Pro-53

Summary
A faithful emulation of the classic Prophet-5. It sounds good and it looks and works like the original. Pros: Classic sound Accurate emulation Cons: Awkward preset selection Quirky modulation
Scores
Features:	Fair
User Interface:	Weak
Sound:	Good
Value:	Weak
Overall:	Fair
TestTone
Reviewed on:	December 15, 2008
Reviewed with:	Logic Pro 8 -
This review used a copy of the product owned by the reviewer. TestTone and its reviewers do not accept payment from developers in exchange for a review. Please see our full Review policy.

Pro-53 Review

The very classic Sequential Circuits Prophet-5 analog synthesizer was renowned for its rich analog sound and its revolutionary modulation features. Produced from 1978 through 1984, the Prophet-5 was one of the first polyphonic synthesizers (it had 5-note polyphony) and one of the first to support memory for storing preset sounds (it could store 40 presets). It's been used by a huge range of artists on classic tracks of the period, from Kraftwerk to Jean Michel Jarre, Kitaro, Thomas Dolby, Peter Gabriel, Talking Heads, and Genesis.

About 7,500 Prophet-5s were built and they originally sold for around $4,500 ($15,000 in today's dollars). These days, on the rare occasions that a Prophet-5 shows up on eBay, it can go for $2,000 or more. That price makes a good plugin emulation like the Pro-53 a great deal at about two hundred bucks. Plus the software version doesn't go out of tune or require expensive maintenance to keep it working.

Touring the user interface

The visual style of the Pro-53 interface mimics the look of the original Prophet-5, though the layout of knobs and buttons is a bit different to accommodate the Pro-53's added features. Let's go through the controls section by section, starting with the oscillators, filter, and envelopes, and then look at the modulation features and the delay section.

Oscillators and mixer

Native Instruments Pro-53 Oscillator and Mixer sections

Oscillator and mix controls set the
frequency, waveform, and mix for two
oscillators and a white noise generator.

Like the Prophet-5, the Pro-53 has two oscillators, named A and B. Both oscillators provide sawtooth and pulse waveforms with a variable pulse width, and oscillator B adds a triangle waveform. Each of the waveforms may be used individually, or in combination to create a richer sound.

Both oscillators include a coarse frequency adjustment that spans 4 octaves. Oscillator B adds a fine frequency knob to detune the oscillator and thicken the sound. The frequency of both oscillators normally tracks the current MIDI note, but oscillator B's "KBD" button disengages keyboard control and leaves its frequency set only by frequency knobs and modulation sources. Oscillator B's "LOFRQ" button converts it into a low frequency oscillator (0.3 Hz to 30 Hz) useful for vibrato, filter sweeps, and so forth.

The "SYNC" button synchronizes oscillator A to B, forcing A to restart its waveform each time oscillator B's waveform restarts. When the two oscillators are at different frequencies, this causes repeated abrupt changes in oscillator A's waveform and introduces interesting upper harmonics.

Finally, oscillator A, oscillator B, and an optional white noise source are mixed together to create an audio signal forwarded to the instrument's filter section.

Low-pass (and high-pass) filtering

Native Instruments Pro-53 Filter Section

Filter controls adjust the
cutoff frequency, resonance,
and ADSR envelope.

The Pro-53 emulates the Prophet-5's distinctive analog 24 dB/octave low-pass filters, and it adds a few new features. The Pro-53's filter section is dominated by knobs to set the filter cutoff frequency, resonance, timing for an ADSR envelope, and the amount by which the envelope modulates the filter's cutoff frequency. Two new features include the "INV" button to invert the filter envelope, and the "HPF" button to convert the filter from low-pass to high-pass. Both of these are welcome additions that nicely expand the range of sounds the instrument can produce.

The original Prophet-5 included a button to engage filter keyboard tracking and automatically adjust the filter's cutoff frequency to match the current note. With resonance turned way up, this enabled the filter to be "played" to create all sorts of eerie whistles. The Pro-53 expands this idea by replacing the tracking switch with a "KBD" knob to vary the strength of keyboard tracking. With the knob turned fully clockwise, the Pro-53 tracks the same way the Prophet-5 did. At lower settings, tracking creates milder filter variations from the low to high end of the keyboard.

Next, the filtered audio signal is forwarded to the instrument's amplifier section.

Amp and analog

Native Instruments Pro-53 Amplifier Section

Amplifier controls set an
ADSR envelope.

Native Instruments Pro-53 Analog Section

The "ANALOG" button adds a
bit of randomness to emulate
analog circuitry drift.

The amplifier section includes more knobs for a standard ADSR volume envelope. To this, the Pro-53 adds a "HOLD" button that causes notes to stick on and never release. This is very useful for keeping notes playing while you fiddle with settings, or when using the Pro-53 as an effects plugin (more on this later).

A few more relevant knobs and buttons are scattered about the user interface. Turn off the "RELEASE" button to override the amplifier's envelope release setting and force notes to end abruptly with a zero release time. The "VEL" button adds keyboard velocity sensitivity not available in the Prophet-5. When pressed, keyboard velocity varies the amplifier envelope by a fixed 90%, and the filter envelope by 70%.

The Pro-53's "ANALOG" knob adds random variations throughout the plugin's synthesis engine to roughly emulate imperfections and drift in analog circuitry. The Prophet-5 didn't have this knob, of course. It had the actual imperfections and drift, and a tune button you had to push periodically to recalibrate the instrument's oscillators.

From here, the amplified audio signal runs into the Pro-53's delay lines for echos, flanging, and chorus. But first, lets jump back to the instrument's modulation features.

Polyphonic and monophonic modulation

Native Instruments Pro-53 Modulation Sections

Poly-Mod controls adjust
polyphonic modulation for
FM and pulse width changes.
LFO and mod-wheel controls
add vibrato, filter sweeps,
and more timbre control.

The modulation sections are the heart of the instrument. They give the plugin character and create the swirly filter-sweepy rich sounds the instrument is known for.

As in most synthesizers, there are two types of modulation: polyphonic and monophonic. Polyphonic modulation affects each note individually, such as when a note's own filter envelope rises and falls without regard to what other notes might be doing at the same time. Monophonic modulation, however, affects all playing notes simultaneously and identically, such as when you move a keyboard's mod-wheel to add vibrato to everything. For the Pro-53, polyphonic modulation is controlled by the "POLY-MOD" section, while monophonic modulation is controlled by the "LFO" and "WHEEL-MOD" sections.

In the "POLY-MOD" section, the "FILTER ENV" and "OSC B" knobs adjust how strongly the filter envelope and oscillator B's signal will each modulate something. The buttons beside the knobs select what will be modulated. "FREQ A" modulates oscillator A's frequency, "PW A" modulates oscillator A's pulse width, and "FILT" modulates the filter's cutoff frequency. You can use all of these in any combination. For example, use oscillator B to modulate oscillator A's frequency to create 2-operator FM bells and other buzzy and clangorous sounds. Switch oscillator B into low-frequency mode, and the same settings add vibrato to oscillator A. Or modulate oscillator A's pulse width to create gradual timbre changes. There are lots of possibilities here.

In the "LFO" section, the "FREQ" knob varies the speed of a low frequency oscillator from 0.04 Hz to 20 Hz. Buttons to the right select between LFO sawtooth, triangle, and square waveforms that may be used individually or in combination. If all three buttons are off, the LFO is disabled. In the original Prophet-5, when all three LFO waveforms were engaged, the result was a complex mixed waveform. In the Pro-53, this instead switches the LFO into a "sample-and-hold" mode that generates a series of random values.

In the "WHEEL-MOD" section, buttons select what will be modulated by the LFO and by the keyboard mod-wheel. "FRQA" and "B" modulate oscillator frequency, "PWA" and "B" modulate oscillator pulse widths, and "FILT" modulates the filter's cutoff frequency. The "LFO NOISE" knob varies the modulation signal mix between the LFO and a pink noise source. For any of these modulation settings, the strength of the effect is controlled by the keyboard mod-wheel.

To create vibrato, use the LFO to modulate the frequency of both oscillators. To add movement to a sound, use a slow LFO and modulate the pulse width and/or the filter cutoff frequency. For interesting rhythmic sounds, set the LFO into "sample-and-hold" mode and modulate the filter. And for cheesy science fiction movie "computer beeps", use "sample-and-hold" to modulate the oscillator frequencies too.

While the original Prophet-5's modulation settings stopped here, Native Instruments has added two more buttons in the "LFO" section. The "MIDI" button syncs the LFO to your DAW's tempo, and the "ENV TRIG" button uses the LFO to repeatedly retrigger the envelopes for currently playing notes. These add more possibilities for rhythmic sounds that pulse or sweep repeatedly in sync with your tune.

Delays for echo, flange, and chorus

Four ganged-together
delay lines give complex
echos and rich flange
and chorus effects.

The Prophet-5 had no built-in effects, but the Pro-53 adds a flexible delay section that does a lot to add richness and texture to the instrument's sound. The section sports four delay lines ganged together and controlled by a common set of knobs and buttons.

The "TIME" knob adjusts the overall delay time from a very short 1 ms for flanging, through 10 ms for chorus, 100 ms for slapback, and up to 1 sec for echos. The "SPREAD" knob spreads out the delay times for the four delay lines. When turned fully counter-clockwise, all four delays use the same delay time from the "TIME" knob. At fully clockwise, one delay is at twice the "TIME" setting, another at a delay time of zero, and the remaining two at points in between. Knob settings between these extremes create a pleasant scattering of echos or a thick multi-voice chorus or flange.

The "RATE" and "DEPTH" knobs control the speed and amplitude of an LFO modulating the delay time for chorus and flange effects. For a thick 4-voice chorus, use a short delay time, a moderate spread, a slow LFO rate, and a gentle LFO depth. For 4-voice flanging, shorten the delay time, slow down the LFO, and turn up the "FDBACK" knob to cause the delay lines to feedback on themselves. Clicking the "INV" button inverts the phase of the delayed audio, making subtle changes to the comb-filtering in flanging effects.

The "LO CUT" and "HI CUT" knobs adjust the cutoff frequency for separate high-pass and low-pass filters for the delayed audio. To create scattered echos that gradually mute and fade out, turn up the delay time, spread the delay lines, use slow gentle LFO settings, add some feedback, and turn down the "HI CUT" knob to cut away high frequencies as the echos cycle through the delay lines. To create "icey" echos instead, turn the "HI CUT" knob full up and adjust the "LO CUT" knob to cut away low frequencies as the echos repeat.

The "MIDI" knob tempo syncs the delay times with your DAW for rhythmic effects that align with your tune. The "SYNC" button enables or disables synchronization of the four delay lines with each other. When enabled, the delay times for the four delays are precisely aligned, but when disabled the delay times vary a bit to create more random and scattered echos, or to thicken up flange and chorus effects.

Finally, the "WET" knob adjusts the wet/dry mix, and the "ON" button enables or disables the entire delay section.

Master settings

Native Instruments Pro-53 Volume Section

Master settings adjust
tuning and volume.

Native Instruments Pro-53 Voices Section

Unison mode plays multiple
voices per note, and glide
adds portamento.

The "TUNE" and "VOLUME" knobs give master tuning and volume control, an "A-440" button adds a 440 Hz tuning tone, and a "MIDI" light blinks whenever MIDI data is received by the plugin.

The "VOICES" readout shows the number of notes of polyphony for the plugin. Click and drag up or down to adjust the value. While the original Prophet-5 was always 5-note polyphonic (thus the "5" in the instrument's name), the Pro-53 has variable polyphony from 1 to 32. Increasing the polyphony does not increase the plugin's CPU use unless you use that polyphony to play more notes.

The "UNISON" button makes the instrument monophonic. Playing a note triggers all of the instrument's polyphony at once to create a bigger sound. Turn up the number of voices to make the sound bigger, and turn up the "ANALOG" knob to make the sound thicker. In unison mode, the "GLIDE" knob adjusts the portamento rate from 0 to 5 seconds to create pitch slides from note to note.

Effects plugin

So far, everything I've discussed uses the Pro-53 as an instrument plugin. But, you can also use it as the Pro-53fx effects plugin. When used as an effect, incoming audio is mixed with the plugin's own audio and sent through the filters, envelopes, and delay section. The amount of incoming audio mixed in is controlled by the "EXT IN" knob below the mixer section.

To engage the plugin, and control its oscillators, you'll need to configure your DAW to route MIDI notes to the plugin along with the audio to be effected (some DAWs can't do this). Alternatively, you can press the "HOLD" button to automatically play and hold middle-C, then use the LFO to repeatedly retrigger the note's envelopes and keep the plugin running forever without sending it any MIDI notes.

Programs, banks, and files

When you've created a great new sound, you can name it and save the sound's settings into the plugin's memory. The original Prophet-5 had 40 memory slots, but the Pro-53 has 512. Programs (a.k.a. presets) are numbered from 1 through 8 in each of 8 banks, for each of 8 files. Press the "FILE" button and one of the eight numbered buttons to select the file, then the "BANK" button and a number to select the bank, and then again one of the numbered buttons to select the program. Or just press the numbered buttons alone to switch between the eight presets in the current file and bank.

To save the current settings, press the "RECORD" button first before selecting a file/bank/program. You can also load and save files, banks, and individual presets from and to files on disk using the file "LOAD" and "SAVE" buttons. Preset files can be in Native Instruments' own format, or even SysEx from a Prophet-5.

Hidden features

Clicking on the "NI" logo reveals a
menu of configuration settings.

While I've covered all of the knobs and buttons, there are a few more hidden features. Click the "PRO-53" name plaque to hide the keyboard at the bottom of the plugin. Or click the "NI" logo to show a menu of configuration settings.

On the "NI" menu, select "Hide Keyboard" as another way to hide the keyboard, or select "Show CPU Usage" to show CPU usage instead of the preset name, and "About Pro-53" to show a window with the product's version and serial numbers.

The original Prophet-5 did not support MIDI (though there was a later retrofit available), but the Pro-53 is very MIDI savey. All of the knobs and switches can be changed by MIDI controllers and automated using your DAW. Select "View Controllermap" to show a list of controller numbers for the instrument's features, "Save Controllermap" to save them into an editable text file, and "Load Controllermap" to reload a file after you've edited the controller assignments. If you "Enable MIDI Learn Mode", you can wiggle a plugin knob then wiggle an external controller knob to link the two.

Choosing "Dump CCs now" immediately sends a stream of MIDI controller messages to your DAW to record all of the current settings. With the "Enable Automatic CC Dump" item selected, the plugin will do this automatically every time you choose a new file/bank/program. The "Enable CC To Host Automation Conversion" menu item makes the plugin use your DAW's custom automation parameter control (if any) instead of MIDI controller messages.

The original Prophet-5 was one of the first hardware synthesizers to support microtuning. The Pro-53 supports this as well using microtuning files that you can load with the "Load Microtuning" menu choice. Choosing "Reset Microtuning" returns the instrument to an equal tempered scale.

The rest of the settings are fairly esoteric. Select "Don't Change Number of Voices To Preset Setting" to prevent selection of a file/bank/program from changing the polyphony setting. Mono lead and bass presets tend to change polyphony to "1", which can be annoying if you've explicitly set it to something else. The "Switch Knob Mode To Circular" menu choice changes the way knobs work. Normally, click a knob and drag up and down to change its value. But if you prefer circular motions, like real knobs, select this menu item.

Using the plugin

Playing the Pro-53 is a lot of fun. Practically every turn of a knob yields a classic sound from favorite tracks of the 1970s and 1980s. The presets that come with the Pro-53 do an excellent job of covering the bases, from rich sawtooth strings to gritty monophonic basses, synced oscillator screaming leads, and self-oscillating resonant filter whistles.

But how well does it emulate a real Prophet-5? Unfortunately, I couldn't find a Prophet-5 for this review. It's been 25 years since the last one was built, and working instruments are getting hard to find. What I did find were published waveforms for a rev 3 Prophet-5, which I've compared below to equivalent waveforms from the Pro-53. They are not a perfect match, but they're close. The Pro-53's waveforms are mathematically precise, while the Prophet-5's are less so. These differences affect the harmonic content of the oscillators and subtly affect the instrument's sound. Remember, though, that the analog circuitry of the Prophet-5 meant that every instrument was a little bit different. Making detailed waveform comparisons is probably not meaningful.


Square, triangle, and sawtooth waves differ slightly for the rev 3 Prophet-5 (top) and the Pro-53 (bottom)

I made similar comparisons for the Prophet-5 and Pro-53 filters and, again, there are differences that may or may not be significant. Ultimately, detailed technical comparisons are probably not the way to go. Instead, in our view if the plugin sounds good, then it is good, whether or not there are subtle differences between it and the original Prophet-5. And the plugin does sound good.

While the instrument is fun to play, I do have some criticisms. Unfortunately, the main problem with the Pro-53 is actually that it emulates a 30-year old Prophet-5. Back in the late 1970s, synthesis hardware was very expensive and corners had to be cut to keep the things reliable, affordable, and small enough to be portable. So, the Prophet-5 had just one LFO, only two envelopes, just one filter, only 5-note polyphony, and a quirky modulation matrix. The Pro-53 today has more polyphony, but to remain true to the Prophet-5 it still has just one LFO, two envelopes, one filter, and a quirky modulation matrix. Compared to other synthesizer plugins today, this is a pretty sparse feature set.

The modulation abilities of the original Prophet-5 were revolutionary in 1978. But in today's context, they're pretty quirky. For example, you can polyphonically modulate oscillator A's pulse width, but not oscillator B's. You can monophonically modulate both oscillator's pulse widths, but only by using the same LFO you might want to use for filter sweeps or vibrato. When you modulate pulse widths, you have to modulate both oscillators by the same amount in the same direction. You can modulate the filter cutoff frequency polyphonically, but only if you switch oscillator B into LFO mode, leaving you with one audio oscillator and a thinner sound. You can use oscillator B to modulate oscillator A's frequency for FM sounds, but you can't use an envelope to modulate oscillator B's volume or frequency for timbre changes. There is no way to modulate filter resonance, oscillator volume, or the A/B/noise mix. Keyboard velocity has a fixed affect on the envelopes, and there is no aftertouch.

The user interface closely mimics the look and feel of the Prophet-5. While the Pro-53 gets an A+ for style, I'd like to have seen the addition of numeric readouts for all of the knobs. I'm also frustrated with the difficult file/bank/program buttons for selecting presets. With 512 presets, pressing buttons over and over is pretty tedious. A scrolling menu of presets would be much friendlier.

Conclusions

The Pro-53 does a nice job of emulating the classic Sequential Circuits Prophet-5 synthesizer from the late 1970s. It sounds good and it looks and works like the original, with a few welcome extras added. If you're a fan of the Prophet-5 and need to read in old SysEx presets to recreate classic sounds, this plugin will do the job and it's a lot cheaper and more reliable than a real Prophet-5. And it stays in tune.

On the down side, the Pro-53 is an emulation of a synthesizer that has, in today's terms, a very limited and rather quirky feature set. There are many other analog-style synthesizer plugins today with more oscillators, LFOs, filters, envelopes, effects, and modulation features.

Alternatives

Arturia's Prophet V is a newer plugin emulation of the Prophet-5. Arturia specializes in detailed circuit emulations to exactly recreate the sound of vintage hardware like the Moog Modular, Minimoog, ARP2600, CS-80, and Jupiter-8. Arturia's Prophet V emulates the Prophet-5 and the obscure Prophet VS wavetable synth. The Prophet V is at about the same price point as the Pro-53.

Of course, the very best Prophet-5 sounds come from... a Prophet-5. Vintage hardware sold "As-is" is occasionally available on eBay, or you can buy restored and warrantied Prophet-5s from Wine Country Productions in the USA. Expect to pay several thousand dollars.

Dave Smith, the founder of Sequential Circuits and the designer of the Prophet-5, has updated the design in the Prophet '08 from Dave Smith Instruments. The new keyboard still has a fully analog signal path but it adds more polyphony, three more LFOs, a looping envelope, an arpeggiator, and more. The keyboard, and a modular version, are available for just under two thousand dollars.

John Bowen, the sound designer for the Prophet-5 at Sequential Circuits, consulted with Native Instruments to develop the Pro-Five (the forerunner to the Pro-53), and later formed Zarg Music to create plugins for the CreamWare DSP cards for Macs and PCs. Bowen has several Prophet-5 emulations, developed for Wine Country Productions as "Software Survival Kits". These include the Proph@t Plus, Pro-One, and Pro-Wave. All of them are inspired by the Prophet-5, but they add features like low and band pass filters, oscillator waveforms loadable from WAV files, effects, and more. Expect to pay a couple hundred dollars for each one, but you'll also need a DSP card from Sonic Core (which bought rights to the CreamWare hardware). Depending upon the card you get, expect to pay nearly a thousand dollars or more. Of course, the DSP card can be used for many more plugins available through Sonic Core.

Sonic Core also sells the Pro-12 ASB, a keyboard-less hardware emulation of the Prophet-5. The Pro-12 has 12 voices, delay and chorus effects, MIDI, and USB. Expect to pay around a thousand dollars.

from Native Instruments

Summary

Pros:

Cons:

Scores

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