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Related Manuals for D.W. Fearn VT-15
Summary of Contents for D.W. Fearn VT-15
- Page 1 D.W. FEARN VT-15 Vacuum Tube Recording Channel Operating Instructions...
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Page 2: How To Contact Us
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: dwfearn@dwfearn.com www.dwfearn.com D.W. FEARN VT-15 Recording Channel... - Page 3 VT-2 VT-3 VT-4 VT-7 VT-15 LP-1 This declaration is based on our understanding of the current RoHS Directive and from information provided by the supplier material declarations with regard to materials contained in the component that make up our products.
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Page 5: Final Test Report
VT-15 Vacuum Tube Recording Channel Serial Number_______________ Mains Voltage 120/240 set to __________________ Date ________________ Tested by ________ VU Calibrated to _______________ dBm Test Equipment ____________________________ Microphone ________________________ Frequency Response: 20 cps to 20 kc/s +/- ___________ dB THD+Noise: 20 cps ______________ %... -
Page 6: Table Of Contents
T a b l e o f C o n t e n t s RoHS Compliance Data ...3 Final Test Report ...5 Warranty ...9 History of the VT-15 ...11 1. Specifications ...13 2. Description...15 3. Installation ...17 4. Operation ...19 5. - Page 7 This instruction manual contains information protected by copyright. No part of this manual may be photocopied or reproduced in any form without prior written consent from D.W. Fearn. Copyright ©2007 D.W. Fearn & Associates D.W. FEARN VT-15 Recording Channel...
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Page 8: Warranty
During the warranty period, D.W. Fearn will, at no additional charge, repair or replace defective 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, or abuse; by the use of parts not manufac- tured or supplied by D.W. -
Page 9: History Of The Vt-15
18 months when we could not keep up with the orders for our VT-7 Stereo Compressor. In fact, I put the VT-15 project on hold entirely for six months. When I returned to it over the summer of 2007, the pieces fell into place and the VT-15 was ready to meet the world. - Page 10 D.W. FEARN VT-15 Recording Channel...
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Page 11: Specifications
Distortion Signal to Noise Ratio Equivalent Input Noise Output Maximum Output Level VT-15 Recording Channel 150 ohms 1.5k ohms -65 dBm nominal -30 dBm without pad -5 dBm with 20 dB pad 1 Megohm 40k ohms +25dBm (+35dBm with pad) <60 dB optimum... - Page 12 Pulse-width modulator 100 cps, shelving 80 cps, shelving 9.8 kc, peaking 0.6 to 1.7 100, 120, or 220 VAC 50/60Hz, 50 W 19” (48.26cm) W 5.25” (13.34cm) H 9” (22.86cm) D (VT-2 13” 22.9cm) 18 lbs (8.16kg) VT-15 Recording Channel...
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Page 13: Description
It is typically used in sound recording studios for recording individual tracks. A quality microphone, electric instrument, or line-level signal is connected to a VT-15 input, and the VT-15 provides a line-level output. In most situations, the VT-15 will feed directly to the input of the recorder. - Page 14 D.W. FEARN VT-15 Recording Channel...
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Page 15: Installation
Be sure the bottom vent slots are not blocked. It is essential that air can flow into the bottom and out of the top of the VT-15. Equipment that runs cool can last for a very long time. - Page 16 If ground loop hum is detected, a careful check of the studio grounding scheme is needed. The VT-15 is less suscep- tible to grounding problems than many studio devices. Connections The INPUT connector is a XLR-3 female wired with pin 1 ground, pin 2 “+”...
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Page 17: Operation
The VT-15 has tremendous versatility, but with that versatility comes the potential for for very unpleasant sound. Think of the VT-15 as a small studio chain in one box: mic preamp, com- pressor, and equalizer. In most studios, these would be three separate pieces of equipment and you would patch them together in a chain feeding your recorder. - Page 18 4. Turn up the Threshold control until the the VU meter indicates compression. Typically you will use from 2 to 10dB of compression most of the time. 5. Adjust the Attack, Release, and Harder/Softer controls for the desired sound. D.W. FEARN VT-15 Recording Channel...
- Page 19 “Mic” will result in very high level and extreme distortion. Although this will not harm the VT-15, it could be dangerous to your speakers and your ears! So make sure the switch is set appro- priately before making the connections.
- Page 20 CONTROLS (see Figure 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 right is the output and power section.
- Page 21 VT-15. A detailed discussion of the application of phase reversal 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”...
- Page 22 Attack and Release times without adding any low-frequency distortion. Equalization Controls: The equalizer section of the VT-15 is derived from the D.W. Fearn VT-4 LC Equalizer. It is a much simplified version of the VT-4, but it retains the same basic circuitry and sound of the VT-4.
- Page 23 In the GR position, the VU meter monitors the amount of gain reduction (compression). As the VT-15 warms up, the normal “0VU” position of the meter needle (with no compression) may drift slightly. This has no effect on the sound of the VT-15 nor the accuracy of the gain reduction measurement.
- Page 24 2. There should be no additional cables, connectors, junction boxes, patch jacks, etc. between the mic and the VT-15 input. 3. The output of the VT-15 should be fed directly to the recorder through the shortest practical length of quality cable. Avoid additional cables, connectors, junction boxes, punch blocks, or patch jacks.
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Page 25: Theory Of Operation
The switching is through sealed gold-contact instrumentation relays with bifurcat- ed contacts. In the “Off” position, the phantom power resistors are completely disconnected from the Input connector. When the VT-15 is in the Line position, the 48V switch is locked out. - Page 26 Either the eq output or the compressor output feeds a 6N1P dual triode with both sections in parallel to provide line-level output. The output transformer is custom-made for us by Jensen Transformers, Inc. and is the same transformer we use on all of our products. D.W. FEARN VT-15 Recording Channel...
- Page 27 VU Meter and Meter Amplifier A two-stage IC operational amplifier is used to isolate the VU meter from the VT-15 output. An output sample is derived from the primary of the output transformer. The meter calibra- tion is set with a 20-turn trimmer potentiometer. Reference level (0 VU) can be set from -20 to over +20dBm.
- Page 28 D.W. FEARN VT-15 Recording Channel...
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Page 29: Maintenance
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 be replaced eventually. - Page 30 Treat each one carefully. Electrolytic Capacitors The VT-15 is designed and built to last for a long, long time, and it is possible that some com- ponents (e.g. electrolytic capacitors) may reach the end of their life long before the equip- ment becomes obsolete.
- Page 31 Call for instructions. We can usually return a properly-performing VT-15 in a couple of days. If repairs are needed, we will discuss it with you before proceeding. We always operate any repaired VT- 15 for at least 24 hours to make sure it is operating properly before return.
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