Multichannel audio on a Pi will get a whole lot easier and cheaper!

[MCH]

I petitioned HifiBerry to see if they had any interest in producing a HDMI input HAT for the RPi5. Unfortunately, they said it wasn't feasible with HDMI licensing.

Michael

Ok i Will give my DIY board a try then

 

[Frunse]

I petitioned HifiBerry to see if they had any interest in producing a HDMI input HAT for the RPi5. Unfortunately, they said it wasn't feasible with HDMI licensing.

Michael

Yes, this is only something for big Companies i guess Licensing is Expensive, also that why you can't do DIY Surround processors, they also need lots of Money for Dolbydigtal and DTS Licensing

It tooks me lot of time to get an working HDMI I2S Multichannel Board, looking already over 10 Years for somthing like that. I am happy that it works now how it is

And also realy Cheep tho.

First i was thinkink need to get that expensive HDMI to 4x SPDIF / ASEBU extractor for 1600€ (Forget the Name of that Device) and now it works for 20-40 Bugs

Didn't think the Soundquality is so much better worth to pay 1560 € more.

Robert

 

[Frunse]

Work in Progress
Found an Solution that will fit into my Hypex Amp.
This way it could work.

Arduino Nanno
Rotary Encoder
Relais Volume 2 Chanels XLR (Twited Pair Audio design)
I2C 2x 20 Character Display
3 MCP 23008 I2C Expander (Clip, DC Error and Power Good, Mute Signals will feed in to the third MCP 23008 with Optical isolators)
TTL to RS485 (Connection to the CamillaDSP Raspi for Remote Control point to point Connection) 7 to 9 Amps at all

Also plan to build an smal Adapter Case with Ethernet RJ45 Connector to 2x XLR and RS485 and 12v, GND so i can use an Ethernet Kabel for the 5-10M to CamillaDSP
there you has 4 twisted pairs in one Kabel (Studios use also that kind of Distrebution) why not at Home

Robert

 

[Frunse]

I agree, IMO the same effect is here - 120R of the mux vs. the 10k of the other resistor, times the mux THD => 0.2% THD * 0.01 ratio => some 0.002%, rough calculation. Absolutely inaudible. Yet IMO worse than performance of a good DAC chip.

IIRC Ivan talked about using FETs as input attenuator switches in his initial versions of his Cosmos Scaler attenuator, unmeasurable distortion. In the end he used relays anyway https://www.audiosciencereview.com/forum/index.php?attachments/dsc_1027-1-jpg.304240/

Back to that attenuator - probably it's not about distortion, but about whether this type of analog attenuator can further attenuate noise floor from a good DAC. If not, IMO no technical reason to avoid digital VC and complicate the design with these analog circuits.

Found an good Analogue Mux but cost 5€ (2,60€ 1500 Piece ) one Piece and has only 4 switches so 20€ for one Channel Volume Control
And you need additional Chips for Controlling no logic in there. Or one 16Bit I2C Expander for one Channel

Analogue Devices ADG1611 Ron = 1,1 Ohm
Minimum distortion: THD + N = 0.007%
Max Dual Supply +/-8V

SSM2404 not in Production anymore was also an good Switch.
Used them already Years ago for an Preamp for input switching with the PG2310 and OP8610 + BUF634 on Outputstage. One Channel for Preamp and one for Headfone Out.
So used 2 Seperate Boards One for Left and one for right Channel.
Build it 2007 and still have them laying around unused \o/

At the End i can get the Omron G6K-2P for around 2€ a Piece if i buy >80 so there we again, using relais is probably the Best Compromise
THD+N wise

Robert