Differences

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--- audio:audio_by_van_alstine_work [2019/05/22 04:13] – [Ultimate 70 and Ultravalve power amplifiers] mithat
+++ audio:audio_by_van_alstine_work [2019/05/22 04:29] – [Vision DAC improved] mithat
@@ Line 73: / Line 73: @@
 **Contribution:** Design and implementation of a next-generation S/PDIF decoder and DAC board.
-**Discussion:** In the mid-1990s, I built AVA a prototype stand-alone DAC that demonstrated to them that producing such a product was within their manufacturing abilities. This ushered in an era of their being able to offer a product that they had previously considered impossible. So it was probably natural that they approached me to design the core PCB for what would form the basis of their next generation of stand-alone DACs. They had preselected the DAC IC they wanted the design based around: originally this was the Wolfson WM8740, but by the time the design was completed we had moved to the WM8742.
+**Discussion:** In the mid-1990s, I built AVA a prototype stand-alone DAC that demonstrated to them that producing such a product was within their manufacturing abilities. This ushered in an era of their being able to offer a product that they had previously considered impossible. So it was probably natural that they approached me to design the core circuits that would be used in their next generation of stand-alone DACs. They had preselected the the Wolfson WM8740 as the DAC IC they wanted the design based around, but by the time the design was completed we had moved to the WM8742.
-AVA’s originally wanted to support only 44.1kHz PCM formats and a single S/PDIF input. Also, their manufacturing capabilities precluded the use of microcontrollers, which would have allowed for advanced use of the receiver and converter ICs. In spite of these constraints, I was able to design in seamless support for up to 96kHz PCM streams, jumper-configurable support for 192kHz PCM, and easy-to-implement multiple inputs. Because of this, AVA was able to use this design for all their DAC production until it was replaced by my DAC MK5 design seven year later.
+AVA originally wanted to support only 44.1kHz PCM formats and a single coaxial S/PDIF input. Additionally, their manufacturing capabilities precluded the use of microcontrollers, which would have allowed for advanced use of the receiver and converter ICs. In spite of these constraints, I designed in automatic support for up to 96kHz PCM streams, jumper-configurable support for 192kHz PCM, and support for multiple inputs. Because of this, AVA was able to use this design to meet subsequent customer demands for high-rate audio support and multiple inputs. This board was used unchanged for all AVA DAC production for seven years until it was replaced by my DAC MK5 design.
 This would be the first time AVA would use predominantly SMD parts in a PCB design. The previous generation DAC had used a single hand-soldered SOIC package. This design used SMD components exclusively.
-I was //not// involved in the development of the analog stages for the first DAC products using this board. However, I was responsible for the analog circuits found in the [[#vision_dac_improved|2015 revision]].
+I was not involved in the development of the analog stages for the first DAC products using this board. However, I was responsible for the analog circuits found in the [[#vision_dac_improved|2015 revision]].
 ===== Fet Valve CF =====
@@ Line 103: / Line 103: @@
 **Contribution:** New reconstruction and output stage based on a discrete, class-A, solid-state gain stage I developed as an independent project.
-**Discussion:** I had been developing a discrete, class-A, solid-state gain stage as an independent project for a number of years. My goal was to create a design that was free of the issues I kept hearing in opamp ICs. Late in 2014 I thought I succeeded and built a single-stage differential-to-single-ended anti-imaging filter/output stage using the module for the Vision DAC board I had designed earlier for AVA. The results impressed AVA enough that it was immediately adopted for their Vision DAC offerings.
+**Discussion:** I had been developing a discrete, class-A, solid-state gain stage as an independent project for a number of years. My goal was to create a design that was free of the issues I kept hearing in opamp ICs. Late in 2014 I thought I succeeded, and so I built a single-stage differential-to-single-ended anti-imaging filter/output stage using the module for the [[#dac_core_for_vision_and_vision_hybrid_dacs|Vision DAC board]] I had designed earlier for AVA. The result impressed AVA enough that it was immediately adopted for their Vision DAC offerings.
 ===== Vision SL improved =====