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美国DWFearn VT-2话筒放大器$ J2 A, W3 c8 l) O H) p7 D. t/ I
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# x, k, ?0 }) k7 @1 P: |" y在设计VT前置放大器时,不允许在声音质量,可靠性或坚固性方面做出任何妥协。与20世纪50年代和60年代的电子管设备一样,VT前置放大器采用重型铝制机箱,采用点对点布线。选择每个真空管以获得***小的噪音和微音,以及的声音清晰度。前面板开关控制密封的金触点精密继电器,用于所有音频切换,消除了脏接触降低声音和***小化内部音频路径的可能性。每个通道中的四个A类三极管放大器部分(在两个管中)包括整个有源电路。这个令人惊讶的简单电路,以及高品质的元件和精心的设计优化,带来了VT前置放大器的声音优势。0 _6 W: s- C n; T# w; b
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All vacuum-tube design8 o' ~- h1 { L& @# J, R/ f
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Lo-Z input position for superior performance with transformerless mics
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Phase (polarity) reverse switch
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9 A" }- A$ x9 O- f+48 volt phantom power (completely disconnected when off)9 Y- y3 z3 ^0 A' w9 O$ f6 j* a7 A
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Custom-design Jensen input and output transformers
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* A% i9 W1 Y2 h5 i1 e20 dB input pad (switchable)
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True VU meters (amplifier isolated)
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All point-to-point audio wiring
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Gold input and output XLR connectors
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# Y5 Z& g6 v! z/ PPolypropylene and polystyrene coupling capacitors
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All audio switching through gold-contact, sealed precision relays
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International operation on 100, 120, or 220 VAC, 50/60 Hz
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CE certified, RoHS-compliant& N1 p4 C! p- h) V. z% O1 @
- S5 H# [. {% J8 L1 ^6 @+4 dBm output
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Conservatively rated precision components and rugged construction for stability and long life. L. i$ @8 h( n. m2 O- j; i! O
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Specifications# b2 u6 e3 ^3 a
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Input 150 ohms
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6 ?6 }& E, m% ^& j5 e1 ?( {8 cInput Load Impedance 1.5k ohms
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! x/ T. s" H- `' n/ k1 h$ wMinimum Input Level -65 dBm nominal
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Maximum Input Level @ 20 cps -30 dBm without pad, -5 dBm with 20 dB pad t, D5 b5 b5 J. J9 ?) x
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Gain 53 dB
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Frequency Response +/-0.25 dB 20 cps to 20 kc; -3 dB @ 0.5 cps and 55 kc! {* H* _9 t# x4 b: _" f, @5 B9 ^
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THD+Noise less than 0.25% 20 cps to 20 kc y% l B6 U/ U% V
8 a0 j% k( n$ X/ LIntermodulation Distortion SMPTE less than 0.02%
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/ M5 L" _3 s, `Signal to Noise Ratio 74 dB minimum6 l# w- Y0 K" o ?, C) y! |
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Equivalent Input Noise -124 dBm maximum* v4 o3 Q7 ^ ~9 V, A% G: F
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Output low-Z, transformer-balanced
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Maximum Output Level +22 dBm, 20k ohm load. H) k$ c( m3 J7 A) _" o
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Power Requirements 100, 120, or 220 VAC, 50/60 Hz
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( E1 R$ y5 H: J- N; ]7 @Dimensions 19” (48.26cm) W, 5.25” (13.34cm) H, 14” (35.56cm) D
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