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:

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Tone

Colour

Low Microphonics

Technical

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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.