C
ULTURE
T
HERMIONIC
TheEarlybird 4
valve microphone pre-amplifier
OPERATING MANUAL
Page 1: ...CULTURE THERMIONIC TheEarlybird 4 valve microphone pre amplifier OPERATING MANUAL...
Page 2: ...after the mains supply has been disconnected It is essential that these capacitors are discharged after the mains supply has been disconnected and the covers have been removed In the event that this u...
Page 3: ...Ltd July 2014 2 CONTENTS Section Page 1 Introduction 3 2 Controls 4 2 1 Gain 4 2 2 Bass filter 4 2 3 Pad 4 2 4 Z 2 5 48V 4 2 6 Phase reverse 4 2 7 Output trim 4 3 Metering 6 4 Operational suggestions...
Page 4: ...d 2 series They have improved Sowter input and output transformers and traditional point to point hand wiring by experts eliminating the slight performance degradation occurring when using circuit boa...
Page 5: ...frequency drops 2 3 Pad Cuts down the input level by 20dB Use with Z set to 1200 for cleanest results 2 4 Z Switches input impedance between 300 and 1200 This is for matching microphones see 4 2 5 48...
Page 6: ...hermionic Culture Ltd July 2014 5 electronics is available when the controls are set to maximum These controls are designed to be both fine level controls and to reduce the output to feed 10dBV system...
Page 7: ...actual output of the electronics less 2dB not necessarily the actual output as they precede the Output Trim controls They will only measure the actual output when the Output Trim is set to the M posit...
Page 8: ...evel inputs eg kick drum use the Pad to reduce level With Pad in the input Z will be 2k Keep Output Level controls near maximum for cleanest results low and increase Gain control if a bit of distortio...
Page 9: ...imum output level MOL 34dBm Distortion THD 1kHz 100Hz unweighted at 40dB gain 0 0035 0 008 Frequency response 0 5dB at 40dB gain setting 10Hz to 35kHz Gain settings dB Mic 40 45 50 55 60dB High pass f...
Page 10: ...pical values for Distortion Noise and Phase shift 40dB 50dB 60dB THD 100Hz to 10kHz 0 003 0 015 0 03 Noise dB ref MOL 117 113 104 Phase shift 100Hz 1kHz 10kHz 20kHz 0 0 1 0 3 14 3 9 28 7 8 0 0 1 4 0 4...
Page 11: ...Thermionic Culture Ltd Harlow Essex UK Tel 44 0 1279 414770 email technical thermionicculture com Thermionic Culture Ltd July 2014 Printed in UK...
