Raspberry Pi 5 and CM5 as players and convolvers with lotsa analog ports

[john61ct]

I want to get into Raspberry Pi audio in a big way, but total noob here.

I have no interest in AVR decoding or expensive closed-algorithm hardware DSP boxen.

I'm excited by the power of Pi5 and now even more by the CM5's modular approach, after seeing that is the HLC platform!

Please, those with rPi experience, help me choose the extra "HATs" and other high SQ add-ons both for RPi5 and CM5 also if you are familiar, ideally with purchase links suitable for ordering in / to the US.

SQ is a priority, but not looking for the "best" gear costing hundred$, past audible improvements, just "decent, great value" level.

Shortcut links to recommended "getting started" HowTo's, blogs etc would also be much appreciated, especially if relevant to this early BoM, "building my shopping list" stage.

These hosts will (in turns) host CamillaDSP and Hang Loose as standalone, maybe other convolvers for learning,

and also connect to "Pico 2" gadgets, primarily for testing DSPi

Likely not act so often as player / renderer but would be nice to also test the main VST platforms.

I do want to be able to easily do ABX testing, and also "in production" route / switch between different modes like "transparent stereo" for music, "multichannel immersive" for testing / learning, so again, "open" protocols and flexible modularity are critical.

My current signal processors and preamps and power amps and sources are all RCA analog I/O only (hence Lotsa ports)

and I will be mostly be using using S/PDIF Coax for DACs and any new digital components

but I want to also route input from / through Wiim Ultra (analog RCA + TOSlink and USB out).

I will occasionally watch films from a PC so I can insert delay on video if latency gets high. My son does game, if that can be accommodated without much disruption.

I saw Sentinel Core carrier for CM5 that allows a standard full PCIe board in a stock ITX case WOW for Lotsa Ports!

I'll likely need 12+ analog channels, so I'm looking at buying up OG bargain interfaces, especially with ADAT expansion 8 I/O per breakout box - but I'm NOT looking to deal with those here please.

I want to focus here AMAP on just Raspberry Pi, limit other discussion tangents, so plan to only post other use case background / context info as needed for revelance to that main topic

Never mind RAM, storage, M.2 connections to external card enclosures, regular PC / IT stuff.

But suitable RaspberryPi enclosures are critical once the HATs etc are selected, I need robust boxen - parts of the system will be used mobile / off grid...

I know I'm asking a lot here, so TIA and thanks for reading so far

I realise I'm entitled to bupkis, please just advise as/when / however much you're willing to

and hopefully the knowledge / links collected will help many others...

 

[welwynnick]

I would start by reading the threads started by mdsimon2 and Keith_W.

 

[john61ct]

Got a DM reco for the HiFiBerry DAC8x

8-channel output HAT designed for Pi 5

also there is the HiFiBerry ADC8x for inputs.

Seems there are OS issues, may ? require? Raspberry Pi OS, overlay? "hifiberry-dacplus-std"

Apparently will also work with a standard CM5 carrier board that supports HATs

 

[charlielaub]

The sound quality is 100% dependent on the audio input and output device, e.g. ADC and DAC. It has nothing at all to do with the software or computing hardware, assuming you are not doing anything stupid.

I use small Linux machines like the Pi platform or a mini PC to do DSP in software, and have been doing that for 10-15 years now. I use a USB pro-audio interface and whatever computer. Since I only use IIR processing the CPU requirements are very modest. I have used e.g. Pi 3B+ and that is overkill even for large multi-way crossovers.

If you desire FIR processing, the best and most popular software out there today is CamillaDSP. If you are OK with IIR processing (analog like filters) I wrote my own software called GSASysCon that is on GitHub. Whatever you use, focus your efforts on finding a very high performance audio I/O unit. HATs are OK but not as good as a very good DAC.

 

[amper42]

"HATs are OK but not as good as a very good DAC."
^
So true!

 

[Bland_username42069]

It’s a lot less hassle, way cheaper, and far neater just to buy a secondhand avr for a couple of hundred dollars

 

[john61ct]

I wrote my own software called GSASysCon that is on GitHub. Whatever you use, focus your efforts on finding a very high performance audio I/O unit. HATs are OK but not as good as a very good DAC.

Yes I am very familiar with your IIR software, which I will try to get to testing once I have working hardware.

and yes I am accumulating very high SQ interfacii / AD / DA I/O "lotsa ports" inexpensively that I will first be integrating / testing on the PC side, involving firewire and PCIe

as with very high port counts I simply cannot afford the modern USB interfaces at high SQ.

I prefer to not get into that here.

What I am asking for in this thread however, is written in the OP.

Beyond just the RPi5 and CM5 themselves, what HATs do you recommend ?

Looks like 6-8 analog ports in and out is the limit before going to PCIe boards? That would be enough to get me started learning.

Cases to enclose everything?

PSU?

What else?

And / or

>> Shortcut links to recommended "getting started" HowTo's, blogs etc would also be much appreciated, especially if relevant to this early BoM, "building my shopping list" stage.

 

[john61ct]

It’s a lot less hassle, way cheaper, and far neater just to buy a secondhand avr for a couple of hundred dollars

Sorry I was not more clear, I am not looking for that, at all. The point is my learning curve, not aesthetics or avoiding hassles.

I will happily save up for more expensive stuff necessary to that end.

 

[john61ct]

So true!

Good value cost per port is my target

>> not looking for the "best" gear costing hundred$, past audible improvements, just "decent, great value" level.

 

[MCH]

Got a DM reco for the HiFiBerry DAC8x

8-channel output HAT designed for Pi 5

also there is the HiFiBerry ADC8x for inputs.

Seems there are OS issues, may ? require? Raspberry Pi OS, overlay? "hifiberry-dacplus-std"

Apparently will also work with a standard CM5 carrier board that supports HATs

The hifiberry is probably one of the best value per channel options, but will never give you the 12+ channels you want. What you need is a USB interface. I.e. Motu ultralite mk5, you have plenty of information about it in the camilladsp tutorial you mention.

 

[john61ct]

The hifiberry is probably one of the best value per channel options, but will never give you the 12+ channels you want.

Yes I now know that. Again, just for learning purposes for now.

If I can might test going modular, e.g. one unit for Left, another for Right, a third for the mono channels...

> What you need is a USB interface

Maybe not, we'll see. I'd love the convenience, but so far trying to stay under $20-25/port.

 

[john61ct]

OK, HiFiBerry multi-channel audio HATs

I see HiFiBerry DAC8x two versions, specifically designed for the Raspberry Pi 5

Raspberry Pi Shield HiFiBerry (consumer) DAC8X $65
8x SE outputs via 4x 3.5mm jacks
2.1 Vrms

Raspberry Pi HiFiBerry Studio DAC8X $90
8x balanced via DB25
4.2 Vrms

both work with the CM5, provided it is using a standard CM5 carrier board that supports HATs and runs Raspberry Pi OS

Since I want "SE + balanced" I guess the Studio version - although an AES59 TASCAM layout TRS patchbay / breakout snake costs like $40+ ?

Add-on 8x analog input channels ADC
HiFiBerry ADC8X $70

 

[john61ct]

requires 64-bit Raspberry Pi OS (Bookworm) and
HiFiBerry DAC+ Standard (DAC+ Std) overlays
PCM512x & I2S, hifiberry-dacplus-std
dtoverlay=hifiberry-dacplus
alsamixer, disables HDMI audio
configure GPIO pins

may not work with Ubuntu

Is this a potential problem?

can't use Moode OS?

I assume HiFiBerryOS will be compatible

Audiophile Linux (AP-Linux, based on Arch Linux) ?

 

[MCH]

If I can might test going modular, e.g. one unit for Left, another for Right, a third for the mono channels...

You cannot do that. The hifiberry gets the audio signal from the raspberry pi i2s, and this is limited to 8 channels. You cannot just plug 3 hifiberries to get more channels.

 

[john61ct]

Separate RPI5s

I am intending to use them as standalone convolvers, working in "passthrough" mode with the music renderer / player on a different device upstream.

Something like Gsonic if needed to ensure perfect synchronization?

 

[charlielaub]

Yes I am very familiar with your IIR software, which I will try to get to testing once I have working hardware.

and yes I am accumulating very high SQ interfacii / AD / DA I/O "lotsa ports" inexpensively that I will first be integrating / testing on the PC side, involving firewire and PCIe

as with very high port counts I simply cannot afford the modern USB interfaces at high SQ.

I prefer to not get into that here.

What I am asking for in this thread however, is written in the OP.

Beyond just the RPi5 and CM5 themselves, what HATs do you recommend ?

Looks like 6-8 analog ports in and out is the limit before going to PCIe boards? That would be enough to get me started learning.

Cases to enclose everything?

PSU?

What else?

And / or

>> Shortcut links to recommended "getting started" HowTo's, blogs etc would also be much appreciated, especially if relevant to this early BoM, "building my shopping list" stage.

If you want to stick with a HAT for the Pi, the DAC8x from HiFiBerry is not bad. Make sure to ask if you can use the input HAT from them at the same time as the output one... I am not sure that they can be used together due to how the hardware is configured.

 

[john61ct]

If you want to stick with a HAT for the Pi, the DAC8x from HiFiBerry is not bad. Make sure to ask if you can use the input HAT from them at the same time as the output one... I am not sure that they can be used together due to how the hardware is configured.

I believe that's handled via

Add-on 8x analog input channels ADC
HiFiBerry ADC8X $70

 

[charlielaub]

Separate RPI5s

I am intending to use them as standalone convolvers, working in "passthrough" mode with the music renderer / player on a different device upstream.

Something like Gsonic if needed to ensure perfect synchronization?

GSASysCon can stream from one computer to N other computers over anything that carries TCPIP and when you can allow remote SSH login. You can do this kind of streaming over WiFi if the signal is good everywhere but will have better success over wired ethernet. GSASysCon uses Gstreamer, which has built in synchronization mechanisms.

 

[john61ct]

Thanks looks great!

But I want my underlying architecture in the "learn / experiment" phase, to be as open as possible to all the available DSP software tools even (OT) stooping to using windoze on the big rig.

After I am au fait with GSASysCon, if I see IIR-only filtering is sufficient for some parts of the "production" system, then maybe those flexible transport options will be the way to go for between those parts.

Can it handle just doing phase / delay tuning? I plan to try just active analog first for the FR magnitude part of bass management.

Analog crossovers, only using DSP to treat issues the analog system cannot fix

If I have Main L/R comprised of a mix 2- 3-way speakers + midbass couplers + stereo trueSubs all co-located Those subs easily switched to mono if that turns out to test better, there are also other trueSubs already in mono thus freely placed, can be treated as a single sub-group in the DSP...

www.audiosciencereview.com

My understanding is, if I do need DSP for certain crossovers, FIR becomes more likely needed at low frequencies?

Same with per-speaker "as anechoic as possible" compensation EQ?

I don't care about overall latency.

 

[john61ct]

Can Gstreamer be used for bare signal transport, simply routing between RPI5 nodes independent of the convolver software in use?

Or better to stick to LV2?

Are there shims to route to your software on just select nodes, from LV2 input over the network?