The TL Audio A1 Dual Preamp features two independent channels, with each channel offering mic and instrument inputs.
The block diagram of one of the channels is shown in fig. 1. A discrete Class A electronically balanced mic input amplifier is used, delivering superior audio performance with very low noise, low distortion and wide bandwidth. The mic input is suitable for low impedance (150-600 ohm) microphones, with a gain control range of +16 to +60dB. Front panel switches provide 48 V phantom power, and 30dB pad for high output mic applications.
The front panel mounted jack socket is suitable for a variety of sources, including electric guitar, acoustic pickup and keyboard. The instrument input has high/low switching, and a dedicated valve input stage.
Phase reverse and high pass filter switches are provided, affecting both mic and instrument inputs.
The tube stage has a variable drive control, with the signal level indicated by the variable intensity “Drive” LED and “Peak” LED. Use of this feature typically introduces 1% to 10% harmonic distortion, predominately second harmonic, without changing the output level from the unit. The tube stage can be selected or bypassed as required.
A VU meter is provided, which can be selected to either channel, and input or output signals. The meter is also provided with a “+10dB” switch, which keeps the reading on the scale when driving a high level out (to a DAW, for example). In the +10 mode, OVU is calibrated as +14dBu out.
Features
- Discrete Class A and Tube Dual preamp / DI
- 2 quality discrete class A preamps
- 2 DI inputs for high/low impedance instrument input
- Phantom Power
- 30dB Pad
- 90Hz High Pass Filter
- Phase Reverse
- Switchable tube stage with rotary drive control on each channel
- Output gain stage
- Analogue style VU metering
- +10 dB metering for use with DAW
- Compatible with DO-2 card for SPDIF digital output
