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Kurzweil Rumour & Mangler

Multi-effects By Paul White
Published November 2003

Kurzweil  Rumour & ManglerPhoto: Mark Ewing

These two stereo multi-effects boxes from Kurzweil bring the powerful processing of their flagship KSP8 more easily within reach of the home studio owner.

Kurzweil made their name producing some of the finest sample-based keyboard synths and electronic pianos around, but they've since diversified into effects, which is not surprising when you consider they had already developed the requisite technologies for use within their keyboard instruments. Their multi-channel KSP8, reviewed back in May of this year, defines the top of their current effects range and offers both stereo and surround processing. While combining good value with performance, the KSP8 is still quite expensive by project studio standards, especially where multi-channel operation isn't required, so Kurzweil have adapted a number of their best stereo algorithms for use in two new 1U stereo rackmount processors, the Rumour and the Mangler.

These are much more affordable than the KSP8 and, rather than create one box that attempts to do everything, Rumour is packed full of studio reverb treatments, while Mangler focuses more on special effects (including some reverb capability, though). Additionally, both units feature a pre-effect, three-band EQ section which is set globally rather than on a per-patch basis.

Hardware & Interface

Both units use exactly the same hardware engine and user interface, so the hardware description part of this review applies equally to the Rumour and the Mangler. The processors are presented in a no-frills 1U rack case, with power coming from an external adaptor. A cursory glance at the control panel might suggest that you're looking at a presets-only machine, but nothing could be further from the truth, as the level of available editing is pretty deep. Not that you don't get presets — there are 192 factory presets per machine and any of the presets may be edited and saved in one of 64 user patch locations. The depth of editing is impressive, but to prevent the less experienced user from being overwhelmed by alien functions, the edit system can be switched between two modes, the simplest of which allows access only to a maximum of 16 of the most useful parameters of each preset. This can be switched to a more advanced mode where all the available parameters become accessible, but the same 16 most useful parameters always appear at the top of the list.

A global setup option allows presets to load as soon as they are selected, or to be cued in advance, in which case the previous effect remains active after a new effect has been selected until the Load button is pressed. For live use, a TRS pedal jack is fitted to the rear panel to allow either one or two footswitches to be connected for using the tap tempo function and for bypassing the unit.

The physical inputs and outputs of the machines comprise stereo ins and outs on balanced jacks plus digital S/PDIF inputs and outputs. Both internal and external digital sync are supported and both the analogue and digital outputs may be used at the same time. The input is strictly one format at a time, selected via the Master menu. Sample rates of 48kHz and 44.1kHz are supported, while the analogue I/O may be switched between -10dBV and +4dBu sensitivities via a rear-panel slide switch. The analogue input can be controlled from the front panel via a regular level control, as may the output level (the control affects both the analogue and digital outputs), though the only way to vary the digital input gain is to use the on-board pre-effect EQ system and then to use the EQ gain as a level trim control.

MIDI In and Out sockets are also fitted for patch dumping and saving, for MIDI parameter control, and for updating the system software held in flash memory, which is done via SysEx transfer. The MIDI Out socket can be switched to MIDI Thru operation, and when in MIDI Out mode MIDI Clock may be sent as well as received for locking effects to tempo.

To keep costs down, the traditional bar-graph level meter has been replaced by green, yellow and red LEDs denoting levels of -48dB, -12dB and Clip. In most instances, setting the levels so that the -12dBV LED flashes periodically, but without lighting the Clip LED, is optimal. There's also a Clip LED above the output level control, which is necessary because some of the effects (and of course EQ boost) can increase the level of the signal considerably. As the output level control is adjusted, the display temporarily shows the actual output gain in decibels.

The rear panel of the Rumour provides identical facilities to that of the Mangler.The rear panel of the Rumour provides identical facilities to that of the Mangler.Photo: Mark Ewing

Operating System

The presets and user memories are normally accessed using the front-panel Bank and Preset selector knobs, where Bank is used to pick from 16 main effect types or categories and Preset is used to choose from 16 presets within that category. External MIDI Bank and Program Change messages may also be used to change patches. Used at this level, the operation is exactly the same as for many preset-based machines and, in many applications, there will probably be something in the factory presets section that will do the job with little or no editing.

The final four banks are labelled User, and this is where edited patches are stored. Parameter adjustment is via a large Value encoder wheel to the right of the front panel, while parameter selection is via the smaller Select rotary control. The currently selected parameter is always shown on the second line of the display, with the patch name on the top line. Other than this, there are only six buttons, two of which deal with patch loading and saving. The remaining four relate to Bypass, EQ, Master and Tap where Master accesses the main setup menu and Tap allows tempo-related effect times to be tapped in by the user. Status LEDs show MIDI activity and digital lock, plus there's also a rotary trimmer for adjusting the contrast of the gratifyingly bright two-line, backlit LCD display.

The effects are based on Kurzweil's KDFX algorithms and, for a description of what these do, you need to download a hefty PDF file from the Kurzweil web site, as no effect or algorithm description of any kind is included in the manual. My own view is that this is taking economy a step too far, as you can't simply assume that all potential users have a computer, or even feel comfortable using one come to that. A basic description of the main effects and their parameters would have sufficed, but as it is all you get is a list of preset names and locations.

Editing effects is pretty straightforward once you know what the various parameters do, and in the case of reverb the first parameter you come to is wet/dry mix. While the parameters relating to the more familiar effects are easy enough to suss, those specific to some of the more abstract effects are somewhat more cryptic, which makes that PDF algorithm file pretty important. In addition to front-panel editing, the first 16 parameters are also mapped to MIDI Continuous Controllers one to 16, so an external hardware controller (or sequencer mixer map) may be used for more hands-on editing — MIDI Continuous Controller 32 is used to change banks. To display more than 16 parameters per preset, the parameter display must be changed from Basic to Extended within the Master menu. Here you can also set the way the Bypass button operates, you can select external digital sync, change the MIDI setup, and select 24-bit/16-bit operation or 48kHz/44.1kHz sample rates. There's also a global insert/send-return mode where selecting send-return sets the wet/dry mix to 100 percent wet. In insert mode, the mix is set individually per preset wherever having a wet/dry mix is relevant. Clearly things like compression, distortion or EQ have no wet/dry mix.

Using these units is not a problem, as the interface is extremely straightforward, with all the edit parameters for any particular preset being presented as a long, continuous list — the most important parameters appear at the top and the more obscure ones towards the bottom. Setting the input gain using the three-LED metering system proved to be perfectly adequate, though there is no gain reduction read-out of any kind for those presets that use compression, which I found extremely frustrating. The audio quality remained clean at all times, other than on the deliberately lo-fi and distortion effects, and background noise was minimal. On a practical note, though, the external PSU connector is rather too easy to dislodge, so in a live situation you'd need to take precautions to prevent inadvertent disconnection mid-show.

Rumour Algorithms

The Rumour is largely dedicated to reverb and ambience treatments, though it does include three banks of effects that cover chorus, flange and delay — mainly as solo effects, but occasionally in combination with reverb or delay. The preset banks are designated Ambience, Small Rooms, Large Rooms, Small Halls, Large Halls, Plate/XXL, Gated/Rvrs/Cmpr, Unusual, Laserverb, Delay+, Chorus+ and Flange+. Within each bank are 16 variations and, similarly, each of the four user banks has 16 slots into which to save edited effects.

Banks one through six provide all the staple 'real' reverb effects, from small closets to immense mosques. In between these extremes are plates, rooms and spaces to cover most eventualities, with bathrooms and gyms joining the usual concert halls, vocal rooms and drum plates. Bank seven is where most of the nonlinear effects are to be found, some of which combine reverb and compression. The Unusual section continues the nonlinear theme, but also adds presets such as Acid Trip Room, High-school Gym and Distant TV Room, just to give you a flavour of the effects on offer.

Laserverb is a Kurzweil speciality treatment that generates tightly spaced reflections that widen with time, so that the effect is that of a resonant delay that falls in pitch. It is effective on drums, where each hit is followed by a metallic, pitch-dropping slide, but (as you might surmise) it's less than ideal for most lead vocal parts! As I discovered, though, it can work brilliantly on clean guitar. After that brief moment of excess, we get a decent selection of basic, multitap and genre-specific delays, a menu of classic chorus effects with and without reverb, and a number of variations on the popular flanging theme, some of which also come in combinations with reverb or delay.

EQ, Stereo Width & Tap Tempo

There is an independent EQ section before the effects processing block, which can only be set globally. This makes sense in a live sound situation, but less so in the studio where you may need a different EQ setting depending on the effect you're trying to create. The EQ is a semiparametric type, by which I mean that the frequencies are variable, but the Q value or bandwidth of each band is fixed. All three bands may be adjusted from 8Hz to 25kHz, with an astonishing gain range of -79dB to +24dB. Further controls adjust the stereo width (width can be narrowed, but not widened), stereo balance and level. You have a choice as to whether the EQ section is bypassed along with the effects or not.

Pressing the Tap button repeatedly four or more times sets the system tempo (when set to internal MIDI Clock sync), which may also be entered numerically if preferred. When external MIDI Clock sync is selected, the tempo will be displayed, but can't be changed. Note that a tempo can be set for an effect that is independent of the system tempo where required.

Using The Rumour

Reverb is a hugely important effect, and one that differs enormously from one manufacturer to another. With experience, it's fairly easy to spot a good reverb, but its not always so easy to describe why. Kurzweil actually do a pretty good job with their reverb algorithms, and avoid the most common pitfalls, among which are: metallic ringing on short, bright presets, other than plates that have a degree of ring designed in; and excessive repeating modulation on very long decay times; and, most importantly, a tendency for the reverb to bury the original sound when the wet/dry mix is on the live side of normal. The latter can be demonstrated quite easily using a cheap reverb, because the hall settings soon overwhelm the dry sound when the level is turned up, whereas increasing the reverb level on a well-designed machine just makes the original sound seem to move further back into the hall. I don't think Kurzweil have nailed this quite so well as Lexicon and TC Electronic have in their high-end models, but they've done a very good job nevertheless. They have also managed to make the spaces sound believable, which is particularly difficult to do when emulating smaller spaces and ambiences.

Because there are so many well-constructed reverb presets to hand, you can normally get what you want by finding an appropriate preset and then adjusting the decay and pre-delay time, with perhaps just the odd tweak of the high-frequency damping, but if you really want to dig deep, you can. All the expected advanced parameters are available, including the ability to balance the early and late reflections, but I must stress that the designers have done a great job with these presets, and in most cases, even their choice of default wet/dry mix is close to ideal.

Laserverb actually turned out to be a lot more musical on electric guitar than I thought it would be. Sure, it does the ringy pitch-drop trick on drums, but set up more subtly, as it is on some of the presets, you can add a lovely watery shimmer to clean guitar lines. This is definitely an effect to explore if you're into ambient music of any kind.

The chorus, delay and flange effects were also good in a 'get the job done' kind of way, which isn't meant to be disparaging, but rather an affirmation that what you get is musical and useful rather than simply gimmicky. There's even an emulation of an old analogue flanger pedal that sounds exactly like my old Electric Mistress did, but without all the noise. The combination effects mainly deploy delay or reverb alongside one of the mod effects and so don't do anything too far out of the ordinary, but, again, they do it in a very tasteful, classy and musical way, so I'm not complaining.

Mangler Algorithms

With a name like Mangler, you might expect something pretty destructive and off-the-wall, but the effects here are in the main well chosen for their musical usefulness. The unit drops most of the conventional reverb treatments to make room for more variations on the delay and modulation effects, and includes all the staple modulation and delay treatments, including rotary speaker simulation and ring modulation as well as Laserverb, filters, pitch-shifters, synth effects, frequency-shifters, distortion, amp simulation treatments, and compression. In addition to the usual analogue distortion simulations, there are also some digital distorters to add aliasing and quantising artefacts and a few instrument-specific treatments for the likes of electric guitar, electric piano and drums. Most of the algorithms concentrate on a single effect, but there are several dual-effect presets and even a handful that combine three. For example, one of the distortion effects combines overdrive, delay and chorus.

If you want to know how each algorithm is put together, and what each parameter does, then you'll need to download a copy of the KSP8 Algorithm Reference PDF file from the Kurzweil web site, as this information is not included in the paper manual of either Rumour or Mangler.If you want to know how each algorithm is put together, and what each parameter does, then you'll need to download a copy of the KSP8 Algorithm Reference PDF file from the Kurzweil web site, as this information is not included in the paper manual of either Rumour or Mangler.The distortion section takes up two banks, and includes a section of usable guitar amp modelling patches, but these don't seem to include any speaker emulation, so they'll only sound 'right' when fed into a guitar amp or into an external speaker simulator. Of course you don't have to use them with guitars, and if you back off the drive to stop the result getting too gritty, you can get some interesting sounds out of synths and drums, especially bass synths. As with Rumour, the modulation and delay effects are really very good, with several types and variations not present in Rumour. Some of the combination effects also make good use of the 'shattering' reflections effect created by Laserverb, but I found the rotary speaker emulations to be fairly unconvincing — they seem to combine chorus with tremolo and, while not unmusical, they just don't have anything like the same timbre or feel as the real thing. Treat them as just another modulation effect and they're fine.

Inevitably, the pitch shifting is also a little grainy when used for anything other than gentle detuning effects, but then this is an observation that applies to almost every effects box on the market, other than some of the most expensive ones. Unusually, there are some pitch-shift effects that create multiple resonant filter peaks that are harmonically related, and some of these come tuned to notes or even chords. Unpitched sounds fed through these filters cause them to ring at their resonant frequencies, an effect that works well on percussive and harmonically rich input signals. Sadly, though, you can't use MIDI Note messages to 'play' the resonant notes in real time.

The filter section is pretty busy, and includes effects based on nine different algorithms, which encompass the usual resonant low- and high-pass synth-style filters we all know and love, as well as a filter specifically designed to suppress odd harmonics, and a couple more that work as enhancers. I was also favourably impressed by some of the compression algorithms, which work particularly well on guitar and percussive sounds, but, as pointed out earlier, lack gain-reduction metering, which makes them very difficult to set up, especially for the less experienced user.


Both these units deliver what they claim, and to a very high standard, though if I had to choose a favourite it would be Rumour, as not only does it handle all the more useful reverb and ambience treatments well, it also provides the means to set up as many chorus, flange and delay effects as most users will ever feel the urge to shake a stick at, unless they live in a very large wood and feel themselves to be sadly short of exercise. On top of that, you get the quirky but musically interesting Laserverb and a smattering of viable combination effects.

Certainly Mangler expands on the modulation and delay effects of Rumour and adds a host more in the way of effect pyrotechnics, but, as a guitar player, I didn't really find much to get excited about in the distortion sections and, while ring modulators are fine for pretending to be a Dalek for five minutes, they have very limited musical applications. It's the same with the tuned resonant programs — because you can't fire MIDI Note messages at them, you can't as easily weave them into a composition as you can with the MIDI controllable Lexicon PCM80/81, so there's a limit on what you can do with them. After a tentative play with each of the algorithm types, I found myself drawn back to the admittedly excellent core effects and to the irresistible Laserverb. Of course, whether you prefer the Mangler's more off-the-wall effects is subjective — if you like experimenting, most of the algorithms have plenty of variable parameters for you to work with. However, for my money Rumour is the real star here, even for the user working in a computer environment. While you can get all manner of plug-ins to create weird and wonderful effects, good native reverb always comes at the price of heavy CPU drain, and I've yet to hear one that sounds nearly as good as Rumour does.

Overall, then, the impressions are favourable, with both units sharing a very simple user interface and having the ability to be used either as preset-based machines or as power-user sound-design tools. The reverbs are particularly strong, but all the familiar effects are delivered with panache, clarity and musicality — attributes which always take precedence over gimmickry.


  • Easy to use for all levels of experience.
  • Good sound quality, especially the reverbs.
  • Some unusual effects, especially Laserverb.


  • External PSU not ideal for live use.
  • No gain-reduction meters on compressor algorithms.
  • Effect algorithm descriptions have to be downloaded from the Kurzweil's web site.


Both these units do what they set out to do, and they do it well, but my own view is that Rumour is the most useful of the two, as it combines an excellent reverb unit with an adequately wide range of 'bread and butter' delay and modulation effects.


Rumour, £625; Mangler, £625. Prices including VAT.

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