C88-Reference (left)
C5 Tiny-Amp
C5 Tiny-Amp


Three-way coaxial studio monitor with correctly timed FIRTEC technology



KSdigital manufactures each of its loudspeakers by hand in its factory Saarbrücken/Germany. Each loudspeaker is measured individually (IFM) and linearized in frequency and phase. This ensures the unrivalled correct reproduction of the music signal.

For over 10 years, the C-Line has been the compact listening reference in many studios around the world.  One of the main reasons for this is the coaxial principle that delivers exact information to the sound engineer even if the room’s acoustics are not ideal. A coaxial chassis avoids different run-times between bass and high-ranges.  Firstly, this means that one can sit at any distance from the sound source, and secondly, much more direct sound arrives at the listening position than is reflected from the room, which is the ideal solution for smaller listening spaces, transmission vans or in the near field at a DAW workstation.  Additionally, the KSD Reference series has now been fitted with patented Firtec/DSP that not only guarantees neutral tonality but also correctly timed reproduction.  This phase linearity permits the exact positioning of individual instruments in the virtual stereo sound stage, with each instrument precisely positioned.  Six user filters serve to adjust the set-up in one’s own studio.  An optional remote control ("KSD-RC") allows not only the access to the user EQ’s and other parameters like "delay" etc. but also allows simple adjustment of the volume and replaces an external monitor controller (with its signal editing and sound losses). Available with a cherry wood front or in complete black.



  • Overview
  • Specs
  • PDFs


The C88 Reference has been developed as a main monitor but can be utilized at very low listening distances (from approx. 1 meter) due to its coaxial chassis. The additional bass chassis serves the lowest octave and relieves the coaxial chassis in that range. The carbon fibre membrane of the newly developed 8" coaxial chassis prevents the usual break-out of the conus up to higher frequencies, while being extremely light-weight at the same time. The 1" self-manufactured tweeter offers lowest harmonic distortion with maximum neutrality. Placed just in front of the 8" chassis, the specially constructed conus, leads to an optimised radiation behaviour and prevents an unstable sound image, as even with higher volumes the hub of the bass chassis doesn’t influence the radiation behaviour of the tweeter.

Test winner in comparison of coax monitor in Stereoplay 02/18: Test Klaus Laumann:"... up to the finest graduated illustration... live-like character, perfect timing and excellent resolution

construction 3-way-coax, nearfild
signalprocessing in FPGA
with 24 Bit ADC - DAC
(+4 dBV)
FIRTEC™ equalization, FIR-crossover,
limiter, 6 User-EQ, patent: 19823110
tweeter 1“ neodym
bass/mid driver

bass driver
8“ carbon

8“ carbon
amplifier 80 W / 175 W /175 W
SPL (max) xxx dB
frequency range 32 - 22000 Hz
weight 22kg
dimensions 480 x 240 x 310 mm
remote control
KSD-RC operates
6 user-EQs, volume, delay etc.