Fine-tuning gain structure

To maximize dynamic range, it's desirable that signal levels be as high as possible wihout clipping. Most likely, choosing a gain setting based on your cartridge's output specification, as listed in Table 1, will provide good results.

However, cartridge output can be significantly different than expected, and records can vary a lot in their peak signal levels. Therefore, some adjustment may be needed to the gain structure. To assist in this, the ADept provides indicators of the two types of clipping:

• If clipping is detected in the ADC (analog-to-digital convertor), the Clip LED and the current Gain selection LED flash rapidly. This indicates that the Gain setting may need to be changed:

• If digital clipping is detected, the Clip LED and the Volume LEDs flash rapidly. This indicates that the digital volume may need to be reduced:

Here is a simple procedure to follow to optimize your gain structure:

1. Choose Low, Medium or High gain based on the output specification of your cartridge. (If you don't know, choose Medium.)
2. If you see the analog clip indication while playing or recording a record, change to a lower gain setting (that is, from High to Medium, or from Medium to Low). If you have reduced digital gain, set it back to 0 dB.
3. If you see the digital clip indication while playing a record, or if you observe clipping in your recordings (that is, a squared-off waveform at the top or bottom), reduce the volume control by 2 or 3 dB. If you are making a recording, redo the recording.
4. If you feel the output level is too low or you have clean modern records and want a higher output level, try changing to a higher gain setting (that is, from Medium to High, or from Low to Medium). Then go back to step 2.