Roland released the SP-404 in 2005 as the successor to their SP-303. For the SP-404 Roland took everything that made the SP-303 sampler so popular and built on that foundation by adding a lot more features. The now-discontinued sampler was succeeded a few years later by the SP-555 as well as an upgrade in the form of the Roland SP-404SX Linear Wave Sampler. The most recent update of the SP-404 is the 2017 Roland SP-404A Linear Wave Sampler.
The SP-404 has all the features you would traditionally expect from a Roland groovebox and can record audio directly using its line input jacks or MIC jack. Also, it has line output jacks, a headphones jack, and MIDI IN connector. The SP-404 is only 7 inches wide and 2-7/8 inches high, with a weight of 2lbs. 14 oz., so it is very compact. It can operate on 6 AA batteries or via an AC adaptor.
Despite its portable size, the SP-404 is not lacking in features. On the front panel, you'll find the volume knob, for adjusting the volume of the line output and the headphones, as well as three control knobs for adjusting parameters that are assigned to them. This section of the SP-404 also has a PEAK indicator to help you adjust the level when sampling. The middle of the device sports a seven segments, three characters LED display for showing information like the tempo of the sample or pattern, values of settings, error messages, and more. The effect buttons can be found on either side of the display, and the display also features illumination by blinking in sync with the tempo of the pattern. The pattern sequencer and sample edit buttons can be found below the screen as well as the bank buttons, and 12 pads.
In terms of features, the SP-404 offers 12 voices of polyphony, realtime loop recording, and sample-editing tools. It has 29 effects, which include BMP Looper, Subsonic, reverb, delay, Voice Transformer, and more. The sequencer of the SP-404 is easy to use and allows you to record up to 8000 notes in realtime. You can store up to 24 patterns in the internal memory and an additional 96 patterns using the CompactFlash card slot. It can hold up to 24 samples in memory simultaneously and up to 772 minutes of sampling time with a 1GB CompactFlash Card.