CONTENTS 1 INTRODUCTION 2 PRECAUTIONS 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 INSTALLATION AC Mains Supply Audio Inputs Unbalanced Line Inputs Instrument Inputs Insertion Points Balanced Outputs Unbalanced Output Ventilation 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.
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.
An expander/gate circuit is also included in the VP-1. The circuit provides variable threshold and attack and release times, and includes a four segment LED bargraph to indicate the gain reduction that is being applied. De-essing of vocal sources is provided, with the depth (i.e. attenuation) of the deessing variable, along with frequency and bandwidth tuning to match the sibilant content of the signal.
2 PRECAUTIONS The TL Audio VP-1 processor requires very little installation, but like all electrical equipment, care must be taken to ensure reliable, safe operation.
3.2 Audio Inputs. The VP-1 has two female, 3 pin XLR connectors, for mic and line sources. Both are compatible with either balanced or unbalanced signals, when the mating connectors are appropriately wired: Balanced inputs: - Pin 1 = Ground (screen). - Pin 2 = Signal Phase (“+” or “hot”). - Pin 3 = Signal Non-Phase (“-” or “cold”). Unbalanced inputs: - Pin 1 = Ground (screen) - Pin 2 = Signal Phase (“+” or “hot”). - Pin 3 = Signal Ground.
3.5 Insertion Points. The insertion points are interfaced via a 3 pin, 0.25” switched jack socket on the rear of the unit. The pin connections are: - Sleeve = Ground, - Tip = Send, - Ring = Return. The insertion points are unbalanced, and operate at a nominal level of -2dBu . If used as an additional send only (e.g. as a send to a tape machine or monitor mixing desk), the Tip and Ring should be wired together, to preserve the signal path through the insertion point. 3.6 Balanced Output.
The VP-1 may be free standing, or mounted in a standard 19” rack where it will occupy 3U of space. 4 OPERATION 4.1 Input Select. The VP-1 is designed to accept mic, line and instrument signals, and the relevant source is selected via a four position selector switch. The four positions are: Valve - selects the microphone input as the signal source, and feeds the mic signal through an all-valve preamp circuit.
4.5 Pad. When activated, the pad switch will reduce the Mic input gain by 30dB. This is useful when dealing with high level mic input signals, such as those produced when recording loud sources with sensitive microphones (drums are a typical example). Without the pad, it’s possible to overload the input stage in these circumstances, causing audible distortion. Activating the pad switch will cure this. 4.6 Phantom Power.
When the signal level returns to a level above the threshold, the gain is rapidly restored to ensure that no transient edges are lost. The Expander/Gate is perfect for removing unwanted background noise during quiet periods of recording. A typical example would be removing the background noise, breathing etc that occurs between vocal phrases when miking a singer. Setting the threshold to a low level will cause the gate to open when the vocalist sings (i.e.
4.14 De-esser Frequency. The Frequency control selects at which particular frequency the gain reduction is made to occur, and covers the range 700Hz to 7kHz. Vocal sibilance normally occurs in the range 3kHz to 5kHz, so it’s normal to set the Frequency control within this range. 4.15 De-esser Bandwidth. The Bandwidth control governs the broadness of the band of frequencies which are affected by the de-esser.
the opposite direction, but our feeling is that as you turn the control ‘up’ it should have more effect! 4.19 Compressor Attack and Release. The attack time governs how quickly the compressor acts to ‘squash’ a signal that has exceeded the Threshold, and is variable from 0.5msec to 50msec. At 0.
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. This results in a more subtle and musical type of compression effect. In “Hard Knee” mode, the curve is more severe, so that signals above the threshold are “squashed” more aggressively.
HF shelving at 2.2kHz, 5kHz, 8kHz and 12kHz The EQ slopes have a second order 12dB/octave response, and the frequency values are -3dB points. An associated gain control on both bands provides up to 15dB of cut or boost on each selected frequency, controlling the full range of frequencies below the LF corner frequency and above the HF corner frequency. 4.27 LM and HM parametric bands. Both mid bands have fully parametric action, meaning that controls for frequency, gain and bandwidth (Q) are provided.
but the EQ Pre switch will route the signal through the EQ first. This can result in a different tonal character, and also allows certain frequencies to be boosted ahead of the compressor, resulting in a certain degree of frequency conscious action by the compressor itself. 4.32 Stereo Link Operation. Two VP-1s may be configured for stereo operation by inserting a Link cable between the two units and activating the Link switch on both units.
4.35 Output Level. This control acts much like the fader on a recording console, in that it regulates the overall level produced at the VP-1’s line outputs. This makes it ideal when recording direct to tape or hard disc, since it enables the level to tape to be precisely controlled. The range of the control is from -∞ (i.e. complete attenuation) through to +15dB.
meter monitoring digital output level. These related front panel controls and meters will have no effect until the DO-1 card is fitted. The DO-1 enables the VP-1 to directly interface with digital equipment that carries these same format inputs, thus bypassing any A/D input stage. 4.38 Bit Rate Select. A three position rotary switch enables the user to select whether a 16, 20 or 24 bit word length is outputted by the DO-1’s digital outputs. The output is properly dithered to the selected word length. 4.
A rear panel Wordclock Input is provided for connecting the VP-1 to an external master clock source. An associated switch on the rear panel selects between external synchronisation and internal clock. In external mode the front panel sample rate selection switch is still active and needs to be set to match the frequency of the incoming wordclock source. The Wordclock input connector is a BNC-type terminated in 75 ohms.
that frequency. This would be an alternative way of de-essing an input signal, by setting the boosted EQ frequency to match that of the sibilance. Q: A: Any tips on using the Expander/Gate? With low level signals such as tape hiss, microphone self noise or even noise from guitar amplifiers the gate will shut off these unwanted elements, but they will be present - often loud and clear - when the required signal opens the gate.
driving, by limiting the maximum output level that the VP-1 generates. A 0VU output reading on the VP-1 should read approximately -18dB on a digital recorder input (using +4dB connections) although this will vary with different recorders. If the limiter threshold is set to approximately +17dB this would be just below the point where the digital recorder may overload, so would be a useful threshold to limit the output of the VP-1.
