I have been thinking and looking around for the last couple of days, thinking that things would have happened to make me go back to active XO setup 'on the cheap' again, but I can't really find what I'm looking for, so I'm hoping to get a discussion going, and maybe some good info will surface 
Here is the background story:
Some years ago I started experimenting with a setup with Win10 laptop, Foobar, EQ APO, and running HDMI to a surround receiver. This was functional, and very interesting to play around with and listen do different XO points, slopes, time alignments etc, but I guess there was some SQ limitations with the HDMI interface/receiver DAC/ Receiver amp stages.
I replaced the receiver with a AUSUS Xonar 6ch soundcard and three stereo amps (played around with several DIY amps). I was pretty happy with the SQ, but it was messy with cables everywhere, especially having a long USB cable from the laptop in the sofa funning to the sound card by the amps. I also missed having a remote for volume control. I had to use 'digital volume control' in the laptop which is not good for bit depth.. I even bought a relatively cheap 6ch volume control with remote, but the SQ/noise was a lot worse than with digital volume control.
I got tired of the cable mess, stacks of amps etc and bought a SMSL Sanskrit 2ch DAC feeding a single class A amp, and made passive XO's for my current DIY 3-way speakers (pretty complex and expensive to build those too).
I took an old laptop and installed Daphile on it, and remote control it via web-interface (using phone or laptop). The SQ went up a little (with some reservations), and installation has high WAF. The SMSL DAC has a volume control via remote, witch is also a big plus.
I have been testing various amps in this 'classic' 2ch setup, and feel that they do different things well. I like my JLH class A best, but it is a bit limited in bass control.
Now, some time later, I started to look at active XO solutions again. I thought prices would have gone down, and suitable products would be available.
Ideally I would like a USB sound card with volume remote and built in DSP and 4-6 channels output. I could just plug it in to the Daphile laptop, and it would be recognized as any 2-channel sound card. Then configure the DSP for XO and room correction to the 6 outputs, and run class A amp(s) for mid & tweeter, and some other amp for bass. Also thinking about building some new speakers, so it would come handy for that.
I could also use 2ch in and 4ch out, using active XO for bass/mid, and running passive XO between mids and tweeters. Most of the problems/cost with passive XO IMHO is with low XO frequencies.
I have found some cheap DSP boards, but they all seem to have analog in.
I don't much like the idea to use my USB DAC feeding a ADC and DAC on a separate DSP board. Then again comes the issue(?) with volume control, I would like it on the signal going to the amps. It seems it would be much nicer if the DSP had usb in, and analog volume control on the outputs.
So what are your thoughts? I guess I can't be the only person looking for something like this?
I'm on a budget, so I know there will be some compromises, just hoping to get some input on alternatives!
Here is the background story:
Some years ago I started experimenting with a setup with Win10 laptop, Foobar, EQ APO, and running HDMI to a surround receiver. This was functional, and very interesting to play around with and listen do different XO points, slopes, time alignments etc, but I guess there was some SQ limitations with the HDMI interface/receiver DAC/ Receiver amp stages.
I replaced the receiver with a AUSUS Xonar 6ch soundcard and three stereo amps (played around with several DIY amps). I was pretty happy with the SQ, but it was messy with cables everywhere, especially having a long USB cable from the laptop in the sofa funning to the sound card by the amps. I also missed having a remote for volume control. I had to use 'digital volume control' in the laptop which is not good for bit depth.. I even bought a relatively cheap 6ch volume control with remote, but the SQ/noise was a lot worse than with digital volume control.
I got tired of the cable mess, stacks of amps etc and bought a SMSL Sanskrit 2ch DAC feeding a single class A amp, and made passive XO's for my current DIY 3-way speakers (pretty complex and expensive to build those too).
I took an old laptop and installed Daphile on it, and remote control it via web-interface (using phone or laptop). The SQ went up a little (with some reservations), and installation has high WAF. The SMSL DAC has a volume control via remote, witch is also a big plus.
I have been testing various amps in this 'classic' 2ch setup, and feel that they do different things well. I like my JLH class A best, but it is a bit limited in bass control.
Now, some time later, I started to look at active XO solutions again. I thought prices would have gone down, and suitable products would be available.
Ideally I would like a USB sound card with volume remote and built in DSP and 4-6 channels output. I could just plug it in to the Daphile laptop, and it would be recognized as any 2-channel sound card. Then configure the DSP for XO and room correction to the 6 outputs, and run class A amp(s) for mid & tweeter, and some other amp for bass. Also thinking about building some new speakers, so it would come handy for that.
I could also use 2ch in and 4ch out, using active XO for bass/mid, and running passive XO between mids and tweeters. Most of the problems/cost with passive XO IMHO is with low XO frequencies.
I have found some cheap DSP boards, but they all seem to have analog in.
I don't much like the idea to use my USB DAC feeding a ADC and DAC on a separate DSP board. Then again comes the issue(?) with volume control, I would like it on the signal going to the amps. It seems it would be much nicer if the DSP had usb in, and analog volume control on the outputs.
So what are your thoughts? I guess I can't be the only person looking for something like this?
I'm on a budget, so I know there will be some compromises, just hoping to get some input on alternatives!
I´m sure the "HD" is a little bit better than the standard 2x4 but it might still be pretty noisy when using highly sensitivity drivers.
I find that low gain amps work best to avoid that and, as you seem to know, volume control after the minidsp (which i still don´t have/use).
The "4x10HD" has volume control (also before the final DAC-output as it seems) but haven´t read too many reviews about it and yes, these are more expensive.
Dayton DSP gets mixed reviews and only has analogue inputs.
I find that low gain amps work best to avoid that and, as you seem to know, volume control after the minidsp (which i still don´t have/use).
The "4x10HD" has volume control (also before the final DAC-output as it seems) but haven´t read too many reviews about it and yes, these are more expensive.
Dayton DSP gets mixed reviews and only has analogue inputs.
That combination was new to me!
Have to do some searching on that.. I'm thinking DAC choices for the RPi? Handling of different sample rates? Camilla DSP GUI etc..
RPi is unknown territory to me, and the learning curve would probably be steep.. The setup sounds complicated, and I don't know about performance/cost ratio? Hoping it would be good since it seems to require a lot of work to get working?
Do you think this setup would run with Daphile (I think it's Linux based)? From a quick search, the driver is for Win machines?
I could probably go to the RPI as player/streamer too, I guess it could do the same stuff as Daphile.
the rpi is set up as a USB gadget device with onboard DSP using camilla and after setup, you can feed it from any OS you like. USB in and USB out to a multi channel USB dac. so basically it acts as a sort of hardware plugin. then you can use whatever USB interface you want. camilla running on rpi4 is much more powerful than any of the DSPs that have been mentioned.
You then run daphile, or whatever player OS you want on any device you want. it sends 2 channel USB out to the gadget, it applies DSP and volume control and sends it onto your USB dac for conversion. (this is where I would do it, unless perhaps if your multichannel DAC has a volume control. then it would be a matter of what you prefer)
You then run daphile, or whatever player OS you want on any device you want. it sends 2 channel USB out to the gadget, it applies DSP and volume control and sends it onto your USB dac for conversion. (this is where I would do it, unless perhaps if your multichannel DAC has a volume control. then it would be a matter of what you prefer)
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This still leaves me without a remote volume control, and it does seem like a lot of 'research' is needed before it's up and running.
Come to think of it, maybe it's possible to do active XO DSP on the Daphile computer, then I could just dust off the Asus multichannel sound card and use the digital volume in Daphile kind of a 'remote volume control' since I use phone etc anyway to control it..
Come to think of it, maybe it's possible to do active XO DSP on the Daphile computer, then I could just dust off the Asus multichannel sound card and use the digital volume in Daphile kind of a 'remote volume control' since I use phone etc anyway to control it..
The gadget supports volume and mute control (via standard USB audio features). That means the USB host has the volume control available in a standard way. On gadget side the feature is available as a regular alsa mixer ctl, with ctl_notifications of value change.
Eventually CamillaDSP could track these volume change notifications (the alsa Rust crate Henrik uses has hooks to these methods Ctl in alsa::ctl - Rust) and either apply the volume to output channels (software volume), or control corresponding alsa mixer controls of the output soundcard (hardware volume).
As of channels - the USB gadget can handle up to 14 channels 192kHz/24bits. That would allow 8ch TrueHD input and e.g. 2x3way + 5x2way + 1xLFE Xover with an 18ch USB2 soundcard, provided RPi4 can handle the computing load (likely so for shorter filters).
As of switching samplerates - the gadget should support multiple samplerates in the upcoming kernel (5.16). CamillaDSP does not support switching samplerates on the fly (because each samplerate requires different filter coeffs), it would have to be solved somehow. I kind of believe Henrik will sort it out, eventually
Next step could be compositing the audio gadget with the existing network gadget and running the CDSP GUI in web browser of the playback computer, using link-local names (address like dsp.local).
Or an inexpensive OEM quad-core Intel Z8xxx tablet with USB-C and USB-A ports which supports the USB gadget mode too (at least my two models do). A streamlined browser on efficient Wayland with the CDSP UI could run on the tablet directly, making the device a smart DSP soundcard with 8"-10" touchscreen for configuration and level meters/spectrograms Intel CPUs are generally a bit more powerfull than RPi4 A72 cores, hopefully so in SIMD instructions.
Yes, the whole setup is not like daphile or moode - a single iso to copy and run, but all the individual components are almost finished. For now it is a nice playground for early adopters with some linux skills.
Eventually CamillaDSP could track these volume change notifications (the alsa Rust crate Henrik uses has hooks to these methods Ctl in alsa::ctl - Rust) and either apply the volume to output channels (software volume), or control corresponding alsa mixer controls of the output soundcard (hardware volume).
As of channels - the USB gadget can handle up to 14 channels 192kHz/24bits. That would allow 8ch TrueHD input and e.g. 2x3way + 5x2way + 1xLFE Xover with an 18ch USB2 soundcard, provided RPi4 can handle the computing load (likely so for shorter filters).
As of switching samplerates - the gadget should support multiple samplerates in the upcoming kernel (5.16). CamillaDSP does not support switching samplerates on the fly (because each samplerate requires different filter coeffs), it would have to be solved somehow. I kind of believe Henrik will sort it out, eventually
Next step could be compositing the audio gadget with the existing network gadget and running the CDSP GUI in web browser of the playback computer, using link-local names (address like dsp.local).
Or an inexpensive OEM quad-core Intel Z8xxx tablet with USB-C and USB-A ports which supports the USB gadget mode too (at least my two models do). A streamlined browser on efficient Wayland with the CDSP UI could run on the tablet directly, making the device a smart DSP soundcard with 8"-10" touchscreen for configuration and level meters/spectrograms
Intel CPUs are generally a bit more powerfull than RPi4 A72 cores, hopefully so in SIMD instructions.Yes, the whole setup is not like daphile or moode - a single iso to copy and run, but all the individual components are almost finished. For now it is a nice playground for early adopters with some linux skills.
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MiniDSP UDIO-8 and your own DACs
miniDSP UDIO-8 - Multichannel USB to AES-EBU interface
OKTO Research DAC8 (virtually impossible to source)
ExaSound 8 channel DACs (spendy)
exaSound Audio Design > Products > e38 Mark II 8-channel DAC
Danville Signal Processing (DSP) dspNexus and its predecessor (spendy)
dspNexus DSP Audio Processor | dspNexus DSP Audio Processor | Products
Various Focusrite Scarlett devices
Lynx HiLo
Hilo - Products - Lynx Studio Technology, Inc.
Wish there were more 8-channel DACs in the market.
miniDSP UDIO-8 - Multichannel USB to AES-EBU interface
OKTO Research DAC8 (virtually impossible to source)
ExaSound 8 channel DACs (spendy)
exaSound Audio Design > Products > e38 Mark II 8-channel DAC
Danville Signal Processing (DSP) dspNexus and its predecessor (spendy)
dspNexus DSP Audio Processor | dspNexus DSP Audio Processor | Products
Various Focusrite Scarlett devices
Lynx HiLo
Hilo - Products - Lynx Studio Technology, Inc.
Wish there were more 8-channel DACs in the market.
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Yes, multichannel DAC's of good quality seem rare and/or expensive..
I guess there is no easy way to use multiple 2ch DACs and get them synchronized in time? I guess just running multiple USB DAC's for bass/mid/tw, the delay would vary between them, and the relative delays would not be the same every time.
I guess if I had 2-3 USB DACs of the same kind, they would not even be properly identified either (a restart could send bass to the tweeters)..?
When it comes to Scarlett sound cards etc it seems people are having trouble using them as multichannel DAC's (drivers etc)?
If the Kubelik is limited to 44k1/16bit, I think it's not enough. I invested some money buying Hi-Res albums, I would like to be able to play back in that format.
I guess there is no easy way to use multiple 2ch DACs and get them synchronized in time? I guess just running multiple USB DAC's for bass/mid/tw, the delay would vary between them, and the relative delays would not be the same every time.
I guess if I had 2-3 USB DACs of the same kind, they would not even be properly identified either (a restart could send bass to the tweeters)..?
When it comes to Scarlett sound cards etc it seems people are having trouble using them as multichannel DAC's (drivers etc)?
If the Kubelik is limited to 44k1/16bit, I think it's not enough. I invested some money buying Hi-Res albums, I would like to be able to play back in that format.
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If the DACs are being fed I2S then there's no way they would become de-synchronized since the BCKs and LRCKs would be in common. With USB though the possibility of synchronization depends on the operating mode.
For hi-res content you'd want to make sure that the DSP in your XO wasn't the bottleneck - presumably you'd need double precision if the DSP was implemented in floating point as single precision would give zero headroom.
For hi-res content you'd want to make sure that the DSP in your XO wasn't the bottleneck - presumably you'd need double precision if the DSP was implemented in floating point as single precision would give zero headroom.
YES!!! Very exciting! A CamillaDSP addon-Box to be simply connected by USB!
I have browsed the net now for a while but couldn't find anything but conflicting and quite (out?)dated infos. This is a pity, because what you outline here is exactly would fit the needs and the interest of many CamillaDSP-ers.
So, could you help with some useful links or hints, please? E.g. how to set up the suited RPi'ns into gadget mode, or how to link CamillaDSP and the USB in_out's?
I could imagine that a concise and up-to-date howto, maybe here, maybe in new and dedicated thread, would be very well appreciated by the interested community.
The MiniDSP UDIO-8 uses either S/PDIF or EAS/EBU outputs to sync the paralleled downstream DACs.
By upstream software.
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Supposedly Apple's OS X has DAC Aggregating software. Haven't used it before and Master/Slave clocking may be required.
Combine multiple audio interfaces by creating an Aggregate Device
An Aggregate Device lets you use audio inputs and outputs from different devices at the same time with audio applications like Logic Pro, GarageBand, MainStage, and most other Core Audio-compliant applications.
Combine multiple audio interfaces by creating an Aggregate Device - Apple Support
Combine multiple audio interfaces by creating an Aggregate Device
An Aggregate Device lets you use audio inputs and outputs from different devices at the same time with audio applications like Logic Pro, GarageBand, MainStage, and most other Core Audio-compliant applications.
Combine multiple audio interfaces by creating an Aggregate Device - Apple Support
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+1.
Multichannels output towards standalone USB: If the XO is made in Mood with the embeded Camilla, what gadget do you need on or after the Rpi ? I assume one still want to use an asynch clock hat to get rid of the Rpi clock whatever an Okto Dac Pro 8 will perform it's own resampling/reclocking (my experience is multiple async in serie are beneficial -well, with a Fifo-)
So is there a Rpi device compatible with multichannels streaming on a standalone USB output ? Allo Signature streamer ? Think I have asked elswhere but not sure I understood the answers.
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DBX driverack VENU360 ? AES in, not USB though so an adapter will be needed in between. Can be controlled through a phone app.