Over the course of developing Vinyl, we got really good at making things sound really bad. Here's a process we've found to be pretty effective for making a track "lo-fi".
1) Get a strong input signal using the Input Gain slider. This will be important if you want to add Wear to the record.
2) Turn up the Wear slider. This simulates a worn record by adding filtering and distortion. The amount of distortion or wear is depends on the input signal, so you need a strong signal to get the best worn sound. Note that the output level will drop slightly for extremely worn records (as would be expected)
3) Turn the Dust Amount knob up to add a lot of dust to the record. We personally like the Dust knob turned up all the way to the right. At the same time, turn up the Dust Level Fader to get an appropriate volume for the dust samples.
4) Add Scratches. Scratches are also sampled sounds, but unlike dust they actually overwrite the audio that is playing - the music is muted while the scratch sample is played. Therefore, getting a matching volume for the scratch is important. To do this, try adding one Scratch by turning the Scratch knob to the first position. We've found that adding more than 1-4 scratches is really a little too much - just try one to start. Turn the Scratch volume fader down all the way, and listen for the gap in the audio. Not realistic, of course, but you're just getting used to how often the scratch occurs. Now turn up the Scratch fader slowly until you hear a scratch instead of a gap.
5) Turn up the faders for the Mechanical Noise and Electrical Noise. In our experience, these are best to be used lightly, in fact, you should turn them up and adjust them while listening to a quiet portion of the track or even silence before or after the track. When the audio is playing, for best results the mechanical noise (turntable click and rumble) and electrical noise (60 Hz hum mainly) should be drowned out. The purpose of these controls is to have intros or quiet parts not sound so "digitally quiet".
6) Our personal favorite - Warp the record. This is a two step process. First, select a Warp curve by pressing Warp model buttons. This selects what the Warp looks like, whether it is warped all the way around or just a dimple or single warp on a corner. Once you have a warp selected, turn up the Warp Depth fader. Higher fader settings will cause greater shifts in pitch, since the warp is deeper. Of course you can get some great extreme effects with high settings, but we've found that even a subtle Warp adds a lot to the whole lo-fi vinyl sound.
Note: The warp feature is only enabled in the AudioSuite and DirectX versions of Vinyl due to limitations imposed by the other plugin formats. Also note that some DirectX hosts do not support warping especially when it's set to extreme values. Warping can be enabled and disabled in the DirectX version by right-clicking on the plugin and selecting "Bypass Warping". If the Vinyl plugin produces a choppy sound when Warping is enabled, your host application may not support warping. In this case, you should keep warping bypassed.
7) Select the Year of the record player. Year 2000 is effectively no effect. Earlier years apply filter models that progressively make the record player more and more bandwidth limited. 1950 and before also switches the output from stereo to mono. Note that this control has to do with the final output of the phonograph (speaker and amp) so it effects the music as well as the scratches and dust.
8) Optionally, you can select an RPM for the phonograph. This does not change the pitch, but it changes the periodic playback of the warp and the scratches (at 78 RPM a scratch happens more than twice as often as a single scratch on a 33 LP, since the record's spinning faster)
9) Adjust output gain as necessary
10) Do the Hustle. (optional - we just needed a tenth step)