User manual DW FEARN VT4

[. . . ] After listening to a wide variety of equalization circuits, it was obvious to me that the passive inductor-capacitor (LC) circuit was the one that sounded the most musical and natural to me. In thinking about how I use equalization, I realized that having simultaneous boost and cut at the low and end frequencies was often very useful. For mid-frequencies, I found that I always cut, usually around 400 Hz, and never had any reason to boost in that range. If I were using a parametric equalizer, I invariably tended to use the low-Q (broadest) settings, and if I had a choice between shelving or peaking on the high and low end, I almost always prefered the shelving curve. [. . . ] It is built to sound great for a long time, with top quality parts used throughout; all the transformers, inductors and many other components are custom-made for the VT-4. All rotary controls use high-quality silver-contact switches for precise repeatability and matching between units. Much of the circuitry for the VT-4 is based on the highly-successful D. W. Since line-level signals are utilized in the VT-4, Class-A Svetlana 6N1P dual triodes are used for all amplifier stages. The input transformer, inductors in the passive equalization circuitry, and the output transformer are custom-made for us by Jensen Transformers Inc. Each one is hand-made and meticulously tested and listened to before shipment to the customer. The philosophy behind the VT-4 is: use only the best components in an optimized circuit, and build it with pride and precision. The VT-4 is designed and built to perform in your studio for decades to come. 3. INSTALLATION The VT-4 is carefully packed for shipment and it should survive all but the most brutal handling. If there is any damage, keep the shipping material for use during any possible claim for damage with the shipper. Included in the box: 1) The VT-4 Equalizer 2) Line cord 3) This instruction manual Mounting The VT-4 is designed for installation in a standard 19 inch rack. It requires 5. 25 inches of vertical space, but additional spacing between it and adjacent equipment is recommended for adequate cooling. Ideally, a ventilated panel at least 1 rack unit high (1. 25 inches) should be installed above and below the VT-4 (and around any other heat producing equipment for that matter). It is essential that air can flow into the bottom and out of the top of the VT-4. The VT-4 can also be used without a rack, placed on a table, counter, or even on the floor. Optional rubber feet are available, when requested at the time of the order. Moderate electrical and magnetic fields in the vicinity of the VT-4 should not cause any degradation in noise performance, due to the well-shielded construction, but proximity to devices with motors or large power transformers (i. e. Although the vacuum tubes in the VT-4 are selected for minimum microphonic response, it is a good practice to avoid mounting locations that subject the VT4 to very high sound or vibration levels. Input and Output Connections Gold-plated XLR connectors are used for inputs and outputs. All connectors are wired according to AES standard: pin 1 is ground (shield), pin 2 is "high" or "+, " and pin 3 is "low" or "-. " A positive voltage on pin 2 of the input will result in a positive voltage on pin 2 of the output Grounding and Shields A full discussion of proper studio wiring schemes is beyond the scope of this manual, but, in general, the Input mating XLR connector must have the cable shield connected to pin 1. Whether the shield is connected to pin 1 of the output connector depends on the standard in your studio. The shield should be connected to ground at only one end of the output cable; however, although not recommended, the shields can often be connected at both ends without a problem. Input Since the input cable will be carrying very high-quality audio, it is important that a well-shielded cable is used. Note that vacuum tube equipment is more sensitive to load impedance than solid state units. [. . . ] Tube life is difficult to predict, but it will probably be measured in years. Catastrophic tube failure is rare with this type of device, but a gradual increase in noise, microphonics, distortion, or a reduction in headroom, should indicate the need for replacement. It is recommended that you periodically perform a quick noise and distortion check on the VT-4 and compare the results to previous measurements. Replacement tubes may be obtained from us (tested and graded for low-noise and microphonics), or other suppliers. Rotary Switches The rotary switches in the VT-4 were chosen for their self-cleaning property. [. . . ]