People who record on cassette four-tracks do not do it for the convenience. They do it because everything that goes through one comes out sounding like a record, and a lot of that sound is the machine getting things slightly wrong. If you want it inside a DAW, the useful question is not "how do I make this sound lo-fi" but "what specifically did the four-track do", because each part of the sound is a separate mechanism, and each can be dialled in on its own.
The five things a four-track did
Narrow tracks and a head bump. A cassette runs four tracks across a tape that was designed for two, so each track is narrow and the record head is small. Small heads have a resonance in the low mids, the head bump, which gives everything a slight lift around the bottom of the guitar range. It is the reason a cassette recording of a band sounds fuller than the same band recorded flat.
Treble that gives out. At 3¾ ips the tape simply cannot hold much above 13 kHz, and at 1⅞ ips it holds about half that. The high end does not roll off gently like a filter; it saturates and disappears. Cymbals become a texture rather than a splash.
An unsteady capstan. The motor and the rubber pinch roller were not precise, so pitch wobbled slowly (wow) and quickly (flutter). A sustained piano chord through a cassette shimmers slightly. Turn it up and it becomes seasick; at the right level it makes a stiff arrangement breathe.
Saturation. Push the record level and the oxide runs out of headroom. Ferric tape (Type I) runs out sooner and keeps more energy in the mids; chrome (Type II) holds more treble and takes more level. Bias trades treble against grit in both directions.
A noise floor that breathes. Cassette hiss was fought with companding noise reduction, which expands the signal on playback and pumps the hiss up and down with the music. With the noise reduction off there is far more hiss but no breathing. Both are part of the sound.
Doing it on one channel
Nebraska 144 is a four-track cassette recorder condensed onto a single channel: one input module feeding a stereo pair of tape tracks at 3¾ ips through Type II companding. Each of the five mechanisms above is a control.
At the input, TRIM drives the preamp as a colour control with the gain taken back out afterwards, and MIC/LINE puts far more gain in front of the stage in Mic. The EQ is a pair of centre-detented TREBLE and BASS faders shelving at 10 kHz and 100 Hz, ±10 dB, like the ones on the machine.
In the tape section, DRIVE sets how hard the signal hits the oxide, BIAS trades treble for grit, and TAPE TYPE switches between I and II (the cassette in the window changes with it). NOISE injects hiss where the expander can breathe on it, WOBBLE is the master depth over wow and flutter, and the dbx switch turns the companding on or off. TAPE SPEED runs 3¾ or 1⅞ ips, and half speed halves the treble and raises the hiss. 2ND GEN bounces through the tape a second time, which is what happened to every four-track mix when it was bounced down.
Behind the DOOR is a service panel with head bump, azimuth, crosstalk, dropouts, pitch and the wow/flutter balance, plus a hidden tape echo with send, time, repeats, tone and return.
Three ways to use it
On a whole demo. Put it on the mix bus at moderate DRIVE with WOBBLE low and the companding on. This is the "does the song survive the cassette" test: if the arrangement still works with the top end gone and the low mids lifted, it is a song.
On one instrument. A clean electric piano or a synth pad through the tape section at 1⅞ ips with some WOBBLE takes on the smeared, slightly seasick quality of a home recording without dragging the rest of the mix with it. MIX is a time-aligned dry/tape blend, so you can pull it back into a parallel effect.
As a bounce. 2ND GEN on a drum loop or a full mix stacks two passes of head bump, saturation and treble loss. It is the sound of a four-track mixdown, and it is remarkably hard to get any other way.
For playing or singing through it live, choose Tracking mode (low latency) from the preset menu: the transport's 6 ms delay drops to a single sample with WOBBLE at zero, and the wobble sounds the same. Nebraska 144 has a 14-day free trial of the full version; the demo-through-the-cassette test is the place to start.