Jan Didden created Linear Audio in 2010 and published 14 Volumes between 2010 and 2017. Each 200-page Volume contains on average 10 articles by expert authors in the field of audio, acoustics, and instrumentation. Whether you are interested in tube amplifiers, solid-state equipment, loudspeaker design, capacitor and resistor distortion or distortion measurement, you are certain to find helpful advice and interesting discussions. From beginner to advanced level, for the audio professional or the serious hobbyist, this ExpertCollection will advance your understanding and offer new perspectives on common issues. Bonus material included with this collection is a 5-part YouTube series on negative feedback as applied to audio by renowned author Jan Didden, and nine additional landmark audio articles and presentations. If you are seriously interested in audio, acoustics, and instrumentation, you can’t afford to miss this! The published material is indexed and fully searchable and will provide an almost limitless resource for many years to come. You can read about Linear Audio’s authors, and the Table of Contents of each Volume, at linearaudio.net.
Some Highlights from the contents Surround-sound decoder Compact amp Sampling rate converter Battery powered preamplifier Titan 2000 amplifier Crescendo Millennium amplifier Audio-DAC/ADC IR-S/PDFI receiver and transmitter High-End Power Amp Hi-fi Wireless Headset Paraphase Tone Control and more… Using Adobe Reader you are able to browse and search the articles on your computer, as well as print texts, circuit diagrams and PCB layouts.
Easy and Affordable Digital Signal Processing
The aim of this book is to teach the basic principles of Digital Signal Processing (DSP) and to introduce it from a practical point of view using the bare minimum of mathematics. Only the basic level of discrete-time systems theory is given, sufficient to implement DSP applications in real time. The practical implementations are described in real time using the highly popular ESP32 DevKitC microcontroller development board. With the low cost and extremely popular ESP32 microcontroller, you should be able to design elementary DSP projects with sampling frequencies within the audio range. All programming is done using the popular Arduino IDE in conjunction with the C language compiler.
After laying a solid foundation of DSP theory and pertinent discussions on the main DSP software tools on the market, the book presents the following audio-based sound and DSP projects:
Using an I²S-based digital microphone to capture audio sound
Using an I²S-based class-D audio amplifier and speaker
Playing MP3 music stored on an SD card through an I²S-based amplifier and speaker
Playing MP3 music files stored in ESP32 flash memory through an I²S-based amplifier and speaker
Mono and stereo Internet radio with I²S-based amplifiers and speakers
Text-to-speech output with an I²S-based amplifier and speaker
Using the volume control in I²S-based amplifier and speaker systems
A speaking event counter with an I²S-based amplifier and speaker
An adjustable sinewave generator with I²S-based amplifier and speaker
Using the Pmod I²S2 24-bit fast ADC/DAC module
Digital low-pass and band-pass real-time FIR filter design with external and internal A/D and D/A conversion
Digital low-pass and band-pass real-time IIR filter design with external and internal A/D and D/A conversion
Fast Fourier Transforms (FFT)
The intention of this book is to offer the reader understandings, ideas and solutions from the perspective of a workbench technician and electronics hobbyist. It is a descriptive text with many tables of useful data, servicing tips and supplementary notes of not so common knowledge.
Today there is a re-emerging, nostalgic interest in vinyl records and associated music entertainment gear. With this interest, there is a paralleled market for the repair of this gear.
This ‘hands-on’ servicing guide opens with fundamental considerations of the work space of repair and servicing. This includes a comprehensive discussion of essential test equipment and tools. Two chapters are devoted to obtaining servicing information about repair and obtaining spare parts. A key chapter is on general diagnosis and testing and includes the discussion of resistance, capacitance and inductance. These electrical properties are regularly in the mind of the repairer, so understanding of them is a key objective of this book. The next chapter is about time saving repair techniques and ensuring quality repair. The remaining chapters discuss entertainment equipment itself. Each of the chapters begins with an orderly discussion of the theory of operation and common and not so common problems specific to the equipment. All chapters conclude with a summary.
The QA403 is QuantAsylum's fourth-generation audio analyzer. The QA403 extends the functionality of the QA402 with improved noise and distortion performance, in addition to a flatter response at band edges. The compact size of the QA403 means you can take it just about anywhere.
Features
24-bit ADC/DAC
Up to 192 kS/s
Fully isolated from PC
Differential Input/Output
USB powered
Built-in Attenuator
Fast Bootup and Driverless
The QA403 is a driverless USB device, meaning it’s ready as soon as you plug it in. The software is free and it is quick and easy to move the hardware from one machine to the next. So, if you need to head to the factory to troubleshoot a problem or take the QA403 home for a work-from-home day, you can do it without hassle.
No-Cal Design
The QA403 comes with a factory calibration in its flash memory, ensuring consistent unit-to-unit performance. On your manufacturing line you can install another QA403 and be confident what you read on one unit will be very similar to the next unit. It is not expected that re-calibration will be required at regular intervals.
Measurements
Making basic measurements is quick and easy. In a few clicks you will understand the frequency response, THD(+N), gain, SNR and more of your device-under test.
Dynamic Range
The QA403 offers 8 gain ranges on the input (0 to +42 dBV in 6 steps), and 4 gain ranges on the output (-12 to +18 dBV in 10 dB steps). This ensures consistent performance over very wide ranges of input and output levels. The maximum AC input to the QA403 is +32 dBV = 40 Vrms. The maximum DC is ±40 V, and the maximum ACPEAK + DC = ±56 V.
Easy Programmability
The QA403 supports a REST interface, making it easy to automate measurements in just about any language you might anticipate. From Python to C++ to Visual Basic—if you know how to load a web page in your favorite language, you can control the QA403 remotely. Measurements are fast and responsive, usually with dozens of commands being processed per second.
Isolated and USB Powered
The QA403 is isolated from the PC, meaning you are measuring your DUT and not chasing some phantom ground loop. The QA403 is USB powered, like nearly all our instruments. If you are setting up remotely, throw a powered hub in your bag and your entire test setup can be running with a minimum of cables.
Goodbye Soundcard, Hello QA403
Tired of trying to make a soundcard work? The calibration nightmare? The lack of gain stages? The limited drive? Are you tired of dealing with the fixed input ranges? The worry that you might destroy it with too much DC or AC? Tired of the ground loops? That’s why QuantAsylum built the QA403.
Specifications
Dimensions
177 x 44 x 97 mm (W x H x D)
Weight
435 g
Case Material
Powder-coating Aluminum (2 mm thick front panel, 1.6 mm thick top/bottom)
Downloads
Datasheet
Manual
GitHub
The State of Hollow State Audio in the Second Decade of the 21st Century
Vacuum-tube (or valve, depending upon which side of the pond you live on) technology spawned the Age of Electronics early in the 20th Century. Until the advent of solid-state electronics near mid-century, hollow-state devices were the only choice. But following the invention of the transistor (after their process fell to reasonable levels), within a couple of decades, the death of vacuum tubes was widely heralded. Yet here we are some five decades later, and hollow-state equipment is enjoying something of a comeback, especially in the music and high-end audio industries.
Many issues surround hollow-state audio:
Does it produce—as some claim—better sound? If so, is there science to back up these claims?
How do hollow-state circuits work?
How do you design hollow-state audio circuits?
If hollow-state equipment fails, how do you go about troubleshooting and repairing it?
Can we recreate some of the classic hollow-state audio devices for modern listening rooms and recording studios?
How can we intelligently modify hollow-state amplifiers to our taste?
These and other topics are covered in The State of Hollow State Audio.
The Elektor Audio DSP FX Processor combines an ESP32 microcontroller and an ADAU1701 Audio DSP from Analog Devices. Besides a user-programmable DSP core, the ADAU1701 has high-quality analog-to-digital and digital-to-analog converters built-in and features an I²S port. This makes it suitable as a high-quality audio interface for the ESP32.
Programs for the ESP32 can be created with Arduino, Platform IO, CMake or by using the Espressif IDF in another way. Programs for the ADAU7101 audio DSPs are created with the free visual programming tool SigmaStudio by dragging and dropping pre-defined algorithm blocks on a canvas.
Applications
Bluetooth/Wi-Fi audio sink (e.g. loudspeaker) & source
Guitar effect pedal (stomp box)
Music synthesizer
Sound/function generator
Programmable cross-over filter for loudspeakers
Advanced audio effects processor (reverb, chorus, pitch shifting, etc.)
Internet-connected audio device
DSP experimentation platform
Wireless MIDI
MIDI to CV converter
and many more...
Specifications
ADAU1701 28-/56-bit, 50-MIPS digital audio processor supporting sampling rates of up to 192 kHz
ESP32 32-bit dual-core microcontroller with Wi-Fi 802.11b/g/n and Bluetooth 4.2 BR/EDR and BLE
2x 24-bit audio inputs (2 V RMS, 20 kΩ)
4x 24-bit audio outputs (0.9 V RMS, 600 Ω)
4x Control potentiometer
MIDI in- and output
I²C expansion port
Multi-mode operation
Power supply: 5 V DC USB or 7.5-12 V DC (barrel jack, center pin is GND)
Current consumption (average): 200 mA
Included
1x ESP32 Audio DSP FX Processor board (assembled)
1x ESP32-PICO-KIT
2x Jumpers
2x 18-pin headers (female)
4x 10 KB potentiometers
Downloads
Documentation
GitHub
Easy and Affordable Digital Signal ProcessingThe aim of this book is to teach the basic principles of Digital Signal Processing (DSP) and to introduce it from a practical point of view using the bare minimum of mathematics. Only the basic level of discrete-time systems theory is given, sufficient to implement DSP applications in real time. The practical implementations are described in real time using the highly popular ESP32 DevKitC microcontroller development board. With the low cost and extremely popular ESP32 microcontroller, you should be able to design elementary DSP projects with sampling frequencies within the audio range. All programming is done using the popular Arduino IDE in conjunction with the C language compiler.After laying a solid foundation of DSP theory and pertinent discussions on the main DSP software tools on the market, the book presents the following audio-based sound and DSP projects:
Using an I²S-based digital microphone to capture audio sound
Using an I²S-based class-D audio amplifier and speaker
Playing MP3 music stored on an SD card through an I²S-based amplifier and speaker
Playing MP3 music files stored in ESP32 flash memory through an I²S-based amplifier and speaker
Mono and stereo Internet radio with I²S-based amplifiers and speakers
Text-to-speech output with an I²S-based amplifier and speaker
Using the volume control in I²S-based amplifier and speaker systems
A speaking event counter with an I²S-based amplifier and speaker
An adjustable sinewave generator with I²S-based amplifier and speaker
Using the Pmod I²S2 24-bit fast ADC/DAC module
Digital low-pass and band-pass real-time FIR filter design with external and internal A/D and D/A conversion
Digital low-pass and band-pass real-time IIR filter design with external and internal A/D and D/A conversion
Fast Fourier Transforms (FFT)
You could use Pirate Audio Headphone Amp to build a tidy, pocket-sized player for local audio files (MP3, FLAC, etc) or for streaming music from online services like Spotify. To help get you started, Pimoroni has built plugins for Mopidy that will let you display gorgeous album art, play/pause your tracks and adjust the volume. The DAC and headphone amp will give you crisp digital amplified audio through your wired headphones. Pirate Audio is a range of all-in-one audio boards for Raspberry Pi, with high-quality digital audio, beautifully-crisp IPS displays for album art, tactile buttons for playback control, and a custom Pirate Audio software and installer to make setting it all up a breeze. Features Amplified digital audio (24-bit / 192KHz) over I2S PAM8908 headphone amplifier chip Low-gain / high-gain switch (high-gain boosts by 12dB) PCM5100A DAC chip 3.5mm stereo jack 1.3' IPS colour LCD (240x240px) (ST7789 driver) Four tactile buttons Mini HAT-format board Fully-assembled Compatible with all 40-pin header Raspberry Pi models
Dimensions: 65x30.5x9.5mm Software The Pirate Audio software and installer installs the Python library for the LCD, configures the I2S audio and SPI, and then installs Mopidy and the custom Pirate Audio plugins to display album art and track info, and to use the buttons for playback control. Here's how to get started: Set an SD card up with the latest version of Raspberry Pi OS. Connect to Wi-Fi or a wired network. Open a terminal and type the following:git clone https://github.com/pimoroni/pirate-audiocd pirate-audio/mopidysudo ./install.sh
Reboot your Pi Downloads PAM8908 Datasheet PCM5100A Datasheet Pirate Audio software
SHIM is an old Yorkshire term meaning 'Shove Hardware In Middle' - we use it for Raspberry Pi add-ons that are designed to be sandwiched between your Pi and a HAT or mini HAT. This one has a clever friction fit header that slips handily over your GPIO pins, doesn't need soldering*, and is easily removable. The MAX98357A combined DAC / amplifier chip takes high-quality digital audio from your Pi and amplifies it so it can be used with an unpowered speaker. The push-fit connectors make it straightforward to connect up your speaker, whether it's a bookshelf or floor-standing speaker, the speaker in an old radio, or any other speaker you might have laying around. Because Audio Amp SHIM adds no extra bulk to your Pi it's perfect for building into a compact enclosure - you could use it to make a tiny MP3 player to play local files or stream from services like Spotify, give a vintage radio the ability to play digital radio streams or incorporate bleepy noises into your very own retro handheld. It's also a handy way to add audio output to your Pi Zero or Pi 400! Please note: Raspberry Pi and speakers are not included with this board. Features MAX98357A DAC / amplifier chip Mono 3W audio out Push-fit speaker terminals SHIM-format board with friction-fit connectors 2x mounting holes (M2.5) for if you want to secure everything together with bolts Fully-assembled No soldering required (*unless you're using a Pi that comes without a header) Compatible with all 40-pin header Raspberry Pi models
Software The easiest way to get everything set up is to use Pimoroni's Pirate Audio software and installer which configures I2S audio, as well as installing Mopidy and our custom Pirate Audio plugins which will let you stream Spotify and play local files. Here's how to get started: Set an SD card up with the latest version of Raspberry Pi OS. Connect to Wi-Fi or a wired network. Open a terminal and type the following:git clone https://github.com/pimoroni/pirate-audiocd pirate-audio/mopidysudo ./install.sh
Reboot your Pi Downloads MAX98357A Datasheet Pirate Audio software Schematic
The OWON XSA815-TG (9 kHz-1.5 GHz) is a cost effective spectrum analyzer with tracking generator included and a frequency resolutions of 1 Hz.
Features
Frequency Range from 9 kHz to 1.500009 GHz
9-inch display
9 kHz to 1 MHz -95 dBm Displayed Average Noise Level, 1 MHz to 500 MHz 140 dBm (Typical), <-130 dBm
Phase Noise
-10 kHz <-80 dBc/Hz
100 kHz <-100 dBc/Hz
1 MHz <-115 dBc/Hz
Resolution Bandwidth (-3 dB): 1 Hz to 1 MHz, in 1-3-5-10 sequence
Tracking Generator Kit: 100 kHz to 1.500009 GHz
Specifications
Frequency Range
9 kHz to 500.009 MHz
Frequency Resolution
1 Hz
Frequency Span
9 kHz to 1.500009 GHz
Span Range
0 Hz, 100 Hz to max frequency of instrument
Span Uncertainty
±span / (sweep points-1)
SSB Phase Noise (20°C to 30°C, fc=1 GHz)
Carrier Offset
10 kHz <-80 dBc/Hz | 100 kHz <-100 dBc/Hz | 1 MHz <-115 dBc/Hz
Resolution Bandwidth (-3 dB)
1 Hz to 1 MHz, in 1-3-5-10 sequence
RBW Accuracy
<5% typical
Resolution Filter Shape Factor (60 dB: 3 dB)
<5 typical
Video Bandwidth (-3 dB)
10 Hz to 1 MHz, in 1-3-5-10 sequence
Amplitude measurement range
DANL to +10 dBm, 100 kHz to 10 MHz, Preamp Off
DANL to +20 dBm, 10 MHz to 1.5 GHz, Preamp Off
Reference Level
-80 dBm to +30 dBm, 0.01dB by step
Preamp
20 dB, nominal, 100 kHz to 1.5 GHz
Input Attenuator
0 to 40 dB, 1 dB by step
Display Average Noise Level Input attenuation = 0 dB, RBW = VBW = 100 Hz, sample detector, trace average ≥ 50, 20°C to 30°C, input impedance = 50 Ω)
Preamp Off 9 kHz to 1 MHz
-95 dBm (Typical), <-88 dBm
Preamp Off 1 MHz to 500 MHz
-140 dBm (Typical), <-130 dBm
Preamp On 100 kHz to 1 MHz
-135 dBm (Typical), <-128 dBm
Preamp On 1 MHz to 500 MHz
-160 dBm (Typical),<-150 dBm
Tracking Generator (optional)
Frequency Range
100 kHz to 1.500009 GHz
Output power level range
-40 dBm to 0 dBm
Output level resolution 1 dB
Output flatness
Relative to 50 MHz | ±3 dB
Tracking generator spurious
Harmonic spurious -30 dBc (Tracking generator output power -10 dBm)
Non-harmonic spurious -40 dBc (Tracking generator output power -10 dBm)
Tracking generator to input terminal isolation
-60 dB (Tracking generator output power 0 dBm)
Tracking generator to input terminal isolation
-60 dB (Tracking generator output power 0 dBm)
Tracking generator to input terminal isolation
-60 dB (Tracking generator output power 0 dBm)
Dimensions
375 x 185 x 120 mm
Weight
3.7 kg
Included
1x XSA815-TG
1x 220 V AC power cord
1x USB Cable
1x Quickstart guide
Downloads
Quick Guide
Specifications