Test Drive: The Yamaha SPX-990 Digital Multi-Effects Processor

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Yamaha-SPX-990

by Jerry Vigil

Have you always wanted to upgrade that SPX-90 to an SPX-1000, but didn't have that much in the budget? And is the SPX-900 just a little less than what you're looking for? Then look no more. It's Yamaha to the rescue with the new SPX-990!

Priced at $1,095, which is $500 less than the SPX-1000, the SPX-990 upgrades you from the SPX-90 or SPX-900 to true stereo processing, 44.1kHz sampling, and clean 20-bit D/A and A/D conversion. You get a lot of the programs and features found on the top-of-the-line SPX-1000 (see RAP Test Drive - November 1989), but there are some sacrifices such as reduced sampling time and shorter delay times. Still, the sacrifices are few considering what you get for the dollar.

The back panel of the SPX-990 delivers balanced inputs and outputs with both XLR and ¼-inch TRS jacks. The broadcast industry will also smile at the Input Level switches that select inputs of 20dB or +4dB for each channel. There's a MIDI IN jack and a switchable MIDI THRU/OUT jack for handling the units extensive MIDI capabilities. Finally, two footswitch jacks on the rear panel enable remote control of the SPX-990. Parameters can be adjusted, and effects can be triggered, selected, or bypassed using the footswitches.

The front panel of this sleek, single-rack space unit provides the same easy-to-read and easy-to-use controls found on most Yamaha effects boxes with a couple of nice additions such as a large Data Wheel and some assignable function keys. At the far left are the concentric Input Level controls for each channel. To the right is the Input Level Meter which consists of eight LEDs per channel. To the right of this is the Memory Area Indicator which consists of three LEDs labeled PRESET, USER and CARD. More on these in a moment. Below the Memory Area Indicator is the Input Select Indicator, two LEDs that indicate STEREO or MONO input configuration. Without having to deal with plugging and unplugging inputs in the back, the inputs can be configured as stereo, mono using the left channel input, or mono using the right channel input. The Input Select LEDs illuminate to show whether the unit is in the stereo or one of the mono modes. Just below these input LEDs is the MIDI Indicator LED which illuminates when MIDI signals are being received at the MIDI IN jack.

To the right of the above mentioned indicators is the large, familiar red LED program number display. When this display is continuously lit, the program selected is active. When it is flashing, the program corresponding to the number is selected, but it is not recalled into memory. That is done with the Recall function key below the LCD display in the center of the unit.

The LCD readout is a 2-line, 24-character display. It provides the usual information such as effect titles, parameter titles and values, messages and so on. Below the display are six function keys, each with various functions depending upon what the display is showing at that time. Primarily, these keys are used as cursor keys to move around the various parameters of an effect while editing. But you can also assign up to four programs to four of the keys for one-button touch recall of your favorite programs. This is an especially nice feature because many times there are only three or four effects that you use all the time. Having them accessible with one key-press eliminates searching for the program with the data wheel then hitting the Recall function button. By the way, the data wheel can also be used for rapid alteration of selected parameters when editing.


To the right of the data wheel are six keys. Two of them are the Page Up/Down keys. These are used for selecting the various "pages" of the LCD display when editing effects or modifying system parameters. The Memory key accesses the different memory areas of the SPX-990. Successive presses of this key switches between the unit's 80 factory presets, the 100 user memory locations, and the 100 user locations of the optional Memory Card. Which memory area is selected is indicated by the Memory Area Indicator mentioned earlier. The optional Memory Card is inserted into the slot provided on the front panel. The 100 user locations can be saved to a card, and the 100 programs saved on a card can be recalled into the unit's user memory. The SPX-990 has more memory locations that both the SPX-900 and the SPX-1000, and this memory card capability simply makes the unit's storage capabilities endless.

The Store Key is obviously used to store edited programs. The 80 factory locations cannot be written over, but these programs can be edited then saved to one of the user locations or the memory card with the Store Key. Next to the Store Key is the Bypass Key which, of course, bypasses all effects and sends the inputs to the outputs.

The Edit Key accesses the various parameters of the SPX-990's effects programs. When pressed, the LCD display takes you to "page 1" of that effect. The Page Up/Down keys get you to the remaining pages of parameters for that effect. Editing the effects is quite painless. If you have any experience editing digital effects algorithms, you'll find editing on the SPX-990 a breeze. The data wheel comes in handy here as do the six function keys below the LCD display.

Enough about the controls; let's take a look at what effects the SPX-990 has to offer. Each effect program is separated into three separate sections. For each program, there is the Pre-effect section, the Main-effect section, and the Post-effect section. There are four Pre-effects: 3-band Parametric EQ, Compressor, Harmonic Driver, and Compressor/Distortion/EQ. The Post-effects are the same less the Compressor/Distortion/EQ algorithm. Any one of the four Pre-effects can be applied to the input signal before it reaches the Main Effect, and any one of the three Post-effects can be applied to the signal after the Main Effects are applied. The Parametric EQ effect provides control over a 20Hz to 16kHz range with frequency, gain, and bandwidth parameters for each band. The Compressor is a stereo compressor with a full array of parameters including threshold, ratio, attack time, release time, and more for each channel. The Harmonic Driver adds harmonics to the signal to add more "presence" or "crispness." The Compressor/Distortion/EQ algorithm (found in the Pre-effects section only) is a basic distortion algorithm for an electric guitar utilizing a pre-distortion compressor and a 2-band post-distortion equalizer.

There are thirty-six Main Effects. This is where the meat of the SPX-990 is found. These thirty-six effect algorithms are used in combination with the Pre- and Post-Effects to create the individual effect programs. Only one Main Effect can be used at a time, though a few of these Main Effects are "multi" effects. The thirty-six Main Effects are separated into eight categories. The first category consists of four Reverb Effects: Reverb, Filtered Reverb, Stereo Reverb, and Echo Room. The next category has four Early Reflection Effects: Thin Early Reflection, Fat Early Reflection, Gate Reverb, and Reverse Gate. There are seven Delay/Echo Effects: Delay L,C,R, Echo, Multi-Tap Delay, Stereo Echo, Tempo Mono Delay, Tempo Stereo Echo, and Tempo Quad Echo. The "tempo" effects enable the user to program delay times based on a song's tempo or note length. The user can also "tap" a footswitch to set the delay times to match the tempo of the song. Musicians will appreciate this function, but so can you. Next time you use some generous delay on a voice track over music, try setting the delay to match the tempo of the music -- nice effect!


There are six Modulation Effects: Flanger, Dual Flanger, FM Chorus, AM Chorus, Phaser, and Symphonic. These are the usual variations of the common flange/chorus effect. The FM Chorus utilizes frequency modulation of the effect while the AM Chorus program uses a less subtle amplitude modulation of the chorus effect. There are four Pitch Change Effects: Mono Pitch Change, Dual Pitch Change, Triple Pitch Change, and Stereo Pitch Change. The Mono, Dual, and Triple Pitch Change effects produce one, two, or three pitch shifted signals at the output. The Stereo Pitch Change program is a true stereo pitch shifter with parameters that effect both channels simultaneously. The SPX-990's pitch programs also feature an "Intelligent" parameter that enables the algorithm's ability to change pitch according to a user selected musical scale.

There are two Pan Effects: Auto Pan and Triggered Pan. The Auto Pan is more complex than most similar pan programs. Along with the usual left to right panning, you also get "front" to "rear" panning. There is only one Freeze or sampling effect. The maximum sampling time is 1.35 seconds, and samples can be looped and pitch shifted. Other functions of the Freeze Effect include overdubbing, reverse playback, and editing of start and end points.

Finally, there are eight Multi-Effect effects: Chorus & Reverb, Symphonic & Reverb, Flanger & Reverb, Reverb(L)/Reverb(R), ER(L)/Reverb(R), Echo(L)/Reverb(R), Chorus(L)/Reverb(R), and Pan(L)/Pan(R). Some of these effects are "multi-effect" programs in that they apply more than one effect to both left and right inputs. The latter programs are "dual effect" programs that apply a different effect to each input such as echo to the left channel and reverb to the right channel -- Echo(L)/Reverb(R). Combined with the available Pre-effects and Post-effects mentioned earlier, it's possible to get up to four, high quality effects simultaneously.

Nearly half the factory presets are reverb programs. The other half is comprised of various delay, pitch, and modulation effects with a few programs utilizing the pan, sampling, and distortion algorithms. There are certainly enough factory presets and a wide enough variety to make the SPX-990 a good pick for the person who hates to program these boxes. On the other hand, editing the programs is easy enough to entice even the novice programmer into an enthusiastic session of creating new effect programs.

Some high quality effects boxes go overboard with the number of parameters available to the user, sometimes making the editing process an arduous task. Other boxes don't provide enough parameters to make the unit versatile. The SPX-990 is pleasantly somewhere in the middle.

As expected, with 20-bit processing, the effects are all very clean. You get full 20-20kHz frequency response, dynamic range above 100dB, and noise below -82dBm. The new Memory Card feature could prove to be one of the nicest improvements to the SPX line, especially if someone writes 100 "radio production" programs and makes them available to other SPX-990 owners in the broadcast industry! The card is much less intimidating to the non-MIDI user than bulk MIDI data dumps and transfers, and it's much more convenient.

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