Stone Box Audio Interview

posted by Sam Davis

Interested in guitar effects pedals? Looking for something different to sit on your pedalboard? Stone Box Audio is a UK based independent guitar electronics company specialising in effects pedal modifications, custom designs and switching units.

Guitar Jar catches up with manager Chris Hutchens, to ask him more about the vision of the company and his thoughts in breaking into such a competitive industry.

…what keeps me motivated is the really positive feedback from people who have used some Stone Box audio products and are much happier with their tone…

Hi Chris, before we get into the details of your company and services, can you let Guitar Jar readers know if you play guitar and if so, who or what inspired you to start learning the instrument?
Hi, yes I started to play the guitar in my late teens. It was the mid(ish) eighties and rock music just wasn’t played on the TV or radio. A friend at school had lent me a really battered audio cassette which had copies of AC/DC’s “Fly On the Wall” and Ozzy’s “The Ultimate Sin” albums on it. I really liked what I heard, obviously nothing like the stuff I was seeing on Top of the Pops each week!

I then got hold of Iron Maiden’s “Live After Death” video… I hadn’t heard or seen anything like it before and was totally blown away by the whole thing. I watched Adrian Smith playing his solo part to “The Trooper” and that was it – incredible stuff – I HAD to save up and get a guitar and learn how to play!
Can you tell our readers about the origins of Stone Box Audio; what inspired you to initially start the business and what is your vision for the company?
I started studying electronics at school and not long after that started playing the guitar, so building effects pedals and amps was a natural progression at the time. I went on to study electronics at university and continued building effects, amps and accessories for myself and a few friends. Since I left university I have spent many years working in electronics, product and technology design based industries and in the past couple of years I have been building, modifying and repairing more and more kit for people, so I decided that I wanted to formalise and expand what I did so that I could offer the company’s services to both a national and international customer base.

There are a few very well known and respected modification companies in the USA and I wanted to create a centre of excellence for effects pedal modification and control in the UK and Europe, to even up the balance on this side of the pond so to speak. I’d like Stone Box audio to be one of the first solutions providers that musicians think of when they are looking for UK designed and hand made tone creation and control products.
The effects pedal modification industry is becoming fairly competitive. Can you explain what pedals Stone Box Audio modify, and what exactly a potential customer can expect in regards to improved components and tone?
Our standard modification range consists of six popular Boss pedals – the Blues Driver BD-2, Compression Sustainer CS-3, Distortion DS-1, Turbo Distortion DS-2, Metal Zone MT-2 and the Super Overdrive SD-1. I have at least two of each of these pedals so that I can always compare my mods against the original stock pedals, using our true bypass switcher. This is important, as without comparing to a stock pedal it is easy to think you have changed and improved the sound of a pedal when in reality there is very little change. It stops you getting misled with the “psycho-acoustic” phenomena of it all. Our side by side comparisons should be going live on the website in March – I’m filming them at the moment.

With regard to components, it usually involves upgrading signal path components to higher quality parts, such as changing signal coupling capacitors to metalized plastic film types. I might change integrated circuits to lower noise parts to reduce background hiss or fit hi-fi grade parts clean up the sound and sharpen the attack.

I also improve the power supply filtering in the pedal, based on my experience in industry of designing equipment to withstand high levels of radio frequency interference. This is more important now, as more and more mains power supplies of the type used for effects pedals are becoming switched mode types. This is partly driven by a European Directive to improve energy efficiency in those “wall-wart” and “in-line” type power supplies. It means that the often lower noise (but less efficient) linear power supplies will become harder to obtain, as manufacturers who produce power supplies in volume will be forced to produce only switched mode types.

The problem with switched mode supplies at the lower price end of the market, tend to be noisier due to the switching frequency they operate at creating noise that is coupled into the pedal and results in audible breakthrough at your guitar amp. The outputs of these supplies often float too, which can also lead to noise problems.

With regard to tone improvement, I’ll listen to a pedal to see what it lacks tone wise. I’ll then undertake a circuit analysis of the pedal and run some computer simulation software and plot frequency responses of the pedal. This helps me determine component value changes to make the pedal less mid-scooped, cut the highs or boost the lows etc. So I will often widen the response of the tone controls and maybe shift the part of the tone they work over.

I also insert a lot of our custom “mini-circuits” into the pedal. These are about the size of a stamp and give massive clean volume boosts by inserting another totally clean boost amp section with a flat frequency response so that you get loads more volume without changing the character of the pedal. I also have some of these circuits to give different sounding distortion options.

We will mod other pedals as well, people should contact us to discuss their requirements, whether it be a tone or volume change, or a true bypass mod, or as simple as adding an indication LED. I’m currently developing a mod for the TS-808. A piece of trivia – we DON’T do “stacked op-amp mods” either…

…building effects pedals and amps was a natural progression…

You also manufacture your own products. I’m particularly curious about the new “Baskerville 7” – sounds very Conan Doyle! Can you shed any light on this pedal or is it still a closely guarded secret?
This is going to be a true bypass distortion unit; however, it is NOT going to be a Tubescreamer, SD-1 or Fuzz Face clone. It will have a number of selectable drive modes from a blues to a rock to a metal tone. There will be tone controls and monster volume available. That’s all I can say at the moment. Apart from being tone wise like a dark night on the spooky British moor land!
In addition to effects pedal creation and modification, do you provide any additional services?
I’ll fit mod kits that people may have bought from other manufacturers if they don’t feel confident or have the right equipment to fit them. I can repair analogue effects pedals and amps, but it’s not the core of our business and it depends on how busy we are as to whether we can fit it in.

I also build custom equipment for musicians – for example you might want a custom switch for your amp that has LED status indicators on it, or maybe a custom cable or power supply for your pedalboard. You may want two or three of your favourite stomp boxes re-housed into a rack unit with a remote switch. Our custom equipment uses hand built uniquely designed PCBs. Then there are our true bypass effects loop switching systems.
I’m curious to know more about your switching systems. At what point do you think a guitarist should consider using a switching system and what products can you provide?
They should use one whenever they want more control over their setup. They may just have one pedal and a tuner they want to switch between, or simply a tone sucking or noisy pedal they need to true bypass out of the signal path. It could be as simple as just having two pedals and needing to use one press to flick between them instead of two. It is really all about making it easier for a musician to achieve and easily control the tones they want. Simplicity allows you to get on with the important part – playing.

Our standard product is our True Bypass Dual Effects Loop Switch. It has two switchable effects loops. You can insert as many or as few effects into each loop as you wish. For example, you may want to use it in the way I have described above, or put all your modulation pedals in one loop and your drives in the other loop, or a different drive in each loop, or a maybe a use a loop for a dirty sound with your drives in it and a loop for a clean sound with compression and chorus. It is very flexible. Two footswitches control the loop switching. There are three switching modes that can be selected using the two footswitches, to make the unit easy to integrate into a musicians set up.

The mode you choose is stored in memory on the device at power down, so it switches on again in your chosen mode. The first mode uses one switch to change the selected loop and the other switch to select true bypass. With this mode you can go into true bypass from one loop selection, change loop whilst in true bypass and thus be in a different loop when you exit the bypass mode. The second mode uses one switch to control loop one and the other switch to control loop two – pressing one switch activates that loop and de-activates the other loop. Pressing the same switch twice puts the unit into a true bypass state. The third mode allows both loops to be on at the same time – each switch either switches on its loop or true bypasses its respective loop.

The unit has a totally analogue signal path, using low noise, gold plated signal relays, but is controlled using a micro-processor. The design is easily scalable, so if people wanted more loops I can do a custom unit with the number of loops required. Last year I built a custom programmable ten loop true bypass system with three banks, allowing up to 30 combinations of stomp box loops. We can also add level controls, volume boosts or buffers loop switchers.
It sounds an exciting, yet challenging prospect breaking into such a competitive market – how do you remain motivated?
Your statement is very true and the question is a good one! In order to answer that and to give your readers some idea I did a very “quick and dirty” bit of market research. I went onto the Thomann website (the huge German musical instrument/accessory superstore) to see how many different effects pedals they sold. They have a choice of nearly 1300 effects pedals – which is one hell of a choice!! Out of that 1300 there were over 300 drive/distortion units and over 70 effects loop switchers! You then have to consider all the hundreds of smaller manufacturers which don’t sell through such large distribution channels – so it really is a daunting prospect to launch into such an established, competitive and well populated market.

What keeps me motivated is the really positive feedback from people who have used some Stone Box audio products and are much happier with their tone or control of their set up. Also, each month I read all the guitar magazines and there is always a constant stream of new amps / fx / accessories being launched, which is exciting and motivating. It is a market that is huge and musicians are very demanding in what they want in terms of new products / old products and variety of choice. A passion for music, playing the guitar and design also helps!

…I insert a lot of our custom “mini-circuits” into the pedals. These are about the size of a stamp and give massive clean volume boosts without changing the character of the pedal…

Guitar “tone” is subjective; each guitarist having their own interpretation of “good tone”. What guitarist has a tone that appeals to your tastes?
Two people that I have seen live recently that have impressed me are Joe Bonamassa, who always nails it tone wise live, the guitar totally fills the venue but at the same time isn’t overbearing and Phil Campbell of Motorhead who has a fantastic rock tone. Anyone who can cut through the live mix against Lemmy’s roaring bass deserves some serious respect!
What are your thoughts about RoHS compliance? Is this a stumbling block for effects/guitar manufactures; will adhering to these regulations compromise on “tone”?
It isn’t something that impacts Stone Box audio products as we only design using RoHS compliant components. I have worked in the electronics industry all my life so it is a directive that has been on the horizon for many years now and most manufacturers should be prepared for it or should have designed around it.

The immediate products that spring to mind are some boutique loop switchers, phasers, tremolos, wahs and compressors that use LDRs (light dependent resistors) and resistive output opto-couplers. These components are often non RoHS and there would be significant re-design to remove them from existing products, which would be likely to have an impact on the tone of the pedal.

Manufacturers really should be looking to steer their designs away from using any non RoHS parts though, as it is a high probability that non RoHS parts will have end of life and obsolescence issues.
What’s your favourite effects pedal from another manufacturer?
That is a tough one, but I guess at the moment I’ll go with the bog standard off the shelf MXR Phase 90. It is a great phaser, gives the signal a bit of boost too and I love its one knob simplicity.
A DeLorean time machine has just burst onto your front lawn. With your hover-board in hand, you’re ready climb in and hit 88mph. Will you go to the past or the future and why?
I’ll go to the future – the electronics industry in changing at an ever increasing rate. Many surface mount components are now the size a grain of sand, integrated circuits can now have mixtures of software configurable analogue, digital, micro-controller, touch screen display driver technologies and memory included onto a single small package. So even now it is feasible to have just one stomp box with an iPod style touch screen display for knob twiddling that would allow you to turn it into any one of those 1300 pedals that Thomann sell! Will large scale IC integration make many of the analogue components used in effects pedals of all price ranges obsolete?

I am also fascinated to see how far digital modelling technology will go and to see the life of the valve amp. With faster sampling rates and higher resolution ADCs (analogue to digital converters) being designed all the time, as well as increased mathematical processing capabilities in DSP ICs (digital signal processors) will the technology and implementation of mathematical modelling algorithms be so good that you really can’t tell the difference, leaving the warm glow of the valve amp to start to fade?

At the moment the appeal of the valve amp is as hardy as a cockroach and I personally hope this doesn’t change. I think there is a place for both in the guitarists arsenal, I just wonder if manufacturing costs and economic or regulatory pressures may eventually force the music equipment manufactures hand, particularly if relying, as many do on small companies to produce parts such as low volume bespoke wound transformers, valves etc.

A lot of these companies are run by an older generation of very experienced guys, but often the experience isn’t being passed onto a younger generation as there aren’t the people coming through to take over when these guys decide to pack it all in. The current economic pressures for those niche industries must be immense at the moment.

Plus, of course going to the future means I could always pick up those National Lottery Draw numbers for the week ahead!

…simplicity allows you to get on with the important part – playing…

Your house is burning down. What’s the one guitar item you would save?
My ebony Gibson Explorer in one hand and UK hand-wired Hayden MOFO valve amp in the other! Can I really only save one? It will be the Gibson Explorer then!
If you could form a super group using famous musicians past or present, who would you have on drums and why?
Iron Maiden’s Nicko McBrain I guess – he’s bonkers mad but I don’t think there are many styles that he couldn’t turn his hand to.
Lager or Cider?
After answering all these questions I’ll have a pint of each please!
What’s the plan for Stone Box Audio for the next 12 months?
To continue to grow the business and get the Stone Box audio products and services out there. I am working on a TS-808 mod, there’s the Baskerville7 distortion, there’s a multi-loop switcher in the pipeline as well as an effects pedal power supply based product.