PX5 USB Audio problems & finds discussion thread

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mh5039

Member
Oct 9, 2019
7
0
Hi,

If I'm honest a lot of this is over my head and I'm struggling to follow a lot of it. I've a fair knowledge of Hifi but not even the slightest knowledge of programming and especially not android programming.

Could someone give me a quick answer to these two questions:

I have an Erisin Android 9.0 HU with a PX5 chip - can I install a USB DAC of some sort to improve sound quality and how do I do this?

I noticed a few people mentioning DSPs; is this Digital Signal Processing? I know the head unit I took out of my car as part of the factory install BOSE system had a DSP system which was a noise cancelling system to reduce background noise in the car. I assume the microphone in the car and playing in the inverse signal of the background noise back through the speakers - is this possible to recreate?

Cheers, Mike!
 

mahtew

Senior Member
Nov 9, 2011
80
15
Same here Android 9. It must be the Topping D10 giving it a problem then..

Sent from my SM-N950W using Tapatalk

Hi,

If I'm honest a lot of this is over my head and I'm struggling to follow a lot of it. I've a fair knowledge of Hifi but not even the slightest knowledge of programming and especially not android programming.

Could someone give me a quick answer to these two questions:

I have an Erisin Android 9.0 HU with a PX5 chip - can I install a USB DAC of some sort to improve sound quality and how do I do this?

I noticed a few people mentioning DSPs; is this Digital Signal Processing? I know the head unit I took out of my car as part of the factory install BOSE system had a DSP system which was a noise cancelling system to reduce background noise in the car. I assume the microphone in the car and playing in the inverse signal of the background noise back through the speakers - is this possible to recreate?

Cheers, Mike!


Hello, I have a USB ->> SPDIF/COAX converter based on XMOS XU208. to push music through USB i need to use UAPP (no radio, youtube, bt etc.; Android9 doesn't support UAC2 or any UAC(shame!!!)).
with 'direct mode' i can get 24/96kHz sent via SPDIF.. and it works!

I had a brief test (no more than 3-4minutes) because it's still WiP but from what i remember there was no pops, clicks etc.
also volume control does not work. yet it's not a big issue.

i can make some more testing if needed
 

lennylen

Member
May 14, 2016
44
7
Hello, I have a USB ->> SPDIF/COAX converter based on XMOS XU208. to push music through USB i need to use UAPP (no radio, youtube, bt etc.; Android9 doesn't support UAC2 or any UAC(shame!!!)).

with 'direct mode' i can get 24/96kHz sent via SPDIF.. and it works!



I had a brief test (no more than 3-4minutes) because it's still WiP but from what i remember there was no pops, clicks etc.

also volume control does not work. yet it's not a big issue.



i can make some more testing if needed
I'm able to push audio through usb just by plugging it in. Works with everything except radio. But only problem is popping and clicks. Far as i know A9 supports DACS.

You're saying you got it working without pops or clicks?

Sent from my SM-N950W using Tapatalk
 

mahtew

Senior Member
Nov 9, 2011
80
15
I'm able to push audio through usb just by plugging it in. Works with everything except radio. But only problem is popping and clicks. Far as i know A9 supports DACS.

You're saying you got it working without pops or clicks?

Sent from my SM-N950W using Tapatalk

hello,
I've made a video. image is compressed a bit, audio is mp3 320kbps
it's a 3min of music 44/16bit and 96/24bit. no clicks, pops etc.

Youtube and other digital sources doesn't work, only UAPP plays music. but it will not be a problem - i'll use RCA's for analog and system sound and SPDIF for music via UAPP.

my device is PX6 / Android9 Malaysk

https://www.sendspace.com/file/rknohh
 

lennylen

Member
May 14, 2016
44
7
Update:

Bought a new unit which is a px6 w/DSP (CHS variant) and topping D10 is delivering USB audio without pops or hissing/static!

However, the only stipulation remains that when I plug the DAC in. A9 doesn't recognize it an audio device. My previous headunit did. As a result I can only listen to music through UAPP, and playback through any other app is not possible.

Using Hal9k android 9 ROM. I wonder if this function was stripped out of custom ROMs. My old unit ran A9 stock and was able to reroute all audio through the DAC.


Anyone have any ideas on how to solve this issue? I may try reverting back to stock A9 to see if that solves the issue..

Sent from my LYA-L0C using Tapatalk
 

pankrok78

Member
Nov 11, 2018
14
2
I dont know if it helps at all (probably not) but as an update i have connected my dasaita px5 , with Hal9k A9 rom to the HEC module of helix dsp ultra and I have all audio EXCEPT Fm radio through the usb.

What would be awesome , is if somebody knows the way to control HELIX volume through A9 buttons. There was a guy in Russia (AntOxaNSK) which can be found on drive.ru and youtube who has made an adaptor for the volume control (he drives a mazda 3 which is very convenient because I am driving a mazda cx7 and most of the extras will work on mine too) but i had no way to contact him.
 

droc.noles

Senior Member
Jul 22, 2012
67
8
I dont know if it helps at all (probably not) but as an update i have connected my dasaita px5 , with Hal9k A9 rom to the HEC module of helix dsp ultra and I have all audio EXCEPT Fm radio through the usb.

What would be awesome , is if somebody knows the way to control HELIX volume through A9 buttons. There was a guy in Russia (AntOxaNSK) which can be found on drive.ru and youtube who has made an adaptor for the volume control (he drives a mazda 3 which is very convenient because I am driving a mazda cx7 and most of the extras will work on mine too) but i had no way to contact him.

Sidebar question: in looking back through your post history - your Dasaita PX5 variant appears to have been an out-of-box Oreo unit? The reason why I ask is that I'm at a crossroad trying to decide how to build out an external audio system for the Dasaita PX5 2GB / 32GB unit that I have had for a few years now in my Corolla (6.0.1 unit - MD725 type 2 BT). To date, I've just used the in-built audio with front / rear Focal Integration components / 6x9s. I just recently purchased a 4GB / 32GB PX5 SOM from a member here that is on the way (thanks again Didier), but this SOM is also a 6.0.1 unit to preserve Bluetooth functionality for now with the referenced MD725 type 2 chip that my unit (unfortunately) has.

Here's my planned build out, as I am just simply trying to get a clean, amplified signal for the same Focal speakers with a single Focal subwoofer being added to the trunk:

-Alpine PDX-V9 or PDR-V75 5-channel amp
-Helix DSP Mini, with Wifi Control module instead of Director for control (I have a Verizon hotspot in car serving Wifi network for control instead of having to use Wifi direct) - would require moving to at least Android 7 on PX5 for the app to show up in Play Store from what I can tell
-Instead of HEC USB module, suffer through using analog outputs from Dasaita to Helix Mini analog inputs until AF releases Audiostage module allowing for direct playback from within app / external HDD - in effect bypassing any possible HU firmware funkiness inducing clicks or pops, as long as the AF app implementation is smooth

My question is - from what I can tell, the analog preamp outs on these PX5 units are across the board pretty poor in both D-A output and voltage - wondering just how much the analog input sensitivity is going to need to be cranked up on a Helix Mini in order to get a decent signal, until AF releases the Audiostage module? The manual references 2-4V input sensitivity range. I've been told by Dasaita that the analog outs should be 2V but there's quite a bit of evidence out there that these outs aren't reaching that voltage - particularly the sub output voltage (which wouldn't be a factor with the Helix Mini with 4-channel input in play, but would if connecting directly to amplifier via splitter from single jack output). Was thinking once the Audiostage module is installed, can use the analog setup for radio or other signals as needed - I don't see the need in taking a chance on instability with the HEC USB module if the Audiostage setup will eliminate any uncertainty upon release.

Just to be able to use the Wifi Control app, I'd need to move up to a custom ROM with Oreo or greater, which is going to nullify Bluetooth connectivity given MD725 type 2 on my unit - I suppose I can live with that if I can get clean sound from an external setup.

I haven't seen a whole lot of feedback on PX6 USB audio users, at least within this thread, beyond lennylen's post above from January - promising that no clicks / pops seem to be present. I had tinkered with using an Audioquest Dragonfly just to see if I could get a clean signal out of my current PX5 model with Android 6.0.1 a few times a couple of years back - horrible mess of intermittent clicks / pops even though playback actually occurred via UAPP, tweaks or no. I really, really considered jumping up to a PX6 unit but from what I had seen in researching, these units still used basically the same components outside of the SOM - including USB controller / kernel driver (Designware DWC-OTG 2.0) - is that a bad inference on my part? Or has the USB implementation improved on the newer units with Android 8/9?

Apologies for the tangent relative to your original question.
 

pankrok78

Member
Nov 11, 2018
14
2
Sidebar question: in looking back through your post history - your Dasaita PX5 variant appears to have been an out-of-box Oreo unit? The reason why I ask is that I'm at a crossroad trying to decide how to build out an external audio system for the Dasaita PX5 2GB / 32GB unit that I have had for a few years now in my Corolla (6.0.1 unit - MD725 type 2 BT). To date, I've just used the in-built audio with front / rear Focal Integration components / 6x9s. I just recently purchased a 4GB / 32GB PX5 SOM from a member here that is on the way (thanks again Didier), but this SOM is also a 6.0.1 unit to preserve Bluetooth functionality for now with the referenced MD725 type 2 chip that my unit (unfortunately) has.

Here's my planned build out, as I am just simply trying to get a clean, amplified signal for the same Focal speakers with a single Focal subwoofer being added to the trunk:

-Alpine PDX-V9 or PDR-V75 5-channel amp
-Helix DSP Mini, with Wifi Control module instead of Director for control (I have a Verizon hotspot in car serving Wifi network for control instead of having to use Wifi direct) - would require moving to at least Android 7 on PX5 for the app to show up in Play Store from what I can tell
-Instead of HEC USB module, suffer through using analog outputs from Dasaita to Helix Mini analog inputs until AF releases Audiostage module allowing for direct playback from within app / external HDD - in effect bypassing any possible HU firmware funkiness inducing clicks or pops, as long as the AF app implementation is smooth

My question is - from what I can tell, the analog preamp outs on these PX5 units are across the board pretty poor in both D-A output and voltage - wondering just how much the analog input sensitivity is going to need to be cranked up on a Helix Mini in order to get a decent signal, until AF releases the Audiostage module? The manual references 2-4V input sensitivity range. I've been told by Dasaita that the analog outs should be 2V but there's quite a bit of evidence out there that these outs aren't reaching that voltage - particularly the sub output voltage (which wouldn't be a factor with the Helix Mini with 4-channel input in play, but would if connecting directly to amplifier via splitter from single jack output). Was thinking once the Audiostage module is installed, can use the analog setup for radio or other signals as needed - I don't see the need in taking a chance on instability with the HEC USB module if the Audiostage setup will eliminate any uncertainty upon release.

Just to be able to use the Wifi Control app, I'd need to move up to a custom ROM with Oreo or greater, which is going to nullify Bluetooth connectivity given MD725 type 2 on my unit - I suppose I can live with that if I can get clean sound from an external setup.

I haven't seen a whole lot of feedback on PX6 USB audio users, at least within this thread, beyond lennylen's post above from January - promising that no clicks / pops seem to be present. I had tinkered with using an Audioquest Dragonfly just to see if I could get a clean signal out of my current PX5 model with Android 6.0.1 a few times a couple of years back - horrible mess of intermittent clicks / pops even though playback actually occurred via UAPP, tweaks or no. I really, really considered jumping up to a PX6 unit but from what I had seen in researching, these units still used basically the same components outside of the SOM - including USB controller / kernel driver (Designware DWC-OTG 2.0) - is that a bad inference on my part? Or has the USB implementation improved on the newer units with Android 8/9?

Apologies for the tangent relative to your original question.

USB in my unit suffers with artifacts most probably due to this inherent problem of controlling the serial traffic often found in px5 Oreo units.
If you open another up like navigation you may here pops and clicks
Generally it will be better to either wait for the audiostage or buy a native pie unit.
I have tested the app in last year's Emma eurofinals and was everything you might need. Supports Spotify , possibly tidal , tune in radio and few more other apps. It is as clean as it should be and the only think missing will be the navigation app which still has to run through headunit.
Generally regardless what it is written here and there , these units will hardly satisfy demanding users like us in the audio section.
Their analog out is as good as an old school mobile , noisy ,low voltage , without drive , they lack full digital output to mobile sound cards etc.
Hey are only good enough if you don't have audiophile desires and need a unit for an old car that does things found in new cars.
 
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droc.noles

Senior Member
Jul 22, 2012
67
8
USB in my unit suffers with artifacts most probably due to this inherent problem of controlling the serial traffic often found in px5 Oreo units.
If you open another up like navigation you may here pops and clicks
Generally it will be better to either wait for the audiostage or buy a native pie unit.
I have tested the app in last year's Emma eurofinals and was everything you might need. Supports Spotify , possibly tidal , tune in radio and few more other apps. It is as clean as it should be and the only think missing will be the navigation app which still has to run through headunit.
Generally regardless what it is written here and there , these units will hardly satisfy demanding users like us in the audio section.
Their analog out is as good as an old school mobile , noisy ,low voltage , without drive , they lack full digital output to mobile sound cards etc.
Hey are only good enough if you don't have audiophile desires and need a unit for an old car that does things found in new cars.

Exactly what I needed to hear, and that is great that you were able to test the app. Have you seen any indication as to when the Audiostage module is supposed to be released? Everything I found hinted at a release near the beginning of this year.

I'm thinking if I can just grit and bear the analog preamp signal from the Dasaita to a Helix Mini until that module comes out, I should be good to go.
 

pankrok78

Member
Nov 11, 2018
14
2
I was if the idea that it would be included in WiFi app so surprised when the wifi app was only control and nothing more.
Anyway will wait to see , otherwise will try to fit 10" 4g tablet which are far more descent when working with either BT or USB
 

droc.noles

Senior Member
Jul 22, 2012
67
8
Anyone tested Hal9k's 9.0 ROM with OTA updates? Apparently OTA 4.0.1 offers an option to drop USB port speed to 1.1 from 2.0. In my initial testing, this change has completely smoothed out clicks / pops for my Audioquest Dragonfly. Going to continue to stress the Dasaita PX5 4GB/32GB unit I have to see if I can induce any hiccups, but after a few minutes of playback, even hot swapping the device, has been smooth - Android seamlessly switches between MCU and USB DAC when hot swapped.

https://xdaforums.com/showpost.php?p=82809393&postcount=1561

EDIT: After jumping between apps, updating apps, browsing the web and whatnot, all is not perfect - I can still get the unit to generate a few here-and-there dropouts typical of these units, but overall, not too bad at all. Especially if network traffic is minimized or not running. Pretty smooth, and pretty encouraging IMO.
 
Last edited:

Cavalier Condorelli

Senior Member
Nov 25, 2010
204
45
Anyone tested Hal9k's 9.0 ROM with OTA updates? Apparently OTA 4.0.1 offers an option to drop USB port speed to 1.1 from 2.0. In my initial testing, this change has completely smoothed out clicks / pops for my Audioquest Dragonfly. Going to continue to stress the Dasaita PX5 4GB/32GB unit I have to see if I can induce any hiccups, but after a few minutes of playback, even hot swapping the device, has been smooth - Android seamlessly switches between MCU and USB DAC when hot swapped.

https://xdaforums.com/showpost.php?p=82809393&postcount=1561

EDIT: After jumping between apps, updating apps, browsing the web and whatnot, all is not perfect - I can still get the unit to generate a few here-and-there dropouts typical of these units, but overall, not too bad at all. Especially if network traffic is minimized or not running. Pretty smooth, and pretty encouraging IMO.

I have a Maisaita Max6 PX6 HU, Hal9k Rom, USB port speed to 1.1, USB to Optical DAC is recognized and present in /proc/asound/cards file,
BUT /etc/audio_policy.conf file does not exist.
There is no audio output from DAC while playing music from any android players such as Poweramp.
I have never installed direct players such as UAPP.

Do you have such /etc/audio_policy.conf file?

Thanks
 

droc.noles

Senior Member
Jul 22, 2012
67
8
I have a Maisaita Max6 PX6 HU, Hal9k Rom, USB port speed to 1.1, USB to Optical DAC is recognized and present in /proc/asound/cards file,
BUT /etc/audio_policy.conf file does not exist.
There is no audio output from DAC while playing music from any android players such as Poweramp.
I have never installed direct players such as UAPP.

Do you have such /etc/audio_policy.conf file?

Thanks

No /etc/audio_policy.conf file on my system - just checked. This is what I see in /proc/asound/cards:

 
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droc.noles

Senior Member
Jul 22, 2012
67
8
I dont know if it helps at all (probably not) but as an update i have connected my dasaita px5 , with Hal9k A9 rom to the HEC module of helix dsp ultra and I have all audio EXCEPT Fm radio through the usb.

What would be awesome , is if somebody knows the way to control HELIX volume through A9 buttons. There was a guy in Russia (AntOxaNSK) which can be found on drive.ru and youtube who has made an adaptor for the volume control (he drives a mazda 3 which is very convenient because I am driving a mazda cx7 and most of the extras will work on mine too) but i had no way to contact him.

As you can see from my recent post history, I couldn't stay on stock Android 6.0.1 for long - I just had to test out something else. Ended up with Hal9k's ROM with OTAs - the 4.0.1 USB 1.1 speed fix seems to have transformed my test DAC (AQ Dragonfly) to usable, although not 100% without here-and-there interrupts. Still though, was a pretty transformative moment to hear a clean audio stream for the first time in literally years through the Dragonfly after applying the USB speed reduction setting in Hal9k's ROM.

I am curious, since I'm considering making the leap to a Helix DSP - do you have your Dasaita PX5 set to USB 1.1 speed in Hal9k's ROM by chance? I'm trying to determine just how much you are seeing USB audio get interrupted if you've had to tweak to get a stable signal. I now have the 4GB / 32GB SOM installed in my Dasaita PX5, and I just wired up an Alpine PDR-V75 to the Dasaita analog RCA outs. I'm finding that the outputs are actually not all that noisy so far, but I can clearly tell that the preamp voltage is such that I could do far better. I'm able to completely turn the volume up to 30 and it is apparent that there is still a ton of headroom on the Alpine amp. Pretty loud and clear, but I know that if I had a stronger preamp voltage, I'd be able to achieve cleaner output at lower volume - this doesn't even account for the fact that having an external DAC would be a large step up from the Dasaita PX5 internal DAC.

I actually emailed Audiotec Fischer to see when the Audiostage HEC module would be coming out; Doug Dobson with MSC America mentioned that there is no timetable at this point for release, so I'm now reconsidering the HEC USB Audio module. Your input might help me determine if it is worth it. I think I'm pretty well convinced that I'd want to do the Wifi Control module rather than Director, but only if it is not too cumbersome to deal with controlling volume within the app. I'd also be curious if you find a way to control the volume through the steering wheel controls / Dasaita hardware buttons. I think more than anything having a handle on volume as you first turn the car on, and while you are going down the road is the main thing - adjustments to the DSP itself is not really a reactionary, on-demand type of control - almost always you are going to be parked, taking your time when adjusting audio settings of the DSP itself.

I'd also be curious if anyone has ever had any experience with this obscure DSP:

https://phoenixgold.com/products/digital-signal-processor

Doesn't appear to have much of a following, but does support USB audio (who knows how well on Android, however), as well as apparently wifi direct on some sources. 5V preamp outs, USB host for thumb drives - not sure how well that would work. Big deal breaker is not being able to have the DSP use client mode on first glance. I'd take 16bit/44khz audio via wifi if it were stable, but the DSP not being able to join an in-car wifi network is a pretty big deal. Also, there's basically no reviews on the unit anywhere (one bad Youtube video), and the app hasn't been updated in basically a couple of years. Still, I am curious about it.
 

kavatzoulas

Member
Jul 15, 2010
26
6
user of a xtrons 706pl px5, rom Hal9k with helix dsp2 and direct connection with the usb audio hd module of the helix. i have also a second solution that use a diy usb dac/spdif converter.both of the solutions works great without any issues. i control the volume through the helix old controller, i have audio for music, video, internet streaming, youtube and bluetooth calls the only thing that you have pass through analog output rca is the radio fm that i never used ;)

i have not seen the option you can select usb 1.1 or 2 but i can understand why somebody would prefer 1.1 many usb modules dac/spdif converters suffering from hes/stops because they need more power the best solution is to use an external power using an Y cable. from the android 2din usb you give the signal and using the 2 input of the Y cable using an external power supply gives the power to the dac. ( solution used with my old nexus 7 tablet as audio device in car 4 years ago)

ps: the only problem that the output is low with the hal9k. rom but with the original rom the output is more powerfull without change anything to the helix dsp or the amp gain....i have not found any solution on this problem

Inviato dal mio FRD-L09 utilizzando Tapatalk
 
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droc.noles

Senior Member
Jul 22, 2012
67
8
user of a xtrons 706pl px5, rom Hal9k with helix dsp2 and direct connection with the usb audio hd module of the helix. i have also a second solution that use a diy usb dac/spdif converter.both of the solutions works great without any issues. i control the volume through the helix old controller, i have audio for music, video, internet streaming, youtube and bluetooth calls the only thing that you have pass through analog output rca is the radio fm that i never used ;)

i have not seen the option you can select usb 1.1 or 2 but i can understand why somebody would prefer 1.1 many usb modules dac/spdif converters suffering from hes/stops because they need more power the best solution is to use an external power using an Y cable. from the android 2din usb you give the signal and using the 2 input of the Y cable using an external power supply gives the power to the dac. ( solution used with my old nexus 7 tablet as audio device in car 4 years ago)

ps: the only problem that the output is low with the hal9k. rom but with the original rom the output is more powerfull without change anything to the helix dsp or the amp gain....i have not found any solution on this problem

Inviato dal mio FRD-L09 utilizzando Tapatalk

All good information - thanks much. Out of curiosity, which DIY USB DAC / SPDIF converter are you using as a second solution?
 

mahtew

Senior Member
Nov 9, 2011
80
15
Hello
Disclaimer :D : i'm not trying to be rude!

Well then -i don't understand why you have a problem with SQ.
I have DASAITA HU + HELIX DSP (.3 right now; previous was P6mk2). My devices are connected with RCA and SPDIF optical.
HU is connected via pream RCA with DSP's analog in (CH.1&2); i'm also using USB AUDIO via USB-to-SPDIF converter /XMOS XU208/; i'm not using HELIX HEC USB
analog connection is used for all except music (maps, phone connection, youtube); mainly for sound sources that have low quality.
i'm using USBAudioPlayerPRO for music. I have no pops, clicks, etc.; connection is stable; sound is clean and works up to 96/24bit (limited by DSP). my device is not recognized by HU as sound card (no android sounds) yet UAPP comunicates with it
For volume controll i'm using HELIX DIRECTOR (mainly digital; analog can be controlled by stering wheel)
I've bought WIFI CONTROLL yet not tested; i've read that it has limited ability to controll volume (oh why!!!; this simple 'feature' would be perfect!)
another 'mod' i did is to disconect speaker cables and TDA7850 chip from motherboard (no static noise/hiss)

main cons i can think of:
i've red that UAPP can catch volume control from HU; i'm using BITPERFECT mode, so no volume controll via SPDIF;
-uapp is not perfect in usability

one more info:
i've checked parameters of PREAMP out; with maxed volume (+30) and 1kHz 0dB test tone i get aprox. +2,5V and clean sin wave. that's good!
my board is DASAITA MAX6 with ADAU1401 chip.

if needed i can make a video as proof :D
 

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pankrok78

Member
Nov 11, 2018
14
2
As you can see from my recent post history, I couldn't stay on stock Android 6.0.1 for long - I just had to test out something else. Ended up with Hal9k's ROM with OTAs - the 4.0.1 USB 1.1 speed fix seems to have transformed my test DAC (AQ Dragonfly) to usable, although not 100% without here-and-there interrupts. Still though, was a pretty transformative moment to hear a clean audio stream for the first time in literally years through the Dragonfly after applying the USB speed reduction setting in Hal9k's ROM.

I am curious, since I'm considering making the leap to a Helix DSP - do you have your Dasaita PX5 set to USB 1.1 speed in Hal9k's ROM by chance? I'm trying to determine just how much you are seeing USB audio get interrupted if you've had to tweak to get a stable signal. I now have the 4GB / 32GB SOM installed in my Dasaita PX5, and I just wired up an Alpine PDR-V75 to the Dasaita analog RCA outs. I'm finding that the outputs are actually not all that noisy so far, but I can clearly tell that the preamp voltage is such that I could do far better. I'm able to completely turn the volume up to 30 and it is apparent that there is still a ton of headroom on the Alpine amp. Pretty loud and clear, but I know that if I had a stronger preamp voltage, I'd be able to achieve cleaner output at lower volume - this doesn't even account for the fact that having an external DAC would be a large step up from the Dasaita PX5 internal DAC.

I actually emailed Audiotec Fischer to see when the Audiostage HEC module would be coming out; Doug Dobson with MSC America mentioned that there is no timetable at this point for release, so I'm now reconsidering the HEC USB Audio module. Your input might help me determine if it is worth it. I think I'm pretty well convinced that I'd want to do the Wifi Control module rather than Director, but only if it is not too cumbersome to deal with controlling volume within the app. I'd also be curious if you find a way to control the volume through the steering wheel controls / Dasaita hardware buttons. I think more than anything having a handle on volume as you first turn the car on, and while you are going down the road is the main thing - adjustments to the DSP itself is not really a reactionary, on-demand type of control - almost always you are going to be parked, taking your time when adjusting audio settings of the DSP itself.

I'd also be curious if anyone has ever had any experience with this obscure DSP:

https://phoenixgold.com/products/digital-signal-processor

Doesn't appear to have much of a following, but does support USB audio (who knows how well on Android, however), as well as apparently wifi direct on some sources. 5V preamp outs, USB host for thumb drives - not sure how well that would work. Big deal breaker is not being able to have the DSP use client mode on first glance. I'd take 16bit/44khz audio via wifi if it were stable, but the DSP not being able to join an in-car wifi network is a pretty big deal. Also, there's basically no reviews on the unit anywhere (one bad Youtube video), and the app hasn't been updated in basically a couple of years. Still, I am curious about it.

in short
you will need a remote control for volume in any case. Director or some other cheaper. The reason is practical as headunit is unlikely to control the wifi app volume directly - unless somebody has a a fix for this - it would be awesome!

as I recall I use 1.1 connection - it worked better than 2.0.
head unit is PX5 dasaita, main player is UAPP (disappointed from the practical side, as it cannot index my 4tb drive) , processor is 3rd generation DSP ULTRA
I am not sure that low output volume was "feature" of Hal9k roms , unit was already upgraded to hal9k 8.0 before being connected in the car.
unit is considered old - bought in 2018.

hopefully audiostage HEC would be the solution...
 
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  • 6
    Happy New Year guys!

    1. All Rockchips headunits (rk3066/3188/3288/px3/px5) have a big problem with their DWC-OTG USB 2.0 controller kernel driver from Designware/Synopsys.
    This driver generates a huge amount of interrupts on usb bus (about 15000 per second under load and 8000 minimum without any use of usb devices). So any wide streaming devices like USB-DACs, USB-CAM, EasyCAP and others cannot properly function. USB-DACs on samplerates higher 44100 or 48000 Hz and bit depth higher 16 bit generate many pop and clicks in sound or just noise. All usb streams are very slow, even copying files from usb flesh to sd card.
    This problem is well known and it has the resolution - kernel driver needs to be patched.
    Here are some links:
    http://hwswbits.blogspot.ru/2013/09/dwc-usb-interrupt-spam-in-rockchip-socs.html?m=1
    https://www.google.ru/amp/s/ideechaniz.wordpress.com/2014/02/26/dwc-otg-drivers/amp/
    We have not kernel sources to patch it. Any open sources will not go because of many special functions of our HUs have been compiled into kernel. I wrote about this to SHEN ZHEN KLYDE ELECTRONICS CO twice, but no reaction (I have their HU).
    So you cannot play sound higher then 16 bit 44100Hz or 48000Hz. If you try 24 bit and/or 96kHz you can hear clicks and pops or just a noise. The first step to make the situation better is to get usb-dac/converter with only FULL-speed (12Mb/s) usb-reciever chip, like sa9023, te7022, pcm2704(6) (mono!) etc. Unplug all usb devices except usb-dac from usb. Note that wifi and processor's loads affect too. Edit /etc/audio_policy.conf to limit sr and bd to 44100 and 16 for usb_device section. If you want to use your high speed usb-dac you can try to find and use a full speed usb hub on ali or ebay.

    2. All android HUs for now have mcu and android boards inside. All apps like youtube, navigation, poweramp etc are sounding from android board and all of them can be routed to play through usb-dac using usb audio function of android. But dvd, bt hands-free, radio are located on and managed by mcu board. So sound from them does not going to/through android board. The only one way to get their sound on your car audio processor is connection of rca-outs and set processor to auto switch between analog and digital inputs by signal determination (helix dsp and many others can do that).

    3. The volume. The best way for SQ is to use the dsp's volume adjustment. Note for digital volume adjustment every -6bB from max level excludes 1 bit from effective bit depth. So you loose your sound quality (dynamic range) by digital volume adjusting on HU because you can only have 16bit output (see 1). But if you WANT to do it there is one difficult way - write your own app service to catch mcu's broadcast commands for volume adjusting and then send alsamixer's comnands to change usb dac volume same level (need to install alsa). I made it for rk3066/rk3188 HUs on petrows microntec headunit service. Hope this help https://github.com/petrows/RK3066-Headunit-service
    https://www.google.ru/url?sa=t&sour...MQ5YQBCCcwAA&usg=AOvVaw2W8hsXylKrMeQRC2R2mOVt
    This service also can send buttons presses to Poweramp, USB Audio Player Pro, Spotify, PCRadio etc. But it is for MTCB, not for MTCD HUs. I dont know a difference of Microntek services of this versions of HUs. So I cannot say will it work or not on MTCD.
    2
    I know that a lot of people here likes good sound quality and want to use USB DAC on their head unit.
    So I started this thread so maybe someone can come up with a solution to get rid of our USB Audio problems. :good:

    First of all, I have 3 different USB audio interfaces I tried on my MTCD PX5 head unit. I use these for SPDIF Coaxial output, so I can send a clean digital signal to my DSP (MiniDSP 6X8) spdif input.

    My USB audio devices:

    PCM2704 (Worst sound quality of the 3, but still good)
    CM6631A (Nice sound quality)
    SMSL x-usb (XMOS chip) (Excellent, best sound quality of my adapters)

    Here is my findings for each model so far:

    PCM2704 - With native Android USB Audio driver (MTCD Music player, Spotify, Google Music, etc) : Plays without any pops&clicks noises 44khz, 48Khz, 96Khz files (Thats good).. BUT only in MONO, so no stereo ! (That sucks.)

    PCM2704 - With custom USB Audio driver (Usb Audio Player Pro, Neutron, Hibby, Onkyo apps) : Plays perfectly 44khz :)audio files but CANNOT play 48khz or 96khz audio files, there is no sound. at all :crying:



    CM6631A - With native Android USB Audio driver (MTCD Music player, Spotify, Google Music, etc) : Lots of pops&clicks noises, cannot listen to this.. BUT output in stereo, plays 44khz/48khz/96khz files.

    CM6631A - With custom USB Audio driver (Usb Audio Player Pro, Neutron, Hibby, Onkyo apps) : Lots of pops&clicks noises, cannot listen to this.. Output in stereo, plays 44khz/48khz/96khz.



    SMSL X-USB Xmos - With native Android USB Audio driver (MTCD Music player, Spotify, Google Music, etc) : Lots of pops&clicks noises, cannot listen to this.. BUT output in stereo, plays 44khz/48khz/96khz files.

    SMSL X-USB Xmos - With custom USB Audio driver (Usb Audio Player Pro, Neutron, Hibby, Onkyo apps) : Lots of pops&clicks noises, cannot listen to this.. Output in stereo, plays 44khz/48khz/96khz.

    Good to know:
    PCM2704 is USB 1.1 full speed device, isosynchronous.
    CM6631A is USB 2.0 fullspeed/high speed device, asynchronous.
    SMSL X-usb Xmos is USB 2.0 fullspeed/high speed device, asynchronous.

    Also good to know: Android Marshmallow 6 Mono output USB Audio problem is a well known problem across multiple Android devices (Cellphones, tablets, etc.) So lets assume the mono output on the PCM2704 is "normal". What is not normal with the PCM2704 is that it can only play 44khz audio, no 48khz.

    First question that comes to my mind: Does the PX5 USB drivers/kernel has a problem with USB2.0 ?
    Another question: Does our PX5 firmware mess with the sample frequency (44khz, 48khz, etc) ?

    Thanks for any useful comment !
    2
    Congrats.

    And another surprise, BT is going through USB.

    Might not be good as I'm seeing 48/16 sources displaying as 96/32 on my Director.

    Sent from my Nokia 7 plus using Tapatalk
    2
    https://xdaforums.com/showpost.php?p=79357076&postcount=2849

    I jumped from stock to this custom ROM and android USB audio is working.
    1
    As you can see from my recent post history, I couldn't stay on stock Android 6.0.1 for long - I just had to test out something else. Ended up with Hal9k's ROM with OTAs - the 4.0.1 USB 1.1 speed fix seems to have transformed my test DAC (AQ Dragonfly) to usable, although not 100% without here-and-there interrupts. Still though, was a pretty transformative moment to hear a clean audio stream for the first time in literally years through the Dragonfly after applying the USB speed reduction setting in Hal9k's ROM.

    I am curious, since I'm considering making the leap to a Helix DSP - do you have your Dasaita PX5 set to USB 1.1 speed in Hal9k's ROM by chance? I'm trying to determine just how much you are seeing USB audio get interrupted if you've had to tweak to get a stable signal. I now have the 4GB / 32GB SOM installed in my Dasaita PX5, and I just wired up an Alpine PDR-V75 to the Dasaita analog RCA outs. I'm finding that the outputs are actually not all that noisy so far, but I can clearly tell that the preamp voltage is such that I could do far better. I'm able to completely turn the volume up to 30 and it is apparent that there is still a ton of headroom on the Alpine amp. Pretty loud and clear, but I know that if I had a stronger preamp voltage, I'd be able to achieve cleaner output at lower volume - this doesn't even account for the fact that having an external DAC would be a large step up from the Dasaita PX5 internal DAC.

    I actually emailed Audiotec Fischer to see when the Audiostage HEC module would be coming out; Doug Dobson with MSC America mentioned that there is no timetable at this point for release, so I'm now reconsidering the HEC USB Audio module. Your input might help me determine if it is worth it. I think I'm pretty well convinced that I'd want to do the Wifi Control module rather than Director, but only if it is not too cumbersome to deal with controlling volume within the app. I'd also be curious if you find a way to control the volume through the steering wheel controls / Dasaita hardware buttons. I think more than anything having a handle on volume as you first turn the car on, and while you are going down the road is the main thing - adjustments to the DSP itself is not really a reactionary, on-demand type of control - almost always you are going to be parked, taking your time when adjusting audio settings of the DSP itself.

    I'd also be curious if anyone has ever had any experience with this obscure DSP:

    https://phoenixgold.com/products/digital-signal-processor

    Doesn't appear to have much of a following, but does support USB audio (who knows how well on Android, however), as well as apparently wifi direct on some sources. 5V preamp outs, USB host for thumb drives - not sure how well that would work. Big deal breaker is not being able to have the DSP use client mode on first glance. I'd take 16bit/44khz audio via wifi if it were stable, but the DSP not being able to join an in-car wifi network is a pretty big deal. Also, there's basically no reviews on the unit anywhere (one bad Youtube video), and the app hasn't been updated in basically a couple of years. Still, I am curious about it.

    in short
    you will need a remote control for volume in any case. Director or some other cheaper. The reason is practical as headunit is unlikely to control the wifi app volume directly - unless somebody has a a fix for this - it would be awesome!

    as I recall I use 1.1 connection - it worked better than 2.0.
    head unit is PX5 dasaita, main player is UAPP (disappointed from the practical side, as it cannot index my 4tb drive) , processor is 3rd generation DSP ULTRA
    I am not sure that low output volume was "feature" of Hal9k roms , unit was already upgraded to hal9k 8.0 before being connected in the car.
    unit is considered old - bought in 2018.

    hopefully audiostage HEC would be the solution...