What are Impulse Responses and how are Marshall using them to take your guitar sound from ‘meh’ to ‘yeah!’?
Posted: 4 September 2019
Since the 60’s Marshall has been synonymous with great guitar tone, and a large part of that is down to the legendary Celestion speakers. From the iconic G12 greenbacks through to the Seventy80s, the Vintage series and beyond, Marshall and Celestion have become the ultimate power couple. Like Bonnie and Clyde or bacon and eggs, they’ve become inseparable and formed an iconic partnership that has stood the test of time.
Which is why when Celestion dove headfirst into the bold new world of Impulse Responses Marshall were only too happy to become their partner in crime and make use of their new IR range. We’ve spent almost 60 years creating some of the greatest guitar sounds in the world, and now there’s a way to accurately capture that and share those sounds with players around the world? Well that sounds exactly like our cup of tea.
Find out below exactly what an IR is and why Marshall has used them to record samples of each of our amps. If you can’t wait to hear them, head over to our amp pages now.
Put simply an Impulse Response (IR) is a sound measurement that digitally captures the qualities of a guitar amp speaker, microphone and room. Hyper realistic and incredibly accurate, a top-notch IR is sonically indistinguishable from the real thing. Think of a cabinet simulation that has been taken to the next level and you’re about there.
Take an IR that captures a 1960AX recorded in Abbey Road Studios with a Shure SM57 placed a foot away. If you go anywhere else - be it on any stage, in your living room or even in the studio - and play with the same guitar and head, then you can accurately replicate that sound as if it had been recorded at Abbey Road, recorded through that signal chain.
Be it at home, in the studio or on the stage, our amps turn up everywhere. But whilst the quality of our equipment is always top notch, there are many factors that can lead to differences in the final sound. Key variations are usually the venue and microphone positioning when you’re recording, but even the temperature and air pressure can lead to changes in the overall sound. This means when we record backstage at a festival, in a professional studio or at Marshall HQ we often end up with differing tones even if the amplifier is the same.
The videos below were each recorded without the use of IR's. See for yourself the difference the location can have on recordings...
So how could we create an accurate representation of each amplifier to showcase how good they really sound? Well up step the IRs, which allowed us to record each amp in a controlled environment where the only variable would be the guitar and the amp model itself. Using IRs we could now record the sound of the amps in a high-quality studio space, with premium microphones that were guaranteed to be in the exact same positions for each take. This means that on marshall.com you can hear each of our amplifiers in the same surroundings, so you can judge their sound for yourself.
First up we had our in-house player Steve Smith record a few segments directly into Logic. As they hadn’t gone through an amp or cab these recordings sounded dry and harsh, but we will be colouring the recordings in with the amp and IRs shortly to sort this.
We now had the guitar signal that was going through each of our amps and were ready to introduce the IRs. Each amplifiers individual waveform was put through three separate IRs, one with a Royer 121 microphone in front of the cab to give a balanced and warm sound, along with a left and a right room microphone (this time a pair of Neumann TLM 107s) to reconstruct the ambient sound of the surroundings.
These recordings of Steve Smith were then re-amped out of Logic into an amplifier. For each amp we tapped the speaker output using a DI box, to then send the raw amplifier signal to our recording interface. This meant we could get an accurate representation of each amplifiers tone. From there the signal went back into Logic where we had pre-loaded the Celestion IRs.
Each amplifier webpage now has soundclips of the amp being put through its paces in a range of settings. Looking for that signature JVM crunch? How about comparing the Studio Jubilee with its bigger brother, the Silver Jubilee? Now you can get an exact take of our iconic amps without annoying the neighbours!