Instruction/ maintenance manual of the product VT-15 D.W. Fearn
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VT-15 Vacuum Tube Recording Channel Operating Instructions D.W. FEARN.
D.W. FEARN VT-15 Recording Channel Ho w to Cont act us: T elephone: 6 1 0-793-2526 F ax: 6 1 0-793- 1 479 Mail: P .O. Bo x 57 , P ocopson, P A 1 9366 U .S.A. Shipping A ddress: 1 82 Bragg Hill R oad W est Chester , P A 1 9382 U .S.A. e-mail: dwf ear n@dwf ear n.
D . W . F EARN H AND - CR AFTED PR OFESSION AL RECORDIN G EQUIPMENT www .dwfear n.com P .O. Bo x 57 P ocopson, P A 1 9366 U .S.A. T el: 6 1 0-793-2526 F ax: 6 1 0-793- 1 479 Cer tificate of RoHS Compliance D.W . F ear n is committed to manuf acturing pr oducts t hat ar e fully-com pliant wit h t he EU R oHS Dir ectiv e.
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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 .
D.W. FEARN VT-15 Recording Channel 7 Table of Contents R oHS Com pliance Dat a .................................................................. 3 Final T est R epor t ............................................................................ 5 W ar ranty .
D.W. FEARN VT-15 Recording Channel 8 D.W . F ear n shall not be liable f or technical or editorial er r ors or omissions in t his manual, nor f or incident al or consequential damag es r esulting fr om t he use of t his material. This instr uction manual cont ains inf or mation pr otected b y cop yright.
D.W. FEARN VT-15 Recording Channel 9 Limited 5-Year Warranty During t he w ar ranty period, D.W . F ear n will, at no additional char g e, r epair or r eplace def ectiv e par ts wit h ne w par ts.
D.W. FEARN VT-15 Recording Channel 11 History of the VT-15 Vacuum Tube Recording Channel W it h t he success of t he VT - 1/VT -2 V acuum Tube Micr ophone Pr eam plifiers, t he VT - 4 LC Equalizer , t.
D.W. FEARN VT-15 Recording Channel 12.
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 Instr.
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.
D.W. FEARN VT-15 Recording Channel 15 2. DESCRIPTION The D.W . F ear n VT - 1 5 utilizes cir cuitr y de v eloped f or t he VT - 1/VT -2 V acuum Tube Micr ophone Pr eam plifiers, t he VT -7 Ster eo Com pr essor , and t he VT -4 LC Equalizer .
D.W. FEARN VT-15 Recording Channel 16.
D.W. FEARN VT-15 Recording Channel 17 3. INST ALL A TION The VT - 1 5 is car efully pack ed f or shipment and it should surviv e all but t he most br ut al han - dling. If t her e is an y damag e, k eep t he shipping material f or use during an y possible claim f or damag e wit h t he shipper .
D.W. FEARN VT-15 Recording Channel 18 t he back panel f or inst allations t hat use separate chassis gr ounding. If gr ound loop hum is detected, a car eful check of t he studio gr ounding scheme is needed. The VT - 1 5 is less suscep - tible to gr ounding pr oblems t han man y studio de vices.
D.W. FEARN VT-15 Recording Channel 19 4. OPER A TION INITIAL SET-UP IS CRITICAL for getting the best performance from your VT-15! The VT - 1 5 has tr emendous v ersatility , but wit h t hat v ersatility comes t he potential f or f or v er y un pleasant sound.
D.W. FEARN VT-15 Recording Channel 20 Control Set-up In put togg le switches: Mic/Line switch - as appr opriate f or t he sour ce 0/-20 switch - 0 1 50/Lo-Z switch - 1 50 (unless y ou ar e using a non.
D.W. FEARN VT-15 Recording Channel 21 6. A djust t he Eq contr ols f or t he desir ed sound. (R emember to use t he Boost and Cut tog et h- er to shape t he sound.) 7 . Switch t he VU meter back to t he VU position. 8. A djust t he Gain contr ol f or a nor mal indication.
D.W. FEARN VT-15 Recording Channel 22 C ONTR OLS (see Figure 1 .) The VT - 1 5 fr ont panel is divided into t hr ee main ar eas of contr ols. On t he left is t he In put sec - tion, to its right is t he Com pr essor section, fur t her right is t he Equalizer section, and f ar right is t he output and po w er section.
D.W. FEARN VT-15 Recording Channel 23 es t he polarity of t he output of t he VT - 1 5. A det ailed discussion of t he application of phase re v ersal of individual micr ophones is be y ond t he scope of t his manual.
D.W. FEARN VT-15 Recording Channel 24 add distor tion to lo w fr equency sounds. (This is tr ue of all com pr essors.) A f ast r elease time adds density to t he sound, often wit h t he com pr ession becoming mor e obvious.
D.W. FEARN VT-15 Recording Channel 25 should r esult in “0 VU” on a pr operly aligned r ecor der . (This r ef er ence le v el can be chang ed; see t he Maintenance Section.) This is a tr ue VU meter , and conf or ms to AS A St andar d C1 6.5- 1 954.
D.W. FEARN VT-15 Recording Channel 26 1 . Use t he best quality mic cable y ou can. W e don’t belie v e y ou ha v e to use esoteric wir e, but do use a good cable designed f or lo w im pedance micr ophones. A quality cable wit h gold-cont act connectors is best.
D.W. FEARN VT-15 Recording Channel 27 5. THEOR Y OF OPER A TION Preamp Section Input section Micr ophone le v el (1 50 ohm sour ce im pedance, balanced, -50 dBm nominal) or line le v el (600-ohm sour ce, +4dBm nominal) audio enters t hr ough t he XLR-3 f emale INPUT connec - tor to t he In put selector switch bank.
D.W. FEARN VT-15 Recording Channel 28 r esponse, lo w phase shift, ex cellent squar e w av e r esponse, lo w distor tion, and high noise immunity . The secondar y of is connected dir ectly to t he grid of t he first am plifier st ag e.
D.W. FEARN VT-15 Recording Channel 29 VU Meter and Meter Amplifier A tw o-st ag e IC operational am plifier is used to isolate t he VU meter fr om t he VT - 1 5 output. An output sam ple is deriv ed fr om t he primar y of t he output transf or mer . The meter calibra - tion is set wit h a 20-tur n trimmer potentiometer .
D.W. FEARN VT-15 Recording Channel 30.
D.W. FEARN VT-15 Recording Channel 31 6. MAINTENANCE The VT - 1 5 is built wit h only t he highest quality par ts and will pr o v e to be extr emely r eliable. V acuum tubes and electr olytic capacitors, ho w ev er , ha v e a finite useful lif e and must be r eplaced e v entually .
D.W. FEARN VT-15 Recording Channel 32 Tubes also sometimes de v elop a micr ophonic r esponse — t he y will r espond to ambient noise and vibration. This can be an insidious pr oblem since measur ements in a quiet r oom will indi - cate per f ect per f or mance.
D.W. FEARN VT-15 Recording Channel 33 Troubleshooting Most pr oblems will be traced to def ectiv e v acuum tubes. Ho w e v er , if nor mal tests do not eas - ily r e v eal t he pr oblem, f eel fr ee to call t he f actor y f or assist ance.
An important point after buying a device D.W. Fearn VT-15 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought D.W. Fearn VT-15 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data D.W. Fearn VT-15 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, D.W. Fearn VT-15 you will learn all the available features of the product, as well as information on its operation. The information that you get D.W. Fearn VT-15 will certainly help you make a decision on the purchase.
If you already are a holder of D.W. Fearn VT-15, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime D.W. Fearn VT-15.
However, one of the most important roles played by the user manual is to help in solving problems with D.W. Fearn VT-15. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device D.W. Fearn VT-15 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
