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General discussion/planning for "fully digital" DIY speaker - DAC boards, protocols, interfaces etc

xplo5iv

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The problem with that is keeping the multiple cards in sync as they all have different clocks. Pro audio adapters often have master clock connections so that you can keep multiple adapters in sync, but you won't find them on many stereo devices.
Does that actually matter in this case? At no point are you going to re-combine the signals in the digital domain, so it's only any effect on the timing/phase of the analogue signal that matters, and with identical async usb devices I would expect it to be irrelevant? E.g. even several cycles difference of mclk is a tiny phase shift in an audio signal.
I'll be honest, I've never tested it, would be interested to know if anyone ever has.
 

D!sco

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The clock is to keep phase consistent over a long period of time. The wandering effect will exaggerate over time depending upon individual chips. Silicon is ultimately a quality lottery and products will vary.
 

somebodyelse

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Does that actually matter in this case? At no point are you going to re-combine the signals in the digital domain, so it's only any effect on the timing/phase of the analogue signal that matters, and with identical async usb devices I would expect it to be irrelevant? E.g. even several cycles difference of mclk is a tiny phase shift in an audio signal.
I'll be honest, I've never tested it, would be interested to know if anyone ever has.
As a quick ballpark check take a single lasting 200s and clocks matched to 10ppm - by the end of the song the DACs will be 2ms apart, more than enough to mess with your mid/tweeter crossover. I don't have multiple DACs of the same model to test with, but the calc doesn't look encouraging for simple multi-card output like in alsa. There may be something else that uses ASRC to keep them in sync I suppose.
 

airborne

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Hello forum,

given all the available DIY boards and modules, it should be possible and not overlay complicated to build a DIY speaker that's pretty much fully digital. With that I mean: You connect it to a computer and you're done.

i suppose if the goal is to throw away money.

otherwise i would keep all electronics in a rack so that they can be repurposed in the future.

i will never build anything into a speaker - not even a passive crossover. everything will be kept external so that it can be modified, swapped etc.

i was dealing with a moron on another forum who built dual 18" subwoofers and internally paralleled them and then couldn't find an amp to drive them. i told him if he had any sense he would have given each woofer its own set of terminals.

what exactly is the benefit of locking things inside a box - just to screw yourself down the line ? absurd.

this isn't rocket science - the box is for holding drivers in place and acoustically loading them - each driver gets a set of terminals - everything else is external.

do you also lock the keys inside the car and then weld the doors to the frame just to keep it extra well organized ?
 
OP
Shefffield

Shefffield

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i suppose if the goal is to throw away money.

otherwise i would keep all electronics in a rack so that they can be repurposed in the future.

i will never build anything into a speaker - not even a passive crossover. everything will be kept external so that it can be modified, swapped etc.

i was dealing with a moron on another forum who built dual 18" subwoofers and internally paralleled them and then couldn't find an amp to drive them. i told him if he had any sense he would have given each woofer its own set of terminals.

what exactly is the benefit of locking things inside a box - just to screw yourself down the line ? absurd.

this isn't rocket science - the box is for holding drivers in place and acoustically loading them - each driver gets a set of terminals - everything else is external.

do you also lock the keys inside the car and then weld the doors to the frame just to keep it extra well organized ?

The goal is to learn.

I admit that part of the motivation for this is "because it's possible and unconventional". That doesn't mean that I throw away money though. Quite the opposite.

My design has always been modular. So what should stop me from making these modules serviceable? Just put a U-shaped aluminium channel at the back of the speaker, mount the electronics modules there and close it with a decorative piece of perforated sheet metal.

Modern DAC and amp modules are tiny. Why should I put them in bulky cases? Just to show off the nice cases on my hifi altar? Are you aware that in a conventional 19" home hifi device a massive chunk of the cost goes into the housing and not into the actual performance of that unit? Check the market for DIY amp modules and you'll find out that the housings for such amps cost quite a bit more than the amp boards themselves.


The aspect of clocking such a setup could be challenging. Another topic to look into. There are professional solutions to clocking, but I don't expect the common DAC modules to be compatible with that.
 

airborne

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The goal is to learn.

I admit that part of the motivation for this is "because it's possible and unconventional". That doesn't mean that I throw away money though. Quite the opposite.

My design has always been modular. So what should stop me from making these modules serviceable? Just put a U-shaped aluminium channel at the back of the speaker, mount the electronics modules there and close it with a decorative piece of perforated sheet metal.

Modern DAC and amp modules are tiny. Why should I put them in bulky cases? Just to show off the nice cases on my hifi altar? Are you aware that in a conventional 19" home hifi device a massive chunk of the cost goes into the housing and not into the actual performance of that unit? Check the market for DIY amp modules and you'll find out that the housings for such amps cost quite a bit more than the amp boards themselves.


The aspect of clocking such a setup could be challenging. Another topic to look into. There are professional solutions to clocking, but I don't expect the common DAC modules to be compatible with that.

yes housings have cost but amplifiers go up to 8 channels per housing in various wattages from about 100W to 1,000W per channel X 8 channels. i have seen class AB ( QSC ), class D ( Crown, Powersoft ) and even class TD ( Lab Gruppen ) amps in 8 channels. if you're using a 3-way you can bridge 2 channels into the woofer thus for a pair of 3-ways you use all 8 channels in a 8 channel amp.

you then need one rackmount soundcard with 8 channel output ( these are very common ).

two housings total.

you could certainly pull it off your way - but what if you later decide to change something ? with a rack it would be literally ZERO effort. with your setup it might require re-engineering everything from scratch.

with a rack you could literally sell your amp or soundcard on Ebay whenever you want and replace it with a different one on a whim.

if it is simply not DIY enough for you - why not make the chassis yourself ? but make it rackmount so that it plays well with everything else and not locked to some speaker that 2 years from now you will want to upgrade.

or how about this ! find an electronics repair shop in your area and see if you can buy from them a chassis from something they couldn't fix for like $10 and use that ...

im sure they would also give you a bulk discount such that for $100 you would be able to fill your entire car with empty steel cases from amps etc ...
 
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Razorhelm

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You might find my system interesting.

I converted some LS50's to active with dual subs using a raspberry Pi running camilladsp and I love how it sounds!

Simpler than some of the proposed systems here but it works well.

 

airborne

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You might find my system interesting.

I converted some LS50's to active with dual subs using a raspberry Pi running camilladsp and I love how it sounds!

Simpler than some of the proposed systems here but it works well.


how are you finding camilladsp ? it was recommended to me as a way to save money by not having to buy a dedicated crossover box ( i have the Behringer DCX but it makes scary pops when you change settings ) ...

the person who recommended camilladsp said it was more painful to use than Equalizer APO which drove me a little mad initially but after i got used to it - it's fine.

i found HornResp initially infuriating as well but after getting used to it - it's fine.

basically all these free programs just don't seem go give a sh1t if their interface makes any sense to anybody but the person who created them ... they aren't getting paid to do it so it's your problem figuring out how it is supposed to work.

so how does camilladsp fit into this ? would you use it on a serious system or go with a professional solution-in-a-box type deal ?

do you feel like it has some unacceptable shortcomings versus something like Q-Sys or even something simple like DBX DriveRack or MiniDSP ?
 

Razorhelm

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I would say camilladsp is very good the author has made a massive effort with the documentation, so you can sit down and work it out. I think it is logical, you create a config file and then the program applies the steps you have described, it even has useful error messages most of the time.


I think a skilled linux user could make a professional solution with it, it's stable and robust if you know the linux parts, start on boot, auto restart etc. I however do not have these skills!

For a serious personal system definitely, mine works great and if Linux does anything weird I remote in, restart and I'm back to working happily (I used to have an issue with camilladsp quitting if I left it on for days but I installed a fresh copy of Pi OS and now it has been happily running for weeks)

I have had no pops, static, etc I did my testing with cheap speakers and I have a protective capacitor on the tweeter.
 

airborne

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I would say camilladsp is very good the author has made a massive effort with the documentation, so you can sit down and work it out. I think it is logical, you create a config file and then the program applies the steps you have described, it even has useful error messages most of the time.


I think a skilled linux user could make a professional solution with it, it's stable and robust if you know the linux parts, start on boot, auto restart etc. I however do not have these skills!

For a serious personal system definitely, mine works great and if Linux does anything weird I remote in, restart and I'm back to working happily (I used to have an issue with camilladsp quitting if I left it on for days but I installed a fresh copy of Pi OS and now it has been happily running for weeks)

I have had no pops, static, etc I did my testing with cheap speakers and I have a protective capacitor on the tweeter.

i had Linux for like a week 20 years ago and it felt like some kind of torture chamber for me ...

my idea is to build a rackmount HTPC running Windows 10/11 and put it in the same rack with the amps ...

then in the same rack install a USB ( or better ) audio interface with 8 or more output channels and run the amps off of those channels ...

so the PC would do double duty - it would be the source for music and movies and also the DSP ...

however i want to be able to also use TV as a source because that results in better picture quality for whatever reason ... but there are some scenarios where PC has to be used instead ...

so i want to be able to play video from either PC or TV and have Camilla do the DSP thing and have the sound come out from the USB ( or whatever ) interface and to the amps ...

what do you think ?

i'm not touching Linux that is 100%.
 

Razorhelm

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I know camilladsp can run on windows but it is not something I have tested myself. I think the tricky bit would be switching between the tv input and pc, if it was just pc audio I think it would be relatively easy. You would need to input the tv audio into the pc and route it through camilladsp, I have heard of people using a virtual cable to do this but I have no experience of this.
 
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Shefffield

Shefffield

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You might find my system interesting.

I converted some LS50's to active with dual subs using a raspberry Pi running camilladsp and I love how it sounds!

Simpler than some of the proposed systems here but it works well.


Very interesting!

I even thought about getting a pair of the KEF drivers myself and building something around them. I know they're good.

And Camilla DSP is also interesting. Back in 2009..10 when we built Zoé we used BruteFIR for convolution. I do like it because I am a Linux guy for almost 20 years now, and it is finished software that appears to be pretty bug-free now. However, setting it up can be cumbersome, modern GUI convolvers are definitely more accessible.
 

somebodyelse

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How does

Is there anyone who dared to do this? If Sonos did it, it should be possible to do this :D
Not that I know of, at least not in a diy friendly way. On wired networks PTP works well (µs level), but it gets upset by WiFi and power line networking. NTP and the similar method used by gstreamer's original network time sync apparently outperform PTP in those networks, but it's in ms which won't really cut it for crossovers or stereo.
https://github.com/ford-prefect/gst-sync-server
https://arunraghavan.net/2017/01/quantifying-synchronisation-oscilloscope-edition/
https://coaxion.net/blog/2015/05/ptp-network-clock-support-in-gstreamer/
I don't know if Sonos have found a better time sync method at the network level, or whether they're using something lower level like the nonstandard things the access point manufacturers were doing to make proprietary meshes. It's probably covered in one of their patents if you can decipher the legalese and obfuscation. Using a non-wifi sync beacon of some sort could also be an option. The GPS 1PPS signal isn't a great example for indoors, but its pulse start should sync to something like 100ns.
 

dc655321

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Not that I know of, at least not in a diy friendly way. On wired networks PTP works well (µs level), but it gets upset by WiFi and power line networking. NTP and the similar method used by gstreamer's original network time sync apparently outperform PTP in those networks, but it's in ms which won't really cut it for crossovers or stereo.
https://github.com/ford-prefect/gst-sync-server
https://arunraghavan.net/2017/01/quantifying-synchronisation-oscilloscope-edition/
https://coaxion.net/blog/2015/05/ptp-network-clock-support-in-gstreamer/
I don't know if Sonos have found a better time sync method at the network level, or whether they're using something lower level like the nonstandard things the access point manufacturers were doing to make proprietary meshes. It's probably covered in one of their patents if you can decipher the legalese and obfuscation. Using a non-wifi sync beacon of some sort could also be an option. The GPS 1PPS signal isn't a great example for indoors, but its pulse start should sync to something like 100ns.

Distributed clock synchronization is tricky business. Not necessarily talking about wall-time here…

If the source is accessible (?), Chromecast would be a good place to look, or even outright use as a starting point.
 

julbo

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Same boat, looking to active drive a Directiva R1 design and trying to figure out the best way.
I've ordered a SY-DAP2002 for experimentation purposes, it integrates a ADAU 1701 DSP which is similar to the DSPs found in the Hypex PAs.
Might try a DSP board with ADAU 1452 and a codec board, it is a more powerful DSP enabling FIR filters - xover/eq experimentation and room correction
The end target is a clean and spartan look in my living room, WAF has no tolerance with gear racks and wires. I'm aiming towards two daisy chained FA123 with a toslink interface to my venerable (and still kicking) Squeezebox Touch
I do not trust my PC to xover, I have had power outages kill computing and display gear so most of my valuable stuff runs off UPS now.
Wireless audio as in the WISA sense piques me to try, for now I assume wired connection between the FA123s
Initially I thought of minidsp HD + 4-ch Hypex 250 amp, more flexible and has Dirac potential but defeats WAF
Anyway, I'm also open to suggestions. Plan to make a learning adventure out of this :)
 

airborne

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Same boat, looking to active drive a Directiva R1 design and trying to figure out the best way.
I've ordered a SY-DAP2002 for experimentation purposes, it integrates a ADAU 1701 DSP which is similar to the DSPs found in the Hypex PAs.
Might try a DSP board with ADAU 1452 and a codec board, it is a more powerful DSP enabling FIR filters - xover/eq experimentation and room correction
The end target is a clean and spartan look in my living room, WAF has no tolerance with gear racks and wires. I'm aiming towards two daisy chained FA123 with a toslink interface to my venerable (and still kicking) Squeezebox Touch
I do not trust my PC to xover, I have had power outages kill computing and display gear so most of my valuable stuff runs off UPS now.
Wireless audio as in the WISA sense piques me to try, for now I assume wired connection between the FA123s
Initially I thought of minidsp HD + 4-ch Hypex 250 amp, more flexible and has Dirac potential but defeats WAF
Anyway, I'm also open to suggestions. Plan to make a learning adventure out of this :)

in the grand scheme of things it could have been worse

you could have been one of those people with transmission line loaded full-range speaker running off a tube amp and a vinyl turntable ... perhaps with alnico magnets and silver wires just to be safe

i'm going to go ahead and allow you people to proceed with this endeavor LOL

because it would be wrong to nit pick over the details - at least you aren't those people ...

can't demand the same brutal efficiency of others as i do of myself ...
 

tinnitus

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Hello Axel,
Integrating everything into the speakers is not flexible enough for me.

My system is designed to be as digital as possible. My modular speakers in concrete housing have nothing but drivers and wiring. Via various combinations I have now arrived at the following system.

Controlpoint on the smartphone is BubbleUpnP.

The player/renderer(upmpdcli) and the DSP software(CamillaDsp) run on a Raspberry3b+ (Raspbian Bullseye).
A streamer such as the Yamaha wxc50 with digital pre output can also be used as a player, in which case you also need the HIFIBerry DIGI IO+ card for the Raspberry to have an SPDif input. Unfortunately the driver for this card is "very weak".

CamillaDSP filters the crossovers and room correction with ((Acourate)) FIR filters (65K taps). For me, only 4 output channels are necessary. However, I have also tried this with 8 channels and it works well.

With the next module, the DAC, there is not so much real DAC choice.
There is the Essence Evolve II-4K, a DAC with HDMI input. Another HDMI DAC (8 channel) is the X6000K 7.1 from suptronics, which is unfortunately no longer manufactured :(
As an alternative, there are the audio interfaces from MOTU Focusrite etc. available. I use the Focusrite Scarlett 4i4 and 18i20. The ASUS Xonar U7 has too much noise.

The choice of power amplifiers is virtually "infinite". I use the Aiyima A07 for the small system with 2 woofers per way. For the next level with 4 woofers, an IMG Line 2000D.

This has been running for some time now and there have been no faults with the DSP that have affected the drivers. I have been using CamillaDSP since the earliest 0.XX versions. Here are a few pictures of what it looks like.

IMG_20220130_161627.jpgIMG_20220212_141812.jpgIMG_20220130_151023.jpgacourateTest-ripol-1x2buero (2).jpg
 

airborne

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Hello Axel,
Integrating everything into the speakers is not flexible enough for me.

My system is designed to be as digital as possible. My modular speakers in concrete housing have nothing but drivers and wiring. Via various combinations I have now arrived at the following system.

Controlpoint on the smartphone is BubbleUpnP.

The player/renderer(upmpdcli) and the DSP software(CamillaDsp) run on a Raspberry3b+ (Raspbian Bullseye).
A streamer such as the Yamaha wxc50 with digital pre output can also be used as a player, in which case you also need the HIFIBerry DIGI IO+ card for the Raspberry to have an SPDif input. Unfortunately the driver for this card is "very weak".

CamillaDSP filters the crossovers and room correction with ((Acourate)) FIR filters (65K taps). For me, only 4 output channels are necessary. However, I have also tried this with 8 channels and it works well.

With the next module, the DAC, there is not so much real DAC choice.
There is the Essence Evolve II-4K, a DAC with HDMI input. Another HDMI DAC (8 channel) is the X6000K 7.1 from suptronics, which is unfortunately no longer manufactured :(
As an alternative, there are the audio interfaces from MOTU Focusrite etc. available. I use the Focusrite Scarlett 4i4 and 18i20. The ASUS Xonar U7 has too much noise.

The choice of power amplifiers is virtually "infinite". I use the Aiyima A07 for the small system with 2 woofers per way. For the next level with 4 woofers, an IMG Line 2000D.

This has been running for some time now and there have been no faults with the DSP that have affected the drivers. I have been using CamillaDSP since the earliest 0.XX versions. Here are a few pictures of what it looks like.

View attachment 194983View attachment 194982View attachment 194984View attachment 194985

i like your little rack - very cool !

when using computer for filter / XO how low can you go with FIR filters ?

i know with off the shelf FIR boxes you run out of taps pretty quickly as you try to approach bass - but what about a full blown windows computer for example ?

could i for example mix sealed and vented subwoofers in the same system an FIR EQ the phase of them so they sum properly ?

or would i be adding so much delay at this point that i would get lip sync issues when watching movies ?

is there a way to delay the picture somehow ?
 

tinnitus

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My XO starts with 20Hz up to 20kHz. The Filter generation is done with a Windows PC (Acourate runs only on Windows).
The Convolution with this Filters can be done with DSP Software also on a RPI3B+. The latency of 65k taps is over 700ms.
Therefor not usable for Videos. You can convert the Acourate filter to minimum phase and reduce latency, but you lost the phase correction,
or you can reduce the filter length and reduce the frequency interval.
There is no lucnch for free, as Uli said. I think you can filter different Subs with linear Phase FIR Filter.
And I don't know of any video delay system for home theatre applications. I use my Filters only for Audio ;)
 
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