All user reviews of 4/5 for the Yamaha SPX90

It's a basic multi-effects including all sorts of reverbs, echoes, chorus, flanger, phaser, compression, and pitch shifting. Effects cannot be used simultaneously.
It has basic MIDI connections that can't be edited, except maybe with a PC via Midiquest, which is useful to recall the program you are looking for.
12bit audio processing technology, which is not very high and is technologically outdated.
The controls are not too practical (two +/- recall buttons and two +/- parameter buttons), but they are not complicated.
It's rack-mountable (1U).
Easy setup but its poor usability is tiring in the long run.

UTILIZATION

Easy setup but its poor usability is tiring in the long run.

SOUND QUALITY

This is where the unit is interesting, because it has very unique sound.
The 12-bit technology and the Yamaha digital processing make this multi-effects very particular and it suits all instruments and vocals. The chorus effect, with a very "wet" setting, is very good for guitar, bass, synth, and synth bass. The cathedral reverb is ideal for vocals.

OVERALL OPINION

I used it since it came out in 1985 and resold it in 1992 because I didn't use it and I wanted a multi-effects whose effects were better and could be used simultaneously, which I never did found, except at ridiculously high prices. In fact, I kept my other multi-effects, an old Boss SE50, which I use as a Swiss-army knife.
All my musician friends reprimanded me for selling it, since it has a unique sound.
And yes, the sound is great, very fat and percussive.
I regret having sold it.

The Yamaha SPX 90 is a digital multi effects unit. The effects it includes are distortion, flange, tremolo and delay. The effects can be used singularly or they can be mixed and matched together. I believe the connections are XLR and the unit is rackable.


UTILIZATION

The configuration of the Yamaha SPX 90 is easy to follow and manipulate. The dials and buttons are easy to read and while it takes a bit to figure out exactly what does what, as it is all laid out easy enough. The only reason it takes a bit of getting used to is simply because there are so many different effects and different ways to alter them. I don't have access to a manual but I would think it would be helpful in figuring out all the ins and outs of this model.


SOUND QUALITY

I really like all of the effects on the Yamaha SPX 90 for various uses on various instruments. My favorite effect is the delay, as it is easy to get a variety of delay sounds from it. I've used it on everything from vocals to guitars and anything else that could use a cool effect or twist to it. You can get a sound anywhere from short, subtle delay to a beautiful, wide, cavernous one. The repeats can get extremely quick and almost crazy sounding. When mixed with some of the other effects it can make for some seriously unique tones. I also like using both the flanger and the tremolo for creating a really thick and wide flange tone or a wobbly tremolo. There are plenty of dials to manipulate each effect to get a real wide variety of sounds for a variety of applications.


OVERALL OPINION

I first used the Yamaha SPX 90 about 2 years ago and while I no longer have access to it, I wish I did. They are even cheap enough where almost any studio owner could own one and it is a great bang for your buck. If you are looking to expand and get some time based effects that are not in plug in form, this is a great model to get started with.