G U I T A R I N T E R F A C E S Y S T E M User's Manual May be covered by one or more of the following: U.S. Patents #4538297, 4647876, 4696044, 4745309, 4881047, 4893099, 5124657, 5263091, 5268527, 5319713, 5333201, 5402498 and 5493617. Other patents pending. Foreign patents pending.
Contents Introduction ----------------------------------------------- 1 Front Panel ------------------------------------------------ 2 Rear Panel ------------------------------------------------- 4 Placement ------------------------------------------------- 5 Connections ---------------------------------------------- 6 Guitar applications ------------------------------------------------------------ 6 Using auxiliary input signals ----------------------------------------------- 7 Mixing applications --------
Introduction Thank you for purchasing the new Rocktron GIS PC Preamp the world's first guitar/vocal processor designed to interface directly to your computer. The GIS PC Preamp turns the computer into a virtual guitar amp system with clean/distortion tones along with a 3-band EQ. Connection of your CD or tape player to AUX input makes playing or singing along with your favorite tunes extremely easy. Record them right to the PC using any wave recording software.
Front Panel 1 ¼" phone INPUT jack This ¼" standard phone jack provides an input to the GIS PC Preamp. 2 GAIN control This control determines the amount of gain applied to the signal in the distortion mode. 3 BASS control This control determines the amount of bass in both clean and distortion modes. 4 MID control This control determines the amount of midrange in both clean and distortion modes. 5 TREBLE control This control determines the amount of treble in both clean and distortion modes.
8 CLN/DIST switch This switch is used to select CLEAN or DISTORTION mode. 9 CLN LED When lit, indicates that the CLEAN channel is currently active. In the clean mode, the internal SSM2000 HUSH IC is configured to provide compression. 10 DIST LED When lit, indicates that the DISTORTION channel is currently active. In the distortion mode, the SSM2000 HUSH IC is configured to provide HUSH noise reduction.
Rear Panel 1 3" OUTPUT jack This 3" phone jack provides the main output of the GIS PC Preamp. All processed signals, including those applied to the AUX inputs, will be fed to this output. This jack is configured for RTS operation, where T=left, R=right, and S=GND. 2 7" OUTPUT jack This 7" phone jack provides the main output of the GIS PC Preamp to be connected to the 7" mic input of the sound card on the computer. This jack is also configured for RTS operation, where T=left, R=right, and S=GND.
Placement The GIS PC Preamp can be placed in any convenient location. However, note that some monitors can introduce additional noise if the preamp is located too close. If a noisy condition should occur, re-adjust the position of the GIS PC Preamp until the best results are achieved.
Connections Guitar applications 21
Using auxiliary input signals 22
Mixing applications 23
Block Diagram 24
Operation About HUSH noise Reduction Dynamic Filtering Dynamic filtering is achieved by dynamically-controlling a low pass filter which opens and closes the bandwidth of the output signal dependent upon the amount of mid and high band information present in the input signal. The filter bandwidth will only open far enough to pass the highest frequency information in the input signal, thus reducing the noise above it.
Downward Expansion The second half of the HUSH® process incorporates downward expansion. The low level expander of the HUSH system operates like an electronic volume control. The HUSH system utilizes a voltagecontrolled amplifier (VCA) circuit which can control the gain between the input and the output from unity to 30, 40 or even 50dB of gain reduction. When the input signal is above the user preset threshold point, the VCA circuit remains at unity gain.
About the Analog Devices SSM2000... The SSM2000 is an advanced audio noise reduction system based on patented HUSH® technology. The SSM2000 is commercially available from Analog Devices, produced under the license of the HUSH patents. HUSH® combines a dynamic filter and downward expander to provide a high level effectiveness without the sonic artifacts normally associated with noise reduction systems.
Specifications 28 Maximum Input +10dB Maximum Output +2dB Input Impedance 470KW Output Impedance 1KW TREBLE Control ±14dB @ 5kHz MID Control ±15dB @ 1kHz BASS Control ±19dB @ 120Hz GAIN Control 80dB of gain Current Consumption 186mA Power Requirements 9VAC/1.
