FAQ

We are already  receiving  allot of  interest and even enquiries towards the availability of this DIY project:

Assuming we will get it to work as intended: All material will be available like:

• Printed circuit boards: single boards are available as artwork only with bill of material and, if applicable, calibration procedures and software
• Printed circuit boards: double sided, will be produced and available at cost. Also with bill of material and, if applicable, calibration procedures and software
• SMD's will be made available already soldered and tested on piggyback PWBA at cost.
• Controller: of the shelf product

The actual availability is pending  extensive testing of the control functions before the proto is completely available. The availability of our design could extend into he winter of 2010/11 as this is a large winter "labour of love" project without commercial strings attached.

 

 

Introduction 

( life draft document 2010-02-02)

 

In the ever ongoing battle to obtain  echo equipment  that is comparable with the vintage tape and disc echo's the solution we present here  is based on classic electronics. Although we have already designed a VST module in software called eTAP2 we think that there is a large community out there who are only interested in echo solutions if they can put it among the guitar and the amp. Many of those electronic solutions are there already and based on DSP and/or BBD technologies but are not renewed anymore due to the non-profitable commercial market for this special type of equipment.

 

These days, available commercial echo gear is based on different characteristics like only multitap and not our required variable amplitudes per tap(head), the possibility that someone is presently designing gear  especially for our type of music is therefore to be very slim or even non existence. We are aware of the fact that people are presently designing DSP solutions to possible achieve the same result. The design we present is using BBD's to assure the tape/disc artifacts are there since they are key to our music.

What we present here is a mix of "old" electronics by using transistors, BBD's and Opamps but also very modern electronics like microprocessors  including surface mounted technology SMT devices. By carefully applying those techniques, with also cost aspects in mind, a hybrid design is presently being formed to deliver a "best in class" echo device. The other objective is to design this equipment in a modular way so that the do-it-yourself enthusiast  can use the idea's, diagrams, print developments and supporting documentation to come up with his own equipment.

 

To allow for this, the emphasis is therefore on single board designs and readily available components. For area's outside the single board deliverables we provide additional support. The modular approach allows also for a low-cost version where the BBD's are replaced with a DSP unit. 

 

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Functional Description

 

The presented design is based on a classic BBD Bucket Brigade Device design with very much improved  timing over existing BBD designs . Additional functionality based on tape/disc artifacts is added including an additional reverb module to compliment the echo generation towards studio recording methodes as allegedly used by "the Shadows". From a control point of view, the unit is controlled by means of a microprocessor and a I2C protocol controlling potentiometers and switches allowing for various configurations with accuracy to be offered to the user.

 

Modules

A Low cost Wow&Flutter Generator 

A possible solution creating W&F into a delay circuitry based om integrated devices like BBD's and electronic digital delays is a methode based on a microcontroller generating the required waves in the correct ratio. In this particular case the microcontroller creates pure sinewaves in accordance with the article we've created here on this site. The interface to the audioworld is with a special optical coupler that couples directly into a LDR with a very low dark resistance. The solution at hand is augmented with an inverted path so it can be applied to various requirements.

The R5 potentiometers at 12 o"clock" is regarded as optimal. At 7:00 its off and at 17:00 it's maximized.

The waveform to modulate the BBD's, as obtained through extensive simulation, looks like this. It is based on two outputs who are 180 degrees shifted in phase. With this approach all possible W&F configurations can be achieved.

 

 

 

 

The diode-pump based on the 555 timer and some diodes to generate -9Volts is featured on this board to make it an universal sollution . When there are other means of providing this -9 volts the pump circuitry does not to be part of the board. Here is a YouTube video of the process creating the first batch of boards by the pro-printmaker André

Pre and Post Amplifier board 

 

The pre amplifier is designed to allow for two different inputs: Through a FET and directly to an Opamp. The output is also features with an Opamp output and a low impedance output to allow direct connection to a amplifier.

 First BBD board

Here is already a 3D representation of our first BBD board design. This board  is the central unit designed so it can accept the W&F injection including the other tape artifacts.  This board works in unison with the multi-BBD board. Although the board is fully designed we are still puzzled by the exact filter requirements. In the BBD world the specification is for lowpass filtering before and after de BBD's of 40dB/octave. The exact troughput curve is key for our music so this part is still not yet fully defined and pending tests.

Status: 2010-03-10

The required filters are now defined and a testboard is already available to check the curves (when the ordered components are installed) also available is the extended clock testboard including the CMOS drivers. The mulit-BBD board, again as a testboard is assembled and testing can begin.  With this all except the I²C controlling is available for testing.