PSP 42/84 Bundle Review by Richard Zvonar

What Is It?

One of the truly wonderful things about living inthe global village is that genius and craftsmanship now know no nationalboundaries. We've seen some amazing digital tools coming out of Germany,France, Israel, Spain, and now with the advent of Professional Sound Projects(PSP), from Poland. PSP is a small company, but as their first collectionof products demonstrates, they know their stuff.

Following their first successful release, VintageWarmer (to be discussed in a future article), PSP introduced (initiallyvia the company's own Web site and now through international distribution)the PSP42, a software emulation of the classic Lexicon PCM42 delay. PSPdid such a good job that Lexicon blessed the product by allowing it tobe called the "Lexicon PSP42." In most respects this is a feature-byfeature sound-alike (though there are a few small differences to be discussedlater). It was an immediate hit, and PSP have followed it with an expandedversion, the PSP84, and several other products. The plug-ins come in bothmono and stereo versions and run under both Macintosh and PC host applicationsat sampling rates up to 192kHz.

Installation, Documentation, and Support

Installation for all PSP plug-ins is by the familiarclick-through installer method. You'll be given a choice of installingdifferent operating system versions (in my case Mac OS 8/9 or X) and PDFdocumentation, after which the installer will present you with a listof possible plug-in folders for your various host applications. PSP plug-inscome in VST and DXi for Windows users and VST and MAS (and soon RTAS andAudio Units) for Macintosh. The first time you run each plug-in you'llhave to enter your authorization name and a 10-digit authorization key.That's it.

The documentation is well-organized clearly written,with only a slight tinge of "translation blur." Tweakers shouldbe pleased by some of the deeper technical discussion and clear blockdiagrams. The PSP84 manual in particular has some useful discussions onthe technical particulars and design
philosophy.

Because PSP's technical support department is in PiasecznoPoland, you may prefer to use their on-line support system or to communicatevia e-mail. Still, the company does provide telephone and fax numbers(hint: Poland is in the Central European Time Zone, one hour later thanLondon). My own e-mail was answered promptly and I had a series of veryproductive exchanges with the developer. I'm quite pleased to report thatthis correspondence resulted in the correction of some shortcomings inthe design of the Infinite Repeat function, leading to a new update ofPSP42!

PSP42

The Lexicon PCM42 was designed by signal processingmaestro Gary Hall and was released in 1981 on the heels of a popular seriesof Lexicon Prime Time delays. In addition to having that "Lexiconsound" integral to so many current recordings, the PCM42 was designedwith performance in mind, with external control and synchronization featuresthat were quite revolutionary. Although they never really disappearedfrom many studios, these instruments have experienced a renaissance thathas driven the cost of used units back up to the original list price andbeyond.

With PSP42 we can now fulfill our fantasies and runas many instances as our computer will support. The software emulationhas several other advantages over the original hardware. For one thing,PSP42 can run in stereo, for another it has twice the memory of the original.It can also run under complete automation control within a host sequencerprogram, and of course it has presets (something all the old timers longedfor in the PCM42).

Signal Path

PSP42 is based on the model of a single delay linewith feedback that was the standard architecture for the PCM42 and mostmonophonic delay processors of the day. The audio input is protected bya combination of an anti-aliasing filter and a "saturator" (analogtape simulation). The delay time is specified through a combination ofthe playback clock rate (continuously adjustable from 0.5 to 1.5 of thenominal rate) and the delay tap (this being the point along the delayline where the output signal is extracted - not to be confused with "taptempo"). There is also a button to switch between normal delay time(at full bandwidth) and double delay time (at half bandwidth of 8kHz).

On the PCM42 the clock rate could be controlled witha front panel knob or from an external input that could accommodate apedal or an control voltage, and PSP42 emulates these functions. The clockcan also be modulated by either an input envelope follower or a sine/squarewave LFO (with continuous blending between the two). This variable clockrate is what sets vintage delays apart from later designs based on a fixedclock. Varying a clock in real time results in smooth frequency changessimilar to the effects of varispeed on an analog tape deck. Variationsin delay time resulting from changing the delay tap result in discontinuitiesin the signal, i.e. "glitches." It takes a good bit of craftyprogramming to avoid such artifacts and to emulate that "analog"sound. Happily, PSP have done a marvelous job. The clock sweeps in PSP42sound like the real thing.

Sound

For this review I didn't have the benefit of a PCM42for A/B comparison, but if I can trust my ancient ears and sonic memoryI will declare PSP42 to be damned close to the original. The PCM2 hadthat "suave" Lexicon sound that allowed it to sit comfortablyin a mix without cluttering up the high frequencies (its nominal bandwidthwas 16kHz). PSP42 has a sound carefully modeled on its forebearer, includingthat forgiving input saturation and the hi cut filter and phase invertin the feedback path. It comes with a set of 16 factory presets that runit through its paces. "Light flanger," "wow tape,"and "doubler" all sound as you'd expect. "Didgee"gives a deep static resonance like a didgeridu and while "lezlie"may not sound exactly like a Leslie cabinet, it sounds exactly like aPCM42 imitating a Leslie!

Automation and Control

All parameters can be automated or externally controlledusing MIDI Control Change messages, hard-coded in the controller rangeof 102 to 118. The MIDI CC resolution of 7 bits is adequate for all parametersexcept Delay Time, which requires two controllers for coarse and fineadjustments. In addition, Delay Time can be slaved to System Tempo.

Looping and Sync

Although people will use PSP42 for its delay and modulationfunction, there is a cadre of PCM42 looping enthusiasts who will be keenlyinterested in how the PSP stacks up. The Lexicon PCM42 was perhaps thefirst digital delay that was designed from the get-go to work as a performancelooper. It offered up to 4.8 seconds of memory and five parameters couldbe dynamically controlled by a foot pedal or an external control voltagesource. The 42 could also be modified with additional memory and otherfunctions offered initially by its designer Gary Hall and later by fellow-LexiconianBob Sellon.

The initial release of PSP42 did not emulate the PCM42sInfinite Repeat function precisely, though this was largely a consciousdecision. One difference (in my opinion an improvement) is that when PSP42is put into Repeat mode the length of the loop equals the current delaysetting. The PCM42 always looped the entire contents of memory so youcould never capture a short loop. This did have its advantages, though.By setting the delay time to a subdivision of the full memory length youcould play with a short echo but loop a longer phrase, and the loop wouldcontain the echoed material (you can still do this by running two instancesof PSP42 in series).

I also discovered a few anomalies in the way the repeatfunction related to the input and feedback signals, but these problemshave since been corrected by a quick response by the developer to my "bug"report. The forthcoming version 1.3 will capture running feedback intoa loop and will apply echo effects to the contents of a loop when it isreleased. Hats off to software designers who go that extramile!

Another difference in implementation is in the programmableclock feature. The PCM42 provided a timing pulse, suitable for drivingan analog sequencer or a drum machine. This could be set as a proportion(e.g. 1/2, 3/16, 7/32) of the entire memory time and it was independentof the delay setting as defined by the inc/dec buttons. PSP42 uses ostensiblythe same interface to set both clock output and delay time. This is moreconsistent with contemporary sync practice but it sacrifices the polyrhythmicpossibilities of the original (I'm not sure how significant this mightbe, since I never actually used the original feature myself!). PSP42 alsocan act as a slave to system clock, so the repeat rate will automaticallylock to tempo.

PSP84

What if Lexicon hadn't shifted its focus in the mid1980s to high-end digital reverberation units and had continued developmentof digital delays? We might have had a hardware version of the PSP84!This plug-in is at heart a two channel evolution from the PSP42, but withthe addition of a multimode dynamic filter, overdrive, and reverberatorand with a greatly enhanced modulation section. All the components ofthe PSP84 have been designed with a consistent awareness of producinga vintage sound characteristic of the early 1980s (Ah yes, I rememberit well!). To my ear they have done an excellent job.

The two delay lines can be feed individually by theleft and right channels of a stereo send or insert. They can be linkedor can run independently with different delay and feedback settings. Delaytimes can be set manually or slaved to the clock rate, with a maximumtime of 5 seconds. Outputs of the twofeedback paths can be panned independently. The filter section can beplaced at the input, in the feedback path, or at the output, and the filtercharacteristic can be low pass, band pass, or high pass. Filter resonanceis fully adjustable and cutoff frequency can be set throughout the fullrange up to 15kHz. The Saturation, or Drive, module is at the input tothe delay line and affects both the input signal and the feedback signal.It has a single control that regulates both the saturation amount andthe input envelope follower sensitivity.

The modulation section can be used to control boththe delay clock and the filter cutoff frequency. It offers a choice ofenvelope follower and LFO with sine, pulse, triangle, sawtooth, and randomwaveforms, with a rate from 0.01 to 15 Hz. The reverb section offers achoice of vintage spring or plate characteristics. The spring settinghas a periodicity or "sproing" that works well in certain situations,while the plate gives a denser and smoother sound. A damping control regulatesthe decay characteristics. The reverb can be placed either in the delaypath or at the output mix.

Just as with PSP42, all parameters of PSP84 can becontrolled in real time either from a VST host program or via MIDI. Eachparameter is hard-coded to a particular MIDI Continuous Controller messagein the range of 20 and above (keeping them out of the way of the morecommon dedicated controllers).

Summary

Those of us who have been kicking ourselves for notbuy a used PCM42 when they were still cheep can rejoice. The PSP42 isa worthy emulation of the sound and functionality of the Lexicon classic,at about 10% of the price. The PSP84 builds on this basic architectureto provide a stereo processor with analog-style filter, vintage reverberation,and a greatly enhanced modulation section. As a company, PSP is small,dedicated, and responsive to their customers, with excellent support,an appreciation of good-quality sonics, and creative ideas. PSP have broughtback an old friend and have introduced us to some new ones!