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

[airborne]

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

what is this Acourate stuff - i never heard about it.

any link you want to share ?

 

[tinnitus]

what is this Acourate stuff - i never heard about it.

any link you want to share ?

AudioVero

AudioVero - official website

www.audiovero.de

Acourate User Group - Index page

the german audio pocket knife

 

[airborne]

AudioVero

AudioVero - official website

www.audiovero.de

Acourate User Group - Index page

the german audio pocket knife

my OCD would never let me run a site with a fuzzy banner like that ...

literally hurts to look at as well ...

may have to browse that forum later though ...

thanks.

 

[maxxevv]

There is a very detailed discourse on how it was done using an Okto 8 DAC by @dualazmak over at his thread.

Definitely worth a long read if you want to go down this route.

Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC

Edit: Please find here (on this thread) and here (remote independent thread post) the Hyperlink Index of this thread and some of my related posts in remote threads ************************************************** Edit on August 8, 2023 Jus for your reference,,, - The latest system setup of my...

www.audiosciencereview.com

 

[airborne]

There is a very detailed discourse on how it was done using an Okto 8 DAC by @dualazmak over at his thread.

Definitely worth a long read if you want to go down this route.

Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC

Edit: Please find here (on this thread) and here (remote independent thread post) the Hyperlink Index of this thread and some of my related posts in remote threads ************************************************** Edit on August 8, 2023 Jus for your reference,,, - The latest system setup of my...

www.audiosciencereview.com

very interesting.

the reason i want to go windows route is because:

1 - a windows PC can do many things that are useful other than just act as a crossover and even a video source - such as post on this forum for example !
2 - i don't want to invest in hardware that will be obsolete in 5 years - with a PC you just upgrade the software
3 - windows PC has the flexibility to deal with audio and video so in theory it should be possible to delay the video to match the latency of FIR filters whereas audio-only solutions like Q-Sys, as powerful as they are, can never delay the video signal ...
4 - you need a PC or otherwise a computer to configure Q-Sys or Mini-DSP anyway, so why not already use it as the crossover ...

really now that i think of it i don't see how anything else even makes any sense at all and why i even considered other options ...

to be fair with the exception of a single vote for Q-Sys ( mark100 from diyAudio ) literally everybody told me to go the PC route. not one person recommends MiniDSP anymore and even MiniDSP themselves on their own forum say that their system will never be as advanced as Q-Sys because they aren't targeting the high-end market. mark100 said he upgraded from MiniDSP to Q-Sys many years ago and would never go back.

one of the biggest selling points of Q-Sys apparently is you can simulate filters on the PC and try them on the PC before downloading them to the Q-Sys "core" ... well if you are already running them on the PC why download them anywhere ? just keep running them there LOL.

i understand for prosound use you wouldn't want to drag around 50 desktop computers with you on a tour - you would want to use one computer to program 50 Q-Sys "cores" and use that instead ...

but for home use ? what is the point ? i asked mark100 how he controls his Q-Sys to adjust volume etc and he is doing it with his laptop ... so he's using a windows computer ANYWAY ...

i say just build a rackmount home theater PC and call it a day ...

as i see it a Q-Sys "core" is basically a rackmount PC audio interface with a mini PC built in ... but this mini PC doesn't do anything useful except run the audio interface ... it runs some kind of Linux OS ...

what's the point of crippling a computer like this ? use a fully functional computer instead - it doesn't cost that much more and now you can do anything you want with it - like hook up display, keyboard and mouse directly and install any software you like not just the one piece of software that it came with.

reminds me of when my cousin brainwashed me into getting "roku" for grandma so she could watch TV in her language ... the logic was a computer would be too complicated for grandma to use ... well i later migrated grandma to the computer and she's doing fine at almost 100 years old and the roku is in the trash ...

i don't see how Q-Sys for home use is any different than roku ... except it costs 50 times more ...

maybe it's some kind of a flex like - look how expensive my setup is ... mark100 isn't running the entry level "core" either ...

 

[tinnitus]

I forgot to explain the silver button on the front side off the rack.
With this button you can start all modules (rpi(player,dsp), dac, amp) and also with a longer tip shut down the rpi switch off the rpi, dac and amp.
Can this also be realised with a windows pc?

 

[maxxevv]

very interesting.

the reason i want to go windows route is because:

1 - a windows PC can do many things that are useful other than just act as a crossover and even a video source - such as post on this forum for example !
2 - i don't want to invest in hardware that will be obsolete in 5 years - with a PC you just upgrade the software
3 - windows PC has the flexibility to deal with audio and video so in theory it should be possible to delay the video to match the latency of FIR filters whereas audio-only solutions like Q-Sys, as powerful as they are, can never delay the video signal ...
4 - you need a PC or otherwise a computer to configure Q-Sys or Mini-DSP anyway, so why not already use it as the crossover ...

Which is what essentially was done in that thread. Just use modular amps instead of AVR's if you do not have any need for AV codex decoding.

 

[dualazmak]

There is a very detailed discourse on how it was done using an Okto 8 DAC by @dualazmak over at his thread.

Hello maxxevv and OP airborne,

Thank you for your introduction and interests on my project thread.

OKTO DAC8PRO is really amazing and I fully enjoy the full 8-channel sync DAC operations with amazingly excellent sound quality. One problem in getting DAC8PRO would be still-small availability of the units from OKTO Research; now they have too many backorder and they tentatively stops (again!) accepting purchase requests.

I recently had an interesting discussion on the thread entitled "Why aren't we pushing for more 4-8 channel DACS for a quality Stereo setup", and I (we) could confirm (throughout this post to this post) that, as an alternative for DAC8PRO, FOCUSRITE Scarlett 18i20 2nd gen (and 3rd gen) (CS4272 [x4] + CS4392) as well as MOTU UltraLite Mk5 (two ES9026pro) supports simultaneous sync 10-channel DAC processes, even though the total sound quality would be very slightly inferior to OKTO DAC8PRO.

 

[airborne]

Hello maxxevv and OP airborne,

Thank you for your introduction and interests on my project thread.

OKTO DAC8PRO is really amazing and I fully enjoy the full 8-channel sync DAC operations with amazingly excellent sound quality. One problem in getting DAC8PRO would be still-small availability of the units from OKTO Research; now they have too many backorder and they tentatively stops (again!) accepting purchase requests.

I recently had an interesting discussion on the thread entitled "Why aren't we pushing for more 4-8 channel DACS for a quality Stereo setup", and I (we) could confirm (throughout this post to this post) that, as an alternative for DAC8PRO, FOCUSRITE Scarlett 18i20 2nd gen (and 3rd gen) (CS4272 [x4] + CS4392) as well as MOTU UltraLite Mk5 (two ES9026pro) supports simultaneous sync 10-channel DAC processes, even though the total sound quality would be very slightly inferior to OKTO DAC8PRO.

everybody uses MOTU but when i used MOTU once my $700 soundcard died after about a year and i am still butthurt about that and will never use MOTU again. i also found their software painful.

haven't had any problems with my Focuscrite interface even though it's a more modest one than what MOTU was.

if i can choose between MOTU and Focusrite i'm definitely going with Focusrite.

i don't think DAC quality matters as long as it's not Behringer or some other fake Chinese crap.

any REAL studio equipment should be clean enough for playback use.

in a recording studio the signal paths may get long and complicated and equipment has to be very clean or the noise and distortion will add up ...

at home the signal path is short and simple so as long as you're using legit studio quality gear it shouldn't be an issue.

in other words if there is only a single D/A conversion in your playback chain and the DAC isn't a behringer or some other trash like that i think it should not matter too much what it is.

that said i never actually listened to my Focusrite - i always ran it through Benchmark DAC so i can't vouch for the sound quality though i assume it's good enough.

maybe a good idea to have some digital outputs so that if you can hear something wrong through maybe the tweeters or whatever you could add a dedicated DAC to just that one frequency band and run the rest ( subs, woofers etc ) from the interface directly.

i can see how it might be possible to hear some noise from the DAC through compression tweeters or 100 db / watt ribbons or something like that but definitely not through subs !

 

[dualazmak]

Hello OP airborne,

I essentially agree with you that almost all of the nice modern DACs have acceptable sound quality.

In comparison of FOCUSRITE Scarlett 18i20 2nd gen (and 3rd gen) (CS4272 [x4] + CS4392) and MOTU UltraLite Mk5 (two ES9026pro) as pure multichannel DACs, I myself prefer MOTU since it uses two of ES6026pro DAC chip which is almost identical to my beloved OPPO Sonica DAC (one ES9038pro) and OKTO DAC8PRO (one ES9026pro).

If you would really hesitate for MOTU (or FOCUSRITE) software, I believe you may use MOTU UltraLite Mk5 (or FOCUSRITE Scarlett 18i20) just as pure multichannel DAC with ASIO driver providing capable of 10-channel outputs without using MOTU or FOCUSRITE software; you may use other software XO-EQ (DSP), like EKIO I am using, for multichannel processing.

If needed you would please contact with @mdsimon2 since it looks he actually uses FOCUSRITE Scarlett 18i20 2nd gen and MOTU UltraLite Mk5, as we discussed from this post through this post on that remote thread.

 

[julbo]

I’d like to see a nicely built class d amplifier that runs off a pure digital input rendering the dac stage completely redundant. Something along the lines of TI’s new TAS6584, which also integrates some DSP capabilities

 

[voodooless]

I’d like to see a nicely built class d amplifier that runs off a pure digital input rendering the dac stage completely redundant. Something along the lines of TI’s new TAS6584, which also integrates some DSP capabilities

Why? Class D is not digital. Most solutions that offer digital input are mediocre at best. See here as well. There is however a Dutch startup that offers a digital input Class D driver IC that seems to offer very good performance, but so far, not many products that use it.

 

[airborne]

Why? Class D is not digital. Most solutions that offer digital input are mediocre at best. See here as well. There is however a Dutch startup that offers a digital input Class D driver IC that seems to offer very good performance, but so far, not many products that use it.

exactly class D is analog, just switching.

if you want a better sounding alternative to class D use class TD ( Lab Gruppen ).

i never heard class TD myself, but the real problem with class TD is that most if not all the amps are at least 1 kilowatt per channel which is subwoofer territory and class D is already ideal for subwoofers

this is why class TD is dying ... audiophiles are fine with class AB and prosound is fine with class D ... Lab ( who of course did NOT invent class TD ) wanted to do an amp that can do both at the same time but no audiophiles need to run tweeters at 1 kilowatt+ power.

i think the only real challenge left in audio is directivity and room interactions. i think it is trivial to produce perfect sound on-axis in an anechoic chamber. to produce even decent sound in a real room is almost impossible.

 

[julbo]

Why? Class D is not digital. Most solutions that offer digital input are mediocre at best. See here as well. There is however a Dutch startup that offers a digital input Class D driver IC that seems to offer very good performance, but so far, not many products that use it.

IMHO class D is more digital than analog similar to a SMPS, let aside the feedback loop. Roughly speaking class D is driving a digital waveform signal into the power stage, the information is in the (PWM) phase. An analog input signal is converted into a PWM signal that eventually goes into the power stage. An input digital signal (PCM) conversion to PWM in the digital domain is straightforward by two digital counters yielding zero loss.
The new TI chip looks good, albeit not as good as a 3255
I'm a mixed signal chip designer, zero experience with audio though

 

[voodooless]

if you want a better sounding alternative to class D use class TD ( Lab Gruppen ).

I doubt they will perform better than a Purify or Ncore amp, except for power, but who needs more for a home environment.

 

[voodooless]

IMHO class D is more digital than analog similar to a SMPS

https://www.researchgate.net/publication/242013327_All_amplifiers_are_analogue_but_some_amplifiers_are_more_analogue_than_others

 

[airborne]

IMHO class D is more digital than analog similar to a SMPS, let aside the feedback loop. Roughly speaking class D is driving a digital waveform signal into the power stage, the information is in the (PWM) phase. An analog input signal is converted into a PWM signal that eventually goes into the power stage. An input digital signal (PCM) conversion to PWM in the digital domain is straightforward by two digital counters yielding zero loss.
The new TI chip looks good, albeit not as good as a 3255
I'm a mixed signal chip designer, zero experience with audio though

the word "digital" refers to "digits" which means NUMBERS

digital audio is represented in numbers ( binary )

we can define *BIT* depth for a digital signal ...

nothing in class D is represented in numbers

there is literally nothing *digit* all about it

class D amp basically works similar to ANALOG radio - you have a carrier frequency and it gets modulated by signal ...

i guess the difference is class D uses a square wave ...

that's why they call amplifiers like class AB "linear" to differentiate them from "switching" amps ...

but "digital" is definitely not the word ...

SMPS is also not "digital" ... it is switching ... although there is diode switching in a so-called "linear" power supply as well ...

yeah we could use better terminology but calling either class D or SMPS "digital" is not something even professionals at marketing BS are comfortable with so it's definitely not OK for serious people ...

 

[airborne]

I doubt they will perform better than a Purify or Ncore amp, except for power, but who needs more for a home environment.

if a class TD was optimized for quality over power it might outperform the cleanest class D amps ...

after all Benchmark outperforms the cleanest class D amps ...

but Lab Gruppen is a prosound company so they focused on power ...

the downside of class TD is it requires heat sinking ... i estimate it is only 50% efficient versus 85% for class D ... though 50% is still a big improvement over class AB and even class H ...

basically class TD is efficient enough to deliver big power but not so efficient that you can just throw a module in a box and not worry about cooling.

Lab Gruppen amps have copper heat sinks and four 80mm fans, which is probably why nobody uses them anymore. everybody uses Powersoft now.

the Chinese are still making Lab Clones but obviously it takes time to rip off something - they are starting to come out with powersoft clones now as well.

 

[airborne]

https://www.researchgate.net/publication/242013327_All_amplifiers_are_analogue_but_some_amplifiers_are_more_analogue_than_others

also if you could build a digital amplifier it would suck.

because the job of amplifier is to interact with the load - not merely produce output.

powersoft class D amplifiers actually recharge their capacitors using energy extracted from the subwoofer driver just like how an electric car can charge the battery while coasting downhill or during braking.

DACs drive resistive loads. amplifiers drive reactive loads.

Powersoft and B&C jointly developed the 21" iPal subwoofer driver that has something like 100 to 1 ratio of max to min impedance - it is almost a purely reactive load - you need a special powersoft module to drive this subwoofer. you can't even drive it with a regular amplifier let alone a gigantic power dac.

 

[voodooless]

As I said before: there is one exception at this moment: https://www.axign.nl/