Sunday, 28 September 2014

Optimising XMon Performance

This week I have been setting up our new Monitor Remote (Now called the TMC-1) on the XMon.  I have heard some bad reports about XMon so I wanted to be sure that I knew how to optimise the setup. 

XMon cannot be considered in isolation but as part of a monitor system that consists of the XMon, Power amps and Speakers.

The main gain section of XMon uses digital gain control to provide a gain range of +31dB to -95db.  As can be seen on the chart below to optimise the signal to noise it is important that XMon is run at between 0dB and +10dB gain for normal levels.

The Speaker trim section of the XMon provides a gain range of 0dB to -63.5dB in 0.5db steps. As can be seen in the chart below the signal to noise remains the same for the first 4dB of attenuation but then the noise floor levels out so that the signal to noise degrades as attenuation is increased.

The factory default settings of the TMC-1 XMon controller are as follows 
Main Gain Section +4dB gain.
Speaker Trim -4dB
Overall gain 0dB

Speaker trim range is restricted to +/- 4dB
Input makeup gain +20dB to -10dB

The default setting provides 5dB of analogue headroom above the digital clip point when set in this mode (XMon clips at approximately +25dBm).