Page 2 - VT-15 Recording Channel
D.W. FEARN VT-15 Recording Channel How to Contact us: Telephone: 610-793-2526 Fax: 610-793-1479 Mail: P.O. Box 57, Pocopson, PA 19366 U.S.A. Shipping Address: 182 Bragg Hill Road West Chester, PA 19382 U.S.A. e-mail: [email protected] www.dwfearn.com
Page 3 - Certificate of RoHS Compliance; The following products are compliant:
D.W. FEARN H AND - CR AFTED PROFESSIONALRECORDING EQUIPMENT www.dwfear n.com P.O. Box 57Pocopson, PA 19366 U.S.A.Tel: 610-793-2526Fax: 610-793-1479 Certificate of RoHS Compliance D.W. Fearn is committed to manufacturing products that are fully-compliant withthe EU RoHS Directive. The following produ...
Page 5 - VT-15 Vacuum Tube Recording Channel; Operational Tests
D.W. FEARN VT-15 Recording Channel 5 VT-15 Vacuum Tube Recording Channel Final Test Report Serial Number_______________ Mains Voltage 120/240 set to __________________ Date ________________ Tested by ________ VU Calibrated to _______________ dBm Test Equipment ____________________________ Microphone...
Page 6 - T a b l e o f C o n t e n t s; List of Illustrations
D.W. FEARN VT-15 Recording Channel 7 T a b l e o f C o n t e n t s RoHS Compliance Data ..................................................................3 Final Test Report ............................................................................5 Warranty ..........................................
Page 8 - Limited 5-Year Warranty
D.W. FEARN VT-15 Recording Channel 9 Limited 5-Year Warranty During the warranty period, D.W. Fearn will, at no additional charge, repair or replacedefective parts with new parts. This warranty does not extend to any VT-15 that has been damaged or rendered defective as a result of accident, misuse, ...
Page 9 - History of the VT-15 Vacuum Tube Recording Channel
D.W. FEARN VT-15 Recording Channel 11 History of the VT-15 Vacuum Tube Recording Channel With the success of the VT-1/VT-2 Vacuum Tube Microphone Preamplifiers, the VT- 4 LC Equalizer, the VT-7 Stereo Compressor, and the VT-I/F and VT-3 Vacuum Tube DIs,there was a great temptation to combine the fea...
Page 11 - S P E C I F I C A T I O N S
D.W. FEARN VT-15 Recording Channel 13 Mic Input 150 ohms Input LoadImpedance 1.5k ohms Minimum InputLevel -65 dBm nominal Maximum InputLevel @ 20 cps -30 dBm without pad-5 dBm with 20 dB pad Instrument Input impedance 1 Megohm Line InputLoad Impedance 40k ohms Maximum Line InputLevel @ 20 cps +25dBm...
Page 13 - D E S C R I P T I O N
D.W. FEARN VT-15 Recording Channel 15 2 . D E S C R I P T I O N The D.W. Fearn VT-15 utilizes circuitry developed for the VT-1/VT-2 Vacuum TubeMicrophone Preamplifiers, the VT-7 Stereo Compressor, and the VT-4 LC Equalizer. The Model VT-15 Recording Channel is designed to provide recording professio...
Page 15 - I N S T A L L A T I O N; ) This instruction manual
D.W. FEARN VT-15 Recording Channel 17 3 . I N S T A L L A T I O N The VT-15 is carefully packed for shipment and it should survive all but the most brutal han-dling. If there is any damage, keep the shipping material for use during any possible claim fordamage with the shipper. Included in the box: ...
Page 16 - I n p u t a n d O u t p u t C o n n e c t i o n s
D.W. FEARN VT-15 Recording Channel 18 the back panel for installations that use separate chassis grounding. If ground loop hum isdetected, a careful check of the studio grounding scheme is needed. The VT-15 is less suscep-tible to grounding problems than many studio devices. C o n n e c t i o n s Th...
Page 17 - O P E R A T I O N; INITIAL SET-UP IS CRITICAL; So follow these steps for the initial; Figure 1. VT-15 front panel controls and indicators
D.W. FEARN VT-15 Recording Channel 19 4 . O P E R A T I O N INITIAL SET-UP IS CRITICAL for getting the best performance from your VT-15! The VT-15 has tremendous versatility, but with that versatility comes the potential for for veryunpleasant sound. Think of the VT-15 as a small studio chain in one...
Page 19 - M i c I n p u t; of the specifications. In modern studio equip-
D.W. FEARN VT-15 Recording Channel 21 6. Adjust the Eq controls for the desired sound. (Remember to use the Boost and Cut togeth-er to shape the sound.) 7. Switch the VU meter back to the VU position. 8. Adjust the Gain control for a normal indication. Peaks should rarely go into the red (0VU). This...
Page 20 - Supplies 48 volts for phantom powered con-
D.W. FEARN VT-15 Recording Channel 22 C O N T RO L S ( s e e F i g u r e 1 . ) The VT-15 front panel is divided into three main areas of controls. On the left is the Input sec-tion, to its right is the Compressor section, further right is the Equalizer section, and far rightis the output and power s...
Page 21 - Switches between the rear panel input connector (for mic or line
D.W. FEARN VT-15 Recording Channel 23 es the polarity of the output of the VT-15. A detailed discussion of the application of phasereversal of individual microphones is beyond the scope of this manual. Even when there is only one microphone being recorded, it may be useful to try the“Reverse” positi...
Page 23 - Primary power is applied to the VT-15 circuits when the Power; B e n c h Te s t
D.W. FEARN VT-15 Recording Channel 25 should result in “0 VU” on a properly aligned recorder. (This reference level can be changed;see the Maintenance Section.) This is a true VU meter, and conforms to ASA StandardC16.5-1954. In the GR position, the VU meter monitors the amount of gain reduction (co...
Page 25 - T H E O R Y O F O P E R A T I O N; P r e a m p S e c t i o n
D.W. FEARN VT-15 Recording Channel 27 5 . T H E O R Y O F O P E R A T I O N P r e a m p S e c t i o n I n p u t s e c t i o n Microphone level (150 ohm source impedance, balanced, -50 dBm nominal) or line level(600-ohm source, +4dBm nominal) audio enters through the XLR-3 female INPUT connec-tor to ...
Page 26 - C o m p r e s s i o n S e c t i o n
D.W. FEARN VT-15 Recording Channel 28 response, low phase shift, excellent square wave response, low distortion, and high noiseimmunity. The secondary of is connected directly to the grid of the first amplifier stage. F i r s t s t a g e The first stage is a selected 6072 configured as a Class A vol...
Page 29 - M A I N T E N A N C E; voltages could result in serious injury or death.
D.W. FEARN VT-15 Recording Channel 31 6 . M A I N T E N A N C E The VT-15 is built with only the highest quality parts and will prove to be extremely reliable.Vacuum tubes and electrolytic capacitors, however, have a finite useful life and must bereplaced eventually. T o p C o v e r R e m o v a l Re...
Page 30 - V U M e t e r C a l i b r a t i o n
D.W. FEARN VT-15 Recording Channel 32 Tubes also sometimes develop a microphonic response — they will respond to ambient noiseand vibration. This can be an insidious problem since measurements in a quiet room will indi-cate perfect performance. Gently tapping the tube shields while listening to the ...
Page 31 - T r o u b l e s h o o t i n g
D.W. FEARN VT-15 Recording Channel 33 T r o u b l e s h o o t i n g Most problems will be traced to defective vacuum tubes. However, if normal tests do not eas-ily reveal the problem, feel free to call the factory for assistance. If you lack access to a qual-ified service technician with vacuum tube...
