Modular pre-amplifier

Except for very expensive ones the number of inputs and outputs on HiFi equipment are usually fixed and when you have a lot of different audio equipment to connect you are in trouble. With our modular preamplifier we offer you a real High End solution for this. 10 slots on the backplane offer plenty possibilities to plug in the inputs and outputs you need. Line in and out, balanced or unbalanced, phono stages, headphone stage and even crossover stages are available. A microcontroller keeps track of everything and with its LCD display keeps you informed about the controls and settings you make and a infrared remote control makes it complete.

Backplane

Everything comes together on the backplane board. 10 rugged gold plated DIN41617 connectors to plug in application boards to configure your pre-amplifier. The basic configuration consists of the backplane, power supply with transformers, microcontroller with LCD display and a volume control board. The microcontroller and volume control board occupy a slot each so this leaves 8 free slots to occupy with input and output boards. Boards that are plugged in will be detected by the microcontroller and configured in the user interface automatically at the press of a button.

 

Prower supply

The power supply consists of a board with two toroidal transformers one for the digital electronics (12V) and a second one for powering the analog stages (plus and minus  13V). The power supply connects to the backplane with a 6 pole molex cable that next to the supply voltages also carries the control signal for the analog stage supply, the digital stage is always ON and the analog stage is controlled by the microcontroller.

Volume control

Controlling the voltage on the pre-amplifier is done by means of a motorized potentiometer controlled by the microcontroller. Both the rotary encoder on the LCD board as the IR remote controller can control the motor of the potentiometer so the shaft of the potentiometer does not need to be fed through the amplifier faceplate, It is implemented like this to have a real analog volume control rather than a digital one.

Microcontroller with LCD display and rotary encoder

This board together with the LCD board holds the firmware of the system that is needed to operate the pre-amplifier. The LCD board is connected to the microcontroller by a serial bus on a 4 pole cable with molex connectors. 


This board also hold the IR controller interface as well as the 12V trigger circuit to control the power amplifiers remotely the power button and the PWM controlled power LED. The firmware controls volume, input select and settings.

IR Remote control

Just four buttons are on the remote control unit, one for power on/off one for select and two for volume up and down. The unit is powered by a single CR2032 button cell. 

 

Unbalanced output stage

Cinch or unbalanced output is achieved by this board. It can be used together with multiple other output boards as needed or just as a single output for the pre-amplifier.

The output stage boards can be configured as pre-out or rec-out. In pre-out configuration the output signal is controlled by the volume control and in rec-out the selected input is amplified and send out to the output of the board.

Balanced output stage

XLR or balanced output is achieved by this board. It can be used together with multiple other output boards as needed or just as a single output for the pre-amplifier.

Unbalanced input stage

 

Balanced input stage

 

Phono stage 01

 

Phono stage 02

 

Headphone stage

This headphone stage drives even the most demanding headphone with low or high impedance. The sound of this board is exceptionally nice and crisp with plenty of bass.

One or more of these boards can be used in the pre-amplifier at the same time.

2 way crossover stage

A 2 channel 12dB per octave Linkwitz Riley cross-over board to drive separate amplifiers for woofers and tweeters. The frequency can easily be set or changed with a small and convenient plugin board. A nice terminal bracket is available that holds the cinch terminals for the outputs.

 

User application board

3 way crossover stage

Coming soon

Terminal brackets

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