SPL Channel One Mk3 Channel Strip

In the latest SPL Channel One Mk3 version, this classic unit has been completely overhauled. It now features a higher internal audio voltage of +/-18V, providing an even better and more detailed sound. The preamplifier section has been further improved, and there is now an integrated Transient Designer, a Tube Saturation stage, and a Mic A/B comparison option for using two microphones, along with other fantastic features that elevate the quality of modern recording and mixing studios.

Essential tools like a de-esser, compressor, and equaliser are still included, making this a true channel strip. Whether you’re working with microphone, line, or instrument signals, the Channel One Mk3 ensures that any source will sound professionally recorded. The new design of the SPL Studio Series enhances the sonic qualities of this 3rd generation Channel One.

Features

• Discrete Preamplifier – The Channel One Mk3 comes with a discrete preamplifier.
• Gain – The gain control allows for precise adjustment of preamplification. For microphone signals, amplification up to 68 dB is possible, which means even highly sensitive microphones can perform at their best. The range for line signals is between -20 dB and +16 dB, while for instrument signals it ranges from -6 dB to +30 dB.
• Mic A/B Comparison – Comparing two microphones? No problem! The Channel One Mk3 has two microphone inputs (Mic A and Mic B) on the rear panel, so you can easily switch between them without unplugging anything, streamlining your workflow.
• 48V Phantom Power – The 48V switch activates phantom power for condenser microphones, and it can be applied individually to both microphone inputs.
• Preamp Out – Direct Recording – The Preamp Out captures the signal directly after the microphone amplifier. This can be recorded onto a separate track in a DAW as a safety measure, allowing you to adjust settings later if needed without losing the original take. You can then re-process the signal through the Channel One Mk3 with tools like the Tube Saturation or Compressor.
• Analogue Plugin Functionality – The Channel One Mk3 can process line-level signals, making it possible to use its de-esser, compressor, limiter, and equaliser with signals from an audio interface, essentially turning the unit into an “analogue plugin” within a DAW insert.
• PAD – The PAD switch attenuates the microphone input signal by 20 dB, making it suitable for processing high-level sources such as loud percussion or brass recordings.
• Phase Reverse (ø) – The phase reverse function flips the polarity of the signal by 180°. It’s a useful tool for correcting phase issues, such as with headphone monitors or voiceovers where natural sound can be affected by phase interference.
• Highpass Filter – A 6 dB per octave highpass filter cuts off frequencies below 80 Hz, helping to reduce unwanted low-end rumble or impact noise.
• Tube Saturation – The Tube Saturation control lets you dial in harmonic distortion, ranging from subtle warmth to more pronounced effects. Unlike solid-state devices, the tube doesn’t hard clip; instead, it gradually reaches its limits, producing a softer, more musical saturation effect. This can be compared to the sound of tape saturation.
• Tube Post – The Tube Post switch allows you to change the position of the Tube Saturation stage within the signal chain. When engaged, the Tube Saturation comes after the EQ and before the output; when disengaged, it comes directly after the preamp.
• De-Esser – The Auto-Dynamic De-Esser effectively removes harsh S-sounds in vocal recordings by detecting and cancelling them without affecting the overall tonal quality of the voice, even at high reduction levels.
• SPL De-Esser Technology – Unlike traditional de-essers that use compression, SPL’s De-Esser utilises phase cancellation to remove sibilance without impacting the rest of the signal. This results in a natural and neutral sound, with no need for constant adjustments thanks to its Auto Threshold feature.
• S-Reduction – The S-Reduction control allows for precise adjustment of sibilance reduction, with settings between -2 dB and -8 dB being ideal for most applications.
• Low & High Band De-Esser – The Low and High switches control different frequency bands for de-essing. The Low band centres around 6.4 kHz, while the High band centres around 11.2 kHz. Both can be activated together or independently.
• SPL Transient Designer – The Transient Designer allows manipulation of audio signal envelopes without relying on level thresholds. You can adjust the attack and sustain of signals with just two controls.
• Attack – The Attack control adjusts the transient phase by up to ±15 dB, allowing you to either increase or reduce the impact of the transient.
• Sustain – The Sustain control adjusts the sustain phase by up to ±24 dB, allowing you to extend or shorten the duration of the signal.
• Transient Designer Technology – The Differential Envelope Technology (DET) enables level-independent control over the transient response of audio signals, ensuring optimal results regardless of the input characteristics.
• Compressor – The compressor is designed to be easy to operate with just one knob, offering unobtrusive and musical performance.
• Compression – The Compression control allows you to set a threshold between 0 dB and -20 dB. The lower the threshold, the more the compressor is engaged.
• Make-up Gain – The Make-Up Gain control compensates for the level reduction caused by compression. You can set a value between 0 dB and 20 dB to increase the level post-compression. Using the Gain Reduction display on the panel, adjustments are straightforward – for example, if the loudest signal results in a reduction of -9 dB, you would set the Make-Up Gain to around +9 dB.
• Gain Reduction – Gain reduction is shown on the large VU meter. To view it, switch the VU meter to GR mode using the VU switch, which then displays the amount of compression applied in dB.
• Compressor Technology – In the Channel One Mk3 compressor, time constants like attack and release are automatically adjusted based on the input signal. This allows the compressor to respond quickly to sharp sounds, like plosive consonants, while reacting more slowly to smoother sounds to prevent distortion. Large level changes are handled with faster attack times, and sustained notes receive longer attack times for natural sound processing.
• Release time is similarly adaptive, with large and fast level changes processed more quickly than smaller increases. This balance of fast response and minimal distortion results in a transparent, natural sound.
• The compressor’s dual VCA circuit further enhances sound quality. One VCA receives a phase-correct signal, while the other processes a phase-inverted signal. The differential amplifier then combines these, eliminating distortion and noise, providing a clean, clear, and transparent sound stage for voices and instruments.

Equaliser

• LMF (Low/Mid Frequency) – The LMF control adjusts the centre frequency of the half-parametric bass filter, covering a range between 30 Hz and 700 Hz (approximately 4.5 octaves). This filter is useful for shaping both deep bass and lower mid-range frequencies. The adjacent -/+ control allows for boosting or cutting the LMF frequencies by up to +/-12 dB. The filter operates on a proportional-Q principle, meaning the bandwidth narrows as the boost or cut is increased, allowing for precise and musical adjustments.
• MHF (Mid/High Frequency) – The MHF control adjusts the centre frequency for mid-to-high frequencies, ranging between 680 Hz and 15 kHz. Like the LMF, this filter covers 4.5 octaves. The -/+ control allows for boosting or cutting by up to +/-12 dB. It also uses the proportional-Q principle for musical adjustments.
• Air – The high-frequency filter, labelled Air, is centred at 19 kHz. With a maximum boost or cut of +/-10 dB, it provides clarity and presence to vocals and instruments. It is ideal for enhancing the upper frequency range, adding a smooth and natural tonal quality. The equaliser section is activated via the On switch.
• Output – The output control allows for attenuation by up to -20 dB or amplification by up to +6 dB, ensuring optimal signal levels for downstream devices or AD converters. The VU meter displays the output level when set to the Out position.
• Mute – The Mute switch silences all output signals, and the VU meter will display no level when the VU meter switch is in the Out position.
• VU Meter – The illuminated VU meter can display input level, output level, or gain reduction, selectable using the VU switch below the meter. It can also be adjusted to show different signal ranges using the switch on the left side of the meter. In position 0, 0 dB on the VU meter equals an output of +6 dBu. In the +6 position, 0 dB equals +12 dBu, and in the +12 position, 0 dB equals +18 dBu.
• OVL LED – The OVL LED lights up when the device detects overload at any point in the signal path. This ensures that the unit is always processing signals positively without causing any distortion.
• DE-ESS LED – This LED illuminates when sibilance is detected by the de-esser, alerting you to adjust settings if necessary.
• EQ Pre TD – The EQ Pre TD switch changes the signal order, placing the Equaliser before the Transient Designer when engaged.
• Tube Post – The Tube Post switch moves the Tube Saturation stage after the Equaliser and before the Output stage, when activated.

Inputs and Outputs

• The Channel One Mk3 is equipped with Neutrik XLR connectors and gold-plated contacts, ensuring reliable and high-quality signal transmission. The signal is electronically balanced with a nominal level of +6 dBu.
• Microphone Input A & B – The rear panel offers two microphone inputs (Mic A and Mic B), simplifying the comparison or switching of microphones. Phantom power can be activated individually for each input, with a relay circuit ensuring noiseless switching.
• Line In – Line inputs are suitable for signals with impedances below 1 kΩ, such as those from D/A converters, synthesisers, or samplers.
• Instrument Input – The unbalanced instrument input is designed for high-impedance signals, such as electric bass or guitar.
• Outputs – Two balanced output jacks are provided, offering parallel outputs that share the same signal. This eliminates the need for an external splitter during recording sessions.
• Preamp Out – The Preamp Out provides a clean, unprocessed signal directly from the microphone preamp, allowing you to record a safety track in your DAW for later re-processing through the Channel One Mk3.