Build Your Own Clone Digital Echo & Ping-Pong Kit
- Nov 17, 2010
- in Guitar Kit Builder - Pedals & Effects
The Digital Echo and Ping Pong effect pedal from Build Your Own Clone (BYOC, www.buildyourownclone.com) uses the new generation of analog-voiced digital-delay chips to achieve the controllable delays of the digital world with the warmer analog delay sound favored by most guitar players. Before we listen to a video that demonstrates the capabilities of this pedal, let's go over a little of the technical background.
Analog delay chips move a signal along a chain of analog storage elements (capacitors) in a manner akin to the way water gets transferred in an old-time firefighting bucket brigade. In fact these chips are referred to as Bucket Brigade Delay (BBD) devices. The total delay time is determined by the number of storage capacitors (buckets) and the time it takes to move from one bucket to the next, which is controlled by a clock chip. In the BBD chip, there is signal 'loss' at each bucket transfer, similar to water spillage when pouring from bucket to bucket. These losses degrade the quality of the delayed signal by introducing noise and distortion. And when longer delay times are desired, more buckets are needed, resulting in yet more loss, noise and distortion. The delay can also be increased by slowing the clock signal, but then extra filtering is required which also reduces the quality of the delayed signal. This is what places practical limitations on the maximum delay times that can be achieved with analog BBD devices.
In a digital delay the signal is digitized mathematically and stored in memory to be read out at a later point in time and converted back to an analog waveform. The total delay capacity is determined by the size of the memory. In contrast with the Bucket Brigade Device, digital delays experience no loss of fidelity after the conversion process, and can have very long delay times without loss of quality. This is great for applications needing long delay times, but the complaint has been that digital delays sound cold and sterile when compared with the warmth and organic sounds of an analog delay. To address this issue, chip makers developed analog-voiced digital- delay chips with built-in filtering and distortion (in either analog or digital) to simulate the sonic degradations that occur in the analog BBD chips. These delays can sound excellent, and are able to offer many features by exploiting the programmability and virtually unlimited storage space available in the digital system.
One such chip is the PT2399 Echo Processor IC made by Princeton Technology Corp. This chip uses a high sampling frequency and a large internal memory to achieve very low distortion (THD<0.5%) and very low noise (No BYOC advises that this is one of their most difficult kits, so it requires care and attention from even experienced builders. The kit cost is just under $99. Find out more about the kit and how to order at BYOC Digital Echo & Ping-Pong Kit.