Introduction An impulse response (IR) is a method for measuring the characteristic of a violin, or indeed any acoustic instrument, space or object that responds to sound. Convolution is a process that calculates the difference between two responses. IR Effect pedals take the input from your instrument and use a pre-determined convolution process to output a sound that represents the “target” instrument. They use different techniques to do this, but the intention is the same. The marketing goal of using an IR pedal is to be able to play an amplified violin and for it to sound like a chosen acoustic violin. The dream would be to play a £100 plastic violin fitted with a pickup and for it to sound like a Stradivari. Popular devices in 2020 include, but are not limited to: Signal Wizard - V sound Fishman - Aura Audio Sprockets - Tonedexter Mooer - Radar Lodigy - EPSi View fullsize View fullsize View fullsize View fullsize View fullsize The ToneDexter For this review I was loaned a Tonedexter from Audiosprockets UK. The Tonedexter measures the input from your violin pickup and a microphone at the same time to compute what Audiosprockets refer to as a “WaveMap”. When a suitable WaveMap is created it is saved within the device and operates in real time on your violin signal, which can also be blended in as required. Test Violin and Microphones. Unsurprisingly I used my own Sonic Heritage Violin and ran tests with many microphone set ups. As this is not a microphone review I settled on using the DPA 4999 as this is for good reason the most popular choice for live sound. View fullsize View fullsize View fullsize View fullsize View fullsize View fullsize The Results I created a WaveMap that sounded as close to the DPA as possible. I also set up an EQ on my direct signal from the Sonic Violin using the 5 band fully parametric EQ in the digital mixer and an EMT plate reverb for “space”, to get as close as possible to the DPA sound. I then recorded in the following order: Sonic Violin direct output DPA 4999 Sonic Violin + ToneDexter Sonic Violin + EQ Each set up was connected through the mixing desk to an RCF HD10 powered speaker to simulate a live setup and recorded using a stereo microphone array in a small treated room. The desk, RCFs, room and mics all effect the final sound, as does your own listening system, but all are constants so the relative sound comparison is accurate, whether you approve or not, ditto my playing. Conclusions Firstly I think the ToneDexter does a good job of achieving a convincing match to the microphone sound, and I’m sure that other systems may be similar. I loaded a 3Sigma (Italian violin 4c) IR into Max for Live as a comparison to the ToneDexter with similar results, recorded below as follows: ToneDexter then 3Sigma. Convolution results however will largely be dependent on the quality of the sound sources used; the ISI twin pickup and matched pre amp in the Sonic Violin produces a detailed representation of the instruments full character, and the DPA microphone is also regarded as one of the best in the business; lesser equipment will inevitably result in a less satisfactory sound. I would propose that the Sonic Violin with EQ also comes reasonably close to that of the DPA mic, albeit with a slightly fuller sound that the pickup provides. Bearing that in mind many would blend the pickup sound with the mic sound to provide this fuller sound that is often needed on stage. Here are just those two recordings again DPA followed by Sonic Violin+EQ with the part split into three sections for easier comparison. I ask whether IR effects are really necessary? The answer lies with your own individual set up, preferred sound, and on stage requirements. IR will not make your instrument sound like a Stradivari; and even if it could, is that indeed how you wish to sound? Yes IR will match more closely to the mic you chose to create the convolution, but again is that the sound you wish for, close miking a violin is in itself a significant compromise compared to the acoustic sound. If you use a microphone on stage and have issues with feedback then IR may assist a solution, but of course you’d have to fit a pickup to your violin, which may well be unacceptable and the reason why you were using a mic in the first place. If you already use a pickup and are disappointed with the sound then IR will help you, but maybe no more than a comprehensive EQ system, and you’ll need a good microphone to set it up. There are many more considerations – not least of which is whether you manage your own sound or rely on event engineers. PHOTO BELOW IS GENERIC FROM A&H WEBSITE - SETTINGS DO NOT RELATE TO THOSE USED IN TESTS The Bare Naked Truth? Because EQ is an essential prerequisite and integrated into all live sound, whether dealing with microphone or DI, it makes sense to fully understand and explore its potential. In many ways EQ is the most underrated tool available to all musicians, and when combined with reverb and delays can sculpt excellent results. When you heard that acoustic violin sound that you adored so much, be aware that you were also listening to the space in which it was being played. IR is now used extensively in Convolution Reverb systems for which it is a very appropriate tool, and therefor very capable of modelling that space in which you heard that violin. Reverb and delay are additive effects that provide depth and space, IR pedals do not add anything to a sound that may well be lacking in information to start with… …you cannot expect the sound of a solid bodied electric violin to be transformed into the sound of a quality acoustic violin any more than you can expect a Ford transit to win an F1 race.

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