To rectify this, you can either turn the input level higher on the amplifier, or normalise.
However before normalizing, they are a few things to note. If you are going to record an entire album, it is strongly recommended to record the whole album as one session. If you normalise individual tracks, sound forge will scan to the loudest noise, which in many cases with vinyl maybe a pop, or a click. As these vary in loudness, normalising individual tracks may result in inconsistent volume levels through an album.
It is recommended to normalise to -3db, during the clean up and processing stages of restoring vinyl. If normalisation is taken to 0db (maximum loudness), some declicking and denoising processes may distort the signal.
Will continue through at the moment, assuming we are making a compilation.
To start the normalisation process, first click on the "process" on the top of the screen. Then on the drop down menu, select normalise. You should have a dialog box that resembles figure 8. You'll find a slider to the left (1), that can be dragged either higher or lower, depending on how loud you want the file to sound. On top of the slider is the normalisation value. This is where the loudness level will be specified (2). This setting will most probably be set at 0.00 db (100.00%). You can use your mouse the change the values, but this can be fiddly, so I just set it in the rough proximity of -3.00db. Then by touching the up and down arrows on my keyboards keypad, I would make the finer adjustments. The setting should now be at -3.00 db (70.79%).
The last thing to always check is the peak level setting (3). Sound Forge can either normalise to a peak level of a sound file (the loudest level output), or the Average RMS Power (average loudness of the sound file). To keep things simple, I always normalise using the "peak level" setting. The other setting leads in to complex territory, which will just confuse things further, so we'll just skip this function, as it's not relevant for this project.