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Digital should not remain a barrier for diyAudio beginners. Before the digital age, diyAudio was about designing a PCB and soldering through-hole components on it.
Nowadays, diyAudio encompasses digital. It requires designing a PCB hosting SMD (Surface Mounted Devices), and it requires creating a DSP (Digital Signal Processing) program. Those are the two new difficulties.
Ten years ago, most diyAudio enthusiasts would have failed building a digital audio system from scratch. The situation has changed. There are more and more hobbyists dealing with 32-bit microcontrollers. There are more and more hobbyists overcoming the SMD difficulty.

Here is a digital audio system built from scratch. Diptrace got used for drawing the schematic and converting it to a PCB.

The PIC32MX2 gets debugged and programmed using Microchip MPLAB ICD 3 ($189.99) . A simple experimental application would read the stereo audio entering the WM8731, apply some processing like filtering, equalizing, splitting, dynamic compression or expansion, then deliver the processed audio on the WM8731 stereo outputs. (continue reading…)

Things are moving fast. Want to build your own miniDSP? Operated within Analog Devices SigmaStudio Digital Audio Compiler? Try ordering the  ADAU1701 Carrierboard from Audiodesine. Quite surprising, the company presents itself as specializing in “Audio Design for an Analog World”.

Such statement doesn’t imply that Audiodesine people reject or ignore digital. How possible anyway, now that virtually all audio material get recorded, mixed and edited in digital?

“We love analog, but we do not hate DSP, though we do regret the fact that to get into DSP you seem to need SMD soldering skills and a lot of math”.

Audiodesine selected the ADAU1701 DSP because of SigmaStudio (from Analog Devices) requiring no programming. SigmaStudio allows you to drag and drop prebuilt blocks such as “State Variable Filter”. In a few minutes you have a circuit. (continue reading…)

Most soundtracks you are listening to, actually depend from Steinberg VST. Such technology is at the heart of digital sound creation (the VST instruments) and sound processing (the VST effects). From a diyAudio perspective, it is worth knowing a few VST basics, especially when experimenting with Synthmaker or Flowstone.

Here follows a neutral compilation of covering most important VST aspects. Worth visiting, is the Steinberg website, where it shows how VST has deeply penetrated all compartments of the sound industry.
Steinberg is currently promoting the The Art & Science Of Sound Recording video tutorial series on music production, presented by multi-platinum producer Alan Parsons. In more than 10 hours of footage, more than 40 fellow professionals join Alan Parsons in this guide to modern recording, including Erykah Badu, Jimmy Douglass, Jack Joseph Puig and Simon Phillips. This 10-hour DVD set applies classic, old-school recording experience to the modern recording scene and will be a standard work on the subject for years to come. (continue reading…)

LTspice is a popular simulation software, freely available from Linear Technology. Many diyAudio enthusiasts designing phono amplifiers, pre-amplifiers, crossovers and power amplifiers keep trusting LTspice while checking, trimming and optimizing their schematics. No doubt they are right.

LTspice delivers reliable simulations provided there are no integrated opamps involved. The problem is that most LTspice integrated opamp models are still behavioural, not yet transistor-level based. They were designed this way, 30 years ago, for speeding up the computation. Nowadays with GHz-class computers, LTspice simulates a transitor-level based opamp containing 25 semiconductors in a snapshot. Or refuses to converge. That’s another issue. That you don’t face with behavioural models. Most behavioural models are implicitly hooked to the ground, making them unsuitable in particular configurations like floating supplies amps. Most behavioural models don’t accurately simulate the currents running in the supply pins, making them unsuitable in Kuroda structures. Knowing this, only the simulations relying on transistor-level can be said “clean” and “accurate”, but honestly, when was last time you tried replacing your standard NE5532 model by a transistor-level one, not ruining the convergence ? And about the TL072 ? And the offset voltage dispersion ? That’s the art of simulating analog systems. It may be difficult, it may be funny, sometimes it doesn’t work.

Under LTspice, for getting a Bode Plot, one need to enter the schematic, connect a virtual signal source at the input, and launch what is called an .ac (sweep) simulation by enabling the “.ac oct 100 100 10k” command.  A second windows automatically opens, blank, supposed to display the Bode Plot from 100 Hz to 10 kHz, with a resolution of 100 values per octave. From this point, all what is needed for actually displaying a Bode Plot, is to tell LTspice what signal line to compute. Hovering on the schematic, the mouse pointer transforms into a probe when crossing a signal line. Left-click the probe, and the corresponding Bode Plot immediately shows. This is magic. (continue reading…)