The Module LAB is a non-feedback JFET Line level Amplifier and Buffer.

The Module LAB can be used as a:

- preamp i.e. voltage amplifying line stage. Typical application circuit has the gain of 3.25 but the Module LAB is extremely versatile in this regard, and the gain can be set to practically any value up to about 20. More info on the Module LAB configured as a preamp can be found here.

- buffer only. A gain stage can be omitted and the Module LAB can work as a voltage follower i.e. buffer only. It can be used whether as an output buffer in the source device (DAC, CD, SACD) or as an amplifier input buffer. This buffer design is a current embodiment of the circuit usually known as Pedja Rogic's JFET buffer, which is in fact one of the most famous and most venerable audio buffers for several years now. More info on Module LAB configured a buffer can be found here.

- I/V stage for DACs / CD players. Yes, the Module LAB can be used as a transimpedance stage with low impedance input, and thus it can perform the I/V conversion. Again, no feedback and the output is buffered. (Besides, those still rather inclined toward passive resistor I/V conversion may find the voltage gain of up to 20 useful to amplify usually low resulting voltage to the regular line level.)

In other words, the Module LAB can be used as about any stage that operates with line level signals.

The figure below shows the Module LAB revision A simplified circuit. A low input leakage current of the JFET makes possible to avoid input coupling capacitor, and very high input impedance can be set, if needed. When used as a buffer only, very low output offset can be achieved too, and thus the output cap can be replaced by coupling transformer, or it can be simply omitted.

 

Other than the signal circuit itself, the PCB of the Module LAB includes relatively simple yet very high class regulated supply as well (this part of the module is shown below), and this supply also doesn't employ a feedback. The grounds of two channels, including supply grounds, are kept galvanically separated, so the Module LAB normally operates as dual mono device.

The Module LAB is available as fully built and tested PCB module, with encapsulated mains transformer. We can also supply PCB module only. Occasionally the Module LAB may be available also as unpopulated PCB. Complete Assembly Manual is provided with either of these.

Populated PCBs comprise quality parts like Schottky rectifying diodes, Panasonic FC/FM capacitors in supply and Black Gate N/NX capacitors in signal circuit, Toshiba JFETs, ALPS potentiometer, Allen Bradley resistors etc. The PCB itself is double sided, plated through, with solder mask and silk screen.

The modules can be preset for any desired gain, or can be supplied without gain stage at all. When supplied as an I/V stage, the Module LAB is set for 0V DC offset at its input, which is adequate for chips like TDA1541A or PCM1702/1704.

The price of the Module LAB kit with transformer is 280 EUR, shipping included. Online ordering is possible.

For additional technical information on Module LAB, please check the dedicated thread at diyhifi.org.