frequency response and dispersion patterns as well as the room`s acoustical response.

The software then uses the particulars of the room and speaker location to calculate settings for the FIR filters and stores this information as a new preset in non-volatile memory in the integrated controller. During playback the controller compensates for the acoustical imbalances in the room, and thereby usually makes it possible to achieve significant sonic improvements in the studio.

Please note that this type of acoustical optimisation requires a certain level of experience and the appropriate equipment. In any case it represents an economical alternative to a serious investment in a structural acoustic renovation of the studio.

Extraordinary transducers
In selecting transducer elements for each new loudspeaker system, KLEIN + HUMMEL seeks out the world`s leading custom manufacturers of loudspeaker components, and provides technical documents specifying that each driver used must meet the strictest quality requirements. This ensures that only the latest driver technology and the most advanced materials serve as transducers in our systems. Most importantly, it results in sonic accuracy so revealing that it makes the engineer`s critical job of evaluating a mix relatively easy.

The demands placed on the O 500 C for acoustic authenticity were so high that only specially selected driver components of uncompromising quality would be considered:

The 1-inch (25 mm) titanium fabric dome combines the transparency of a titanium dome with the low distortion of a fabric dome. It is precisely tuned to the elliptical horn that is integrated into the baffle, a fact which helps it achieve the wider listening area ("sweet spot") mentioned above.

This unusual fabric dome, with its membrane / voice coil diameter of 3 inches (75 mm), has a significantly lower membrane weight than that of a comparable cone system. The advantage is clearly audible; far better impulse response and very even frequency response. Furthermore, this mid-range driver is so strong that it ensures minimal distortion and compression even at peak levels.

For bass, the O 500 C employs a 12" (305 mm) cone woofer with a cast aluminum basket. The heavy-duty construction and the high degree of self-damping of the cone membrane ensure low distortion levels over its active frequency range even at peak levels, and the bass driver’s extremely long throw contributes to these results. As the cumulative spectral decay plot demonstrates, the flutter performance is exemplary: unwanted overtones and resonant peaks are practically non-existent. One new design element of special note is the rear-ventilated voice coil, which greatly increases the load capacity and minimizes power compression.

The whole is greater than the sum of these excellent parts. The three drivers, the FIR Filter technology and high-performance amplification all work in concert like a superbly balanced orchestra to form the kind of integrated acoustical whole that is representative of the quality standard of KLEIN + HUMMEL studio monitors.

High-performance power amplifiers with extended dynamic range
With over 50 years of experience developing high-or the O 500 C KLEIN + HUMMEL would only select first-class amplification.

Our patent-pending switching power design. Based on the latest developments in amplifier technology and the end result is great in comparatively great efficiency and extremely low total harmonic distortion. Even at full power the non-linear distortion (THD+N) remains under -95 dB. The extraordinary dynamic range of 132dB (A) ensures that the full dynamic spectrum of the original recording will be reproduced with extremely fine resolution. Power ratings of 400 watts for bass, 230 watt for the mid-range and 290 watts for the high-frequency driver provide more than ample headroom.

The power amplifiers are protected against overloading and overdriving by an absolutely dependable protective circuit. The operational reliability of KLEIN + HUMMEL amplifiers is proverbial; the user can rest assured that these monitors can be expected to offer trouble-free service for a long, long time.

Modern cabinet design with striking good looks
The O 500 C stands out with its striking baffle design, smooth matt enameled finish and numerous mounting and setup possibilities.

Integrated into the baffle is a rotating waveguide insert for the tweeter and mid-range domes. A 90° rotation of this insert makes the speaker ready for either horizontal or vertical use. This rotation, however, is done at the factory. (Please specify your preference when ordering).

The position of the bass reflex ports near the midpoint of the enclosure is precisely calculated and tuned to the cabinet geometry to keep internal standing waves to a minimum. The generously dimensioned ports avoid bass compression—air movement is inaudible.

Clear labeling on the rear of the monitor makes connections straight forward. Onboard room-compensation EQ offers a great deal of variability in modifying the frequency response of the loudspeaker in three separate frequency ranges that are critically relevant to common placement locations within the room.