SPL P8 + ADC8

8-channel discrete microphone preamplifier with ADAT converter

• Eight identical discrete-component microphone preamps, with no integrated circuits
• Pre-installed AD ADC8 converter: 8 channels, 24-bit, using AKM AK5538 chips, from 44.1 to 192 kHz
• Optical ADAT outputs to connect the P8 directly to the digital inputs of your audio interface
• DB25 analog output always available in parallel, for an external converter or a backup system
• 48 V phantom power, -20 dB PAD, polarity reversal, and independent high-pass filter on each channel
• Word Clock in/out with low-jitter quartz oscillators, in a 1-unit 19" rack mount

The SPL P8 + ADC8 is SPL’s 8-channel microphone preamp featuring discrete technology, supplied with the ADC8 analog-to-digital conversion module already installed. In a single rack unit, you get eight high-end preamps and an 8-channel converter with ADAT outputs: the most straightforward solution for adding eight high-quality microphone inputs to an audio interface equipped with ADAT ports, ideal for recording drums, live bands in the studio, or acoustic ensembles in multitrack.

SPL Discrete-Component Microphone Preamps

All eight preamps in the P8 are built using discrete transistors rather than integrated circuits—a design choice typical of high-end preamps and the foundation of their sound quality. The sound is open and transparent: the microphone and sound source reach the converter exactly as you hear them in the room, without any coloration imposed by the circuitry.

Gain from +8 to +62 dB for any type of microphone

Each channel has its own analog gain control ranging from +8 to +62 dB. You have headroom for ribbon and low-output dynamic microphones, but also the low sensitivity required for large-diaphragm condenser microphones placed close to loud sources. A three-color LED per channel indicates signal presence and approaching full scale, with the red threshold set at -3 dBFS of the converter.

Phantom power, PAD, polarity, and filter on each channel

Each of the eight channels individually provides 48 V phantom power for condenser microphones, a -20 dB PAD for percussion, brass instruments, and high-volume amplifiers; 180° polarity reversal to correct phase issues in multi-microphone drum setups; and a 6 dB/octave high-pass filter that reduces impact noise and unwanted low frequencies below 80 Hz.

ADC8 AD Converter: 8-channel 24-bit / 192 kHz ADAT

At the heart of the ADC8 module is the AKM AK5538 8-channel, 24-bit conversion chip, with sampling rates ranging from 44.1 to 192 kHz. It brings all the detail of the P8’s discrete preamps into the digital domain, without any intermediate steps or additional analog wiring to an external converter. The optical ADAT outputs via TOSLINK ensure compatibility with a wide range of audio interfaces.

Low-Jitter Clock and Word Clock Synchronization

High-precision quartz oscillators generate a clean, low-jitter master clock. When an external synchronization signal is present, the internal oscillators are automatically disabled to prevent interference. The Word Clock section includes an input, an output, and a termination switch, so the P8 can serve as the master for your digital setup or sync to the studio clock.

Sampling Frequency and Clock Source on the Front Panel

The AD Converter button on the front panel cycles through 44.1, 48, 88.2, 96, 176.4, and 192 kHz, as well as the WCLK option for an external clock. A dedicated USB service port is reserved for module firmware updates and is not intended for audio transfer.

Analog DB25 output for an external converter or backup

With the ADC8 module installed, the ADAT outputs replace the P8’s second DB25 output, while the first remains available with line-level signals from channels 1–8. This allows you to record digitally via ADAT and simultaneously send the same analog signal to a second converter or a backup system.

SPL Studio 1U rack-mount construction

4 mm black anodized aluminum front panel, machined aluminum knobs, and powder-coated steel chassis. Many key components are mounted using through-hole technology, allowing you to select them based on sound quality, and the internal linear power supply with a shielded toroidal transformer ensures stability and a low noise floor.

SPL P8 + ADC8 Technical Specifications

• Type: 8-channel microphone preamplifier with discrete circuitry and pre-installed ADAT ADC
• Inputs: 8 x balanced Neutrik XLR microphone inputs with gold-plated contacts
• Analog Outputs: 1 x balanced DB25 line-level (channels 1–8)
• Digital outputs: 2 x optical ADAT (TOSLINK)
• Gain: +8 to +62 dB
• Per-channel functions: 48 V phantom power, -20 dB PAD, polarity reversal, 6 dB/octave high-pass filter at 80 Hz
• Maximum input level (Mic): 13.5 dBu
• Input impedance: 10 kΩ
• Output impedance: 75 Ω
• Frequency response: 15 Hz – 200 kHz
• Equivalent Input Noise (EIN): -124 dBu
• Noise (A-weighted, 150 Ω): -94 dBu at 30 dB, -66 dBu at 62 dB
• Common-mode rejection (1 kHz): < 78 dB
• THD+N (1 kHz): 0.003% at 30 dB, 0.022% at maximum gain
• Signal indicators: green -25 dBu, yellow 0 dBu, red -3 dBFS (+12 dBu)
• ADC8 converter: 8 channels, 24-bit, AKM AK5538 chip
• Sampling rates: 44.1 / 48 / 88.2 / 96 / 176.4 / 192 kHz or external Word Clock
• Synchronization: Word Clock in/out with switchable termination, low-jitter crystal oscillators
• USB service port for firmware updates
• Audio electronics operating voltage: ±18 V
• AD board operating voltage: +12 V / +3.3 V
• Power supply: Internal linear power supply with shielded toroidal transformer
• Mains voltage (selectable): 230 V AC / 50 Hz; 115 V AC / 60 Hz
• Fuses: T 315 mA (230 V), T 630 mA (115 V)
• Power consumption: max 27 VA
• Dimensions (W x H x D): 482 x 44 x 237 mm (19" rack, 1U)
• Weight: 4.15 kg
• Shipping weight: 5.4 kg