Go Back   Home > Forums > >

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Whazon, a S/PDIF switch built around WM8805
Whazon, a S/PDIF switch built around WM8805
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 8th April 2017, 05:02 PM   #1
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
Default Whazon, a S/PDIF switch built around WM8805

A S/PDIF switch can be useful when we have more digital audio sources than the number of inputs available on a DAC.

I wanted to do this a long while ago and finally managed to get at it recently.

This little project makes use of the internal 8-channel selector offered by WM8805 S/PDIF receiver, and was designed to select one out of up to 8 S/PDIF feeds under the monitor and control of an Arduino Nano micro controller board.

Unlike a usual switch-and-buffer type of device, WM8805 re-clocks its on-chip S/PDIF transmitter and does not pass the incoming jitter on to the output, therefore upkeeps the S/PDIF signal quality in terms of jitter reduction/rejection. That is why so my choice was.

Whazon’s operation is simple, it keeps polling the 8 inputs in turn and stops at the first one its PLL manages to lock up to. A duplicated, de-jittered S/PDIF signal is then sent out with the S/PDIF transmitter, available in coaxial and optical form.

Whatzon receives remote control via an inexpensive Bluetooth-serial I/O tranceiver, model HC-05, paired with a smart phone running a Bluetooth terminal app.

The channel polling described above can be enabled/disabled with the phone. Forced channel change to desired channel, and next higher channel are also easily implemented.

An I2S copy of the selected input signal is also sent out at WM8805’s bidirectional digital audio interface for future project expansion. It is however not being put to use at present, except that a buffered copy of the LRCK is sent to the Arduino for exact sample rate detection (that WM8805 is not fully capable of).

The PCB is a compact 10cm * 10cm double sided design, with a break-away optical I/O section. Whazon accepts 4 coaxial (BNC) and 4 optical inputs with current PCB design. It is possible to replace the optical input receivers in the current breakaway design with BNC connectors to make all channels BNC input. The coupling and termination circuit layout around the WM8805 works with both types for that 4 channels.

Whazon is powered by a 5Vdc cell phone charger through a micro USB port that serves as a programming port for the Arduino as well when connected to a PC that runs Arduino development system.

Successful so far: input channel polling, PLL locking, exact sample rate detection -- tested good with 44.1, 48, 88.2, and 96KHz signals, haven't tested 32KHz, 176.4KHz, and 192KHz yet as I don't have such sources.

Being worked on: an OLED screen display that shows current input channel and sample rate --- Done.

In the plan: A button push or a remote that forces switching to the next input and starting the polling/channel rotation --- Remote done.

The PCB layout screen shot is of top side of Rev.2 design to be sent to a PCB house soon.

There is a youtube video in post #5 below that shows this project in action.
Attached Images
File Type: jpg BUILD.jpg (56.4 KB, 743 views)
File Type: jpg assy-small.jpg (601.5 KB, 752 views)
File Type: jpg rev2.jpg (523.2 KB, 732 views)
Attached Files
File Type: pdf sch.pdf (58.8 KB, 205 views)

Last edited by nattawa; 6th November 2017 at 01:59 AM.
  Reply With Quote
Old 12th April 2017, 06:11 PM   #2
Gusser is offline Gusser  United States
diyAudio Member
 
Join Date: Feb 2014
While your project has more capabilities, there is a much simpler way to make an SPDIF switch.

SPDIF is basically the same bandwidth and electrical parameters and NTSC analog video. 1volt into 75ohms 6mhz.

So any plain old analog video switch will work. Maxim makes many video crosspoint chips with built in cable drivers. TI does a s well. With a MAX453 you can make an 8x1 switch with just 1 IC and a few resistors. No need for transformer coupling. Most of these switch IC's are DC coupled although AC coupling would work just fine as well.

If using an OEM professional video switch you just need to be sure it doesn't have sync tip clamping enabled if so equipped. As we know SPDIF does not have a sync pulse and the clamp may chew up the data stream
  Reply With Quote
Old 13th April 2017, 10:51 PM   #3
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
I agree that there can be many and simple ways of switching SPDIF feeds. Whazon is perhaps more of a SPDIF receiver than a mere switch. An I2S interface makes it possible to hook up with other DIY projects in the forum that also come with I2S I/O, an OLED display makes it a toy of a little more fun. A bit of automation and remote control make it an practicable device in a stereo equipment rack too -- living room worthy was one of the objectives. Coupling transformers may help cut down ground loops loops among but can always be opted out when not needed.
  Reply With Quote
Old 14th April 2017, 03:48 PM   #4
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
The OLED display is up and running

Channel polling in action

All Channels Down

Channel 4 has something

CH4 is good
  Reply With Quote
Old 18th September 2017, 12:32 AM   #5
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
Smile Whazon made living room worthy

I finally managed the most tedious part of the project, making an enclosure. Now it's in the system and doing its deed.

In Action Video

A few pictures inside and back.

Remote control is via a Bluetooth serial tranceiver module HC-05 paird with a smartphone running a Bluetooth Terminal app.
Attached Images
File Type: jpg whazon-main-pcb-p.jpg (858.4 KB, 537 views)
File Type: jpg Inside-Whazon.JPG (642.9 KB, 516 views)
File Type: jpg Whazon-Rear.JPG (490.5 KB, 200 views)
  Reply With Quote
Old 9th November 2019, 06:21 AM   #6
raptorlightning is offline raptorlightning  United States
diyAudio Member
 
raptorlightning's Avatar
 
Join Date: Jul 2009
Location: The luminiferous ether
In my searches for a source switch I realized I would like to switch signals as early as possible to avoid analog degradation. This meant switching in the digital domain, and the common denominator for digital audio is S/PDIF. It is easy to find HDMI audio extractors that have S/PDIF outputs these days, and most devices are configurable for PCM output. I couldn't find any acceptable designs or products, besides nattawa's design, that focuses around high quality switching/jitter cleaning of S/PDIF signals. The WM8805 is really a great chip and this design recognizes all available, realistic sampling rates. Nattawa's microcontroller code intelligently handles the quirks of the WM8805, allowing perfect software control over the switching and sample rates. I've modified the design a bit to simplify the architecture and created my own version of his design that works excellently.

Click the image to open in full size.

Click the image to open in full size.

If you have multiple digital sources and need a way to switch between them, I highly recommend this project.

Last edited by raptorlightning; 9th November 2019 at 06:27 AM.
  Reply With Quote
Old 28th October 2020, 08:37 PM   #7
gemby is offline gemby  Croatia
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by nattawa View Post
I finally managed the most tedious part of the project, making an enclosure. Now it's in the system and doing its deed.

In Action Video

A few pictures inside and back.

Remote control is via a Bluetooth serial tranceiver module HC-05 paird with a smartphone running a Bluetooth Terminal app.
Hello nattawa, is it possible to share schematics, pcb files and arduino sketch? I am in process of designing preamp with dac and would like to have switch for digital imputs.
  Reply With Quote
Old 29th October 2020, 04:18 AM   #8
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
Hi gemby, yes, I'm more than happy to share the design. I'll make ready a file package and come back to you in a couple days.
  Reply With Quote
Old 29th October 2020, 08:24 AM   #9
gemby is offline gemby  Croatia
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by nattawa View Post
Hi gemby, yes, I'm more than happy to share the design. I'll make ready a file package and come back to you in a couple days.
Tnx, i appreciate it ;-)
  Reply With Quote
Old 31st October 2020, 11:19 AM   #10
nattawa is offline nattawa  Canada
diyAudio Member
 
Join Date: Apr 2010
Location: Mississauga, Ontario
Check your PM, gemby
  Reply With Quote

Reply


Whazon, a S/PDIF switch built around WM8805Hide this!Advertise here!
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WM8805 Software & S/PDIF mode - 96kHz Problems SlapBug Digital Line Level 12 5th April 2016 11:44 AM
FS: Twisted Pear Teleporters + 4-Channel S/PDIF Level Converter + Switch + IVY 2 kumori Swap Meet 2 10th February 2015 04:12 PM
Has anyone built an OTL amp with switch mode power supplies. kimbal Tubes / Valves 4 3rd December 2012 08:25 PM
TP 4-Channel S/PDIF Input/Switch Module/Placid HD BiPolar Kits rklein Swap Meet 1 17th July 2012 11:19 PM
where to find old pot's with switch built in nhuwar Tubes / Valves 3 17th January 2007 08:11 PM


New To Site? Need Help?

All times are GMT. The time now is 02:37 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki