Paul White studio tests Roland's versatile modelling guitar amplifier, which has applications both on stage and in recording.
The Roland VGA7 guitar amplifier is based on the same COSM physical‑modelling technology developed for the VG8 and VG88 systems and combines in‑depth modelling, a range of effects, a redesigned 'knobular' interface and two‑way stereo amplification. Given the VGA7's heritage, it's no surprise that many of the more advanced features are only accessible using a divided pickup such as Roland's GK2A, though you can plug your guitar into the VGA7 directly if you're happy to sacrifice these more advanced features — see 'The GK2A Pickup' box for further details.
Assuming that you are using a guitar fitted with the GK2A, the individual strings of your guitar can be picked up by the VGA7, which gives it some considerable advantages over some of the competing systems. For example, it can model different types of pickup and guitar, including acoustic and semi‑acoustic models. The divided pickup also allows you to set up open tunings and capo‑style effects using selective pitch‑shifting. Roland's COSM modelling system can also create abstract synth‑like sounds, using their proprietary HRM process, and these respond to the full spectrum of your playing technique.
The solid state power amp drives a 2 x 12 bass combo, ported to the rear, with a pair of horn treble units to provide full frequency range coverage. The system is rated at 65W per channel, and the speakers can operate in stereo to get the best out of effects such as reverb and chorus. The whole package is pretty hefty, measuring 770 x 300 x 640mm and weighing in at 37.6kg. Detachable castors are included but, as the only means of lifting is via the strap handle, it won't be much fun to haul up the social club's fire escape!
There's rather more going on behind the VGA7 than you'd expect of a guitar amplifier: no fewer than nine quarter‑inch jack sockets. Four of these are for optional footswitches, which may be used to bypass Reverb, Chorus, Delay and Effects sections, while a fifth accepts an Expression Pedal for level or wah‑wah control. The Delay socket also accepts a dual footswitch, with which the tap tempo facility can be accessed. Footswitches can also select patches and activate Manual mode (see below).
The next two jack sockets provide a stereo external input, which allows you, for example, to feed a guitar synth through the amp, and the final pair of sockets provide a stereo line output for recording or feeding to a PA system. One omission, however, is a GK2A Thru socket, which would have allowed one guitar to feed both the VGA7 and a GR‑series guitar synth, for example — even though there is an optional splitter available which does this, there is little real excuse for not building it into the amplifier. Finally, MIDI In and Out connectors are situated to the left of the jack sockets. The MIDI implementation allows you to dump and restore patches, as well as allowing you to use external MIDI devices to alter parameters and select patches.
Clearly the front panel is a little busier than you'd expect from a typical guitar combo — and some might say less attractive — but everything you need to control the amplifier is clearly presented using large knobs and buttons, together with numerous status LEDs. Newcomers to the VGA7 will probably want to start by trying some of the factory patches, which are organised into eight banks of 10 patches each. A row of buttons at the top of the control panel permits direct patch selection from within the current bank, though there are also bank and patch increment/decrement buttons below the display. A further dedicated button allows selection of user patches, of which there are also 80.
To set up your own sound, you start at the left‑hand side of the front panel and work across. You can work using one of the presets as a starting point if you wish, in which case each knob must be moved through its stored position before it becomes active, or you can use the dedicated button to switch to Manual mode, forcing all values to the current physical knob positions. First you select the guitar you want to model by stepping through the six basic types listed to the left of the front panel — if you need more choice you can access several variations on each type by holding down the Edit button and pressing the Parameter keys. Printed metal plates on top of the amplifier list the options, so that you can do without the manual. A similar selection system follows for each of the other processing blocks, making the VGA7 very simple to set up.
In addition to the more familiar guitar models, there are the eight Special models, which use Roland's HRM synthesis to model bowed, bass, synth and organ sounds. However, because these sounds are created from the original string harmonics, they are able to be far more responsive to different types of playing technique than traditional guitar synths. What's more, this synthesis method does not suffer from any tracking problems — a welcome change from a traditional guitar synth, where the pitches have to be recognised before triggering of the sound source.
Once the guitar type is selected, the next section of front panel specifies the placement and type of the pickups or microphone you want to use. If the guitar being emulated has three pickups, such as the ST model, stepping through the options also produces the middle/neck and middle/bridge combinations.
Next up comes the Tuning section, where individual strings can be pitch‑shifted to provide open tunings, true 12‑string emulations (where the top E and B string pairs play in unison and the other four strings are paired as octaves) and so on. A simple system allows the user to create custom tunings very easily, though common open tunings such as dropped D and open G are provided as presets. Working on a similar principle is the Capo section, where tunings can be both incremented and decremented in semitone steps. When the Capo button is pressed, the current shift is displayed for a few seconds, during which time it can be changed using the Up/Down keys. Given that pitch‑shifting is already suppied, I'm surprised that Roland haven't also implemented automatic harmony generation or perhaps a pedal steel guitar effect in some way.
Once the virtual guitar has been modelled, it is then passed through a virtual amplifier section capable of emulating a number of popular commercial models. Though Roland are a little reluctant to name names, you can hear the usual Fender, Vox and Marshall amp simulations, along with a number of more modern boutique amps and, naturally, the classic Roland JC120 clean sound.
There are Clean, Crunch, Lead, Special and Full Range models available, each with a number of variations. The first three models are fairly self‑explanatory, while the Special section contains fuzzed and layered variations, and the Full Range section provides for acoustic and clean sounds. Controls are provided for Gain, Volume, Bass, Middle and Treble as well as Presence.
After the amp can be placed a choice of modelled speaker cabinets, based around variations on the 1x12, 2x12, 4x10 and 4x12 themes. Following this stage, you can add effects, choosing from Wah, Slow Gear (slow attack envelope), Compressor, Tremolo, Phaser or Flanger, with a pair of knobs to control the two main parameters of the effect selected. Although there isn't a noise gate featured in this list, the VGA7 does offer adjustable‑threshold gating, which can be set up by accessing the System menu from its dedicated button below the display.
Delay, Chorus and Reverb sections follow these effects, and are available at all times. Feedback and Level controls feature in the Delay section, and there is a Tap Tempo button for setting the delay time. The Delay processor can also function as a phrase sampler if you wish, allowing short passages to be looped and overdubbed under footswitch control. The Chorus section has a single Intensity knob, and its three variations cover the classic Roland range, from rich to subtle Dimension‑D style. The Reverb section has a control for Level, and there are three types, Plate, Room and Hall.
Following the three‑digit LED display and its associated utility buttons, there is a Master control for setting the overall amplifier level, a phones output for practice purposes, and the power switch.
The lengths to which Roland have gone in order to model specific guitars and pickup combinations is extraordinary. Both the Les Paul and Strat models are definitely reminiscent of the real thing — they've managed with some success to reproduce the classic 'in‑between' switch positions for the Strat model, in particular. In direct comparison with the real Strat I was using, the model sounded a little brighter, but nothing that a little EQ couldn't compensate for.
As I had expected, the acoustic models were less successful than the electric models. The impression is something like an acoustic guitar amplified via a piezo pickup, and the high end can be a little harsh if you're not careful. However, if you're at a cabaret gig and need to move straight from 'Smoke On The Water' to 'More Than Words', it'll get the job done.
When the HRM guitar models are used, all pretensions to sounding natural are left behind. The radical remodelling of the harmonic structure makes the sounds seem very synthetic, but there is still something about the sound that ties it to the guitar. In combination with the amp models and effects, the HRM sounds can be extremely effective — I'd like to think Roland will explore this more in the future.
The amp models compare well against other modelling systems I've tried, and respond well to playing dynamics. Cleaner sounds remain lively and the effects section is strong, especially the excellent Roland‑signature chorus effects. Patching in an expression pedal also confirmed the wah‑wah effect to be a very respectable emulation of a Cry‑Baby style analogue pedal.
The VGA7 is a hefty piece of kit to lug around, but it's loud, it's versatile and the amp models are easily good enough for session work and gigging. However, the acoustic guitar emulations and treatments that rely on pitch‑shifting probably won't stand up to the scrutiny of commercial record production unless fairly well back in the mix.
So is the VGA7 for you? If you only need a few rock guitar sounds and a couple of clean sounds, with basic effects, then one of the less sophisticated modelling units will do the job fine, but if you really need those acoustic sounds and a comprehensive effects section, the VGA7 is pretty much the only game in town. It's not a substitute for the real thing in all situations, but it is an impressive piece of technology that takes modelling one step further than its competitors.
A dedicated Tuner button mutes the amplifier and turns the display into a guitar tuner, with a row of LEDS above the display providing the usual 'up a bit, down a bit' cues. The 'A' to which the tuner is referenced can be changed, from the System menu, to anywhere between 435Hz and 445Hz, should you find yourself overdubbing against an out‑of‑tune piano, for example. Also from the System menu, you can set the amount by which the amplifier sound is attenuated when the tuner is selected, if you decide that you don't want the feed to the amp muted altogether.
Though you can simply plug a regular guitar into the amp and play, using the front‑panel high‑ and low‑sensitivity instrument inputs, this only allows you to use the amp and speaker modelling and the onboard effects. To access the guitar modelling, HRM and pitch‑shifting effects, you have to use a divided pickup so that the VGA7's modelling system can isolate the vibrations from each individual string.
The GK2A is Roland's divided pickup, specifically designed for their Virtual Guitar systems, and this is available either separately for installation on your own guitar, or built into a new guitar from the likes of Fender, Godin and many others. However, the system can also be set up for compatibility with one of Roland's older GK2 pickups or other inbuilt divided piezo pickup systems. Roland have also included a setup option which can cater for pickups mounted in the opposite direction to normal. Such a configuration might be required for using the GK2A with left‑handed or odd‑shaped guitars, The sensitivity of individual strings can also be adjusted.
In addition to allowing you to send the individual signal from each string to the front panel of the VGA7 through its multicore cable, the GK2A also allows the normal guitar signal to be sent to the processing engine so that you can mix real and modelled guitar sounds prior to the amp section if you wish. The GK2A pickup's control unit features a couple of buttons which can perform a variety of different functions, including pickup selection for the modelled sound, patch selection or activation of the VGA7's onboard tuner.
It is essential that the divided pickup is properly mounted and positioned, and that the VGA7 is set up correctly, if you are to get the best results from a system of this complexity. For example, you have to enter your guitar's scale length and the distance between the pickup and the guitar's bridge, because the harmonic balance received at the pickup depends considerably on these factors.
Roland are so protective about their technology that they haven't even furnished Roland UK with the full details of how the VGA7 system works, but a lot can be revealed by deduction. By siting the GK2A pickup very close to the bridge, the signal picked up from the guitar strings is made as guitar‑independent as possible — though naturally the sustain of the guitar will bear a direct relationship to that of the processed sound. It would be reasonable to assume that specific guitar types are modelled by analysing the harmonic content of the signal derived from the divided pickup, using multi‑band filtering; analysing the signal from the guitar to be modelled in the same way, and for all possible pickup combinations; and then writing a series of conversion tables that redistribute and rebalance the harmonics collected by the divided pickup until they match those of the target instrument. It is also possible that some dynamic element is built into the conversion to approximate the sustain characteristics of the original instrument.
When it comes to the finer details of amp and speaker modelling the manual provides no clues, but it seems to me that the approach isn't too different from that used by other manufacturers. Such differences as do exist are undoubtedly in the mathematical detail of the models — while some feel a speaker emulator can be implemented using a relatively simple filter, others feel the need to model all the bumps and dips of the original. Ultimately all that really matters is that the thing sounds right and also feels right to the player.
Unlike other modelling amps I've tried, Roland have decided to make their sounds work right when played through full‑range speakers, rather than through limited‑bandwidth guitar speakers. This is the reason why the VGA7 is equipped with tweeters, and one clear benefit of this approach is that the modelled amps sound similar whether played via the VGA7's speaker or DI'd into a recording system.
The method of pitch shifting appears to be fairly conventional, but because each string's output is a monophonic source, the algorithm can be optimised to produce far fewer side effects than you would expect from general‑purpose pitch‑shifting. For example, the 'cut and loop' frequency can be made a multiple of the note pitch to cut down on atonal modulation. Even so, when individual strings are heard in isolation, it's still possible to tell that you're listening to a pitch shifter — there's a slight shimmer to the sound — but in the context of a complete performance, the effect sounds reasonably convincing.
- Models guitars, pickups, amps and speakers.
- Friendly user interface.
- Excellent electric guitar and amp emulations.
- Can use regular footswitches and expression pedal for additional control.
- Acoustic and pitch‑shifted sounds aren't to the same standard as the conventional electric sounds.
A great one‑box solution for getting pretty much the whole range of recorded guitar sounds. Though some of the less conventional sounds aren't perfect, they're still likely to sound fine at a live gig.