Category Archives: Audio

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Blue Nebula Demo Recordings

Naturally a number of you have been asking where/when you can hear some demos of the Blue Nebula. Thanks to Steve Reynolds and Alan Simm for permission to post these links to their excellent recordings made using their Blue Nebula pedals.

Update: Two more Blue Nebula tunes. These are from Tonnie Tijssen Рscroll down to the bottom of this post.

Enjoy ūüôā

Wonderful Land (Alan)

Fields of Gold (Alan)

Blue Star (Alan)

Yesterday Once More (Alan)

California Blue (Steve)

In a Persian Market (Steve)

Fairytale (Steve)

What a Wonderful World (Steve)

Iggle Piggle (Steve)

Buganvilla (Tonnie)

Till (Tonnie)


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

Valve Echotapper Recordings

I’ve just completed what I’m calling ‘Stage 3’ of the modifications to the Yuan Jing 6N3 valve (tube) pre-amplifier that Steve Mitchell and I have been working on. As you probably know, Eric Thacker (aka Ecca) originally came up with the idea to use a fairly low-cost ready-made Chinese valve preamp that is available from various sellers on eBay, as a front end to the eTap2HW module programmed by Piet Verbruggen to emulate the vintage echo machines used by ¬†Hank Marvin, the lead guitarist of the British group The Shadows.

Based on the ‘Matisse’ circuit, it’s design is intended as a HiFi preamp and as such the original sound was not ideal when it came to be used as a preamp ahead of the SKRM-eTap2 echo module. Working with a simulation of the circuit, Steve came up with a number of changes to make it more guitar and eTap2 friendly. I then tested these in the real world and gave feedback to Steve which enabled him to make further tweaks until we were happy with the result; though no doubt he’s busy thinking up a few more for me to try even as I’m typing these words ūüôā

I will shortly be providing the details of how to carry out these modifications but in the meantime I feel the time is right to publish a couple of test recordings that I have made using the ‘Stage 3 Modified’ Valve Echotapper so others can judge the results for themselves.

In both these recordings (which are made for the sole purpose of education and research) I have used the original recordings by The Shadows but have been able to turn Hank’s lead guitar parts on and off as and when I wish. I recorded myself playing the lead part to this ‘backing track’ and rendered the finished tracks you will hear below and alternated the lead part between Hank and myself. (There is a short section just after the start of “Theme for Young Lovers” where we both play together).

No additional effects were added to Theme for Young Lovers. Blue Star had some EQ added to the recorded track before rendering it to the final mp3.

eTap2HW Poll Results

Thanks to everyone who took the time to listen to the samples from my three eTap2HW-based EchoTapper variants and cast a vote in my poll on which sound they preferred.

There was a very clear preference for Track ‘C’ which polled 55% of the votes, in second place was Track ‘B’ which polled 30% and coming well up the rear was Track ‘A’ with a mere 15%.

Now it’s time to reveal the details of the ‘competitors’…

  • Track ‘A’ was the unit with the valve preamp (15%)
  • Track ‘B’ was the unit with the unmodified FET preamp (30%)
  • Track ‘C’ was the unit with a modified FET preamp with optimized bias (55%)

Which really makes me wonder about all the fuss and hullabaloo on some of the Shadows forums regarding how ‘good’ the valve preamp-based units sound. My personal opinion is that the valve preamp sounds too ‘mellow’ with not enough bite to get the sound of the early Shadows recordings. It does sound nice but comes nowhere near ‘that sound’ but maybe with some modifications to the circuit it could get closer – we shall see.

Incidentally, I also prefer the sound of the modified FET preamp, it gives more gain and punch though Piet’s original FET design is also excellent and the results of individual units can vary depending on the wide manufacturing spread of the specs for individual FETs.

The original sound samples are still available here if you’d like to audition them (again).

Demo Recordings

I’ve finally got around to making some demo recordings to compare the sounds of my three different EchoTapper Vintage Echo units. In case you haven’t been following the story in this blog, I have (so far) build three different incarnations of the eTap2HW echo machine based on the original work of Piet Verbruggen.

Piet created the DSP programming of the Spin Semiconductors FV-1 chip which provides the emulations of the various vintage echo machines and he also designed a motherboard with a Fetzer Valve preamp  and other support circuitry on which the FV-1 module is mounted.

The Units Under Test

  1. Mark I – is a manual unit built on Piet’s motherboard design with a modified FET preamp. The modifications involve re-biassing the FETs following¬†the¬†work done by Steve Mitchell.
  2. Mark II – is a fully automated version, also using Piet’s motherboard design, with the original FET biassing, with the addition of an Arduino Uno running my automation software
  3. Mark III Рis a fully automated unit, with a two channel valve preamp using two 6N3 dual triode valves obtained ready-built from Hong Kong via an eBay seller. The unit uses an interface board designed by Eric Thacker to interface between the preamp, the FV-1 module and the Arduino Uno.

Test Conditions

The units were connected, in turn, to the HI input of a Laney VC15-110 amplfier. This is a 15W all valve amp with a 10″ Custom Jensen speaker. The amplifier controls were set as follows

Clean Chan, Volume = 5, Bright Sw. OFF, Bass = 5, Mid = 5, Treble = 5, Reverb = 3, Tone = 3

The guitar used was my custom built ‘Hank’ with Fender 57/62 Vintage pickups. The bridge pickup was used throughout with the guitar volume control on full (10).

The sound was recorded using a Samson CO2 condenser microphone placed approximately 9 cm out from grille cloth, and about 15 cm in from Left edge of cabinet. The microphone was connected to Channel 1 on a Focusrite Saffire Pro 24 audio interface, on which the gain was set to 6.

The sounds were recorded (one at a time ;-)) at 48 kHz, 24 bit WAV, on separate tracks in a Reaper DAW. A send was created for each track and the signals were sent to a separate FX track which had an EQ and a Reverb plugin added. This ensures that all the recordings receive exactly the same effect treatment before the final mp3 tracks were rendered.

EQ Plug-in Settings


Reverb Plug-in Settings


Echo Unit Settings

The echo units were set as follows, essentially to attempt to replicate the same settings as far as possible. The differences in the three preamps would have a bearing on where the input Level controls of each unit should be set but the two FET-based units both had their input Level set to 5. The valve unit has an input Level and an Output Level control so it’s difficult to compare these directly with the FET units.

The Mark II and Mark III units were both set to use the built-in Atlantis patch which is taken from the suggested settings of Dave Robinson. The controls on the Mark I (Manual) box were set to match this as well.

Echo Model 5: Echomatic II Classic,  Wet/Dry 5 (126), Prog 3.5 (89), Feedback 5 (125)

The figures in brackets are the approximate stored digital values associated with the knob positions in this patch in the automated units.

The Level controls on the valve preamp were set as: Input Level = 7, Output Level = 6

The Results

The lead guitar has been kept fairly high in the mix so that the differences between the units (if any) can be heard more clearly above the backing track. All tracks were done in one take with no overdubs or punch ins.

Mark I:

Mark II:

Mark III:

Proof of the Pudding …

… is in the testing.

While searching for something else altogether I came across and old digital thermometer project that I never finished. It was to control the heater for my hot water tank ūüėČ but it would be handy to check my heat sink temperature. As you can see below, after being on for 20-30 minutes the temperature settled around 47-48 C.Image

Wiring – Stage 2


Pots, from L-R are: Control pots P2, P1 and P0 then the Output and Input Level controls for the valve preamp, the input jack socket and the ‘peak’ LED..

I’ve finished wiring the pots and the ‘peak’ LED on the front panel. That should be the front panel now completed and ready for the application of the self-adhesive film with the control labels and graphics.