Emulating Brian May's Guitar Amp Sound

TC Electronic's Stefan Moeller

Published in SOS May 2004
Bookmark and Share

People + Opinion : Artists / Engineers / Producers / Programmers

For many years, German designer Stefan Moeller has been on a quest to perfectly emulate Brian May's guitar amp sound. Now, with TC's new TC Thirty plug-in for Powercore, he believes he's cracked it...

Paul White

TC Stefan Moeller.s

Amazingly, Powercore, TC Electronic's stand-alone DSP platform for processing and instrument plug-ins, is already nearly three years old. During that time, the plug-ins available for it have expanded from the original TC Works effects software to include voice-modelling instruments from TC-Helicon. The last year has seen third-party companies joining in, with Sony porting their Oxford TDM plug-ins to Powercore, and now synth company Access have also got involved, announcing a software version of their Virus analogue-modelling synth for the platform, Virus Powercore.

Carry On Amping

Recently, TC took Powercore in a new direction when they announced two new amp-modelling plug-ins for the system. The entry-level Tubifex (originally announced back in December last year in the news pages of SOS as Voltronics prior to a name change) is to be bundled with all Powercore systems from now on, and runs in a hybrid mode utilising both host-powered Native power and the Powercore's DSP chips; apparently the amp modelling runs native and the speaker emulation runs on Powercore. Rather than copying specific amplifiers, this model comprises three virtual 12AX7 tube stages, complete with variable EQ, bias, HT voltage and distortion symmetry. It also includes speaker emulation and comes with a range of presets.

The other amp-modelling plug-in, TC Thirty, is a software emulation of Vox's time-honoured AC30 amplifier, and was developed in conjunction with Stefan Moeller. In contrast with Tubifex, this model is very specific in modelling the sound of the Vox AC30 as used by Brian May and includes a treble-boost emulation based on Brian May's own setup. Stefan, a self-confessed Brian May obsessive, has worked for over 15 years on this project; he started with analogue emulations, and then learned programming to that he could port his work into software. As finished in the form of TC Thirty, the emulation runs entirely on Powercore.

With any guitar-amp model, latency is a concern and Powercore has a processing latency that depends on the I/O buffers set for the soundcard, though using buffer sizes of 128 or even 256, you don't notice the latency. However, you can activate the No Latency mode inside the plug-in to remove Powercore's latency altogether while playing (at the cost of using more CPU power) and then turn this function off again after you have made the recording.

Games For May

I spoke to Stefan Moeller about his fascination with the Brian May guitar sound and he explained the background to the project.

"I have studied electronics for more than 20 years, and have always played guitar, but I was particularly interested in the playing and guitar sound of Queen's Brian May. I tried lots of different amps and guitars, but after reading interviews with Brian, I learned that he used the Vox AC30 along with a guitar that his father built for him. So I bought myself an old 1961 AC30 and built myself a guitar copied from Brian's own, fitted with the original Burns pickups. I used the Brilliant channel and the sound, while quite good, was not quite right, which is when I realised he also used a treble booster before the amp.

TC 02 AC30 Amp.s
Part of Stefan's test rig, featuring a vintage Vox AC30 amp with his analogue treble-boost emulation on top.
Part of Stefan's test rig, featuring a vintage Vox AC30 amp with his analogue treble-boost emulation on top.
Part of Stefan's test rig, featuring a vintage Vox AC30 amp with his analogue treble-boost emulation on top.

"My next step was to try to simulate the exact sound of the vox AC30 using analogue, solid-state circuitry based around op-amps, diodes, FETs and so on. I finally settled on using op-amps and diodes, as that gave me the most design flexibility. During this work, I realised that the Vox is a very unusual amplifier that almost sings! It's both smooth and wild at the same time. There's a lot of information on the Internet about this amplifier where most people will tell you that it's a Class-A amplifier, but it's not really — it's actually a Class-AB amplifier. I tried to measure the behavour of every stage of the amplifier, and then copied it tube for tube, filter for filter, using my circuitry. It worked well and when I played through it, I could feel the same transient response as the real AC30, which is very important. You can feel the 'sagging' effect when you play hard and the noise drops away, then fades back in after a short delay. This turned out to occur naturally in my analogue version after copying each stage carefully, but the work was quite demanding and took me around two years.

"A student who turned out to be good with DSP algorithms helped me to program a software version of the amp using assembler language, and he's now working for TC, so he introduced me to the company. I'd originally done some work modelling the circuitry in the C language, and that was much easier than DSP code. It was also difficult to get rid of the quantisation artifacts that occur in non-linear systems such as distorted amplifiers. TC were impressed with my work, and so we decided that they would develop my algorithms for use on the Powercore platform."

From '30 to Thirty

I was curious as to how accurately Stefan had modelled the real amplifier, as it clearly isn't practical to model every single component. "I looked at the input stage and modelled that as one block. Then I modelled the phase-splitter stage, which is based around two tubes, and modelled that as one further stage. Then I modelled the power amplifier and output transformer as a further block, so this is a three-stage simulation. There's filtering between each stage: a low-pass filter before each stage and high-pass filtering afterwards. The splitter stage has some 'secrets' inside, such as the grid simulation where the bias offsets slightly under conditions of heavy distortion. The splitter stage was a complicated thing to model!

"The loudspeaker was modelled as a separate stage from the power amplifier. When you load the amplifier with a resistor, it works differently to a speaker which has a complex impedance. So I measured the loudspeaker and then modelled its characteristic so that it interacted correctly with my modelled transformer's characteristics.

"Brian May did a demonstration on the Internet where he used only the treble booster and the amp with no effects. I don't know how he miked it, but I listened to it and it was a very typical Brian May sound, so I tried different microphone settings with my original AC30 setup and a replica of Brian's treble boost circuit, and experimented with EQ settings to get much closer to this sound. That took me a further two weeks, then when I was happy that the sound was right, I used that combined speaker and mic response for my model.

"The completed plug-in includes an emulation of Brian May's treble booster, but users have a choice of four resonant frequency values: 4kHz, 2kHz, 1kHz or 500Hz, so that people who are using different guitars can still get close to the sound. And of course it means the user can get more sounds — not just Brian May's sound. I've also included three gain settings to enable the user to simulate by how much the treble booster overdrives the amplifier. Brian uses his guitar's volume control to move from a rhythm to a solo sound and the amplifier just responds to it. The model behaves the same way, so at low volumes it's clean and crisp, whereas at high levels it's like a wild animal!

"So far I have only modelled the Normal channel of the amplifier, which has no tremolo or top boost, though top boost will probably be added to the model during a future revision. I didn't model the Vox's Accutronix spring reverb because I didn't think it was particularly good, and in any event, that wasn't on the original models. I've also left off the Vox amplifier's one tone control, as this was simply a top-cut control and made the amplifier sound rather dull. My model still includes the effect of this control, but it is fixed in its brightest position.

The programming took a lot of time to get right, and I've learnt a lot about DSP programming in the process. As the TC engineers developed the code, I did listening tests at every stage. Now I think the result from the miked-up AC30 we have set up here sounds virtually identical to the sound of the digital model in an A/B listening test."


Similar articles

Peaceful Protest: The PAIX Project | Media

Audio files to accompany the article.

A project that was started to help unsigned bands show solidarity with victims of the Paris attacks has grown to unite musicians, artists and film-makers from around the world. And it’s not finished yet...

Mandy Parnell: Mastering Audio

Video Feature

Thumbnail for article: Mandy Parnell: Mastering Audio

We talk studio secret weapons and walk through a session with Björk and Tom Jones’ Grammy-winning mastering engineer.

Inside Track: Pentatonix

Secrets Of The Mix Engineers: Ed Boyer

Thumbnail for article: Inside Track: Pentatonix

In their conquest of the pop charts, Pentatonix’s only weapons were the human voice — and the skills of mix engineer Ed Boyer.

Rush: Recording & Mixing R40 Live

R Is For Rush

Thumbnail for article: Rush: Recording & Mixing R40 Live

The best engineers thrive on pressure. Which is handy when they’re recording the farewell tour of one of the world’s biggest rock bands, and timecode trouble is brewing...

Scott Jacoby: Producing Ronnie Spector

Video Feature

Thumbnail for article: Scott Jacoby: Producing Ronnie Spector

This month's in-depth video interview features Grammy-winning producer Scott Jacoby. He welcomes us into his own Eusonia studios in New York to show how he created a ‘60s-inspired track for the former Ronnettes lead singer.

Ben Folds

Recording So There

Thumbnail for article: Ben Folds

Fans of singer–songwriter Ben Folds expect piano music — but a full–on piano concerto is certainly a new development!

Inside Track: The Weeknd

Secrets Of The Mix Engineers: Carlo ‘Illangelo’ Montagnese

Thumbnail for article: Inside Track: The Weeknd

Engineer, mixer and producer Carlo Montagnese likens his work with the Weeknd to painting — and he’s not afraid to use plenty of colour!

Thank you to all our readers over the last 30 years...

You are in good company!

Thumbnail for article: Thank you to all our readers over the last 30 years...

“I admire Sound On Sound as the survivor amongst the professional media"...

Jean–Michel Jarre

Producing Electronica

Thumbnail for article: Jean–Michel Jarre

New album Electronica sees Jean–Michel Jarre making connections with a galaxy of other legendary figures from the world of electronic music.

Inside Track: Bring Me The Horizon

Secrets Of The Mix Engineers: Dan Lancaster

Thumbnail for article: Inside Track: Bring Me The Horizon

Where does a young mix engineer learn the techniques to deliver hit rock mixes? In Dan Lancaster’s case, right here!

Chvrches

Lauren Mayberry, Martin Doherty & Iain Cook: Producing Every Open Eye

Thumbnail for article: Chvrches

Like any good SOS readers, Scots electro-pop trio Chvrches used the success of their debut album to buy more synthesizers...

Inside Track: Muse's Drones

Secrets Of The Mix Engineers: Tommaso Colliva & Rich Costey

Thumbnail for article: Inside Track: Muse's Drones

Working on Muse’s hit album Drones gave Tommaso Colliva and Rich Costey unique insight into the extraordinary methods of hitmaking producer ‘Mutt’ Lange.

Rupert Neve: The SOS Interview (Video)

Video Feature

Thumbnail for article: Rupert Neve: The SOS Interview (Video)

In this month's video interview  we meet a living legend of the audio industry, Mr Rupert Neve himself. Over 25 minutes, we talk transformers, software modelling, and get the story of how he created the world's first high-Q equaliser.

75 Years Of The Shure Unidyne 55

One Direction

Thumbnail for article: 75 Years Of The Shure Unidyne 55

In 1939, Shure revolutionised the music industry with a microphone so successful that it is still in production today!

Inside Track: James Taylor's Before This World

Secrets Of The Mix Engineers: Dave O’Donnell

Thumbnail for article: Inside Track: James Taylor's Before This World

The art of music production lies in serving the song — and working with James Taylor, Dave O’Donnell felt that modern production trends would hinder his aim of capturing emotive performances.

John Chowning

Pioneer Of Electronic Music & Digital Synthesis

Thumbnail for article: John Chowning

A visionary in the field of electronic music, John Chowning invented FM synthesis and set up CCMRA, one of the world’s most influential research centres.

Richard King: How To Record Acoustic Ensembles

Recording Yo-Yo Ma

Thumbnail for article: Richard King: How To Record Acoustic Ensembles

Engineer Richard King has brought the art of ensemble recording to new heights in both classical and folk/pop spheres.

Throbbing Gristle ‘Hamburger Lady’

Classic Tracks

Thumbnail for article: Throbbing Gristle ‘Hamburger Lady’

Throbbing Gristle’s highly individualist approach to music extended as far as making their own instruments and, ultimately, their own genre.

Inside Track: Josh Groban’s album Stages

Secrets Of The Mix Engineers: Andy Selby & Bernie Herms

Thumbnail for article: Inside Track: Josh Groban’s album Stages

A combination of technical wizardry and old-school craft helped Bernie Herms and Andy Selby bring Josh Groban’s Broadway album to life.

Pete Keppler

Mixing Bowie, NIN & Katy Perry

Thumbnail for article: Pete Keppler

Pete Keppler’s career has seen him mix shows for some of the biggest artists in the world. We asked him how it all happened.

Slaves - Are You Satisfied?

Jolyon Thomas: Producing Are You Satisfied?

Thumbnail for article: Slaves - Are You Satisfied?

The success of Slaves’ debut album depended on producer Jolyon Thomas finding a way to bottle their raw live energy.

Vlado Meller

Mastering Engineer

Thumbnail for article: Vlado Meller

As one of the world’s leading mastering engineers, Vlado Meller has enjoyed great success — and his share of controversy.

‘Voodoo Ray’ by A Guy Called Gerald

Classic Tracks

Thumbnail for article: ‘Voodoo Ray’ by A Guy Called Gerald

Hailed as the first British acid house single, A Guy Called Gerald’s sublime ‘Voodoo Ray’ has since become a classic in its own right.

Faith No More

Bill Gould: Recording Sol Invictus

Thumbnail for article: Faith No More

Recording and producing your own music is always a challenge — especially if, like Faith No More, your previous albums have been done by the best in the business!

 

Home | Search | News | Current Issue | Tablet Mag | Articles | Forum | Blog | Subscribe | Shop | Readers Ads

Advertise | Information | Privacy Policy | Support | Login Help

 

Email: Contact SOS

Telephone: +44 (0)1954 789888

Fax: +44 (0)1954 789895

Registered Office: Media House, Trafalgar Way, Bar Hill, Cambridge, CB23 8SQ, United Kingdom.

Sound On Sound Ltd is registered in England and Wales.

Company number: 3015516 VAT number: GB 638 5307 26

           

We accept the following payment methods in our web Shop:


Pay by PayPal - fast and secure  VISA  MasterCard  Solo  Electron  Maestro (used to be Switch)  

All contents copyright © SOS Publications Group and/or its licensors, 1985-2016. All rights reserved.
The contents of this article are subject to worldwide copyright protection and reproduction in whole or part, whether mechanical or electronic, is expressly forbidden without the prior written consent of the Publishers. Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents.
The views expressed are those of the contributors and not necessarily those of the publishers.

Web site designed & maintained by PB Associates | SOS | Relative Media