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SM Pro Audio FX01 Prism

Programmable Multi-effects Processor By Paul White

A new company adds another affordable effects unit to the market. But does it have what it takes to compete with the established big names?

SM PRO AUDIO FX01Photo: Mike CameronWe're used to budget effects units being introduced on a regular basis by the big-name audio manufacturers, and given that most of these are derived from earlier products, we tend to have a pretty good idea of what to expect from them. This was clearly not going to be the case with the Australian SM Pro Audio FX01 Prism, as I'd never used one of their units before and indeed knew nothing about the company. Certainly their unit looks very elegant in a minimalist way; it is mains powered rather than using an adaptor, and it has stereo balanced I/O on both jacks and XLRs, with the ability for the jacks to be used unbalanced if required. Connecting just one input gives mono-in/stereo-out operation. There are also separate operating-level trim pots on the rear panel for the left and right inputs that go between the -20dB instrument level and the +4dBu professional line level. While this is a usable way of setting the input sensitivity, having two separate controls makes it too easy to mismatch the levels of the two channels. A single ganged gain control on the front panel would have made far more sense to me.

Basic MIDI functionality is included for sending or receiving patch changes and you get the full set of MIDI In, Out and Thru connectors. A MIDI edit mode allows the user to select a MIDI channel and determine whether MIDI patch data is sent, received or both. There's no SysEx patch dumping or dynamic MIDI control of parameters.

The bright blue, 1U front panel has a two-line backlit LCD display as its focal point plus a data wheel, a power switch and just six buttons. So simple is the operating system that the manual comprises just 14 pages of A4 paper, around half of which is taken up by installation and connection data plus the technical spec. From this simplicity, you might guess that the FX01 Prism is simply a box of effects presets, but it actually goes a little deeper than that. All the patches, which are either single effects or dual-effect configurations, are certainly based on presets, but each effect has a handful of editable parameters that address the most important variables of that effect. For example, once you've selected a reverb preset, you can use the Parameter button to access mix, decay time, high- and low-frequency damping, reflection density and low-pass filtering. There's no pre-delay parameter as such, but you could choose a reverb/delay combination and set up pre-delay that way.

Parameter Surfing

Of the six buttons, one is a Bypass (which is used in conjunction with the Save button for accessing the MIDI setup mode) and one is a Lock button, the purpose of which is to lock out the rest of the function buttons. The Program and Parameter buttons determine whether you're accessing user or preset programs (there are 48 of each), or the program's parameters, the latter button being used to step through the available parameters, any of which can be edited using the data wheel. One incredibly frustrating aspect of this parameter editing procedure is that the mix parameter is set up for each preset patch as though you were using the FX01 Prism as an insert effect. However, if you want to use it as a send effect, in conjunction with a mixer, most of the time you need a 100 percent mix value. Now the mix value is always displayed beneath the program name where you might imagine it's easy to get at, but when you press the Parameter button to edit it, you're immediately sent to the start of the parameter list — and mix is at the other end, so you have to step through all the other effect parameters to get back to it. As mix is the thing you're most likely to want to change, why not have it at the top of the list?

That leaves the EQ/Reset button, which can be held down for three seconds to reset the default values for the current patch or pressed briefly to access the EQ mode. EQ can be applied to any patch and offers a single band of semi-parametric EQ where there are three preset bandwidth options with variable frequency and 12dB cut or boost. The only input level metering is a pair of clip LEDs monitoring the two channels and, given that the trim pots are on the back panel, you'll probably have to set your overall send level at the mixer to which the unit is connected.

SM PRO AUDIO FX01 rear panel.Photo: Mike CameronTechnically, the unit is reasonably well specified, using 24-bit converters running at the rather odd sample rate of 46.875kHz. This yields a noise performance of better than 94dB unweighted with minimal distortion. Certainly I was not aware of noise when using the machine, even though I never got the input clip LEDs flashing.

Auditioning The Effects

The presets on which user edits are based fall into the categories of Reverb, Delay, Chorus/Flange, Gated Reverb, Pitch and Distortion, with the dual effects configurations comprising Delay + Reverb, Chorus + Reverb, Flanging + Reverb, Chorus + Delay, Distortion + Reverb and Pitch + Delay. The same parameters per effect can be addressed in both the single and dual effect programs, the most editable effect being Pitch which, as well as mix, offers independent left and right control over coarse and fine pitch plus overall delay time and feedback. Delay and Distortion are the simplest effects with just three variables each.

Of course the real test of this Aussie wonder-box is how it sounds — will it turn out to be a Dingo or a Kylie? I found that most of the Reverb presets were set up with too much high cut, making them sound a little boxy and honky. Opening up the low-pass filter helped, though in comparison with the Lexicon MPX100 (which I think a fair comparison in this price bracket), the reverbs are just a touch ringy and exhibit an odd decay character where the reverb tail dries up very quickly in what to me seems a rather unsatisfying way. I also compared the reverb with the plug-ins that come with Logic Audio and found that it compared well with the economy plug-ins but that I rather preferred the sound of both the GoldVerb and PlatinumVerb reverb plug-ins in the context of a mix. That's not to say the reverbs are unusable, but you have to work at them to get them sounding OK, and you can't afford to add too much of them to the dry signal. For me the Reverb + Delay and Reverb + Chorus algorithms sounded better on vocals, though I was quite impressed with the Gated Reverb patches, which include reverse and panning gate presets.

The Delay and Chorus/Flange effects are competent, but offer nothing out of the ordinary, though you get some multitap delays and other useful variants plus a couple of modulation effects that try to emulate rotary speakers. In fact the front panel claims 256 effects, but with everything based on 48 presets it's hard to see how this is calculated. As I expected, the pitch-shifter was fit only for making people laugh by doing chipmunk impressions — it's far too rough and wobbly to use for anything musical, but then I've yet to come across one that isn't at this kind of price. Its fine-tuning option is OK for light pitch detuning, but forget chromatic shifts.

There are some useful double effect combinations, and the distortion effect also turned out to be much more subtle and useful than I'd expected, giving a kind of tube emulation at lower settings and a warm thickness at higher settings that would work well on synth sounds. However, I did discover an oddity in the operating system associated with dual effects presets that include distortion — only one parameter was accessible in edit mode, though in the user bank (which includes dual effects with distortion), there was no problem getting to all the parameters.


As budget effects units go, this one has better I/O options than most and doesn't rely on a wall-wart PSU, but the reverbs inevitably fall short of what you'd expect from a more up-market reverb processor, or even a good host-powered reverb plug-in. They're certainly not unusable by any means, but you have to work to hide the inevitable colorations. The other effects are a mixed bag, with some being rather bland and others being surprisingly useful. The operating system has a few mildly annoying quirks, but because everything is so simple, this is a very fast unit to work with. Given its UK price, I can't dispute the fact the FX01 Prism offers good value for your money. But, as I've said before in other budget effects unit reviews, if you can now buy something that sounds really quite good for only a few quid more than this — and you definitely can these days — then it may be false economy to settle for anything less, no matter how cheap it is. However, within its price range, the FX01 Prism stands up well against its direct competitors on effects quality and betters many on build quality and editability.


  • Affordable.
  • Mains powered with good I/O facilities.
  • Easy to operate with reasonable editability.


  • I can't complain about the facilities at the price, but for me the reverb algorithms fall a little short of being genuinely useful in a typical project studio.


The FX01 Prism performs well for its price and is nicely engineered. It performs as well or better than many budget units I've tried, but don't expect pro-studio effects quality.


£180 including VAT.

Audio Inspirations +44 (0)1803 209239.

Published October 2002