User manual ROCKTRON PCPREAMPGIS

[. . . ] ------------------------------- 12 Specifications ------------------------------------------ 13 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. [. . . ] In the clean mode, the internal SSM2000 HUSH IC is configured to provide compression. 9 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. 18 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. 3 RIGHT AUXiliary INput RCA jack This RCA input provides external signal to the ring of the 3" and 7" OUTPUT jacks (#1 and #2 above). The AUX INPUT LEVEL on the front panel determines the overall level of the signal applied at this jack. LEFT AUXiliary INput RCA jack This RCA input provides external signal to the tip of the 3" and 7" OUTPUT jacks (#1 and #2 above). The AUX INPUT LEVEL on the front panel determines the overall level of the signal applied at this jack. POWER jack This 2. 5mm pin jack accepts power from the 9VAC power adapter supplied with the unit. 4 7 19 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. 20 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. For example, if the highest frequency present in the input signal is 8kHz, the filter will open to pass up to 8kHz while the noise from 8kHz to 20kHz would be reduced. If a signal with frequency components up to 20kHz appears at the input, the dynamic filter will open to its full extreme (40kHz). This means that if a signal is present at the input which consists of primarily bass components, the dynamic filter will reduce mid or high band noise. If no mid or high band information is present, the filter will close down to a pre-set cut-off point of 1kHz (allowing only frequencies of 1kHz and below to pass). However, if the input signal has high frequency components present, the dynamic filter will open fully to pass the signal and eliminate the possibility of a loss of high end frequency response. 25 Downward Expansion The second half of the HUSH® process incorporates downward expansion. [. . . ] HUSH® combines a dynamic filter and downward expander to provide a high level effectiveness without the sonic artifacts normally associated with noise reduction systems. In addition, an Adaptive Threshold circuit detects nominal signal levels and dynamically adjusts both thresholds, thereby providing optimal results regardless of program source. Since it is a single-ended system, HUSH can be used on virtually any audio source, including audio and video tapes, radio and television broadcasts, or any other source with objectionable noise. [. . . ]