You can do the exact same thing with an apple airport express. You can mod them very easily to remove the build in power supply and use an external 3.3.V power supply, which is what I have done and am using a simple meanwell supply. Here is an illustration: Tutorial: iPhone Airplay In Car via Airport Express - NASIOC
Have just ordered the TUBULUS ARGENTUS – USB CABLE V2 DUAL HEAD. Will try to supply the power for the power USB-A plug from a clean 5V power source, likely battery, and report my findings here.
I set it up last night but did not do any thorough comparisons. It works well, that is all I can say.
Best to deactivate Airplay in the Airport Express (if it is only used as a bridge, which is the case here).
This solution is very useful if you do not have your router close to your player, which is my case, and don't want to use a power line adapter or a direct wifi connection on the Pi.
Whether it is better than a straight cable to a router/internet box may depend on the router you are comparing it to.
@ Hoptinks : Hi,
so no difference from an audio perspective ?
@ Bertel : Hi,
I 've been thinking of Rolling some tape around the metal end plug of the USB cable to test the shield isolation on the side of the USB B plug soldered on the device ground !
If just the -V bus is allowing to return the current to the ground of the Host we may have less noise as the device or the host may have feriite on this bus just before the host controller & its outputt plug ? The external shielding becomming as well a true shield against external EMI ? instead of just protecting the near outside devices ? (my posts above)
easier and safer than surgeon on cables
so no difference from an audio perspective ?
@ Bertel : Hi,
I 've been thinking of Rolling some tape around the metal end plug of the USB cable to test the shield isolation on the side of the USB B plug soldered on the device ground !
If just the -V bus is allowing to return the current to the ground of the Host we may have less noise as the device or the host may have feriite on this bus just before the host controller & its outputt plug ? The external shielding becomming as well a true shield against external EMI ? instead of just protecting the near outside devices ? (my posts above)
easier and safer than surgeon on cables
Hello,
Ah this adhesiv tape trick seems to have zeo sucess... certainly a bad idea I assume !
Sorry for digging out an old subject... I would like to try active DEM clock on a TDA1541A DAC.
What is the speed of the I2S Bclk line ? Minimum 1.4112 M Hz with Red book materials (16/44.1) ?
And what is the speed one should use between the 176.5 k Hz and 2.4 M Hz advised please with the divider to feed the clock pin 16 inputt of the TDA1541A ?
I would to use a simple circuit : ECDESIGN's shematic 10K R and 0.1U in serie with pin 16 but with just a decoupling on pin 17 (0.1U to ground) : is it ok ?
For people whom tried Active DEM hacked from the Bclk pin 2, what is the frequency you liked best please ?
Many thanks
Ah this adhesiv tape trick seems to have zeo sucess... certainly a bad idea I assume !
Sorry for digging out an old subject... I would like to try active DEM clock on a TDA1541A DAC.
What is the speed of the I2S Bclk line ? Minimum 1.4112 M Hz with Red book materials (16/44.1) ?
And what is the speed one should use between the 176.5 k Hz and 2.4 M Hz advised please with the divider to feed the clock pin 16 inputt of the TDA1541A ?
I would to use a simple circuit : ECDESIGN's shematic 10K R and 0.1U in serie with pin 16 but with just a decoupling on pin 17 (0.1U to ground) : is it ok ?
For people whom tried Active DEM hacked from the Bclk pin 2, what is the frequency you liked best please ?
Many thanks
Can I please share a quick summary of my humble findings regarding the USB power supply topic:
At the moment, I'm still running my Mosaic UV from my PC (with Foobar and Kernel Streaming, works fine) until I have found the most suitable setting for the Mosaic, then I will look into the Raspberry et al. music server side. At first it was not trivial to find an USB port that would actually provide bit perfect playback, some did seemingly work but produced clicks and dropouts as well as no 'bit perfect' green light at any time, but then with two USB ports it worked fine.
As said above, I had then purchased the TUBULUS ARGENTUS USB CABLE V2 DUAL HEAD. Only one of these two USB ports on my computer let me use the data from this port and the power from another - still with bit perfect results, but interestingly the green light went on substantially quicker! I can only guess that the reason for this is less crap on the signal lines, but have no evidence. Although I don't trust subjective observations, I still found sound reproduction quite more detailed, bass a bit deeper and clearer, soundstage more precise, but as said this is all subjective, no measurements or 'correct' A/B testing done.
Now I have connected the Power cable of the Dual Tubulus to my lab power supply to provide clean, mass and potential separated USB power to the Mosaic as signal for host detection - see pictures. Works flawlessly. This way I think we can eliminate the above discussed detrimental USB power issues and their effect on the USB signal (which itself of course is still covered in a lot of crap and dirt as it comes from the PC, but already music reproduction is brilliant). I don't think I will bother to experiment with battery or so but just leave it that way for the moment. Because next up is powerline conditioning for the Mosaic.
At the moment, I'm still running my Mosaic UV from my PC (with Foobar and Kernel Streaming, works fine) until I have found the most suitable setting for the Mosaic, then I will look into the Raspberry et al. music server side. At first it was not trivial to find an USB port that would actually provide bit perfect playback, some did seemingly work but produced clicks and dropouts as well as no 'bit perfect' green light at any time, but then with two USB ports it worked fine.
As said above, I had then purchased the TUBULUS ARGENTUS USB CABLE V2 DUAL HEAD. Only one of these two USB ports on my computer let me use the data from this port and the power from another - still with bit perfect results, but interestingly the green light went on substantially quicker! I can only guess that the reason for this is less crap on the signal lines, but have no evidence. Although I don't trust subjective observations, I still found sound reproduction quite more detailed, bass a bit deeper and clearer, soundstage more precise, but as said this is all subjective, no measurements or 'correct' A/B testing done.
Now I have connected the Power cable of the Dual Tubulus to my lab power supply to provide clean, mass and potential separated USB power to the Mosaic as signal for host detection - see pictures. Works flawlessly. This way I think we can eliminate the above discussed detrimental USB power issues and their effect on the USB signal (which itself of course is still covered in a lot of crap and dirt as it comes from the PC, but already music reproduction is brilliant). I don't think I will bother to experiment with battery or so but just leave it that way for the moment. Because next up is powerline conditioning for the Mosaic.
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Hi, did you experiment with ethernet UTP (plastick jack) cable instead FTP (metal jack : so shielded= gnd linked)?
I see the USB plug of the Mosaic is touching the cabinet : does it make a ground loop with the Earth wire of the supply IEC cable of the Mosaic ? Or it doesn't matter cause it's not on the analog signal outputt ?
Did you try adhesiv tape around one of the side of your usb cable as you use the gnd internal wire ?
I noticed myself small but real improvment with a 30 cm usb wire in spit of a 1.80 m !
I see the USB plug of the Mosaic is touching the cabinet : does it make a ground loop with the Earth wire of the supply IEC cable of the Mosaic ? Or it doesn't matter cause it's not on the analog signal outputt ?
Did you try adhesiv tape around one of the side of your usb cable as you use the gnd internal wire ?
I noticed myself small but real improvment with a 30 cm usb wire in spit of a 1.80 m !
No, I didn't do these experiments or modifications (yet).
- I use the Tubulus cable as it is (75 cm version), with metal plugs on all ends.
- From my understanding, the shielding on the USB data cable is connected to the Mosaic case on the receiving end and to the PC case on the host end, as it should be.
- The shielding on the USB power cable is only connected to the Mosaic case on the receiving end, it's cut open on the other end and I don't know really if and where to connect it to - the case of the lab power supply probably isn't a good idea (as its output is decoupled from mains anyway), maybe mains GND/Earth, I don't know. As long as the shield is not connected on one side, I'm likely creating an antenna (it would probably be better if this part of the Dual Cable, the USB power cable, wasn't shielded?), but not sure if it matters too much - on one hand there's not really any current flowing, as you can see from the power supply's display, just the voltage potential required for sensing the host, on the other hand John explained above that an opto-coupler is being used for this in the Mosaic, so for the time being I would guess that closing this shielding wouldn't matter too much, but I can be wrong of course.
- I use the Tubulus cable as it is (75 cm version), with metal plugs on all ends.
- From my understanding, the shielding on the USB data cable is connected to the Mosaic case on the receiving end and to the PC case on the host end, as it should be.
- The shielding on the USB power cable is only connected to the Mosaic case on the receiving end, it's cut open on the other end and I don't know really if and where to connect it to - the case of the lab power supply probably isn't a good idea (as its output is decoupled from mains anyway), maybe mains GND/Earth, I don't know. As long as the shield is not connected on one side, I'm likely creating an antenna (it would probably be better if this part of the Dual Cable, the USB power cable, wasn't shielded?), but not sure if it matters too much - on one hand there's not really any current flowing, as you can see from the power supply's display, just the voltage potential required for sensing the host, on the other hand John explained above that an opto-coupler is being used for this in the Mosaic, so for the time being I would guess that closing this shielding wouldn't matter too much, but I can be wrong of course.
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Can't edit anymore, so addendum:
It just occurs to me that the shielding for the USB data cable part of the Tubulus Double Head cable is of course physically connected with the shielding of the USB power cable part through the USB B plug... So whatever detrimental effect I cause on one shielding will also be present on the other - which means I do have to care
Will need to decide whether to use no shielding at all on the USB power cable part, or leave the shielding in place and connect to Mains Earth near the lab power supply.
It just occurs to me that the shielding for the USB data cable part of the Tubulus Double Head cable is of course physically connected with the shielding of the USB power cable part through the USB B plug... So whatever detrimental effect I cause on one shielding will also be present on the other - which means I do have to care
Will need to decide whether to use no shielding at all on the USB power cable part, or leave the shielding in place and connect to Mains Earth near the lab power supply.
Thanks Bertel for inputs !
Yep for sure : one side of the USB should be grounded to avoid antenna effect to pick EMI. Perhaps I'm too worried about the gnd external shielding as a path of noise between the sources :both Internet provider box by the shielded ethernet cable & PC by the shielding of the USB cable.
When you say: "as it should be" : it's not so sure from an audio perspective if you read all the links I gave above ! But audio constructors must maybe respect the norms, I dont'k know...
If your splited cable has an external shield from ground to ground on the power cable, indeed you just pick up the noise (if it exists) from the unit which supply it and not on the other unit which is only providing the data ! So if i undersand the cable maker understood this ! And the power cable is shielded both side because anyhow the negative return wire is the ground already (so pick up noise, hence your good result with a quiet supply
Maybe it is just a detail, ECEDESIGNS not answering is perhaps because it's not so important . But I find the subject of picking noise from the sources not so much talked and ECDESIGNS opened an interresting door as usual. I was surprised too cause I have a very good dac and all the IanCanada devices (fifo and low phase noise, isolator, etc) and I do hear difference when Something is changed from the sources : USB cables, powersupply... So why not bother about it ? I will try next an unshielded ethernet (UTP) cable in lieu of my Cat6 (SFTP) betwen my Synology box and the Internet provider box !
Anyhow the Synology I have is quiet as I have better result thtough USB than with the RaspBerryPi battery powered through GPIO header I2S adapter (via impedance matched uf-l cable) to a FIFO card... so sources & care matter !
Thanks again Bertel for the nice review & tests.
Yep for sure : one side of the USB should be grounded to avoid antenna effect to pick EMI. Perhaps I'm too worried about the gnd external shielding as a path of noise between the sources :both Internet provider box by the shielded ethernet cable & PC by the shielding of the USB cable.
When you say: "as it should be" : it's not so sure from an audio perspective if you read all the links I gave above ! But audio constructors must maybe respect the norms, I dont'k know...
If your splited cable has an external shield from ground to ground on the power cable, indeed you just pick up the noise (if it exists) from the unit which supply it and not on the other unit which is only providing the data ! So if i undersand the cable maker understood this ! And the power cable is shielded both side because anyhow the negative return wire is the ground already (so pick up noise, hence your good result with a quiet supply
Maybe it is just a detail, ECEDESIGNS not answering is perhaps because it's not so important . But I find the subject of picking noise from the sources not so much talked and ECDESIGNS opened an interresting door as usual. I was surprised too cause I have a very good dac and all the IanCanada devices (fifo and low phase noise, isolator, etc) and I do hear difference when Something is changed from the sources : USB cables, powersupply... So why not bother about it ? I will try next an unshielded ethernet (UTP) cable in lieu of my Cat6 (SFTP) betwen my Synology box and the Internet provider box !
Anyhow the Synology I have is quiet as I have better result thtough USB than with the RaspBerryPi battery powered through GPIO header I2S adapter (via impedance matched uf-l cable) to a FIFO card... so sources & care matter !
Thanks again Bertel for the nice review & tests.
When I said "as it should be", I was mentioning the USB data cable - as this has metal plugs on both ends, the USB A plug connects to the computer and the USB B plug connecting to the Mosaic, that's how USB cables typically interlink when they are both mains powered (so not one being USB powered by the host), as is the case here with PC and Mosaic. That's how I also read the material in the links you have provided. So in order for the shielding to work properly in my case, both ends are connected with the respective cases of PC and Mosaic, "as it should be" Both cases are grounded to mains earth via their EU mains connector plugs.
It's exactly the other way round: the USB data cable has an end-to-end shielding as described above, the USB power cable which I have connected to my lab power supply doesn't, the shielding is open at the end of the power supply but connected to the case at the Mosaic through the USB B plug. And the negative return wire isn't ground, -V and +V are just a potential difference which the Mosaic sees to sense the host. -V is not connected to GND or mains earth at the end of the lab power supply, as it is "floating". I'll leave the shiled open at that end for the time being I think.
Regarding your upcoming test of unshielded ethernet (UTP) versus Cat6 (SFTP), you might want to read the measurements provided here: The Antenna Myth - Screened and Shielded Network Cabling Standards Guide, By Siemon At least from a shielding perspective, a shielded F/UTP wins hands down. This however looks at how effective the shielding is for keeping the data that is travelling inside intact, would actually be interesting to see how much noise and interference is travelling over the shielding itself when connecting USB host and receiver, which I believe rather is your point.
Both cases are grounded to mains earth via their EU mains connector plugs.It's exactly the other way round: the USB data cable has an end-to-end shielding as described above, the USB power cable which I have connected to my lab power supply doesn't, the shielding is open at the end of the power supply but connected to the case at the Mosaic through the USB B plug. And the negative return wire isn't ground, -V and +V are just a potential difference which the Mosaic sees to sense the host. -V is not connected to GND or mains earth at the end of the lab power supply, as it is "floating". I'll leave the shiled open at that end for the time being I think.
Regarding your upcoming test of unshielded ethernet (UTP) versus Cat6 (SFTP), you might want to read the measurements provided here: The Antenna Myth - Screened and Shielded Network Cabling Standards Guide, By Siemon At least from a shielding perspective, a shielded F/UTP wins hands down. This however looks at how effective the shielding is for keeping the data that is travelling inside intact, would actually be interesting to see how much noise and interference is travelling over the shielding itself when connecting USB host and receiver, which I believe rather is your point.
thanks for the link ! Several thoughts, certainly on a non importance :
-shields are often here to prevent EMI to radiate towards exterior of these cables.
-ground is a reference for impedance, impedance is important ! ground and shield are mixed and it's maybe a problem for audio as it's can be a path for Noisy smps supply towards pcbs (my previous perhaps bad questions)
- (-V) cable in an USB cable is the ground (the return path of the+V) and so is tied to the ground of the host circuit (and so the Earth if the device has IEC grid wall plug) and the receiver most of the time (to be ok with the EMI/EMC norm : i.e. to prevent external EMC/EMI radiation AND not to be protected from them as far the internal cable already have picked up EMI from its host internal pcb)
- in a pro networks environment where there are a lot of cable as a servers room or routers rooms, shielding is important cause both high speeds (10 Go for some local networks) and the number of close ethernet cable (goal is to protect them for each others : we just talk about the external shielding which is interresting us for audio as it links the gnd potantials; the individual screened pairs are not in all the main (only external body of the cable) screened ethernet cable). As we just use a single short cable, I asked myself about UTP vs the the screened with metal jack which is linking the grounds. I'm sure an UTP cable is bit perfect at 100 Mo speed if less than 10 meters !
- maybe all those ground loops and noise of smps travelling trough it is not important at all ! I don't know, hence my questions ! Mosaic input USB seems not isolated from ground, maybe the designer putter a ferrite bead in serie between the YSB plug and pcb ground and the same for the -V bus (ground) !
- think the USB wires makers must respect the norm even if for audio as it's CE rules ! Is it the best for our purpose ? (my doubt)
-shields are often here to prevent EMI to radiate towards exterior of these cables.
-ground is a reference for impedance, impedance is important ! ground and shield are mixed and it's maybe a problem for audio as it's can be a path for Noisy smps supply towards pcbs (my previous perhaps bad questions)
- (-V) cable in an USB cable is the ground (the return path of the+V) and so is tied to the ground of the host circuit (and so the Earth if the device has IEC grid wall plug) and the receiver most of the time (to be ok with the EMI/EMC norm : i.e. to prevent external EMC/EMI radiation AND not to be protected from them as far the internal cable already have picked up EMI from its host internal pcb)
- in a pro networks environment where there are a lot of cable as a servers room or routers rooms, shielding is important cause both high speeds (10 Go for some local networks) and the number of close ethernet cable (goal is to protect them for each others : we just talk about the external shielding which is interresting us for audio as it links the gnd potantials; the individual screened pairs are not in all the main (only external body of the cable) screened ethernet cable). As we just use a single short cable, I asked myself about UTP vs the the screened with metal jack which is linking the grounds. I'm sure an UTP cable is bit perfect at 100 Mo speed if less than 10 meters !
- maybe all those ground loops and noise of smps travelling trough it is not important at all ! I don't know, hence my questions ! Mosaic input USB seems not isolated from ground, maybe the designer putter a ferrite bead in serie between the YSB plug and pcb ground and the same for the -V bus (ground) !
- think the USB wires makers must respect the norm even if for audio as it's CE rules ! Is it the best for our purpose ? (my doubt)
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maybe we just should apply adhesiv tape on the metal (grounded to external shield) plugs at just one side of the cables for both the USB and CAT6 shielded cables; lol ! I don'tknow...
I didn't understand why the guy in the ethernet cables myths is speaking about shieldings in an UTP cable ? UTP is for unshielded twisted pairs ! IIRC UTP have even no main external shields ! I think as well maybe the drain is acting as reference for the unshielded twisted pairs ? Hummm , dunno ! Well, I will try with one side: plug with adhesiv tape around to have the other side pluged to act against antenna and still have not the both ground tied... should have some UTP old Cat5 cables around.
I tried the ferrite bead and I heard no difference, which is not saying one should avoid it.
sorry it's maybe off topic in ECDESIGNS thread even if he opened the talk about noise through USB cables ?
Deserves its own thread or maybe no one cares about this (non) subject ?
I didn't understand why the guy in the ethernet cables myths is speaking about shieldings in an UTP cable ? UTP is for unshielded twisted pairs ! IIRC UTP have even no main external shields ! I think as well maybe the drain is acting as reference for the unshielded twisted pairs ? Hummm , dunno ! Well, I will try with one side: plug with adhesiv tape around to have the other side pluged to act against antenna and still have not the both ground tied... should have some UTP old Cat5 cables around.
I tried the ferrite bead and I heard no difference, which is not saying one should avoid it.
sorry it's maybe off topic in ECDESIGNS thread even if he opened the talk about noise through USB cables ?
Deserves its own thread or maybe no one cares about this (non) subject ?
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Before I go in any more detail, I just made a strange observation which I need to get sorted for me first: every USB cable that I use has the shielding connected to the outer metal cover on the plugs (USB A and B) on either end, and the -V just on the respective pins. Not so the Tubulus: It doesn't have the shielding connected to the USB plugs, but the -V pin of the USB A plug on the USB power cable is connected to the metal cover of the USB B plug! That in my view counteracts everything that we have discussed here on that topic, so will get in touch with the vendor first to clarify this.
Will also build a dual head cabling with S/FTP cables as suggested in the earlier post by John, with proper shielding ;-)
Will also build a dual head cabling with S/FTP cables as suggested in the earlier post by John, with proper shielding ;-)
interresting ! There is a logic here perhaps: as the -V is the gnd, one can find some logic than the external shield of this standalone powercable is connected to the B plug for some shielding purepose and to avoid the antenna effect discussed ! So the external shielding of the power cable is as well tied to the metal plug of the A USB connector I assume ?
That's Strange than the data cable has not one side of the shield connected to one side only for the same reason !
I assume and I hope the Tubulus brand know what they are doing as it's expensive (I can not afford it) or maybe the EMC/EMI CE norms yet ??? Dunno !
looking forward to read about your investigations.
best regards
That's Strange than the data cable has not one side of the shield connected to one side only for the same reason !
I assume and I hope the Tubulus brand know what they are doing as it's expensive (I can not afford it) or maybe the EMC/EMI CE norms yet ??? Dunno !
looking forward to read about your investigations.
best regards
I have discussed this with Aldwin Oomen, owner of the High End Cable Shop in the Netherlands, who make and distribute the Tubulus cables. Here is what he says:
With a regular USB cable, the screening is connected to the outer metal parts of both USB plugs (A and B). Not desirable in audio applications, as this way noise and interference which is picked or comes from the source can enter the DAC. With the Tubulus dual head cable, the screening is only connected to the outer metal parts of the USB A plugs. This way the noise picked up by the screening can't enter the DAC. The screening of the USB data cable and the screening of the USB power cable are totally separated.
To complete the screening, the outer metal parts of the USB B plug are connected to ground. The ground of the USB B plug is connected to -V of the power cable and also connected to the -V pin of the data cable, because according to Aldwin the data lines always need a ground reference. So the outer metal part of the USB B plug is always connected to ground, even if the power cable as in my case is connected to a "floating" power source like a lab power supply or a battery. There's also shielding between the data lines and data ground line.
Makes sense to me I think
With a regular USB cable, the screening is connected to the outer metal parts of both USB plugs (A and B). Not desirable in audio applications, as this way noise and interference which is picked or comes from the source can enter the DAC. With the Tubulus dual head cable, the screening is only connected to the outer metal parts of the USB A plugs. This way the noise picked up by the screening can't enter the DAC. The screening of the USB data cable and the screening of the USB power cable are totally separated.
To complete the screening, the outer metal parts of the USB B plug are connected to ground. The ground of the USB B plug is connected to -V of the power cable and also connected to the -V pin of the data cable, because according to Aldwin the data lines always need a ground reference. So the outer metal part of the USB B plug is always connected to ground, even if the power cable as in my case is connected to a "floating" power source like a lab power supply or a battery. There's also shielding between the data lines and data ground line.
Makes sense to me I think
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It's answering to my interrogations in the beginning of the previous posts !
So the tubulus of the poors cable can be a normal cable with just adhesiv tape on the metal plug of one side (but will not have a standalone cable for both the power and data either ! Perhaps than the crosstalk will be lowered this way as just the -V bus will be grounded from host to device : i.e. better indeed if just a low current less than 5 mA for the sensing because device is self 5V powered !
not sure cat5 cable is ok to make its own USB wire... it's 100 ohms and not 90 ohms (certainly no important cause the distance is short in our case) ; if the data cable is unshielded, I understand than the twisting imunize a little but I will be more worried by the drain wire which can be an antenna picking by iyself (?)... but again distances are short !
Well I will glue to the adhesiv tape trick and short cable (30 cm is ok, my Synology is close to the DAC) and also will try the 100 Mo U/UTP or 1000 U/STP ethernet cables to feed the PC/NAS as it's linked to the network and the noisy outside WAN (internet provider outside network).
Certainly the Mosaic cares already of that and have a sota USB input with some trick for noise immunity... but as a precaution, diy cable or on the shelf USB cable seem to add their good ! (despite all the good designs : fifo, isolator, clean power supply...)