Interview With Mike Scuffham Of Scuffham Amps

The S-Gear Duke

Read Time 19 Minutes

Scuffham Amps Logo

Mike Scuffham

In addition to being the engineering guru behind Scuffham Amps, Mike Scuffham also has the distinction of developing the JMP-1 pre-amp while at Marshall.  (Still found in a number of studio and live rigs, many people consider the JMP-1 to be the holy grail of modular tube pre-amps). After turns developing various audio and video processors, Mike has come back to designing world-class amps with the release of S-Gear but, to co-opt the tag-line from Jaws: The Revenge, “This time it’s virtual” (insert hardware scream of terror here).

The S-Gear Duke
The S-Gear Duke Amp Model- Click to Enlarge

The S-Gear Plugin

The Guitar-Muse 10 Great Products post I wrote at the end of 2011 included this quote about Scuffham Amp’s S-Gear plug-in:

“With only 3 amps and a few effects, you might think that this AU/VST plug-in would be a tough sell in a market with so many models and effects – but when you have the right 3 amps (and some great bundled IRs from RedWirez) it’s not an issue. The tones from the Duke and Stealer amps in this unit sound better than many professionally recorded guitars I’ve heard and they all have the responsiveness and the feel of playing a real amp.”

With one foot rooted in traditional amp design and one in coding, Mike has a unique perspective on both the past and the future of guitar signal processing and amplification. He was generous enough to sit down to discuss a number of topics via e-mail including the path that brought him to modeling, advantages of modeled versus physical circuits and tips for adjusting your guitar to optimize your modeled signal.

The Interview

Guitar-Muse:  For those of us who aren’t familiar with London College of Furniture, I’m hoping you could talk about the steps that brought you there and what you took away from the school. Were you planning on getting into music technology or was it something you fell into?

Mike Scuffham:  I was planning on becoming a rock guitarist and electronics was my back up. I didn’t realize it was possible to study music technology until, by chance, I saw an advertisement for the Music Technology department at London College of Furniture.  I believe the college is now the London Metropolitan University, but London College of Furniture was a design and technology college located in London’s East End with departments for furniture-making, textiles and music technology. The music technology department offered specialisations in piano-making, guitar, early fretted and woodwind instrument-making, and, most interestingly for me, electronics and acoustics.

My studies were a mix of mathematics, electronics, thermionics, acoustics and sound engineering, all with a strong practical emphasis. I was lucky enough to be taught by Tim Orr who was a pioneer of music technology and a designer of EMS synths and vocoders in the 70’s. Tim taught us the essential audio electronic skills and techniques to enter the industry and hit the ground running.

GM: After you left London College, you worked at Marshall as a product designer and played a key role in developing the JMP-1. What was the initial inspiration for that design and how did it come about?

MS: Just about the time I was leaving college, I saw an advert in a pro-audio magazine for research and design engineers at Marshall Amps. I went along with my college projects and a cassette tape of my guitar playing and got the job! My first few days at work were taken up with constructing and painting my desk in the woodshop (which gives you some insight into the culture at Marshall in those days LOL)! A few weeks into the job, I turned up one morning with a sketch for the JMP-1 which I showed to the managing director, Keith Carnall.  Later the same day, Keith came to see me and told me to get working on the development.

The inspiration was to create a simple digitally-controlled analogue 1U rack unit. The ECC83’s (the UK equivalent of 12Ax7s) may have been considered a marketing necessity but whilst they may not have been the primary distortion generator, they did add a lot of character to the sound and dynamics of the JMP-1. I stayed with Marshall for almost six years and during that time I shared an office with Bruce Keir, who later co-founded Blackstar Amplification. We worked hard, drank lots of tea and talked everyday about amp design.

GM: Your bio mentions that you worked at Akai and then transitioned into designing video equipment. As someone who knows very little about design, I would imagine that the experience with working with physical hardware gives you a design edge that people who have only worked with software models are missing. How do you think working with physical design has influenced your virtual design?

MS: Working with physical product development has certainly shaped the way I approach a virtual design. People use the term ‘Amp modeling’, but for me, the process is about modeling the components and then doing the amp design just as I would do in the physical domain. I start by drawing a circuit diagram with tubes, resistors and capacitors. I’ll probably use a circuit simulation tool to check that my circuit is performing as intended. The next task is to translate this design into software, and to do that I use various models that I have developed for tubes, passive filtering, clipping components etc. A lot of the hard work is in creating fast and accurate component models that can then be used in the designs. As an electronics engineer, you need to know how to work with each component, but as a virtual designer, you need to understand the physics of each component so that you can recreate something similar in the mathematical domain.   It is very challenging and also very rewarding.

GM: How did you get into modeling and how did Scuffham Amps come about?

MS: In 2008, my wife Shuroma and I decided that we wanted more adventure in our lives, so we sold our house in London and moved to Tallinn, Estonia with the intention of starting our own business in this up and coming European country. Initially, it was our intention to design and build boutique physical guitar amps.  We spent about ten months researching and planning this business. During that time, I also started toying with some ideas for digital modeling and in particular, creating an accurate mathematical model for an ECC83 tube. When I first began testing my ECC83 model with real-time audio…that was it!

I woke up to the potential of modeling and this area of technology that I had ignored for years was now very interesting to me. Clearly this was where our business needed to focus, so we ditched the physical amp plans in favor of software.

GM: In the Scuffham manual you mention, “At Scuffham Amps we feel that the digital domain makes it possible to create circuits that incorporate only the best and most useable features of tube amps, and tune out some of the more undesirable characteristics that hardware amp owners have just learned to live with over the years. As a result the amps in S-Gear are designed from scratch. They are not just slavish models of vintage equipment that adopt a “warts ‘n’ all” attitude, but carefully crafted, and above all musical, pieces of software.” Can you talk more specifically about some of the undesirable characteristics you’re referring to?

MS: We’re talking about a number of things; microphonic tube; static noise; stability issues; compromises encountered when combining physical hardware between amp channels… etc. These are things that can naturally be avoided (maybe for the better) when working in the software domain. However, some of our customers are calling for us to include more ‘warts’ in the amp designs, so perhaps this is something we will think about in future work.

GM: Do you see a point where software amp models replace physical models entirely?

MS: I am sure that physical amps will always have a place, but without a doubt, software amps will dominate the future. In my view, what makes a great sounding amp simulation might just as likely be in the small detail of the execution as in the particular technology that is used. There are already some good methods and techniques established and the development of such things is progressing at a rapid rate. Perhaps the engineers that are clever enough to pioneer these techniques are not the ones who will ultimately create the best sounding amps and effects. I believe that as the technology proliferates and as more engineers get their hands dirty with software – we will get better crafted and better sounding amps as a result.

GM: We’ve talked about the advantages of virtual amps over physical ones but do you think there are any advantages physical amps have over virtual ones?

MS: I think with any reproduced music it is hard to capture the true feel of the original sound and space. With a guitar amp we are talking about the physics of a powerful guitar speaker moving a lot of air. Even if we manage to create a totally accurate amp/speaker/cab/room emulation, I wonder if we’ll ever match the thrill of using a real tube amp. Like waiting for the valve heaters to warm up and hearing that electrical click when you switch from standby or the crackle of a guitar cable. Or just the idea of hot glass vacuum tubes with high tension voltage and knowing you have that power under your fingers. I think these are some of the reasons why we get so passionate about guitar amps.

GM: What technological limits do you struggle with and what areas do you think should be addressed next to improve the state of modeling?

MS: If I were to identify areas of technological limitation, I would probably say that speaker cabinet emulation is a weaker link in the signal chain – but I can see plenty of development possibilities on the horizon and it won’t be long before we begin to see these developments appear.

The other problem for me is getting the guitar signal into the digital domain. I see an unfulfilled requirement in the audio interface market; the discerning guitarist wants high quality convertors, super low latency and input electronics sympathetic to guitar pickups. Many of the higher quality products are designed for the wider market and not specifically for guitarists.

GM: The standard to judge modeling devices has, so far, been comparing a model to a physical amp. Could modeling units eventually become the new yard stick to judge amps and amp sounds?

MS: Absolutely, I believe that the convenience of modeled amps (especially in the recording world) cannot be ignored. I believe that the plug-in concept is an important element and should not be undervalued.  [The ability] to have a convincing amp model that you can apply to tracks as you wish is really powerful. Eventually certain models will become well known and well used and, as you suggest, the new yardstick.

GM: Do you think that the technology behind modeling is something that will eventually hit a ceiling that can’t be improved upon?

MS: No.  I maintain that designing musical equipment is a craft and crafts move with the times, so there will always be more work to do and new amps to design. If the technology hits a ceiling, then the emphasis will be on making better use of the technology that we have. If we consider the world of physical guitar amp design, this has been evolving for the last sixty years and there is yet still more mileage in combining resistors, caps, tubes and transformers!

GM: One thing I noticed as a key difference is between S-Gear and the competitor’s models is the way that the amps respond dynamically to changes in guitar volume. In your opinion, what are the key differences between S-Gear and the other modelers on the market?

MS: The S-Gear amps are very traditional in their gain structure and I think that this is the reason why they respond well to the guitar volume and tone controls. I’m not sure what else we might be doing differently, other than perhaps the tube model could be more true to a real tube compared with other more simplistic models. I really think that the gain structure is the most important thing.

GM: Based on your research, what do you think other modelers have gotten right and wrong?

MS: This is difficult for me to answer because I honestly don’t spent much time using the other modelers. I’ve downloaded and installed several plug-ins and I’m generally interested to see how the functionality is presented and how the plug-in interacts with the host machine and software. Of the products I have spent time listening to, I’m usually disappointed by the lack of detail in the dynamics.  I’m a very critical listener (no more so than when I am listening to my own stuff). Luckily, I’ve had a lot of opportunity to play loud through classic guitar amps and this is where I keep my focus. I tend to listen a lot to recordings if I am looking for inspiration.

I like equipment (software or hardware) to look inspiring too; and I am not very enamored with the toy-ish way in which some products are presented. Guitar amps can be a bit like cars.  Sometimes we want to be thrilled and inspired when we plug-in and other times we just want something that does the job faithfully. I believe that the modeling world needs to work hard to build mojo into its products, and this won’t be achieved by simply copying other people’s stuff. Probably we should look at the world of boutique amps where the makers are taking inspiration from the classic designs and then carrying this forward into interesting and new products.

GM: I’d like to talk about some of the components of the unit. Starting with the amps; why did you choose those models and what characteristics of the amps were you most trying to capture?

MS: I have a whole bunch of amp models that were kind of experimental, really just created to test my modeled components and techniques. I picked three of those amps and developed them into the S-Gear amps.

The Duke (pictured at top) is a blues amp, designed for maximum tone and expression. The amp inherits a tone stack from the Fender Super Reverb. This tone stack has less mid-scoop than say a Twin-Reverb tone stack, so you don’t get those really round bright twin clean sounds, but you do get a nice complexity in the mid-range which is great for digging into an overdriven tone.

S-Gear Stealer
The Stealer – Click to Enlarge

The Stealer has the format of a classic Marshall and adds something extra with the Bright Contour circuit. With a traditional bright input channel, the brightness comes in as you back off the input level. This gives the Marshalls that really glassy clean sound that can take your head off if you stand too close. The trouble is that you lose the brightness as you boost the gain, so I thought it would be cool to have a constant gain bright control.

The Jackal is a modern style amp inspired by the Soldano SLO100. It has a thick overdriven tone with a lot of high-mid drive available. The SLO100 was a landmark amp design and really something quite different when it was first launched. Mike Soldano used a technique that some people refer to as cold biasing, which is where one of the tube stages has a high value cathode resistor. This certainly contributes to the characteristic sound of the SLO100, and I used this same technique in the gain structure of The Jackal.

S-Gear Jackal

The Jackal – Click to Enlarge

GM: Is there a model that you’re proudest of?

MS: I’m rather proud of The Stealer and the Bright Contour circuit in particular. By adjusting this control you can achieve a whole spectrum of vintage amp sounds.

GM: I want to talk about the FX in the unit but as a bridge to that topic – you’ve added a boost switch to the amps (which seems to have a similar function to an overdrive pedal) and a delay. What made you decide to incorporate these in the design?

MS: The Amp Drive switch actually works in conjunction with the Power Amp section and it serves to drive the power amp harder or softer; it’s kind of a master volume switch! The additional gain is being generated in the power amp as opposed to a boost pedal in front of the preamp.

Delay, reverb and modulation effects are must-have effects for guitar.  We would have been very happy to offer all three from the outset, but our approach with Scuffham Amps is to try to contribute something special with the products and features, so we need to take some time with the development of these effects.

Scuffham Delay

Delay Thing – Click to Enlarge

The first offering, ‘Delay Thing’ is a versatile delay processor with an analogue modeled delay line and optionally a tube stage in the feedback loop. The delay line uses a clocked sample rate technique, just like a bucket brigade device but with more control over the fidelity.

Over the coming months you will see some new effects developments appearing in S-Gear including a configurable rack system and other effect options. (I’m busy working on this right now!)

GM: I have several questions about the Cabinet Emulation but let’s start with RedWirez. How did that collaboration come about?

MS: I was working with Redwirez impulses quite early in my design and I had the choice of either making my own measurements or approaching Redwirez to see if they would be willing to co- operate with us. I was very pleased when Mike Grabinski at Redwirez agreed for us to use a selection of his impulses in S-Gear.

GM: Since you mention Z control on the website; could you talk about what that is?

MS: The Z control works by applying an EQ adjustment to the speaker cabinet and it emulates the effect of tube amp output impedance coupled with the reactive speaker load. The idea for the Z control was suggested separately by both Mike Grabinski and Jerry Stevenson (who was responsible for the S-Gear demo soundclips). Mike had been working on some impedance measurements curves and he kindly suggested that this would be a cool feature in S-Gear. Jerry had suggested the same idea just a couple of days earlier.

GM: What was the design concept behind multiple output processing (i.e. convolution vs. IIR Filter vs. DI)?

MS: The Pro Convolver also includes a few cabinet options based on recursive filters (IIR filters). I thought it would be interesting to include these as an alternative to convolution. They sound and feel different, and some people prefer recursive filters to convolution based filters.

GM: For people who are unfamiliar with the terms, could you talk a little bit more about recursive and convolution filters?

Scuffham Convolver
The Convolver – Click to Enlarge

MS: A convolution based filter uses an impulse response for filter coefficients, usually obtained by taking a measurement from a real speaker cabinet and microphone. Typically the impulse response will have between 1000 and 6000 sample values (or coefficients). A convolution filter can be considered an FIR type filter (finite impulse response). An IIR (infinite impulse response) filter uses a small number of filter coefficients in a recursive filter structure (i.e. one with feedback), and due to the effect of the feedback, the impulse response is effectively infinite.

A typical convolution using a measured impulse response will reproduce a lot of detail in resulting frequency response, and this makes it a great choice for emulating speaker cabinets which have a very complex frequency characteristic. An IIR filter (even with 32 coefficients) will have a much less detailed frequency response, but is more similar in frequency and phase response to an equivalent electronic filter.

Which is better? Well often the IIR will run faster and consume less CPU time. However, the convolution is likely to give more detailed characteristics. Neither is perfect, because they are both linear filtering methods and a real speaker cabinet also has non-linear characteristics.

GM: Given your history with the JMP-1, it’s not surprising that S-Gear features midi control. When designing this, did you imagine the midi functionality more for studio or live use?

MS: The MIDI control was originally envisaged for live use, where you might need just a few controllers for key parameters. However, it transpired that many people wanted more controllers for studio applications, so in the last release we extended the MIDI controller section to 50 controllers.

GM: You mentioned Jerry Stevenson in passing before in regards to the presets and I wanted to bring attention to the really high quality of the presets in the unit. I’ve noticed that I generally don’t need to stray too far from them to get what I’m looking for out of S-Gear. Can you talk about the process used in developing the presets?

MS: Jerry Stevenson created more than half of the presets in S-Gear and he is very meticulous about these things. I know Jerry has various techniques he uses when working on a tone, for example, he explained to me an effective method of mixing two different speaker/cab/mike combinations; first by listening to each cab-mike combination in isolation and using the convolver equalization to achieve a similar result in frequency terms and then mixing and panning the two equalized cabs. Techniques like this allow us to squeeze just a little bit more ‘something’ from the amps, cabs and mikes.

An effective technique I use often when working on tones is to create a bunch of audition edits as I am working on a tone. The NEW button on the softbar of S-Gear takes the current edits and stores them in the next available preset, then loads that preset. So as I am editing a tone and I get something I like, I’ll hit the new button and carry on editing. In the end I’ll have half a dozen similar edits that I will audition and then keep the best.

GM: In regards to a difference I’ve noticed with tube amps and modeling; I play with ’11s or ’12s.  When that signal hits a tube amp it gets a nice tone, but the heavier string gauges are often more of a liability than an attribute with models. I find that the sweet spot on any modeler I’m using is when the guitar volume is set around 70-90%.   Do you have any tips with regards to set up and modeling?

MS: In my experience it is very important not to clip the audio interface since they generally do not sound nice clipped. In fact, I have found that some audio interfaces clip in a really nasty way. With heavy gauge strings and pickups set close, you get a lot of fast transients that often do not register on the audio interface metering. The result is a degraded tone.

Another thing about audio interfaces is that typically the hi-impedance input is around 470k ohms (whereas a typical guitar amp has an input impedance of 1 Mega Ohm). This does make a little difference in the way the guitar sounds and feels since the lower input impedance starts to load the guitar pickups. Many folks are reporting good results using a guitar DI box of some sort.

GM: Do you ever use tube amps and if so, do you have a favorite amp?

MS: I must confess that I don’t often plug into my tube amp any more. I am not gigging at the moment, but if I was, I’d certainly be experimenting with S-Gear through an FRFR (Full- Range Flat Response) system.

Not including all the great sounding boutique amps that are around these days, my favorite amps for raw vintage tone would include the Fender Super Reverb and Marshall JTM 45 or Park 50. I really like the Marshall Silver Jubilee series amps and my first proper valve amp was a 50W 1×12 silver Jubilee. They have a darker overdrive tone than the typical Marshall and a particularly excellent crunch channel. When I was gigging regularly, I used a modified MKIII Boogie with an Electrovoice EVM12L speaker and the Boogie and EV combo really projected the sound. My definitive JMP-1 setup was the EL34 50/50 poweramp with a 1960A (angled) cab loaded with Vintage 30’s.

GM: Do you have any recommendations for using external effects (either physical or software) with the unit?

MS: When chaining plug-ins together it’s important to keep an eye on CPU usage. Even if you have an 8 core machine, it’s quite easy to overload a single core whilst the other cores are sitting doing almost nothing. The problem is that if you chain effects in series, then the CPU cannot leverage its multiple cores by allocating these effects to separate parallel processes.

Furthermore, on a record-enabled track, the audio buffer size is critical because you need to reduce the audible latency.  On playback tracks this less of an issue because the DAW can allocate a bigger playback buffer.

When specifying a new machine for audio, I would recommend going for the fastest processor option along with plenty of memory.

GM: It’s easy to get so caught up in a product that you lose sight of the people behind it. It has to be very difficult to start a music-related business now. You’ve done a remarkable job of getting the word out and increasing visibility for your product but what are the other challenges of running a small company?

MS: As a small business owner, you are responsible for everything! At times it feels like an impossible task. We were very well positioned to start this business; we had good experience with the core technologies, an industry track record, enough savings to allow us to work for zero salary and even some experience with IT systems. Without all these things, I can’t imagine how a small self-funded company would get to the stage of launching a product. It was, and still is, very hard work.

GM: What have been the biggest differences in your perception of what it takes to run a company between when you started it and now?

MS: Marketing is a lot harder than we imagined. The idea of the internet as a viral marketing miracle is something of a myth. Whilst your product message can be distributed to a large number of core internet users very quickly (popular guitar forums are brilliant in this respect), in order to get the product message out to a wider audience, media interest and word-of-mouth recommendations are also important.

The Apple app-store concept is a double edged sword for small software developers. On the one hand, it might be a way to get your software product to a high volume of customers. At the same time, it’s further devalued software in many people’s eyes. Apple can afford to develop and sell their applications at give-away prices because their main interest is selling hardware to consumers. For the independent music software developer trying to produce a high quality specialized product, it is a real challenge to stay competitive.

GM: Where do you see the industry going in the future?

MS: We’ve enjoyed nearly two decades of artificially low prices made possible by low cost manufacturing. Whether this will continue, or should continue, I don’t know. I hope to see an increase in smaller companies manufacturing their own products and selling directly to customers and music shops.

GM: Finally, what’s in store for the future of Scuffham Amps?

MS: We will continue to develop software product, but we will also transition our technology to hardware. We have some very specific plans for complimentary hardware products, and would like to be able to launch the first of these products in the next 24 months. Unfortunately, I’m not in a position to reveal the details yet….

Thank you for your time Mike!

For more information about S-Gear (including mp3 demos, more tech information and a free 15-day downloadable demo) go to

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Scott Collins

Scott Collins is the author of the pedagogical/reference series, <i>The GuitArchitect’s Guide To:</i> and several e-book titles that include: <i>An Indie Musician Wake Up Call</i> and <i>Selling It Versus Selling Out</i>. His playing is inspired by a wide range of western and non-western music, and, as a performer, he specializes in real-time composition.

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