Yamaha DJX in the house

Posted on by

I mentioned the Yamaha DJX-II and its older brother, the PSR-D1 (DJX), in my article about vibe and why we need it. I converted a large number of DJX-II patterns to Genos/PSR styles and always wished to convert DJX styles, too.

Browsing around the Interwebs, one is led to believe that DJX patterns (“styles” in PSR-D1 lingo) were locked away in the DJX and couldn’t be tapped. Yes, the DJX does not send MIDI in SONG mode, but it does transmit MIDI style data in STYLE mode.

So, yeah, I’m crazy — I bought an old DJX (PSR-D1). Guitars 4 Vets was selling two DJXs on the Sweetwater Gear Exchange and I purchased one of them. Like most 25+ year old gear, it’s a bit scuffed up. It cleaned up nicely and is operational enough to yield its “secrets.” Here are a few observations.

Ancient weapons

Fortunately, the DJX Service Manual is available on Elektrotanya in case something goes wrong. The DJX dates back to June 1998 which were truly early days for Yamaha PSR, XG and AWM. Still, we see the beginnings of the classic Yamaha arranger architecture. The clock rates and capacities have changed drastically since 1998, but the general shape (structure) was there.

The key scanning board (MKS3) contains an HD63B05V0F07P CPU. The CPU is an Hitachi 8-bit CMOS microcomputer (8MHz clock) loaded with Yamaha’s custom firmware. The CPU communicates with the tone generator over a serial link. Shades of the E-Bus!

The tone generator is the first member of the Yamaha SWX processor family, the SWX00 (HG73C201FD). SWX processors integrate a host processor, AWM tone generator and effect units onto a single chip. The SWX minimize overall part count and are intended for low-cost keyboards. (The famous RM1x incorporates an SWX00, too.) The SWX00 is clocked by a blazing 8.4672MHz crystal oscillator, demonstrating that you don’t need gobs of gigahertz to perform basic sample-based synthesis.

The SWX00 isn’t going to knock anyone out with sound quality! Hey, it’s DJ-stuff, it’s naturally lo-fi! 22,050Hz evenly divides into 8.4672MHz; that’s 384 clocks per sample which is just about right for early AWM. 22,050 is consistent with sampling time: 6 seconds into 128KBytes of memory. Yes, “kilobytes.”

Caveat: The base sample rate could be as low as 11,025Hz. That divides evenly, too.

Polyphony is 32.

The SWX00 drives an NEC UPD6379AGR DAC. This is a 2-channel 16-bit audio DAC in an 8-pin plastic SOP. The post-DAC LPF is an UPC4570C-based -12dB/octave filter with a 27kHz corner frequency.

Speaking of sampling, the DJX does not have a discrete ADC. The incoming audio signal is routed to one of the SWX00’s analog inputs. The other analog inputs sense the front panel knobs. You ordered lo-fi, right? 🙂

The wave ROM — which contains the front panel voices, GM voices and drum kits — is an enormous 4MBytes. The program ROM is 2MBytes. Working memory consists of a 512KByte DRAM and two 128KByte SRAM devices. SRAM contents are kept alive by its own non-switched power bus. If you want to keep your memory contents alive, you’ll need six D-cell batteries or a reliable power adapter (12V center position 1.5A) — and don’t turn that adapter off! The batteries will slowly drain in the STANDBY power state.

Characteristics

Lo-fi aside, what you get isn’t bad:

  • Front panel voices and General MIDI (GM) sound set
  • GM drum kits plus several “DJ” kits
  • Basic effects: 8 reverb types, 4 chorus types, 33 DSP types
  • 100 styles
  • Two amplified speakers (2 x 6W, 2 x 12cm)
  • 5-pin MIDI IN and MIDI OUT
  • Sustain pedal input
  • PHONES output doubles as the AUX OUT
  • MIC/LINE In for sampling
  • Realtime knobs: cutoff, resonance, groove, assignable, bass boost
  • Ribbon controller and pitch bend wheel

The real-time knobs and master volume control are sturdy enough. The master volume control is a bit scratchy, but it’s set it and forget it. The pitch wheel has taken a real beating, unfortunately.

Arranger people will recognize a lot of basic Yamaha arranger features:

  • One INTRO (“LEAD IN”) and one ENDING (“LEAD OUT”) per style
  • One MAIN A (“BEAT A”) and one MAIN B (“BEAT B”) per style
  • AA, AB, BB and BA fill-ins (BREAK OUTs)
  • SYNC start
  • Chord recognition

That’s where the similarities end. Yamaha was quite creative in those days. There are different key zones and functionality beyond the usual arranger stuff, so be sure to read the manual if you get your own DJX.

Oddities

Here’s a few notable differences and quirks after working with the DJX and making first attempts at style conversion.

Like the DJX-II, the DJX has its own custom drum kits in addition to the GM drum kits (e.g., Standard kit, Jazz kit, etc.) The DJX “Special Kits” are:

  • Analog Kit 2 (T8)
  • Analog Kit 3 (T9)
  • Electronic Kit 2 (T8 + T9)
  • B900 Kit
  • DJX Kit

The Analog Kit 2 and Analog Kit 3 appear to be the predecessors of the well-known T8 Kit (808) and T9 Kit (909). Layout is somewhat different from the modern kits, but the content is similar. Electronic Kit 2 is a zany amalgam of 808 and 909 hits and noises. Maybe Electronic Kit 2 is analogous to the modern Drum Machine kit? Its instrument layout is totally non-standard.

The B900 kit was lifted from the B900 EOS workstation. One must assume that its inclusion was due to an affinity for sound designer Tetsuya Komuro and 1990’s J-Pop. “EOS” stands for “Entertainment Operating System” and is the bridge from QY- and QS-like products to the early Motif era.

The DJX kit was built purposely for the DJX. It includes vocalizations (“Yeah!”, “Go!”, etc.) and scratches. Neither the B900 kit or DJX kits have modern equivalents. The non-standard layouts of the “Special Kits” make style conversion a true PITA.

The DJX-II patterns have chord progressions cooked in. They are the ultimate for the one-finger player. The progressions are hip and are one of the reasons why I like the DJX-II.

The DJX hasn’t decided yet what it wants to be when it grows up. I hear simple progressions in some of the DJX styles. Other styles cater to a single type of extended chord like Cm7(9). Then there is the following description in the DJX manual:

When you play single notes, the DJX automatically produces chords that are based on the root note you play and are best suited to the selected style. For example, all single note chords in the Techno style (#001) are minor, all chords for Trip Hop (#002) are minor 7th 11th, etc. This lets you quickly and easily play the most musically useful and stylistically appropriate chord changes — just by pressing a single key!

Playing full chords may not change the pattern chord as intended. For example, playing major seventh chords will not change the chords of a pattern that has minor and dominant seventh phrases and lines.

There are definitely DJX styles like that. Yikes! It’s going to be difficult to find a consistent transformation from DJX chord behavior to modern arranger fingering behavior. I might need to freeze the chord progressions and make everything one-finger.

Please don’t get me wrong. These differences in behavior might seem like oddities and quirks after using Yamaha gear for so many years. I kinda wish Yamaha would get the old creative mojo again. Both the DJX and DJX-II were nifty inventions.

Copyright © 2026 Paul J. Drongowski