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  5. Operating Instructions Manual

D.W. Fearn VT-15 Operating Instructions Manual

Manual is about: Vacuum Tube Recording Channel

Summary of VT-15

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    Vt-15 vacuum tube recording channel operating instructions d.W. Fearn.

  • Page 2: How to Contact Us:

    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: dwfearn@dwfearn.Com www.Dwfearn.Com.

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    D.W. Fearn h and - crafted professional recording equipment www.Dwfearn.Com p.O. Box 57 pocopson, pa 19366 u.S.A. Tel: 610-793-2526 fax: 610-793-1479 certificate of rohs compliance d.W. Fearn is committed to manufacturing products that are fully-compliant with the eu rohs directive. The following pr...

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    4.

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    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...

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    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 ..........................................

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    D.W. Fearn vt-15 recording channel 8 d.W. Fearn shall not be liable for technical or editorial errors or omissions in this manual, nor for incidental or consequential damages resulting from the use of this material. This instruction manual contains information protected by copyright. No part of this...

  • Page 8

    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 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,...

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    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 fe...

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    D.W. Fearn vt-15 recording channel 12.

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    D.W. Fearn vt-15 recording channel 13 mic input 150 ohms input load impedance 1.5k ohms minimum input level -65 dbm nominal maximum input level @ 20 cps -30 dbm without pad -5 dbm with 20 db pad instrument input impedance 1 megohm line input load impedance 40k ohms maximum line input level @ 20 cps ...

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    D.W. Fearn vt-15 recording channel 14 compression range up to 30db compression method pulse-width modulator equalizer: low-frequency boost 100 cps, shelving low-frequency cut 80 cps, shelving high-frequency boost 9.8 kc, peaking high-frequency q 0.6 to 1.7 high-frequency cut 12 kc, shelving power re...

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    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 tube microphone preamplifiers, the vt-7 stereo compressor, and the vt-4 lc equalizer. The model vt-15 recording channel is designed to provide recording professi...

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    D.W. Fearn vt-15 recording channel 16.

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    D.W. Fearn vt-15 recording channel 17 3 . I n s ta l l at 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 for damage with the shipper. Included in the box: ...

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    D.W. Fearn vt-15 recording channel 18 the back panel for installations that use separate chassis grounding. 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 ...

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    D.W. Fearn vt-15 recording channel 19 4 . O p e r at 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 very unpleasant sound. Think of the vt-15 as a small studio chain in one...

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    D.W. Fearn vt-15 recording channel 20 control set-up input toggle switches: mic/line switch - as appropriate for the source 0/-20 switch - 0 150/lo-z switch - 150 (unless you are using a non-standard impedance mic) +48 switch - on for phantom-powered condenser mics, otherwise off rev/phase switch - ...

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    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). Thi...

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    D.W. Fearn vt-15 recording channel 22 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. Input ...

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    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 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” posi...

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    D.W. Fearn vt-15 recording channel 24 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 hole...

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    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 standard c16.5-1954. In the gr position, the vu meter monitors the amount of gain reduction (...

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    D.W. Fearn vt-15 recording channel 26 1. Use the best quality mic cable you can. We don’t believe you have to use esoteric wire, but do use a good cable designed for low impedance microphones. A quality cable with gold-contact connectors is best. 2. There should be no additional cables, connectors, ...

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    D.W. Fearn vt-15 recording channel 27 5 . T h e o ry o f o p e r at i o n preamp section input section 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 the input selector sw...

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    D.W. Fearn vt-15 recording channel 28 response, low phase shift, excellent square wave response, low distortion, and high noise immunity. The secondary of is connected directly to the grid of the first amplifier stage. First stage the first stage is a selected 6072 configured as a class a voltage am...

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    D.W. Fearn vt-15 recording channel 29 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. ...

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    D.W. Fearn vt-15 recording channel 30

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    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 be replaced eventually. Top cover removal removing the...

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    D.W. Fearn vt-15 recording channel 32 tubes also sometimes develop a microphonic response — they will respond to ambient noise and 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 th...

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    D.W. Fearn vt-15 recording channel 33 troubleshooting 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 equipment r...