Category Archives: Projects

The Last Stage …

“A box without hinges, key, or lid,
Yet golden treasure inside is hid.”
J.R.R. Tolkien, The Hobbit   

The Final Part?

At the end of the last Chapter I told you that I had decided to design an effects pedal-sized version of the vintage echo box that had started out as a rough prototype over three years ago.

Initially I made a few measurements to see if there was any chance that Piet’s original eTap2hw motherboard and my Arduino automation could be squeezed into a typical guitar effect enclosure, such as the Hammond 1590XX. It quickly became apparent that this wasn’t going to be possible so I started a re-design of the whole thing from scratch. At first I simply tried to stick with Piet’s motherboard design and designed a new PCB layout for it. One of the most popular PCB design applications is undoubtedly Eagle but I never really liked it or found it user-friendly and once team member Mick Taylor had pointed me in the direction of DipTrace, I immediately found it intuitive and easy to use.

Following various false starts I was beginning to settle on a two-board design with the audio circuitry on one PCB (basically this was Piet’s original motherboard design) and the ‘brain’ which consisted of the Arduino and the circuitry from Piet’s Universal I/O board on another PCB.

Two Boards

An early design with the Audio (L) and Digital ‘brain’ (R) on separate PCBs

This early design retained Piet’s original preamp including the Fetzer valve input stage but Steve and Mick had been quietly working on a new improved design that used four FETs which would end up as the Stanley-FX Baby Blue pedal, a replacement for the already successful eTap2hw pedal from the same company. (The Baby Blue, effectively a Blue Nebula with the original eight eTap2HW echo effects and without the ‘bells and whistles’ of automation etc., is already available to buy from the Stanley-FX website at £129.99.)

BabyBlue echo

The Stanley-FX Baby Blue

I had also discovered the Arduino Nano which is a much more compact little Arduino which still retained all the memory and processing capability of the Arduino Uno I had used in the original designs.

The team consisting of myself, Steve, Mick and Piet (by the way none of us has, as yet, ever met in the flesh) exchanged ideas and designs via email and Dropbox eventually ending up with a ‘final’ schematic that incorporated the 4-FET preamp, the Arduino Nano ‘brain’, the FV-1 DSP chip, two EEPROM memory chips for the DSP programs and another EEPROM that would store the User patches, allowing up to 128 patches to be stored.

Using Diptrace to capture the schematic from our various efforts I came up with an initial PCB design which Mick, who has vast experience in this area from his own Stanley-FX pedal designs, reworked to improve the layout, give better separation of the digital and analog circuitry and add ground planes that would ensure the Blue Nebula would enjoy excellent low-noise performance.

The design did end up on two PCBs: a Main Board (with most of the circuitry) and a Controls Board which had the pots and navigation switches. In this early design the LCD was a separate module that would be connected to the main board by a short cable. The two PCBs were interconnected with a short ribbon cable.

To ensure the design would all fit correctly in the proposed Hammond die-cast enclosure I used DipTrace to export 3D models of the boards and imported these into a 3D CAD package called DesignSpark.

3D Render Iso3D Render Iso Transparent

At this stage, with everyone happy with the progress so far, I ordered a batch of PCBs and eagerly awaited their arrival so I could start putting together the prototype. The boards arrived and I was very pleased with the quality so I got busy assembling the first working prototype.

Blue Nebula Boards

The prototype Blue Nebula PCBs, Controls Board (top) and Main Board (bottom).

By this stage I had come up with the name Blue Nebula for the new effects pedal and the other guys liked that so that name has stuck but, in honour of the original eTap2HW creator Piet, who is Dutch, I decided to built the prototype in an orange Hammond enclosure 🙂


The prototype Blue Nebula – yes it’s Orange!

This initial prototype was put through extensive testing and enabled us to decide on a number of changes and improvements that would make the pedal better from both the user’s point of view and also simplify the assembly if anyone wanted to build one for themselves. For example we decided to

  • Replace the separate LCD module with one mounted directly on the controls board
  • Replace the small navigation/editing buttons with a larger Navigation switch
  • Have the Controls Board plug directly into the Main board so avoiding the need for special tools for making up a ribbon cable
  • Relocate the MIDI circuitry onto the Controls Board (it was originally on the Main Board)
  • Move the input and output jack sockets slightly further apart for a better fit in the enclosure
  • Move the Up and Down footswitches further apart so wearers of Size 12 boots wouldn’t accidentally stomp on the bypass switch 😉
  •  Fit a Lexan faceplate to protect the LCD from scratches and ingress of dirt and liquids (fancy a beer anyone?)

Mick quickly re-designed the PCBS and after more 3D modelling we ordered a batch which myself, Mick and Steve then used to build a number of final pre-production units to ensure all our modifications had worked out and we hadn’t introduced any other issues.

Blue Nebula 3D Model

Blue Nebula 3D Model


A finished Main Board


The Controls and Main Boards powered up and working.

The hardest part of the assembly is the machining of the enclosure to ensure everything will fit together correctly and we realized that this would be quite tricky for the average builder who would possibly lack either the ability and/or the tools to produce a sufficiently accurate result.

The pre-production Blue Nebula before it received its paint job.

The pre-production Blue Nebula before it received its paint job.

Mick invested in a CNC machine and after some trial and error and making extensive improvements to the machine itself he was happy that he could produce accurately machined Blue Nebula enclosures. Mick (proprietor of Stanley-FX) can also undertake powder coating and silk screen printing and the CNC and finishing processes have resulted in a fabulous result:


The finished Blue Nebula enclosure as received from Stanley-FX

Everything fits together perfectly and the end result is really quite stunning to behold. So, at last, that effects pedal I had imagined way back at the start, is now sitting on my pedal board, looking and sounding great and with features I hadn’t even dreamt of when I set out on this ‘journey’ way back in February over three years ago!

DSC02335 (2)

The Blue Nebula will soon be available from Stanley-FX as a fully built, tested and guaranteed unit at a very reasonable price (To be confirmed). If there is sufficient interest it may also be available in kit form with the finished enclosure as shown above. Further details will be published as soon as possible.

I want to finish this story by saying a big ‘Thank You’ to Piet, Steve, Mick, Ecca, Rolf, Johan and all the others who all played some part in this journey with their generous help, designs, ideas, suggestions and encouragement that kept me going. I hope you all agree that the end result has been well worth it 🙂


If you’d like to be kept up to date on the Blue Nebula development including prices and availability, head over to the Stanley-FX website and subscribe.


New Effects Pedal Launching Soon

As some of you will have heard on social media and various forums a new guitar effects pedal to be called the Blue Nebula will be launching soon. The Blue Nebula is a compact stomp-box style effects pedal design with a strong emphasis on accurately emulating the sounds of vintage tape-based echo units but with the ability for users to upload new effects that cover a wide range of other popular sounds.

Update: The Blue Nebula is available from Stanley FX priced at £249.99 plus £15 shipping to any destination worldwide.IMG_3108Designed by a four-man team including yours truly (firmware and software), Steve Mitchell (new analog preamp design), Piet Verbruggen (DSP programming) and Mick Taylor (hardware and PCB design), the Blue Nebula is released as an open source/open hardware project.

Main Features

  • Accurately emulates many classic tape echo machines
  • Can be loaded with up to 8 additional general guitar effects such as chorus, phaser, reverbs, shimmer verb and other echo effects which can be uploaded via USB
  • Other effects in the pipeline include emulations of the classic Binson Echorec (think Pink Floyd) and an enhanced Vox Long Tom echo.
  • Three parameter control knobs which, for example, can control dry/wet mix, feedback or chorus rate.
  • Built-in USB and MIDI In ports
  • All firmware updates and new effect sets are uploaded via a normal USB cable – no need for additional special ‘programmers’.
  • Advanced built-in automation firmware controls the Blue Nebula and provides full editing facilities
  • Firmware easily updated via the USB port
  • 16×2 Character LCD display shows patch names, parameter knob functions and other details when editing
  • 22 built-in factory presets for classic Shadows tunes such as Apache, Wonderful Land etc.
  • 128 User definable patches to store any other settings you can come up with
  • Can also be used in a simple manual mode – just select your effect and tweak it by adjusting the parameter knobs in real time
  • Up and Down patch change footswitches and True bypass footswitch
  • Advanced low-noise 4-FET preamplifier designed to emulate the valve preamplifiers used in some of the classic tape echo machines
  • Gain and Pre Level knobs control the generation of ‘valve-like’ harmonics and match a wide range of guitar pickups from vintage single coils to ‘hot’ humbuckers
  • Master output level control to match the bypass level or maybe set it for a clean boost with a ‘No Effect’ patch
  • Fully-featured Patch Editor & Librarian application which is Free to download.



Another New Build

This unit was built for Mario Voltolini in Italy. It uses a new motherboard pcb and LCD display board designed by Eric Thacker and a number of new subassembly pcbs designed by yours truly. These new boards support the modifications devised by Steve Mitchell and myself to improve the sound and suitability of the Yuan Jing 6N3 valve preamp for use with a guitar input, rather than its original design purpose as a HiFi preamp.

There is also a neat little MIDI interface board and a switchable Cutting Edge Filter (CEF) as per the design by Charlie Hall.

Mario requested the ability to turn off the echo by using a remote footswitch so I added a bypass circuit using a signal relay to bypass the echo module. It’s not true bypass as we wanted to retain the tone of the valve preamp when bypassed.

Click on the thumbnails below for a larger picture and explanatory captions.

Test recordings

Projects Gallery

Automation is beginning to take off in the EchoTapper world and some excellent units are already completed or will be soon. If you send me some photos and details of your project I’d love to feature them on my blog here. Hopefully this will encourage other EchoTappers to ‘take the plunge’ and add automation to their own projects.

Rolf Holmberg kindly sent me some photos of his excellent  Valve EchoTapper which uses my automation code. He has made a superb-looking unit, as I’m sure you’ll agree.

Steve Mitchell was one the very early adopters of the automation and he also made some very useful contributions to the development of the code (which I based on work originally done by Johan Forrer in the United States). Steve has also been instrumental in optimizing the performance of the eTap2hw FET preamp which was designed by Piet Verbruggen, the creator of the eTap2’s DSP code, along with some suggestions from ChrisG.

Johan Forrer’s original automation code forms the basis from which I developed the current system. Johan has himself produced a hybrid unit which uses valves and an FET circuit to produce very authentic-sounding results, as you can hear if you check out his examples on SoundCloud.