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SKU SPL-21301

SPL Channel One Mk3 Premium Recording & Mixing Channel Strip with Lundahl Input / Output Transformer


SPL Channel One Mk3 Premium Recording & Mixing Channel Strip with Lundahl Input / Output Transformer


Manufacturer's Description

Channel One Mk3 – the perfect front-end for the modern producer

For over 20 years, Channel One has been a synonym for a high-quality and extremely musical recording and mixing channel strip.

In the newest Mk3 version, this classic has been thoroughly revised and, in addition to a higher internal audio voltage (now +/- 18V) for even better, more detailed sound, a further improved preamplifier section, an integrated Transient Designer, a Tube Saturation stage and a Mic A/B comparison option for two microphones and other great features that raise the modern recording and mixing studio to a new level of quality. With de-esser, compressor and equalizer, all the important tools of a real channel strip are still on board. Whether it's a microphone, line, or instrument signal, the Channel One Mk3 makes any source sound like a professionally recorded signal. The new design of the SPL Studio Series perfectly highlights the sonic qualities of this 3rd generation Channel One.

Discrete Preamplifier

Channel One Mk3 is equipped with one discrete preamplifier.

Comparing two microphones? No problem!

Channel One Mk3 offers two microphone inputs on the rear panel – Mic A and Mic B. Two microphones can be connected. This enormously simplifies the workflow. Thus, when comparing or changing microphones, it is no longer necessary to unplug them.

Analog plugin

Channel One Mk3 offers the possibility to process line signals. This means that sources with line level, such as an analog signal from an audio interface, can be processed with de-esser, compressor, limiter and equalizer and then be recorded again. In this way, Channel One Mk3 becomes an “analog plugin” within an insert of a DAW.

Tube Saturation – magical tube sound

With this control the amount of tube saturation can be determined. The output level is accommodated automatically, in extreme settings the level increases by only 6 dB. Therefore decent to expressive harmonic distortions can be easily dialed in by turning just one knob. Saturation effects are generated through the tube being pushed to and beyond its normal operating limits. In contrast to semiconductors, a tube thus pushed to such levels does not clip from a certain level, approaching more gradually its level limits and thereby producing its typical tonal result, which in audio signal processing can have such often profitable aural effects — on one hand (and depending on the amount applied), from subtle to extensive harmonic distortion and on the other hand, a compaction of the sonic event, that is, a limiting effect that exhibits a pleasant, rounded or soft sound. Acoustically and also in its range of applications this can be compared very well with tape saturation effects.

SPL Transient Designer – the revolution in dynamics processing.

With the Transient Designer it is possible to manipulate the envelopes of audio signals level-independently (no threshold!). Accelerate or slow down transients, lengthen or shorten sustain times – with just two controls: attack and sustain. All time constants are automated in a musical way and optimize themselves adaptively according to the characteristics of the input signal.

Optional Equipment: Lundahl Transformers

The Sonic Aspects

Transformers are used as an alternative to electronic balancing stages in the inputs and outputs. Transformers can be found in many classics of audio engineering. They make the bass and fundamental tines rounder and give it a little more punch. The high and overtone range sounds a bit silkier and more present. We find transformers to be advantageous, especially for voices. For highest precision and speed in signal transmission (transient processing), however, electronic stages are better suited. The bottom line is that it is a question of taste and application.

In the Mic Preamplifier

In the case of preamplifiers or channel strips, the 2161 input transformer, which is specially designed for microphone inputs, provides an additional gain of up to 14 dB (depending on the microphone), which must then be added to the scaling. This relieves the microphone preamplifier. Since the transformer ratio passively increases the level, no noise is added. Therefore, the input transformer is more important than the output transformer in preamplifiers.

Operational Safety

When equipped with input and output transformers and completely symmetrical cabling, no voltages can enter the device via the signal connections that could cause damage. The signal transmission is inductive and thus electrically isolated. No hum is guaranteed. And last but not least, transformers drive very long cable runs, which is a welcome feature in live applications at the latest.

The Channel One Mk3 can be ordered with an optional input transformer for the microphone inputs and an output transformer for the output Out 1.

The product with transformer is called: Channel One Mk3 – Premium


Analog inputs & output; XLR & TRS Jack (balanced)

  • Maximum input gain (Mic, +9,5dB – +68 dB) 13.5 dBu (33.5 dBu mit PAD-Schaltung)
  • Maximum input gain (Line, -20 dB – +16 dB) 22.5 dBu (+42 dBu bei -20 dB)
  • Maximum input gain (Instrument, -6 dB – +30dB) 15 dBu (+27 dBu bei -6dB )
  • Input impedance (Mic/Line) 10 kΩ
  • Input impedance (Instrument) 1.1 MΩ
  • Output impedance 75 Ω
  • Frequency range 10 Hz – 200 kHz
  • Equivalent Input Noise (EIN) -126 dBu
  • Noise (A-weighted, Mic Preamp, 150 Ω, 30 dB Gain) -95 dBu
  • Noise (A-weighted, Mic Preamp, 150 Ω, 50 dB Gain) -79.5 dBu
  • Noise (A-weighted, Mic Preamp, 150 Ω, 68 dB Gain) -61.7 dBu
  • Noise (A-weighted, Line/Instr Preamp, 600 Ω, 5 dB Gain) -96.5 dBu
  • Nosie (A-weighted, Line/Instr Preamp, 600 Ω, 20 dB Gain) -84.7 dBu
  • Common mode rejection (1 kHz) Mic Input < 80 dB
  • Gleichtaktunterdrückung (1 kHz) Line Input < 50 dB
  • THD+N Ratio (1 kHz), Mic 30 dB Gain 0.0022 %
  • THD+N Ratio (1 kHz), Mic 50 dB Gain 0.013 %
  • THD+N Ratio (1 kHz), Mic 68 dB Gain (Max.) 0.048 %
  • THD+N Ratio (1 kHz), Line 0 dB Gain 0.0022 %
  • THD+N Ratio (1 kHz), Line 16 dB Gain 0.0017 %
  • THD+N Ratio (1 kHz), Instrument 0 dB Gain 0.012 %
  • THD+N Ratio (1 kHz), (100 kΩ source impedance

Internal Linear Power Supply with Shielded Toroidal Transformer

  • Operating voltage for analog audio +/- 18 V
  • Operating voltage for relays and LEDs +12 V
  • Tubes anode voltage +250 V
  • Tubes heating voltage +12.6 V
  • Phantom power 48 V

Mains Power Supply

  • Mains voltage (selectable) 230 V AC / 50; 115 V AC / 60 Hz
  • Fuse for 230 V T 315 mA
  • Fuse for 115 V T 630 mA
  • Power consumption max. 22.3 VA

Dimensions & Weight

  • W x H x D (width x height x depth) 482 x 88 x 210 mm / 19 x 3.46 x 8.27 inch
  • Unit weight 6 kg / 13.22 lbs
  • Shipping weight (incl. packaging) 7.6 kg / 15.43 lbs