The Forssell CS-1 console strip combines a microphone preamp, equalizer and compressor in a 1U package. Unlike Forssell’s earlier designs – combinations of tube and solid-state circuitry – the CS-1 uses only discrete junction field effect transistor (JFET) operated in Class A.
Product PointsApplications: Studio, broadcast, live sound
Key Features: Single-channel console strip featuring a mic preamp, EQ and compressor; switchable phantom power and phase; compressor side chain; XLR I/O
Contact: Forssell Technologies at 208-263-0286; www.forsselltech.com; e-mail info@ forsselltech.com;
The CS-1 ($2,695) has both mic and line-level inputs that share a single gain control. A switchable high-pass filter (HPF) is at the output of the preamp section, along with polarity reverse and phantom power switches. When the phantom power is off, the input stage blocking capacitors are switched out, creating a DC coupled input to the mic preamp.
The preamp section of the CS-1 uses a DC servo to keep its output offset voltage as close to zero as possible. The HPF corner frequency is variable from 10 Hz to 200 Hz and is hardwire-bypassed when switched out.
The CS-1 equalizer uses a single amplifier for all three EQ bands. All bands are fully parametric with continuously variable center frequency and Q controls. The MF section has a 10X frequency range switch. The LF and HF sections can be switched to either shelving or peaking. 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. Each EQ band can be switched in or out in addition to a master EQ I/O.
The compressor uses an LED/LDR (light dependent resistor) controlled by an active side chain, which has four controls: threshold, attack time, release time and compression ration. The compression ratio range is from 1.2:1 to 12:1. Release time is variable from approximately 60 milliseconds to more than 5 seconds. Attack time is variable from 1 millisecond to 200 milliseconds.
The side chain uses a true RMS detector, which is the right way, in my opinion. When the compressor is switched in, no additional amplifiers are 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 unit. This amplifier is what Fred Forssell calls his new and improved “second-generation” JFET amplifier. As with the preamp section, the output section uses a DC servo to minimize DC offset in the output signal.
The CS-1 comes standard with a single-ended, impedance-balanced output designed to work into an unbalanced or balanced input. “Impedance balancing” means that although the output is really single-ended, the CS-1 can drive a balanced load while preserving its common mode rejection.
The CS-1 is also available with a 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 XLR. This scheme does require an additional amplifier, which could potentially degrade the signal ever so slightly. If the CS-1 is supplied with the balanced output option, both the balanced and the single-ended outputs are available simultaneously via separate output XLRs. With this type of configuration, the balanced output signal is 6 dB hotter than the single-ended output. The microphone preamplifier output is also available on an XLR (standard).
A lighted VU meter can be switched to monitor either the input or output while an LED meter shows compressor gain reduction in ten 1 dB steps.
I used the CS-1 on alto flute as a part of a DSD recording project. A Shure KSM 32 placed about four feet above the flute, fed the CS-1. The resulting signal sounded amazingly close to what it sounded like in the studio. A small amount of compression was used, which exhibited little or no side effects or coloration.
Even though the CS-1 packs a lot into a 1U box, the knobs and switches are well laid out and easy to use. My only complaint is that the input control range is not very uniform. When used in the microphone input mode, most of the usable gain range occurs near the top of the rotation of the pot, where it is difficult to make a fine gain adjustment. Forssell is having a custom pot made that will expand the range of this control, eliminating this problem.
Not to be compared with some of the more colored input channel strips, the CS-1 uses a minimalist approach to provide good, clean uncolored sound. Good solid design along with a high-quality build makes the CS-1 an investment that will stand the test of time.