USB related hum problem [SOLVED]

Author
azslow3
Max Output Level: -42.5 dBFS
  • Total Posts : 3297
  • Joined: 2012/06/22 19:27:51
  • Location: Germany
  • Status: offline
2014/10/25 15:20:53 (permalink)

USB related hum problem [SOLVED]

 
After I have got second "instrument" with the same problem, it is time to find a solution...
 
1) TC VoiceLive Play GTX connected to computer with USB, connected with Kawai CN43 from headphone output (1/8'' stereo) to line input (2xTS)
2) Roland TD-11K connected to XENYX QX1202USB (2xTS), which in turn is connected to computer with USB.
 
Both combinations are working fine for me (there are in different rooms, so different computers and the rest) till I connect either of the instruments (e-drums or DP) to computer with USB. The result is the same in both cases: significant noise/hum in middle/hi frequency (not 50Hz).
 
I have tested several USB cables, no difference. I have tested other USB ports (throw hub, without, etc.), there is a difference, but it is still not acceptable. Notebook on place of any of 2 PCs (especially on accu) works fine.
 
Since I conclude I am getting some ground loop (PC->usb->mixer/VliceLive->DP/e-drum->usb->PC) and I do not like an idea to cut ground on USB cable (I have seen many smoked devices at work after using such "solutions"), I am thinking about some trafos:
 
VoiceLive has balances XLR outputs (mic level), so I think about XLR to TS:
http://www.thomann.de/gb/neutrik_na2mjtx.htm
 
TD-11K has unbalanced TS (also mic level? I am forces to use mixer preamp inputs to get on normal one), so the idea is to "save a bit" with:
http://www.thomann.de/gb/behringer_microhd_hd400.htm
 
Does someone had the same/solved such problem?
 
EDIT:
 Solution: Behringer HD 400 helps in both cases.
post edited by azslow3 - 2014/10/29 06:54:40

Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
#1

20 Replies Related Threads

    tomixornot
    Max Output Level: -58.5 dBFS
    • Total Posts : 1674
    • Joined: 2011/03/05 11:31:26
    • Status: offline
    Re: USB related hum problem 2014/10/25 16:13:29 (permalink)
    I've got good result with the Behringer HD400. I used to hear some digital noise when I turn up the volume of my audio interface to the max - when there is no audio playing. With the HD400, the noise is completely gone. My setup may not be the same as yours, but the HD400 is cheap enough to give it a try.

    Albert


    i7 2600K @ 3.40GHz / MB Intel DP67BG / 16GB Ram
    - ADATA 250GB SSD (Boot)
    - Samsung Spinpoint F1 1TB HDD (Samples)
    Audio interface : Motu 828 MK ii
     
    i7 6700K @ 4.00GHz / MB Asrock Z170 / 16GB Ram
    - Samsung EVO 850 120GB / 500 GB SSD

    Audio interface : Roland Quad Capture
     
    Win 10 Pro / Sonar Platinum
    #2
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/25 17:08:33 (permalink)
    Thanks for the comment. I think I will try HD400 first.
     
    As a piano player, I am more sensitive to the noise on DP. That is why I have thought about Neutrik there, but may be I can somehow test HD400 for piano as well.
     
    You are right, my dinner yesterday was more expensive then all these devices together... my wife has enjoyed the dinner, while she is still skeptical about my hobby 

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #3
    2:43AM
    Max Output Level: -68 dBFS
    • Total Posts : 1147
    • Joined: 2013/06/24 07:59:49
    • Location: PHX
    • Status: offline
    Re: USB related hum problem 2014/10/25 22:44:16 (permalink)
    Azslow3,
    Your original post is a bit confusing in terms of signal chain.  Just for clarity, is it like this?
    [TD-11K Drums]---{Unbal. Audio}--->[XENYX Mixer]---------{USB}--->[Computer]
    [Kawai Piano]-------{Unbal. Audio}--->[VoiceLive Play GTX]---{USB}--->[Computer]
     
    Also, you have have two, separated setups except for the computer (which is the common point).  The instrument setups use different wall outlets, right?.  This can cause a ground loop.
     
    But overall, I think the issue stems from the USB connections.  I experienced the same issue in the past with a Waldorf Blofeld synthesizer. It was horribly bad.  I think I ended up swapping the USB cable for a MIDI cable as the USB-audio feature was a bit crappy anyway.  After the swap, the hum/noise was gone. Regardless, I didn't like the Blofeld so I sold it!
     
    The Behringer HD400 seems like a good solution to try since it is relatively cheap. Buy it at a brick-n-mortar store that will allow a hassle-free return if you're not satisfied.  If it helps clean up some digital noise, as tomixornot has mentioned, then I may try that as well in between a Roland V-Synth (noisy bugger!) and an Alesis Ai3 interface.
     
    EDIT: Since you don't want to break the ground connection in your USB cables, then the Behringer HD400 (or similar device) will safely break the ground connection in your audio cables.  Essentially the result will be the same.  You'll need two HD400's, one between each stereo-audio path from your instruments to your interfaces.
    #4
    tomixornot
    Max Output Level: -58.5 dBFS
    • Total Posts : 1674
    • Joined: 2011/03/05 11:31:26
    • Status: offline
    Re: USB related hum problem 2014/10/26 00:39:51 (permalink)
    My previous setup :
    Quad Capture (unbalanced) -> HD400 (unbalanced) -> Behringer Truth monitors (active).
     
    My current setup :
    Quad Capture (unbalanced) -->>
    -> Nad Amp (driving a JBL Sub woofer)
    -> Nad Amp Rec out (unbalanced) -> HD400 (unbalanced) -> Behringer Truth monitors.
     
    There is no noise from the Quad Capture headphones, only when Quad Capture -> Truth direct. I wonder if using a pair of balanced 1/4" cable would solve the problem too..?

    Albert


    i7 2600K @ 3.40GHz / MB Intel DP67BG / 16GB Ram
    - ADATA 250GB SSD (Boot)
    - Samsung Spinpoint F1 1TB HDD (Samples)
    Audio interface : Motu 828 MK ii
     
    i7 6700K @ 4.00GHz / MB Asrock Z170 / 16GB Ram
    - Samsung EVO 850 120GB / 500 GB SSD

    Audio interface : Roland Quad Capture
     
    Win 10 Pro / Sonar Platinum
    #5
    fireberd
    Max Output Level: -38 dBFS
    • Total Posts : 3704
    • Joined: 2008/02/25 14:14:28
    • Location: Inverness, FL
    • Status: offline
    Re: USB related hum problem 2014/10/26 06:51:31 (permalink)
    I had a hum problem in my Octa-Capture, until I used the correct "Line Out" rather than the headphone out for my studio monitors.
     
    I use TRS plugs for the monitor speakers.

    "GCSG Productions"
    Franklin D-10 Pedal Steel Guitar (primary instrument). Nashville Telecaster, Bass, etc. 
    ASUS ROG Maximus VIII Hero M/B, i7 6700K CPU, 16GB Ram, SSD and conventional hard drives, Win 10 Pro and Win 10 Pro Insider Pre-Release
    Sonar Platinum/CbB. MOTU 896MK3 Hybrid, Tranzport, X-Touch, JBL LSR308 Monitors,  
    Ozone 5,  Studio One 4.1
    ISRC Registered
    Member of Nashville based R.O.P.E. Assn.
    #6
    gswitz
    Max Output Level: -18.5 dBFS
    • Total Posts : 5694
    • Joined: 2007/06/16 07:17:14
    • Location: Richmond Virginia USA
    • Status: offline
    Re: USB related hum problem 2014/10/26 07:05:27 (permalink)
    If it really is a ground loop, the way I always handle it is to use one of those 3 prongs to 2 prongs plug converters (is this an American thing?) on various plugs in the signal chain and check to see where the hum gets louder or softer based on the change.
     
    Sometimes it gets MUCH worse, sometimes much better.
     
    As long as there is a path to ground, you should be ok, but you don't want to lift the ground if there is only one path to ground. So for example, if you have a power strip plugged into the wall and everything plugged into the power strip, don't lift the ground at the wall. Lift it for the items being plugged into the power strip.
     
    ymmv.
     

    StudioCat > I use Windows 10 and Sonar Platinum. I have a touch screen.
    I make some videos. This one shows how to do a physical loopback on the RME UCX to get many more equalizer nodes.
    #7
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/26 08:26:18 (permalink)
    2:43AM
    Azslow3,
    Your original post is a bit confusing in terms of signal chain.  Just for clarity, is it like this?
    [TD-11K Drums]---{Unbal. Audio}--->[XENYX Mixer]---------{USB}--->[Computer]
    [Kawai Piano]-------{Unbal. Audio}--->[VoiceLive Play GTX]---{USB}--->[Computer]
     
    Also, you have have two, separated setups except for the computer (which is the common point).  The instrument setups use different wall outlets, right?.  This can cause a ground loop.

    The second setup is:
    VoiceLive (headphone output)->Kawai (unbalanced line input)
    VoiceLive (USB)-> PC(USB)
    And the problem comes when there is (in addition)
    Kawai (USB) -> PC(USB)
     
    I have already mentioned that 2 setups are on 2 different computers in 2 different rooms. In each room all equipment is connected to the same outlet. So, there is no usually mentioned "power ground" loop.
     
    tomixornot
    There is no noise from the Quad Capture headphones, only when Quad Capture -> Truth direct. I wonder if using a pair of balanced 1/4" cable would solve the problem too..?

    My (stage) monitor is connected from XENYX with TRS (balanced). In case I use TS (unbalanced), I get more noise. But the effect is negligible compare to what I get in the case of USB loop. With TRS, the background noise level is the same as with disconnected boxes (cheap stage monitors are not noiseless, but they are cheap and big, that is what I wanted for drums ).
     
    I have ordered HD400, I will report the results with both setups once I get it.
     

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #8
    fireberd
    Max Output Level: -38 dBFS
    • Total Posts : 3704
    • Joined: 2008/02/25 14:14:28
    • Location: Inverness, FL
    • Status: offline
    Re: USB related hum problem 2014/10/26 08:55:38 (permalink)
    The Behringer looks like a knockoff of the Ebtech hum eliminator.   I keep an Ebtech on hand in case its needed.

    "GCSG Productions"
    Franklin D-10 Pedal Steel Guitar (primary instrument). Nashville Telecaster, Bass, etc. 
    ASUS ROG Maximus VIII Hero M/B, i7 6700K CPU, 16GB Ram, SSD and conventional hard drives, Win 10 Pro and Win 10 Pro Insider Pre-Release
    Sonar Platinum/CbB. MOTU 896MK3 Hybrid, Tranzport, X-Touch, JBL LSR308 Monitors,  
    Ozone 5,  Studio One 4.1
    ISRC Registered
    Member of Nashville based R.O.P.E. Assn.
    #9
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/26 09:06:36 (permalink)
    fireberd
    I had a hum problem in my Octa-Capture, until I used the correct "Line Out" rather than the headphone out for my studio monitors.

    The hum from "incorrect" line out is on the level I do not care. The connection is there just to sing along with piano without reconnecting my headphones every time (I keep all "surrounding equipment" off when not in use, so the headphones are always connected to the piano).
     
    gswitz
    If it really is a ground loop, the way I always handle it is to use one of those 3 prongs to 2 prongs plug converters (is this an American thing?) on various plugs in the signal chain and check to see where the hum gets louder or softer based on the change.
     
    Sometimes it gets MUCH worse, sometimes much better.

    That is some kind of "USB ground loop". Most probably incorrect design of the related circuits. Why someone has decides electrically connect USB ground to something? I remember times when network interfaces was grounding cables, burning motherboards within seconds.
     
    As I understand, 3to2 plug is something I have found by Neutrik. I will try that in case Behringer does not work in my case (Neutrik is 2 times more expensive, next step can be Palmer, which is again 1.5 in $$$ compare to Neutrik).

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #10
    tomixornot
    Max Output Level: -58.5 dBFS
    • Total Posts : 1674
    • Joined: 2011/03/05 11:31:26
    • Status: offline
    Re: USB related hum problem 2014/10/26 12:18:06 (permalink)
    fireberd
    The Behringer looks like a knockoff of the Ebtech hum eliminator.   I keep an Ebtech on hand in case its needed.

     
    I actually bought the Behringer HD400 together with the Ebtech HD-2-XLR at the same time, in case one doesn't work. While the HD400 has been operating without any problem, the Ebtech gives a small buzz from day one... must be a faulty unit as the buzz came out from both channels.

    Albert


    i7 2600K @ 3.40GHz / MB Intel DP67BG / 16GB Ram
    - ADATA 250GB SSD (Boot)
    - Samsung Spinpoint F1 1TB HDD (Samples)
    Audio interface : Motu 828 MK ii
     
    i7 6700K @ 4.00GHz / MB Asrock Z170 / 16GB Ram
    - Samsung EVO 850 120GB / 500 GB SSD

    Audio interface : Roland Quad Capture
     
    Win 10 Pro / Sonar Platinum
    #11
    fireberd
    Max Output Level: -38 dBFS
    • Total Posts : 3704
    • Joined: 2008/02/25 14:14:28
    • Location: Inverness, FL
    • Status: offline
    Re: USB related hum problem 2014/10/26 12:33:17 (permalink)
    Must be a bad unit as I've only used the ebtech a couple of times but it worked every time. 
     
    One issue on XLR cables/connectors.   If the ground is connected to the ground lug on XLR connectors, on both ends, it can cause hum in some cases.  Some cables are made with the ground connected to the XLR connectors on both ends.  Ground not connected or only on one end is OK.  Got this from a retired TV broadcast engineer friend (who also had a consulting company for recording studios and video studios). 
     
     
     

    "GCSG Productions"
    Franklin D-10 Pedal Steel Guitar (primary instrument). Nashville Telecaster, Bass, etc. 
    ASUS ROG Maximus VIII Hero M/B, i7 6700K CPU, 16GB Ram, SSD and conventional hard drives, Win 10 Pro and Win 10 Pro Insider Pre-Release
    Sonar Platinum/CbB. MOTU 896MK3 Hybrid, Tranzport, X-Touch, JBL LSR308 Monitors,  
    Ozone 5,  Studio One 4.1
    ISRC Registered
    Member of Nashville based R.O.P.E. Assn.
    #12
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/26 14:17:14 (permalink)
    Grounding in electronic is even more confusing then the meaning of ACT in SONAR.
     
    We have several "grounds":
    1) "ground" connector on power socket. It should be "real" ground (well connected with the earth). It should not be used to deliver elictricity. It is there just in case the power wire is by occasion touch metal parts we can touch as well, so "overcurrent" somehow switch electricity off and prevent our death. The theory is good, but the practice, especially in consumer area, is far from perfect. I was born in Russia, where outlets had no such connector.
    2) "ground" (0) wire on power socket. That is used to deliver electricity (together with the power wire). It is normally "close" to the real ground, so for example we do not feel us bad in case we touch it. Well, if everything is correctly connected and it is not in use by some powerful device, in which case the wire own resistance produce significant potential shift. For that reason, it should not be connected with the "real" ground.
    3) circuit "ground", as a reference for other (not power) signals inside the device. Depending on the power supply of the device, it can have virtually any potential compare to (1) or (2).
    4) signal "ground" for transferring the signal (for example audio)
    5) shield "ground", just to have the shield potential on some stable level.
     
    So, for XLR it is quite logical:
    * if both ends have the "ground" pin connected to the shield (inside device), it make no different how we connect it in the cable
    * in all other cases of it's connection ((3) or (1)) we are looking for troubles (till at one end it is disconnected, inside the device or in the cable)
     
    Theoretically, the same is valid for USB.
     
    But there is one small problem... all "grounds" except (1) can be different between powered devices. The shield on all devices is (should be) connected such way, that the difference on it can not "kill" the device. It can create hum/noise or even switch off the device, but it should not kill it. From information in the Internet, audio circuits (at least in (semi)pro level) are also prepared for such "surprise". But for USB I am not so sure...
     
    I must admit that my background in electronics has not helped me eliminate my hum, so I am waiting for the trafo
     
    PS. Sorry for so long post.

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #13
    johnnyV
    Max Output Level: -48.5 dBFS
    • Total Posts : 2677
    • Joined: 2010/02/22 11:46:33
    • Location: Here, in my chair
    • Status: offline
    Re: USB related hum problem 2014/10/27 00:06:23 (permalink)
    Is there not something called a ferrite USB cable? 
     
    I just google this and holy cow, I have a few of these already and didn't know it. I never new what that bump was for. Anyhow if you read up on it, it's a feature that helps reduce hum in audio related systems due to power transfer over the cable. USB buss powered audio interfaces are often terrible for background noise. A friend of mine bought the Focusrite 2i4 and had a bad hum. Later when I asked him he said he got rid of most of it by using a ferrite choke. 
     
    Personally I think we are expecting to much from pour little usb. USB 3.0 was supposed to be better a supplying more power but seems more people are having trouble with USB 3.0 not working right than with 2.0. 

    Sonar X3e Studio - Waiting for Professional
     Scarlett 6i6
    Yamaha Gear= 01v - NSM 10 - DTX 400 - MG82cx
    Roland Gear= A 49- GR 50 - TR 505 - Boss pedals
    Tascam Gear=  DR 40 - US1641 -
    Mackie Gear= Mix 8 - SRM 350's 
    i5 Z97 3.2GHZ quad 16 Gig RAM W 8.1  home build
    Taylor mini GS - G& L Tribute Tele - 72 Fender Princeton - TC BH 250 - Mooer and Outlaw Pedals  Korg 05/RW
     
    #14
    johnnyV
    Max Output Level: -48.5 dBFS
    • Total Posts : 2677
    • Joined: 2010/02/22 11:46:33
    • Location: Here, in my chair
    • Status: offline
    Re: USB related hum problem 2014/10/27 00:11:40 (permalink)


    Sonar X3e Studio - Waiting for Professional
     Scarlett 6i6
    Yamaha Gear= 01v - NSM 10 - DTX 400 - MG82cx
    Roland Gear= A 49- GR 50 - TR 505 - Boss pedals
    Tascam Gear=  DR 40 - US1641 -
    Mackie Gear= Mix 8 - SRM 350's 
    i5 Z97 3.2GHZ quad 16 Gig RAM W 8.1  home build
    Taylor mini GS - G& L Tribute Tele - 72 Fender Princeton - TC BH 250 - Mooer and Outlaw Pedals  Korg 05/RW
     
    #15
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/27 06:46:22 (permalink)
    johnnyV
    Is there not something called a ferrite USB cable? 

    Interesting idea, thanks! I have not tried to use such cables in the setup, but I have them. Cost nothing to try while waiting for trafo.

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #16
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/27 06:46:29 (permalink)
    Unfortunately no luck with ferrite... Absolutely no difference in my case (tested 2 cables in Piano setup).
    post edited by azslow3 - 2014/10/27 16:40:46

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #17
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/29 07:01:13 (permalink)
    So, HD-400 is effectively eliminating problematic loud noise in both setups.
     
    Thanks for suggestions!
     
    I am not sure I will get the second HD400 or try Neutrick for DP. I have to investigate from where some kind of "radio noise" still comes (it sounds like radio interferences on SW radio receiver, with changing frequency and tone), but that is not USB related and on the level of "you can not hear it in headphones when computer is working in the near". Ferrite is not helping with it (I really hoped, because ferrite is targeting RF...). But that is not a problem till I play some "ppp" classic and I do not need other devices "on" in that case.

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #18
    fireberd
    Max Output Level: -38 dBFS
    • Total Posts : 3704
    • Joined: 2008/02/25 14:14:28
    • Location: Inverness, FL
    • Status: offline
    Re: USB related hum problem 2014/10/29 08:53:59 (permalink)
    Back in the mid 70's, I worked on "cleaning" a recording studio that was near an AM radio transmitter site.  The radio station was coming in on the AC power line, recorders, console, etc.  and headphones.  I was able to get the radio out, or at a low enough level that it didn't matter in everything except the headphone system.  I couldn't get it completely out of the headphones. 
     
    Most of what I did was bypass capacitors. There was some shielding but the bypass caps fixed most of it.

    "GCSG Productions"
    Franklin D-10 Pedal Steel Guitar (primary instrument). Nashville Telecaster, Bass, etc. 
    ASUS ROG Maximus VIII Hero M/B, i7 6700K CPU, 16GB Ram, SSD and conventional hard drives, Win 10 Pro and Win 10 Pro Insider Pre-Release
    Sonar Platinum/CbB. MOTU 896MK3 Hybrid, Tranzport, X-Touch, JBL LSR308 Monitors,  
    Ozone 5,  Studio One 4.1
    ISRC Registered
    Member of Nashville based R.O.P.E. Assn.
    #19
    azslow3
    Max Output Level: -42.5 dBFS
    • Total Posts : 3297
    • Joined: 2012/06/22 19:27:51
    • Location: Germany
    • Status: offline
    Re: USB related hum problem 2014/10/29 14:16:44 (permalink)
    Capacitor in parallel with some induction, connected to headphones... That was my first self build AM receiver.
     
    The first time I have got that (the same) "noise" from DP, I have started to play Mendelssohn's Leads I have learned between soldering. That subtle effect of radio waves far behind piano music from XIX century adds some life to otherwise "perfectly dead" sound of DP
     
    Probably it comes from bad "phone out"->"line in" cable I currently use. At place where I am, it is hard to receive radio. Also I am not getting that noise with other equipment (combinations).

    Sonar 8LE -> Platinum infinity, REAPER, Windows 10 pro
    GA-EP35-DS3L, E7500, 4GB, GTX 1050 Ti, 2x500GB
    RME Babyface Pro (M-Audio Audiophile Firewire/410, VS-20), Kawai CN43, TD-11, Roland A500S, Akai MPK Mini, Keystation Pro, etc.
    www.azslow.com - Control Surface Integration Platform for SONAR, ReaCWP, AOSC and other accessibility tools
    #20
    wst3
    Max Output Level: -55.5 dBFS
    • Total Posts : 1979
    • Joined: 2003/11/04 10:28:11
    • Location: Pottstown, PA 19464
    • Status: offline
    Re: USB related hum problem 2014/10/30 13:53:01 (permalink)
    Grounding is not mysterious, nor is it voodoo. It is, however, difficult to manage because of the myriad ways manufacturers apply basic grounding rules, and that's complicated by the mix of balanced and single-ended interfaces.
     
    The basics:
     
    A balanced output provides an equal impedance from each leg to reference ground. There is no requirement that both sides of the line are driven, although the most common topology applies a signal of equal amplitude, and opposite polarity, to the two legs. Signal symmetry has nothing to do with balancing a line, other than you can't have signal symmetry on a single-ended output.
     
    A balanced input takes the difference between the two signal lines, which is probably why this is confusing. But it is the impedance balance between the two legs that provides the noise immunity. If each leg is impedance balanced, and noise is impressed on both legs it will cancel out. But in order to accomplish this both input pins must also have equal impedance to the reference ground. The cool thing is that the reference does not have to be remote!
     
    Another thing people trip over - the shield on a balanced line is not required to transmit, and recover the signal. In fact, it is a really bad idea to connect the shield anywhere other than the chassis itself. If the shield enters the device you have problems - most commonly referred to as the "Pin 1" problem.
     
    And now you probably see the problem... a single ended interface usually uses the shield as one of the signal conductors, which means that it necessarily has to enter the chassis. Well, ok, there are ways around even that, but they are not terribly effective.
     
    The really bad news? It takes only one poorly implemented interconnection in an entire system to drag it into noise heaven. And USB is very often that culprit.
     
    The good news is that most audio manufacturers seem to have figured out how to properly handle USB. My new Presonus 1818VSL exhibits no pin 1 problems.
     
    There is a lot more to audio interfacing, but my fingers are getting tired, and I sense many eyes are glazing over.

    -- Bill
    Audio Enterprise
    KB3KJF
    #21
    Jump to:
    © 2024 APG vNext Commercial Version 5.1