User manual DW FEARN VT7

[. . . ] FEARN VT-7 Vacuum Tube Compression Amplifier Operating Instructions How to Contact us: Telephone: 610-793-2526 Fax: 610-793-1479 Mail: P. O. FEARN VT-7 Compression Amplifier 3 VT-7 Vacuum Tube Compression Amplifier Final Test Report Model _______________ Serial Number_______________Mains Voltage ______________ Date ___________________ Tested by ________ VU Calibrated to _______________ dBm Test Equipment _______________________________________________________________ Channel A Frequency Response: 20 cps to 20 kc/s +/- ___________ dB THD+Noise: 20 cps ______________ % 200 cps _____________ % 2 kc/s _______________ % 20 kc/s ______________ % Noise: ______________ dB below +4 dBm out Channel B Frequency Response: 20 cps to 20 kc/s +/- ___________ dB THD+Noise: 20 cps ______________ % 200 cps _____________ % 2 kc/s _______________ % 20 kc/s ______________ % Noise: ______________ dB below +4 dBm out Operational Tests: Compression Range ________ Attack ____________________ Release __________________ Shape ___________________ Link _____________________ GR Meter ________________ Listening Test ____________ Operational Tests: Compression Range ________ Attack ____________________ Release __________________ Shape ___________________ Link _____________________ GR Meter ________________ Listening Test ____________ VT-7 Compression Amplifier D. W. FEARN 5 Table of Contents Final Test Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 History of the VT-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. [. . . ] Generally speaking, a fast attack time is best when complete control of the maximum instantaneous level is required. However, a more natural sound is usually obtained with a slightly slower attack time. Long attack times can be useful as an effect, adding power to percussive instruments. Release The Release control adjusts how long it takes for the gain to return to normal after a sound ceases (or drops in level). Fast release times add more energy to the sound, but can add distortion to low frequency sounds. (This is true of all compressors. ) A fast release time adds density to the sound, often with the compression becoming more obvious. Long release times make the compression less obvious and more natural, but can "punch holes" in the lower level audio under certain conditions of high percussive levels. Harder/Softer This control adjusts the nature of the compression curve. Toward the "Harder" end of the control, the compression ratio is higher and the levels more tightly controlled. At the "Softer" end, the compression ratio is lower and the compression is more gentle. This is not merely a ratio control, however, as other parameters also change as the control is adjusted. This control interacts with the Threshold, Attack, and Release controls, so after changing the Softer/Harder control, you should experiment with others to obtain the effect you desire. Although the compression ratio changes with this control, there are other parameters that are changed as well. Its operation is complicated to explain, so it is much easier to understand it simply by experimenting. Link/Separate This is a two-position switch that links the two channels together for stereo operation. In the Separate position, the two channels operate completely independently, and can be used on totally different sources without any interaction. In the Link position, the two channels track each other precisely, so that the stereo image will remain constant even if one channel has much more level than the other. You can run a stereo signal with the switch in the Separate position for an effect. On a stereo pair such as a piano or other sub-mix stereo source, the image will tend to shift from left to D. W. FEARN VT-7 Compression Amplifier 19 right as the signal becomes louder in one channel compared to the other. This would be disconcerting on a stereo bus, but could be interesting on individual stereo tracks. When operating in the Link position, only the left side (Channel A) controls are operative. The only exception is the Gain control, which will still adjust the level of the B channel in the Link position. Meter Switch The VU meter can be switched to read either output ("VU") or gain reduction ("GR"). In the VU position, the meter will indicate the actual output level of the VT-7. The "0" VU mark indicates +4dBm output In the "GR" position, the meter indicates the amount of gain reduction (compression), in dB. [. . . ] Tubes are made of glass and will break if dropped or even bumped in a critical area. Handle with care. Electrolytic Capacitors The VT-7 is designed and built to last for a long, long time, and it is possible that some components (e. g. electrolytic capacitors) may reach the end of their life long before the equipment becomes obsolete. The electrolytic capacitors used in the VT-7 typically will last at least twenty years. [. . . ]