D.W. Fearn VLC, Operating Instructions Manual

Page 1: ...HAZELRIGG INDUSTRIES VLC Vacuum Tube Preamplifier EQ DI Operating Instructions...

Page 2: ...e Preamplifier EQ DI HAZELRIGG INDUSTRIES 2 How to Contact us Telephone 567 DW FEARN 567 393 3276 Shipping Address 124 Tartan Terrace Chalfont PA 18914 U S A e mail support hazelriggindustries com www...

Page 3: ...committed to manufacturing products that are fully compliant with the EU RoHS Directive The following products are compliant VT 1 VT 2 VT 24 VLC 1 VT 3 VT I F VDI VT 4 VT 5 VT 7 VT 15 LP 1 PDB This d...

Page 4: ...Tube Microphone Preamplifier Final Test Report Serial Number Mains Voltage VAC Date Tested by THD Noise 20 cps 200 cps 2 kc s 20 kc s Operational Tests 48V 20 pad Phase Reverse EQ In Line Input Instru...

Page 5: ...EQ DI HAZELRIGG INDUSTRIES Table of Contents Warranty 6 Specifications 7 Description 8 Installation 9 Operation 12 Theory 18 Maintenance 20 List of Illustrations Rear Panel Connections 11 Front Panel...

Page 6: ...y but are warranted for 90 days from date of purchase Except as expressly set forth in this Warranty D W Fearn Hazelrigg Industries makes no other warranties express or implied including any implied w...

Page 7: ...Line Input Load Impedance 40k ohms Gain 55 dB minimum Frequency Response 0 5 dB 20 cps to 20 kc THD Noise 0 35 20 cps to 20 kc Intermodulation Distortion SMPTE 0 80 Signal to Noise Ratio 72 dB typica...

Page 8: ...warmth that solid state preamps lack Its modern design and construction allows the VLC to exceed the performance of vintage vacuum tube preamps It is designed for use in the professional recording env...

Page 9: ...fit all your equipment The VLC 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 electr...

Page 10: ...and pin 3 or low The VLC is optimized for feeding balanced bridging inputs Virtually all modern audio equipment has bridging inputs The output is transformer balanced The GND terminal is for use when...

Page 11: ...hields 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 With most microp...

Page 12: ...then fed back to the control room Avoid locating the VLC where it will be subjected to high sound levels or excessive vibration such as on a drum riser Output The output of the VLC is line level trans...

Page 13: ...xperiment with the microphone pad if it has one the VLC 20 switch position or both Let your ears be the judge Slight to moderate overdriving of the VLC often adds edge power or excitement to the sound...

Page 14: ...cs Although leaving the 48 on will not damage any properly wired balanced mic some ribbon mics have reportedly been damaged when connected or disconnected from phantom powering Also some engineers fee...

Page 15: ...built before standardization may reverse the polarity in the recording monitoring chain The effect of reversed absolute polarity is usually subtle but can be significant with some sounds If the rever...

Page 16: ...king but it is suggested that you turn on the power at least five minutes prior to use The tubes are often noisy until all the internal elements reach a stable operating temperature Initial Set Up The...

Page 17: ...located in the studio or in the control room but use the shortest possible cable between the mic and the VLC 2 Use the best quality mic cable you can We don t believe you have to use esoteric wire but...

Page 18: ...ystyrene capacitor This stage operates as a Class A voltage amplifier with a gain of approximately 30 The plate is coupled through a polypropylene capacitor to the top of a conductive plastic rotary p...

Page 19: ...mary taps for 115 and 220 240 volt operation A switch on the rear makes it quick and easy to go between voltages Be sure to also change the fuse to the appropriate value Filament supply The power tran...

Page 20: ...roblem since measurements in a quiet room will indicate perfect performance Gently tapping the tube shields while listening to the output at a normal monitor level should reveal nothing more than a sl...

Page 21: ...ps noise the filter capacitors should be suspected They should be replaced with new capacitors of equivalent capacitance and voltage rating and the replacements should be specified for a minimum ten y...