To come clean right from the start of this review, I love the Leslie simulator known as the Tube Rotosphere, and it is probably my favourite item of musical equipment. It's one item I really would not wish to part with.
I am not a professional musician: I have gigged in the past semi-professionally, but really could only class myself as an enthusiastic amateur. I state this so that the reader might keep this in mind as there really must be others, who are better qualified than I, to review this product from a professional point of view. However, I do know what a tube Leslie sounds like, in the flesh as it were (I have a model 145 in my lounge at home) and from having heard many, many, recordings on vinyl and CDs, and also from having played various models in hotels and pubs.
The Rotosphere is a simple (from the point of view of operation) analogue effects pedal with really only one raison d'etre. It has been cleverly designed to emulate the tremelo effects of the special amplifier and loudspeaker cabinet known as a 'Leslie,' which has become an almost obligatory addition to the electronic and electromechanical organ, and is thought of as an instrument in its own right. This unit,therefore, mainly stands or falls by how well its achieves this emulation. This critique, therefore, concentrates on this aspect.
The physical description is that of an over-sized stomp box made, in a fairly substantial manner, out of metal and plastic which makes it heavy enough to stay wherever it is put to use.
Its interface with the outside world consists of four quarter-inch jacks, which are variously annotated, right/mono and left, both in and out. There is also a stereo jack socket which may be used by two generic foot pedals to switch the slow-fast control and operate the bypass switch. This is achieved by connecting the hot wires of the two pedals to either the tip or ring of a stereo jack plug.
There is a switch on the back of the unit to allow for the connection of keyboard or guitar. Using this switch adjusts the impedance and alters the frequency response of the unit.
The one other connection is that of the imfamous wall-wart [Ed: AC adapter]. Except that they have to be used because there is no user choice in the matter, in my opinion there should be a new category of Olympic Games events to be known as "hurling the wall-wart," where the item would be held by the mains plug, swung round at speed (400rpm makes a pleasant sound), and finally sent the furthest distance possible away from harm's way. The wall-wart really has only one saving grace, particularly from a European point of view, and that is that it is a cost-effective way of allowing for multi-voltages to be accommodated, as separate transformers can easily ship to the 220V European market or the larger US 110V market.
The base of the box has a soft rubber mat which stops slide and saves scratch damage to other surfaces. There are plastic side cheeks which remove to faciltate changing the tube; of which more later.
The top of the box has three metal foot buttons and three controllers and a cute plastic window so that you can admire the tube, which glows in the dark. Otherwise, there are five LEDs, and that's it.
The three controllers affect the input and output; controlling overall volume and tube drive so that you can dial in a nice over-driven tube effect, actually a distortion, that is much enjoyed by the organ fraternity, giving a warm animal growl to the organ, and also guitar tone. The third controller is a tonal balance control which sends more or less of the sound to the virtual 'lower bass rotary drum' or the upper virtual 'rotary treble horn'.
I would critise the Rotosphere on the following points. The breaker switch is an unlatched switch, which cannot be accessed from other than the foot button on the unit itself. As the slow/fast and bypass switching can be accessed from separate discrete foot pedals, then it could arguably be of benefit to forego the bypass accessibility and use the foot pedal facilty for the breaker switch. I always use a separate foot pedal to operate the device, which is much easier to do in the dark, and keeps my size nines from damaging the unit. I cannot therefore make use of the breaker switch at all.
The breaker switch should, I believe, be a latching switch, as many R & B players prefer the stop setting rather than the slow, and as it's set, up you have to keep the switch pressed like a dead man's handle. The switch can be changed by a tech, although it would probably invalidate the warranty. This should be checked out with Hughes-and Kettner, who I have found respond to emails.
The unit does not respond to midi switching as is, but this can be achieved by some additional expense from the likes of MIDI Solutions. [Ed: MIDI Solutions makes a box which converts MIDI CC# commands to relay contact closures.]
Elsewhere I have read unfavourable comments on the fact that, having the tube encased as it is, within a sealed enclosure behind a little plastic window, is a recipe for disaster; the thought being, I suppose, that as the heat generated by the tube is contained within the unit, it could cause eventual damage. I have been using the device for three years now, almost every day, and there has been not a hint of a problem.
The tube, an essential and ultimately failing (electronically) ingredient of the whole, is physically not best situated to be easily removed and replaced, as it is positioned well inside the unit. As the tube gives plenty of warning of its impending demise it should not ever be necessary to replace a tube mid-gig, and really does not present too much of a problem, even for a non tech like me. Hughes-and Kettner suggest that the unit should be returned to a reputable tech to do the deed, but if I can do it, believe me, so could you.
I have heard others critise the unit because it imparts some noise into the mix. I will not critise it on this account as the noise, such as there is, is very tolerable, and if a suitably pre-amped signal is fed into the unit, is really quite minimal -- and I suspect inevitable, if it is using analogue pass-the-bucket delay circuitry.
Excellent, indeed remarkable; with one, I believe important, proviso. It requires that its stereo field is adjusted according to circumstances. It is here that I believe it may have been marked down in previous shoot-out tests in competion with other simulators.
I have found that if used in a stereo amplification system where the speakers are configured left and right in the usual manner, then the tremolo spread is far too wide, which effectively destroys its imitative sound-image. Partially cross-fading, left and right signals brings the Leslie effect into focus, as it were, and indeed there is a good case for using the mono out rather than the stereo signal where the option to cross-fade is not a readily available option. The right/mono output must be used for this purpose, not the left jack socket. Optionally the stereo loudspeakers may be arranged in a placement fairly close together, with drivers facing outwards like the fingers of a clock at twenty past and twenty to the hour. The Rotosphere in Mono, sounds pretty much like a factory-new Leslie as heard from a short distance, with its deflectors in place and rear panels still attached, and is really as good as it could get, especially considering that the effect is entirely circuit driven. In particular, the difficult to emulate fast tremulant setting is very good, and in my opinion misses only by a hair's breadth, and its missing is to do with the slight edginess, that slightly rough, raw power, that a true Leslie imparts to the sound on full spin.
The Rotosphere is, if anything, perhaps just slightly too polite, and could do with just a tad more amplitude modulation. This critism is being very picky indeed, and I believe that the Rotosphere is the very best option where convenience and performance are both required. Indeed, if I were hoping to compete with the guitarist's Marhall stacks, I would think the Rotosphere to be the perfect choice.
The expression 'Blow them out of the water' comes to mind.
Its slow rotation is immaculate and the speed up/down, a joy. The tube imparts a wonderful organic warmth to the sound, and the whole effect is completely musical beyond a doubt. Apart from the advantages of cost and weight over a real Leslie cabinet, the Rotosphere obviously does not need to be miked. This allows for easy sound re-inforcement and recording, of course, and also, joy of joys, silent practice, which is definitely a boon in my home. Headphone use is best achieved by using the Rotosphere's mono option into a stereo mix.
Other simulators have come and gone and had various degrees of success: the Rotosphere motors on. I do hope Hughes-and -Kettner maintain production. If mine ever breaks I want another one, please.
The above is my, hopefully, objective opinion, on an arguably, subjective matter. Your view may differ. C'est la vie.
Thomas Adamson. UK.
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