The CS-1 (Channel Strip) combines a microphone preamp, equalizer, compressor, and line driver into a single 1U rackmount chassis. The CS-1 is the latest in a long line of highly accurate, minimalist designs from Forssell Technologies (see Forssell/Millennia Media Connection for more information). Only the basic functions most commonly used in a high quality recording chain are found in the CS-1. The CS-1 contains none of the frills commonly found in other all-in-one boxes such as DI inputs, De-Essers, or fancy switching functions. Such frills are usually added to a design by marketing staff to increase the number of "combinations" of a product or to create a sonic effect.. With the CS-1 you get the simple, pure, signal path used by engineers who demand the finest cleanest sonic signal path.

The CS-1's signal path is comprised solely of discrete Class A, junction field effect transistor (JFET) amplifiers. There are no IC opamps, bipolar transistors, or transformers, and virtually no capacitors (there is a single capacitor switched into the Mike Input signal path when the +48 Phantom Power is switched on) in its main signal path. The mike/line preamp is balanced and transformerless utilizing discrete class A jfet amplifiers. The equalizer uses a single jfet amplifier that is hardwire bypassed when switched out. The compressor uses an LED/LDR (optical) cell as a shunt element in a simple passive attenuator. There are no additional signal amplifiers are used in compressor circuit. The CS-1 output buffer amplifier is also a discrete, class A, jfet amplifier. An optional balanced differential floating output is also available.

The CS-1's has both mike level and line level inputs with a single gain control. There is a switchable high pass filter (HPF) control on the output of the preamplifier section as well as polarity reverse and phantom power (mike input only) switches. When the phantom power is switched off, the input stage blocking capacitors are switched out, creating a DC coupled input to the mike preamp. This allows a direct coupled input to the mike preamp circuitry; ideal for dynamic and ribbon mikes. The preamp section of the CS-1 uses a DC servo to keep its output offset voltage near zero. The HPF corner frequency is variable from 10 Hz to 200 Hz and is hardwire bypassed when switched out.. An optional buffered preamp output is available if desired.

The CS-1's Equalizer is a single amplifier, three band EQ. All bands are fully parametric with continuously variable center frequency and Q controls. The LF and HF sections of this EQ can be switched to shelving mode from peaking mode, disabling the Q control. The Q is adjustable from 0.5 to 5.0. The boost/cut control range is -15 dB to +15 dB in 21 steps. The boost/cut control provides 1 dB steps until approximately 5 dB of boost or cut, at which time the step size slowly increases. Please see the CS-1 test data for more information. Stepped frequency and Q controls are also available as options.

The CS-1's compressor's gain control element is a completely passive device controlled by an active side chain which has four controls. These controls are threshold, attack time, release time, and compression ratio. The compression ratio range is from 1.2:1 to 10:1. Lower maximum ranges are available at a small additional cost. Release time is variable from approximately 60 milliseconds to 3 seconds. Attack time is variable from 1ms to 200 ms. The side chain of this compressor uses a true RMS detector not the usual peak detector found in most other optical compressors. When the compressor is switched in, there are no additional amplifiers in the signal path. The Compressor can be switched from post EQ to pre EQ with a front panel switch.

The CS-1 output amplifier uses the same discrete, class A, jfet amplifier found in the rest of the CS-1. This amplifier is what we call a "second generation" jfet amplifier. It differs from our older "first generation" jfet amplifiers (used by other companies) in that it is a more evolved design. Subjectively the second generation jfet amplifier has many of the same characteristics of the first generation, but with an even more open sounding, silky sonic quality and a much more solid and deeper bottom-end. Objectively it measures better, has lower and more stable DC offset, lower input capacitance, a wider frequency response range, and symmetrical clipping. See our JFET-992 product literature for more information regarding this design. You can also see a schematic of the first generation discrete, class A, on this website at Class A JFET Opamp Circuit. All of the class A jfet amplifiers used in the CS-1 are true high current devices (30 ma) when compared to the more common monolithic IC opamps (usually around 2-4 ma). This enables class A performance over a fairly wide range of signal amplitudes while driving commonly encountered load impedances.

The CS-1 comes standard with an "impedance balanced", single-ended output configuration. "Impedance balancing" means that while the output is really single-ended, the CS-1 is able drive a balanced load while preserving common mode rejection performance of the load. This approached is used by other companies who often pass it off as "Fully Balanced". It isn't. However it is a better approach than the simple single-ended output. The CS-1 is available with a high performance balanced output option that provides a true floating differential output capable of driving either balanced or single-ended loads without having to rewire the output connection. If the CS-1 is purchased with the balanced output option, both the balanced and the single-ended outputs are available simultaneously via separate output XLR jacks. In such a configuration the balanced output signal is +6 dB over the single-ended output.

All of the CS-1 internal circuitry uses moderately high voltage power supply rails (+ and - 24 VDC) with very carefully designed power supplies and single resonate point, wideband, bypass filtering at each amplifier. The power supplies for the CS-1 have current rating much higher than required by the CS-1, resulting is cooler operating temperatures, more reliable power supplies, and better sounding audio circuitry.