DAC na PCM1794A + DIX9211 Made in Poland

I start a topic concerning my new project that is DAC based on PCM1794A chips. On chips because it may be built either on two or one PCM1794 chip what is configurated by appropiate set of elements (more details on schematic).

Schematics: PCM1794_DIX9211_DAC_V10

As a S/PDIF receiver and I2S switch I used relatively not well known DIX9211 chip. Its main advantages are twelve S/PDIF inputs, support for all formats ranging till 192kHz, a possibility of connecting to three additional 12S signal sources (it may also allow DSD format) and controlling via I2C. DAC also has a space for amanero module with its own power supply and galvanic isolation ISO7640.

Module’s inputs are:

• USB via amanero or similar
• 2x Coax
• Toslink
• AES/EBU
• inner iput I2S e.g. for bluetooth module

DAC is controlled by microcontroller STM32F100RBT6B. STM32F100RBT6B has big amount of periphery that allow to expanse DAC, a lot of GPIO and 128kB of flash memory and that all is well-priced. Additional simplification which is Cube makes there is no other choice. Encoder was planned to be responsible for controlling. Active input indication via separate PCB with OLED on SPI display or 8 LEDs on 74HC595. There is possibility to control via remote control or UART. Updates are made via UART. To PCB programming ST-Link V2 is needed. It is available on each Discovery STM32 module.

Power supplying is extended. I divide it on three sections, each supplied from separate transformer winding.

• USB interface power supply
• PCM + DIX + STM digital section power supply
• PCM analogue section power supply

Each section is built in similar way:

Rectifier -> big snap capacitor -> discrete pre-regulator (V1.2) -> post-regulator

Post- regulators may be chosen between LT1763 and discrete module. Additionally, I put LC filters in digital sections. Thanks to that they are better separated. Digital module contain 10 voltage regulators. In MONO mode (one PCM1794 for canal?) there is possibility to supply the chip from different regulators (4pcs,) or mounting jumper and using only two – one for digital and one for analogue.

The whole construction I divide on two different modules – digital PCB with DAC chips (150x120mm) and totally symmetrical analogue module with the same dimensions (not ready yet). Such division make it elegant and not as big as a computer board, and what matters more it leave a space to experiment with other analogue variants, also with lamps.

I plan to build analogue module as follow:

• I/V converters on single opAmps SMD AD797 or OPA1611 type
• symmetrical filter based on MFB on OPA1632 configuration
• power supply either LT1963/3015 or discreet modules, two per each canal
• mute for noise elimination
• without capacitors in signal path

Later I will work out lamp module.

The whole circuit, where it possible, in SMD. The elements dimensions from 0603 to 1210. PCB is still being worked out. I attach the look/view.

Better and stronger – V2.0 Series Power Supply

Big success of V3.1 regulator shows me that this topology has a huge potential to implement in many applications. For those who uses my V3.1 regulator to create its standalone power supply I have got something interesting! V2.0 power supply which is better and stronger implementation of V3.1 topology.

Better means 3 more current sources which replace resistors. This give us better PSRR, more gain in error amplifier and better immunity to output current ripple.

Stronger means that is equipped with powerful TO220 transistor on dedicated heatsink. This gives me possibility to increase output current up to 3A!

But this is not the end! At the input, after rectifier and smoothing capacitor there is LC pi filter based on Common Mode inductor. Such filter could help to block disturbances which are coming from mains and passes transformer. It is also working in opposite way and blocks disturbances from supplied circuit and not allow them to pass to the transformer.

The PCB of this power supply was created in such a way that helps to remove heat from heatsink. Beneath it there are many holes which in shortest way cool it down.

Dimensions: 45 x 90 mm, high 50 mm

Hot and powerful! – V2.1 Shunt Power Supply

Shunt power supplies always are not so simple in use as series but all shunt fans knows, that this effort will pay of. And for that people’s I have got something special. New power supply with high current capability. Input CCS can be set up to 1000mA!

For everyone who would like to say that it is Salas I want to say: you are wrong! It is my proprietary, bipolar design, similar to V8.0 regulator and taking best from both – V3.1 and V8.0 regulators.

Designed in the way that can be used instead of popular „S” power supplies or even replace it in ready designs. Comparing to its famous competitor:

– requires less voltage drop across regulator – typically 1,5V

– is more flexible  – from few up to 1000mA BIAS current
– output voltage can be set from 3 to 15V by fixed resistor or helipot.

– very stable output voltage during warming – no more worry about your circuit!

– stable output voltage in function of output current – no more worry about your circuit!

– CLC input filter to block noise in both ways

From user experience I can guarantee that performance and sound is similar or even better.

Big Thing – 10A 100V Linear, Discrete Power Supply – Awesome!

Last time I presented integrated solution for heavy power supply, but one integrated solution is enough for some time. Now it’s time for something, as usual – discrete.

Let me show you my precious!  Long awaited power supply for applications like:

• supply for audiophile computers
• regulated supply for power amplifiers

The main reason to design and build it, was that I want to replace switching power supply for my small PC where my Daphile music server is installed.

Thanks to the complexity of design, board can be configurated as positive or negative regulator. Please, have a look at this board, isn’t it pretty?

Maximal output current is: 10A

Maximal input voltage: 100V

Higher ratings of current and voltage are possible but have not been tested yet. Maximal values can be achieved interchangeably. It is not possible to build 10A 100V power supply, but f.e.

• 10A 12V
• 5A 100V
• 5A 19V

During the test, 120W of heat was dissipated on my dummy load so I decide to put it outside the window.

 

Small but Complex – V3.X series regulator

Welcome in my first post!

I would like to show you my lovely child – V3.X series voltage regulator based on discrete components.

Specially designed to power precision audio components like: DACs, ADCs, S/PDIF receivers, clock circuits.

Output voltage can be set by components in negative feedback circuit from 1V2 to 9V eg. : 1V2, 2V5, 3V3, 5V, 6V, 8V, 9V. For higher output levels I recommend V3.0max version. Transistor circuit allows to build version for negative voltage.

Voltage reference based on LED diode to ensure low noise. There are possibility to use precision voltage reference instead of LED diode for good voltage precision and temperature stability.

Simply decoupling circuit on regulator PCB is sufficient to ensure stability of regulator but external high capacity can be connected to provide low ripple with high speed output current change.

Dropout voltage is at least 1,5V, but I recomend values from 2V to 3V. You must calculate this for power dissipation max. 1W.

Maximal output current is 500mA, but for provide good stability I recommend max. 200mA.

For better power dissipation additional heatsink can be used:

Pinout compatible with standard LM78XX regulators like LM7805 and similar. If LM78XX regulator will be replaced by V3.1 only 3 central pins can be used. If board is developed specially for V3.X all 5 pin can be used:

Pin assignment and dimensions:

Overall dimensions: 30 mm x 15mm.

V3.X series are tiny implementation of my design used few years ago to supply analog circuit of PCM63P-K DAC. This implementation is specially developed for Buffalo III DAC to replace Trident regulators.

V3.0 inside my Buffalo III DAC:

Thanks for your attention!