Knif Rauman writes: “Loudspeaker design is the ultimate craft in audio reproduction and making one is poised with difficulties. It is no coincidence that a wide variety of different basic operation principles and solutions exists to overcome the inherent difficulties and shortcomings. All of them carry some advantages and disadvantages, some more obvious than others.”
All known loudspeakers technologies include compromises and the craft is a lot about finding the right ones. How to fit together the need for even frequency response and even radiation patterns? How to reproduce the huge dynamic range of well made recordings?
DESIGN GOALS
The ultimate goal is where the acoustical requirements and estetically pleasing design meet. Everything works in harmony, and there is nothing extraneous. This is where Knif Rauman Nº1 wants to stand. Form follows function in the smoothly flowing surfaces of the sound wave guiding front panels. Aluminum castings provide visual rhythm to the enitireness.
CROSS-OVER’S IMPORTANT ROLE
The basic semiactive operation principle is somewhat unusual but firmly based in the aim to build the ultimate loudspeaker in its class.
Low frequency cross-over is best done before amplification for three reasons:
Passive parts for low frequency cross-over are huge, expensive and most importantly imperfect. The curves which can be realized without loosing amplifier’s control over drivers are very limited.
Modern class D amplification is small, inexpensive and perfect for low frequency amplification. More exotic and low powered amplifiers can be used where they still have an edge, namely on mid and high frequencies.
Simple high quality analog equalizer can be implemented in the cross-over unit to tremendously ease the task of finding the correct balance and tame room resonances.
PHASE LINEAR RESPONSE FROM BASS TO MID RANGE
This speaker is equipped with symmetrical element positions with the same acoustical path length from all the elements to listeners ear. Combined with an active X-over between bass and the rest of the elements, producing true first order slopes, this creates phase linear response from bass to mid range.
WAVEGUIDE AND TREBLE DRIVER
Treble driver, a true ribbon flagship model from RAAL, and mid-range drivers are placed in a to a single metal wave guide casting. It has superb impulse response with almost non-existing resonances and very wide frequency response. The waveguides raise the sensitivity and max SPL from the drivers, lower distortion, and produce one of the best of axis responses ever seen.
MID RANGE DRIVERS
The mid range drivers (120mm SEAS magnesium Excels) are placed in their own enclosures, which are sort of inverse horns, tapering to the end and damping the back wave effectively. The mid range drivers work as perfect pistons throughout their whole range and produce impeccable impulse response with no stored energy release.
BASS RANGE DRIVERS
Bass enclosure is equipped with passive radiators, which are tuned to a very low frequency in order to keep the group delay of important bass frequencies low and to provide good low bass headroom. Active X-over flattens the response to a respectable -3dB@25Hz. Drivers are 220mm SEAS magnesium Excels.
ACTIVE CROSS-OVER AND BASS AMPLIFIERS
The active X-over is a separate unit. It is equipped with two band parametric EQ for simple room correction.The unit is built to the same standards as Knif Audio’s products and includes Elma rotary switches, class A discrete OP amps, and both XLR and RCA inputs and outputs.Bass amplifiers are integrated to the loudspeaker cabinets. The amplifiers are 500W Hypex N-core modules.
TECHNICAL SPECIFICATIONS
LOUDSPEAKER
- Enclosure materials Airgrade plywood, resin and metal castings
- Dimensions 168 x 43 x 60 cm
- Mid+Treble impedance 4 Ω
- Mid+Treble sensitivity 92 dB/2,83 V
- Freq response, -3dB points 25 Hz and 40 kHz
- Integrated bass amplification Hypex Ncore, 500W per channel
ACTIVE CROSS-OVER
- Input impedance 20 kOhms per phase, balanced or unbalanced
- Output impedance 50 Ohms per phase, quasi balanced
- Dimensions 44 x 32 x 9 cm