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Model type: AT-3 Low noise Mic-Pre (single channel)
The AT-3 is a tube and balanced transformer Mic/Line/DI pre using a custom made mic input transformer that features a Hi/Low Z winding to accommodate a cross section of mics for a wide range of responses for added tone and character when matched or un-matched in the usual way. The AT-3 features switchable inputs and a front panel 1/4" un-balanced high Z direct input for instruments. The signal flow is kept entirely on the board ensuring the shortest signal path using discrete relays. The mic input features a custom made Sowter high/low Z transformer type.
With the following functions:
Switchable XLR MIC-LINE input
Switchable HIGH-LOW Z Mic IP
Switchable 15db pad
Switchable LOW CUT 75Hz
Switchable DI high Z input
Switchable PHASE
Switchable PHANTOM
The Line input features a Lundahl LL1935 transformer with the following response specs:
Frequency response (reference 1.0 kHz)
10:1, source 100 kΩ , secondary open: 20 Hz – 20 kHz +0 / -3 dB
10:1, source 100 kΩ, load 1 kΩ 10 Hz – 45 kHz +0 / -2 dB
1:10, source 200 Ω, secondary open 10 Hz – 80 kHz +/- 1dB
The Line Output features a Lundahl LL1940 transformer with a high turns ratio transformer with the following specs
Frequency response.
Source impedance 10k. Load 600 ohms
Secondaries connected in parallel
20 Hz – 50kHz + 0 / - 3 dB
40Hz – 30 kHz + 0 / -1 dB
Frequency response.
Source impedance 50k. Load 600 ohms
Secondaries connected in parallel
50 Hz – 40kHz + 0 / - 3 dB
Distortion.
Source impedance 10k. Approx 1% THD at
50Hz, 20dBU primary level.
The gain stage is a single 12AX7 cascaded feeding the OP stage as a cathode follower.The tube type for this stage is a 12BH7 and not a 12AX7 as this is is better suited for driving the output.
The AT-3 Mic pre offers a richness of tone and colour suitable for all types of modern and vintage microphone with the following unique features:
Custom 1445 Sowter HIGH - LOW impedance MIC input transformer.
12AX7 & 12BH7 double triode tubes.
Lundahl LL1935 balanced LINE input transformer.
Lundahl LL1940 balanced LINE output transformer.
The AT-3 is a beautiful and natural sounding mic pre amplifier that brings out the tone and colour of your music. The unique features of it's legendary 3 stage design allow all types of program sound warm and pleasing to the ear adding detail and clarity to your music.
The all tube and transformer AT-3 is warm and natural sounding, low noise mic pre amplifier that features:
Tone
Colour
Low Microphonics
Technical
12AX7 and 12BH7 dual triodes
Switchable Mic / Line input
High-Low 600/150 impedance switching for Mic input
15db pad for the Mic input
Switchable 75hz Low end cut
48v Phantom switching
Switchable high impedance DI instrument unbalanced 1/4" Jack input.
Linear power supply
Fully regulated DC heaters
Switched IEC mains socket US & EUK adjustable
High quality non-inductive carbon composition pot (Type PEC)
About the AT-3 Mic pre:
The AT-3 comes as a 'Stand-Alone' desktop unit.
2u half 19" width space
Free racking kit available (for mounting 2 units into 19" rack slot)
Weight is 6.5kgs
Dimensions 83 x 216 x 310
The AT-3 is a simple 2 stage gain mic pre based around classic simple tube circuits of the 50's which is simple to use with 1 large variable gain knob and large coloured latching switches accessible from the front panel.
A switchable High impedance 'Direct' signal input for instruments is also available from the panel. Unlike many other mic pre's that have this standard feature the AT-3 is 'Relay' switchable instead of using a 'Jfet' for a more direct and and cleaner signal path.
Other features include a very low noise linear power supply. Non inductive hot moulded carbon pot PEC gain pot, 15db pad for the mic input. A 75hz low cut. Phantom supply and phase switching. All front panel switching is low illuminated for studio use. Switchable 120/230vac.