User manual TL AUDIO VP-1

[. . . ] CONTENTS 1 2 3 3. 1 3. 2 3. 3 3. 4 3. 5 3. 6 3. 7 3. 8 4 4. 1 4. 2 4. 3 4. 4 4. 5 4. 6 4. 7 4. 8 4. 9 4. 10 4. 11 4. 12 4. 13 4. 14 4. 15 4. 16 4. 17 4. 18 4. 19 4. 20 4. 21 4. 22 4. 23 4. 24 INTRODUCTION PRECAUTIONS INSTALLATION AC Mains Supply Audio Inputs Unbalanced Line Inputs Instrument Inputs Insertion Points Balanced Outputs Unbalanced Output Ventilation OPERATION Input Select Input Gain High Pass Filter Phase Reverse Pad Phantom Power Drive and Peak LEDs Expander/Gate Section Gate Threshold Gate Attack and Release Gate Meter De-esser Section De-esser Depth De-esser Frequency De-esser Bandwidth De-esser Meter Compressor Section Comp. Hold Mode 4. 25 4. 26 4. 27 4. 28 4. 29 4. 30 4. 31 4. 32 4. 33 4. 34 4. 35 4. 36 4. 37 4. 38 4. 39 4. 40 4. 41 4. 42 4. 43 5 6 7 Equaliser Section LF & HF Bands LM & HM Bands LM/HM Frequency LM/HM Gain LM/HM Bandwidth EQ Pre Stereo Link Operation Ducking or Gating Peak Output Limiter Output Level VU Meter Digital Output Option Bit Rate Select Sampling Freq. Select Digital Output Meter Lock Status Output Formats Wordclock Input USER TIPS / FAQs SERVICE SPECIFICATIONS 1 INTRODUCTION Congratulations on purchasing the VP-1 Mono Valve Processor from TL Audio. The VP-1 combines classic Pentode and Triode valve techniques with Class A discrete and solid state circuitry to produce a unit providing comprehensive facilities for all aspects of single channel microphone and instrument pre-amplification and processing. [. . . ] Due to this automatic modification of the time constants, the controls are simply calibrated "fast" to "slow". 4. 20 Compressor Ratio. The Ratio controls the degree to which signals over the threshold are compressed, and is expressed as a ratio of the input and output signals. For instance, a ratio of 1:3 means that for every increase of 3dB in the input signal, a 1dB increase in output level results. The ratio may be varied from 1:1. 5 (very gentle compression) to 1:30 (near limiting). the compression is gradually introduced as the signal passes the threshold, in which case the ratio refers to the compression eventually obtained. 4. 21 Compressor Gain Make-Up. When a signal is compressed its gain is reduced, and the gain make-up control allows up to 20dB of extra gain to be applied to bring the level of the compressed signal up to that of the original. This retains the subjective loudness of the signal, and allows easy A/B comparisons of the original and compressed signals without a change in level occurring when switching between the two. 4. 22 Compressor Knee. This switch allows a choice of two compressor response types - Hard or Soft Knee. Soft knee mode means that once the signal has exceeded the threshold, gain reduction is introduced gradually, since the response curve of the compressor around the threshold is gentle. In "Hard Knee" mode, the curve is more severe, so that signals above the threshold are "squashed" more aggressively. 4. 23 Compressor Opto Mode. The VP-1 offers two distinct and independent types of gain control circuit. The normal mode employs the trademark TL Audio transconductance amplifier circuit, as featured in many other TL Audio products, notably the C-1 compressor. This circuit uses a solid state transconductance amplifier to accurately control gain, with a triode valve stage in the gain make-up circuit to add warmth. The VP-1 `Opto' mode replaces the transconductance amplifier with an optical gain control circuit, with the valve still active in the gain make-up circuit. The opto circuit uses a LED/light dependent resistor device to control gain, which yields a slightly more coloured sound with a slower response time. Many vintage compressors employ opto designs, and its inclusion on the VP-1 allows a much wider palette of compression sounds to be obtained. 4. 24 Compressor Hold. The Hold facility on the VP-1 delays the onset of release for approximately 10msec after the input signal reduces below the threshold. This feature helps to reduce the distortion commonly caused when using a compressor with a short release time to process a low frequency signal, for example a bass guitar, where the compressor attempts to modify the gain during each half cycle of the input waveform. If distortion is experienced under these circumstances, activate the hold facility. 4. 25 Equaliser Section. The VP-1 boasts a four band valve EQ stage with low and high frequency shelving and two fully parametric mid bands, giving an ideal combination of simplicity and flexibility. Before switching the EQ into circuit, it is advisable to set the cut/boost controls to their centre, or flat, position. The EQ is brought into circuit with the overall "EQ-ON" push switch, signalled by a green LED. [. . . ] It can be hard to set the gate threshold point for some signals as the signal dynamics may vary too much. Because of this problem it can be much easier to set the threshold point on signals that have a smaller dynamic range, such as compressed signals. Gating at higher levels can help to "tighten" instruments up. For example fine tuning the gate threshold, attack and release controls for a bass guitar signal can help it to sit more tightly with the drum parts. [. . . ]