This 500 series mic pre is Geoff's renowned design in a single slot format for your lunchbox!
The GT500 can accommodate any signal you care to throw at it, including highlevel line inputs. The sensitivity switch provides 100dB of gain adjustment from +80dB to –20dB and the level pot allows for fine adjustments. The level pot has an audio taper and is –20dB at half rotation. I would recommend using the level pot between ¾ and full rotation and never below ½ rotation unless part of a deliberate overdrive.
If you have to turn the pot below ½ way, the sensitivity switch must be adjusted at least 2 clicks more to restore the signal level at the expense of input headroom! Operating the unit with the output level at maximum ensures that you keep the headroom in the designed 26dB region.
The D.I. input overrides the normal input and has 10 Megohm input impedance and around 10dB gain. It can be used (to great effect) with musical instrument pickups, but works equally well with high-level signals like a D.A.T. or CD player. The same gain structure rules apply.
The High Pass Filter is selected by moving its toggle switch to the right and a blue LED will glow to indicate section. Four frequencies are provided with 47Hz, 82Hz, 150Hz and 270Hz for the selections.
Features
- Preamp with +80dB Gain
- Instrument DI
- Hi-Pass Filter with 4 Frequencies
- Separate Output Control
- LED Level Indicators
- Single Slot, 500 Series Design
Specifications
- Input Impedance = 1.2Kohm balanced and floating, transformer coupled.
- DI Input impedance = 10Mohm unbalanced
- Output Impedance = <75ohm balanced and floating, transformer coupled
- Output drive capability = >+24dBu into any load of 600 ohms and above
- Frequency response = 20Hz to >75KHz ± 3dB
- Total Harmonic Distortion = < 0.1% @ 0dBu I/P @ 1KHz
- Noise = < -45dB filtered 20Hz to 20KHz @ +80dB gain
