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#41
Posted to rec.audio.pro
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USB hum/noise isolation?
w_tom wrote:
Currently we don't even know is the noise is differential mode or common mode - and in what electrical loop (circuit). Get a 6 ft USB cable and perform the test; to answer those unknowns. From his description, it's neither. He says he hears the noise in headphones plugged into the interface, with nothing other than the computer plugged into it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#42
Posted to rec.audio.pro
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USB hum/noise isolation?
"w_tom" wrote...
"StudioDog" wrote: OK, gentlemen..... I'm going to go play some Paddy's Day gigs while you two carry on ****ing in each other's cornflakes..... if you must. No problem. Meindert is finished confusing the issue. And I am finished trying to explain to him so many times over why his posts are irrelevant to your problem. Currently we don't even know is the noise is differential mode or common mode - and in what electrical loop (circuit). Get a 6 ft USB cable and perform the test; to answer those unknowns. Remember that just because the OP calls it "ground loop" or even "hum" doesn't make it so. His description sounds more like high-frequency digital hash than anything like "traditional" ground-loop 60Hz power mains hum. Remember he said he still hears it with no inputs connected, and he still hears it with only headphones. Either of those casts significant doubt on "traditional ground loop" as the primary issue. |
#43
Posted to rec.audio.pro
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USB hum/noise isolation?
Richard Crowley wrote:
Remember that just because the OP calls it "ground loop" or even "hum" doesn't make it so. His description sounds more like high-frequency digital hash than anything like "traditional" ground-loop 60Hz power mains hum. Remember he said he still hears it with no inputs connected, and he still hears it with only headphones. Either of those casts significant doubt on "traditional ground loop" as the primary issue. If he hears it without only headphones, it's not a ground loop, because there is only one single ground path. (Well, it COULD be internal grounding issues inside the box, but there's nothing he can do about that.) And if it's not a ground loop, fiddling around with cables isn't going to improve anything. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#44
Posted to rec.audio.pro
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USB hum/noise isolation?
"Scott Dorsey" wrote in message
... If he hears it without only headphones, it's not a ground loop, because there is only one single ground path. (Well, it COULD be internal grounding issues inside the box, but there's nothing he can do about that.) Was that interface powered by USB or did it have it's own power supply? There could be a loop. The best way for him to try is to connect the interface to a laptop running on it's battery. Headphone on the interface and nothing more. This ensures there is absolutely no ground loop. If the hum/noise is still there, it must the interface itself. Meindert |
#45
Posted to rec.audio.pro
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USB hum/noise isolation?
"Meindert Sprang" wrote ...
Was that interface powered by USB or did it have it's own power supply? There could be a loop. I thought the external power supply was a wall-wart with a 2-prong power mains plug. |
#46
Posted to rec.audio.pro
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USB hum/noise isolation?
"Richard Crowley" wrote in message
... "Meindert Sprang" wrote ... Was that interface powered by USB or did it have it's own power supply? There could be a loop. I thought the external power supply was a wall-wart with a 2-prong power mains plug. No loop through ground then. But even then it should best be plugged in the same power strip as the laptop. Just the other day I had a mixer in one outlet (grounded) and a drumcomputer in an other (wall wart), which whas on a drifferent mains group of a 3phase system. Huge 50Hz hum. Meindert |
#47
Posted to rec.audio.pro
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USB hum/noise isolation?
Hi all. To clarify power supplies: external USB interface is USB powered- no external p/s mixer's intertnal USB interface is powered by mixer psu, which is 2- pring wall wart. (Alesis multuimix 8USB). all other gear is 3-pring IEC cable I have also just added an ART PB4x4Pro power conditioner to the rack - seems to quiet the noise somewhat when I use the external USB interface, but no difference using the Alesis mixer's built-in interface. I'm game to try the USB cable experiment that generated so much traffic here. I opened a spare usb cable to find : a RED wire, a BLACK wire, a GREEN wire and a WHITE wire. I believe these wires are assigned as: Red - power, White - Data neg. Green - Data pos, and Black - Ground. Can someone back me up on this before I cut the wrong wire? Also, if grounding is an issue, as I gather it is/may be from the earlier flurry of posts, if I cut the red wire but leave the ground intact, would this maintain the ground between the computer and the USB interface? If someone can confirm the wiring assignment, I will conduct our little experiment tonight and post results asap. |
#48
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com... I'm game to try the USB cable experiment that generated so much traffic here. I opened a spare usb cable to find : a RED wire, a BLACK wire, a GREEN wire and a WHITE wire. I believe these wires are assigned as: Red - power, White - Data neg. Green - Data pos, and Black - Ground. These colors are correct. Can someone back me up on this before I cut the wrong wire? Also, if grounding is an issue, as I gather it is/may be from the earlier flurry of posts, if I cut the red wire but leave the ground intact, would this maintain the ground between the computer and the USB interface? Yes. Meindert |
#49
Posted to rec.audio.pro
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USB hum/noise isolation?
Meindert
I snipped the red wire to cut the usb power and connected the mixer's internal USB port to the USB hub that connects to my computer in the next room. I didn't get any response from the computer ie. the computer did not recognize that I had plugged a device in, Thus, no driver instal, and no sound.... Any suggestions? I can't imagine why the Alesis mixer would need to power its usb interface via the usb bus, as the mixer is powered by wall wart AC.... I'm not sure exactly how to continue diagnosing this issue, as my other usb interface (Behringer UCA202) is USB Bus powered, with no option for AC, so I can't use it with a cut Vcc lead in the cable. My thanks in advance for any advice. |
#50
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote ...
Meindert I snipped the red wire to cut the usb power and connected the mixer's internal USB port to the USB hub that connects to my computer in the next room. I didn't get any response from the computer ie. the computer did not recognize that I had plugged a device in, Thus, no driver instal, and no sound.... Any suggestions? I can't imagine why the Alesis mixer would need to power its usb interface via the usb bus, as the mixer is powered by wall wart AC.... I'm not sure exactly how to continue diagnosing this issue, as my other usb interface (Behringer UCA202) is USB Bus powered, with no option for AC, so I can't use it with a cut Vcc lead in the cable. It would appear that the USB port/driver depends on seeing a load on the power source to detect when a device is connected. Not programmed to call unless it thinks somebody is home. Well, that knocked that experiment right in the head. Of course, we are assuming that the colors connected to what we think they should. Note that if you are making cables (especially molded ones which likely nobody will ever peek inside of), it doesn't really matter which color you use, as long as it is the same on both ends. I would have confirmed the pinout before cutting anything. You can stick a straight pin (or safety-pin) through the insulation to test which color is connected to which pin. etc. before cutting anything. Did you ever mention whether there was any change in symptoms when all the equipment was together in the same room? Without any extensions of any kind? |
#51
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
ups.com... Meindert I snipped the red wire to cut the usb power and connected the mixer's internal USB port to the USB hub that connects to my computer in the next room. I didn't get any response from the computer ie. the computer did not recognize that I had plugged a device in, Thus, no driver instal, and no sound.... Two possibilities he either the USB interface is bus powered and gets no supply. When it is self powered, the USB standard requires a device to connect D+ to VBus through a 1k5 resistor. Without Vbus (you cut the wire) the computer will not detect the device. Any suggestions? I can't imagine why the Alesis mixer would need to power its usb interface via the usb bus, as the mixer is powered by wall wart AC.... To prevent ground loops? It is perfectly feasible that an audio device has an isolated USB interface to prevent any ground loops. The USB interface can then be bus powered and the link with the rest of the electronics can be made through high-speed opto-couplers. I'm not sure exactly how to continue diagnosing this issue, as my other usb interface (Behringer UCA202) is USB Bus powered, with no option for AC, so I can't use it with a cut Vcc lead in the cable. Try to eliminate things. If your Behr also produces noise with only a headphone connected, the noise can either come from the interface or it is produced in the computer. Swap the computer/laptop and check again. Is the noise in the recordings or is it just produced by the headphone amp? I know My FireBox has a little high frequency hiss on the headphone output, but the recorded material is clean. When I play it through the line outputs to a headphone amp or mixer, it sounds clean. Meindert |
#52
Posted to rec.audio.pro
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USB hum/noise isolation?
"Richard Crowley" wrote in message
... Of course, we are assuming that the colors connected to what we think they should. These colors are dictated by the USB standard, as are a whole bunch of things, like wire gauge, mechanics etc. Meindert |
#53
Posted to rec.audio.pro
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USB hum/noise isolation?
"Meindert Sprang" wrote ...
"Richard Crowley" wrote ... Of course, we are assuming that the colors connected to what we think they should. These colors are dictated by the USB standard, as are a whole bunch of things, like wire gauge, mechanics etc. Of course. But that is not the same as saying that all USB cables consientiously actually use the proper colors. I suspect that if you were some production manager under the gun somewhere in interior China somewhere you wouldn't stop the production line because your latest shipment of wire had blue instead of green. Its not as if it actually affects the functionality or performance. The USB standards also prohibit A-to-A or B-to-B or "extention" cables, but that doesn't prevent people from making and selling them everywhere without apparent consequenses. |
#54
Posted to rec.audio.pro
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USB hum/noise isolation?
The noise appears with whatever computer I use. I have tries it with
an IBM Thinkpad laptop, a generic P3, and my new AMD 64x2 3800+ dual core system. All produce this noise (although the laptop, ironically, is the quietest - just doesn't have the brain-power to handle much audio processing). I have also swapped out usb interfaces - tried the Alesis' on-board interface (that's why I bought the mixer after all!), and then the Behringer UCA202, which is quieter. I have also tries using a brand- new Behringer Xenyx 1204 mixer that came bundled with a UCA 200 usb interface (essentially a UCA202 without a headphone output). All setup variations give me the noise. I'm stumped, really. My guess, if I had to make one at this point, is that the computer is generating the noise - perhaps a power supply issue? Perhaps a feedback loop in the circuitry? No idea how I'd test for that, either. I'll keep tinkering with things, and post back if I get lucky! I still haven't heard anything useful from Hewlett Packard as to whether there may be a fault with the computer itself, but I think that's a long shot. HP's not likely tp take responsibility for this one! |
#55
Posted to rec.audio.pro
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USB hum/noise isolation?
On 19 Mar 2007 17:29:06 -0700, "StudioDog"
wrote: The noise appears with whatever computer I use. I have tries it with I have also swapped out usb interfaces - tried All setup variations give me the noise. Then, beyond the language barrier, there's something you're not telling us. Whatever could it be? What else is connected to these computers? List everything, or risk wasting another week. Chris Hornbeck |
#56
Posted to rec.audio.pro
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USB hum/noise isolation?
The red wire should have been the correct wire. But more important
was which wires are twisted and untwisted. Two wires twisted around each other are the wires to not cut. You must cut both untwisted wires. Leaving a ground wire discovers nothing. Cutting the ground wire is necessary to make the experiment work. You want both untwisted wires cut between computer and mixer. Ignore everything Meindert was posting about grounds. It was all totally irrelevent. Why no response? Well if the red wire was a twisted pair wire, then you have killed the signalling. Meanwhile, it does not matter whether computer push music through the mixer. That noise will be there anyway. However you can continue to experiment. Simple strip and twist those two untwisted wires together. Make the connection. With noise still there, disconnect only two untwisted wires. Does noise disappear? That is useful information. However before doing any of this, first confirm the red and black wires are the untwisted wires and that other wires (green and white?) are twisted. Cut and strip the untwisted wires. Reconnect those wires. Setup the USB test. Listen for noise. Learn what happens to that noise as those untwisted wires are disconnected while live. And again, don't worry about any posts about potential damage. Those warnings would be bogus and irrelevant. Now once those untwisted wires are disconnected, the computer may then report the disconnect. But that is also useful information. USB detection for connection, bus speed, and disconnection are all performed on the signal (twisted) wires. If both boxes have their own power, then voltage power on untwisted wires is not necessary. Removal of that unnecessary power should cause no disconnect detected when untwisted wires are disconnected. What happens when you perform that experiment will be very informative. I am not lost. What makes sense is that, as Chris(?) suggested, wire color codes are wrong. That is why I did not list any colors - why instead I was careful to only call the wires 'twisted' and untwisted'. Believe me. I have been very careful in what I posted which is also why Meindert's warning had long ago been considered (before he even posted) and discounted. Go back to verify every wire in the setup is are defined so many days ago. Also verify which wires are twisted and untwisted. Then perform the experiement with untwisted wires temporarily connected when USB cable is powered; verify noise exists; disconnect untwisted wires; and report those details. On Mar 19, 5:34 pm, "StudioDog" wrote: I snipped the red wire to cut the usb power and connected the mixer's internal USB port to the USB hub that connects to my computer in the next room. I didn't get any response from the computer ie. the computer did not recognize that I had plugged a device in, Thus, no driver instal, and no sound.... Any suggestions? I can't imagine why the Alesis mixer would need to power its usb interface via the usb bus, as the mixer is powered by wall wart AC.... I'm not sure exactly how to continue diagnosing this issue, as my other usb interface (Behringer UCA202) is USB Bus powered, with no option for AC, so I can't use it with a cut Vcc lead in the cable. My thanks in advance for any advice. |
#57
Posted to rec.audio.pro
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USB hum/noise isolation?
On Mar 19, 5:34 pm, "StudioDog" wrote:
... I'm not sure exactly how to continue diagnosing this issue, as my other usb interface (Behringer UCA202) is USB Bus powered, with no option for AC, so I can't use it with a cut Vcc lead in the cable. BTW, when doing the 'temporary spliced together' test, use scotch tape to keep those wires from accidentally shorting to each other or to anything else. |
#58
Posted to rec.audio.pro
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USB hum/noise isolation?
"w_tom" wrote in message
oups.com... Now once those untwisted wires are disconnected, the computer may then report the disconnect. But that is also useful information. USB detection for connection, bus speed, and disconnection are all performed on the signal (twisted) wires. Yes, but in conjuction with the power wires. From VBus drives internal circuitry which in turn injects for instance +3.3V on D+ to indicate a device is full speed.. Without the presence of VBus, the device will not send ANYTHING on the data wires and will therefore not be detected. And since the Ground wire is needed to reference any of thos signals against, cutting either wire will report the device as disconnected. Apart from that, cutting the ground wire of the usb cable alone, is makeing the entire supply current of the device through the datalines with will be detected as a fault situation in the host port which will be shut down. If both boxes have their own power, then voltage power on untwisted wires is not necessary. One had, the other didn't. And as you could have read, cutting the VBus wire to the Alesis did also 'disconnect' the device. Removal of that unnecessary power should cause no disconnect detected when untwisted wires are disconnected. Wrong by the USB standard, proven wrong by SoundDog. You now better stop making a fool of yourself by constantly ignoring and denying expert advice. I am not lost. We are. If SoundDog tells us that even the bus powered device produces noise on a headphone, there are no groundloops anymore that could cause this. If computers swapped still produce the problem, it cannot be the computer. Besides, the sound in the computer is digital, so interference in the computer can affect that data and not crash the computer. Power supply noise of the computer cannot affect the digital datastream. There is something else going on which we are not told yet. Meindert |
#59
Posted to rec.audio.pro
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USB hum/noise isolation?
On Mar 19, 11:56 pm, Chris Hornbeck
wrote: On 19 Mar 2007 17:29:06 -0700, "StudioDog" wrote: The noise appears with whatever computer I use. I have tries it with I have also swapped out usb interfaces - tried All setup variations give me the noise. Then, beyond the language barrier, there's something you're not telling us. Whatever could it be? What else is connected to these computers? List everything, or risk wasting another week. Chris Hornbeck Chris. Hi. There is nothing else connected to the studio computer (and no language barrier, btw, only crappy typing!). As I said before, even stripped right down to the barebones computer --USB interface-- headphones configuration, the noise is present on any computer I try. |
#60
Posted to rec.audio.pro
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USB hum/noise isolation?
On Mar 20, 12:48 am, "w_tom" wrote:
The red wire should have been the correct wire. But more important was which wires are twisted and untwisted. I understand what you're saying, but is it possible we're talking about different cables? Is there a difference between a USB 1.1 cable and a USB 2.0 cable? I have not found any twisted pairs in the cable I'm dissecting. All four coloured wires in my cable are singles, made up of mutli-stranded steel-coloured wire. It's a USB A male to USB B male cable, btw - probably came with the Alesis mixer, which is USB 1.1. |
#61
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com On Mar 20, 12:48 am, "w_tom" wrote: The red wire should have been the correct wire. But more important was which wires are twisted and untwisted. I understand what you're saying, but is it possible we're talking about different cables? Is there a difference between a USB 1.1 cable and a USB 2.0 cable? Clearly, a USB 2.0 cable has to pay more attention to the usual details - the potential data rate is what 40:1 higher? IME USB 1.1's max 12 Mb/s data rate isn't a license to be completely sloppy, but 480 Mb/s is clearly much more demanding. It's 40 times faster! USB 1.0 was only 1.5 Mb/s and that is more of an "anything goes" situation for typical consumer lengths of cable. I have not found any twisted pairs in the cable I'm dissecting. There are more than one ways to come up with the right impedance. All four coloured wires in my cable are singles, made up of mutli-stranded steel-coloured wire. It's a USB A male to USB B male cable, btw - probably came with the Alesis mixer, which is USB 1.1. |
#62
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com... Chris. Hi. There is nothing else connected to the studio computer (and no language barrier, btw, only crappy typing!). As I said before, even stripped right down to the barebones computer --USB interface-- headphones configuration, the noise is present on any computer I try. That suggests that the hum is produced somewhere in the analog output circuit of the USB interface. Is the noise also present when you don't playback a track? Meindert |
#63
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote ...
"w_tom" wrote: The red wire should have been the correct wire. But more important was which wires are twisted and untwisted. I understand what you're saying, but is it possible we're talking about different cables? Is there a difference between a USB 1.1 cable and a USB 2.0 cable? At DC, there is no difference between USB1.x and 2.0 The major difference is likely that the (differential) data pair is likely twisted in a 2.0 cable (to maintain somewhat better impedance at higher data rates). Same kind of thing used in Cat5 network cabling, etc. I have not found any twisted pairs in the cable I'm dissecting. All four coloured wires in my cable are singles, made up of mutli-stranded steel-coloured wire. It's a USB A male to USB B male cable, btw - probably came with the Alesis mixer, which is USB 1.1. If it were a 2.0 USB cable, more likely for the data pair to be twisted. But for your purposes, probably of no consequence. |
#64
Posted to rec.audio.pro
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USB hum/noise isolation?
On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley"
wrote: If it were a 2.0 USB cable, more likely for the data pair to be twisted. But for your purposes, probably of no consequence. Is there evidence that two types of USB cable are made? |
#65
Posted to rec.audio.pro
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USB hum/noise isolation?
On Mar 20, 11:43 am, "Meindert Sprang"
wrote: "StudioDog" wrote in message oups.com... Chris. Hi. There is nothing else connected to the studio computer (and no language barrier, btw, only crappy typing!). As I said before, even stripped right down to the barebones computer --USB interface-- headphones configuration, the noise is present on any computer I try. That suggests that the hum is produced somewhere in the analog output circuit of the USB interface. Is the noise also present when you don't playback a track? Meindert hi Meindert. That's probably an important piece of info which I thought I had already posted, but I just rechecked all my posts and I seem to have omitted it! Whoops! Yes, the noise is present as soon as I open Cubase or any other recording software that accesses the usb audio drivers. It doesn't matter which driver I use (ASIO DirectX Full Duplex, ASIO Multimedia Driver, usb-audio.de, etc). All pass on the noise as soon as Cubase boots, and continue the noise until I shut Cubase. |
#66
Posted to rec.audio.pro
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USB hum/noise isolation?
Laurence Payne lpayne1NOSPAM@dslDOTpipexDOTcom wrote:
On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley" wrote: If it were a 2.0 USB cable, more likely for the data pair to be twisted. But for your purposes, probably of no consequence. Is there evidence that two types of USB cable are made? The Hitachi cable catalogue lists two pages of different types of USB bulk cable. I am not sure what the various merits and demerits of each are. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#67
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USB hum/noise isolation?
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#68
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USB hum/noise isolation?
"StudioDog" wrote in message
ps.com... hi Meindert. That's probably an important piece of info which I thought I had already posted, but I just rechecked all my posts and I seem to have omitted it! Whoops! Yes, the noise is present as soon as I open Cubase or any other recording software that accesses the usb audio drivers. It doesn't matter which driver I use (ASIO DirectX Full Duplex, ASIO Multimedia Driver, usb-audio.de, etc). All pass on the noise as soon as Cubase boots, and continue the noise until I shut Cubase. And does that happen with both the Behringer interface and the Alesis used as output device? Meindert |
#69
Posted to rec.audio.pro
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USB hum/noise isolation?
"Laurence Payne" lpayne1NOSPAM@dslDOTpipexDOTcom wrote in
message On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley" wrote: If it were a 2.0 USB cable, more likely for the data pair to be twisted. But for your purposes, probably of no consequence. Is there evidence that two types of USB cable are made? I've certainly seen cables that would work fine for USB 1.1 connections, but fail to work for USB 2.0 connections. Type of device most likely impacted: USB flash memory. Experiment: Attach USB 2.0 flash memory 1 directly to computer USB 1.1 port. It works. Attach USB 2.0 flash memory 1 to computer USB 1.1 port through extension cable A. It works. Attach USB 2.0 flash memory 1 directly to computer USB 2.0 port. It works. Attach USB 2.0 flash memory 1 to computer USB 2.0 port through extension cable A. It fails to work. Attach USB 2.0 flash memory 1 to computer USB 2.0 port through extension cable B. It works. Attach USB 2.0 flash memory 2 directly to computer USB 1.1 port. It works. Attach USB 2.0 flash memory 2 to computer USB 1.1 port through extension cable A. It works. Attach USB 2.0 flash memory 2 directly to computer USB 2.0 port. It works. Attach USB 2.0 flash memory 2 to computer USB 2.0 port through extension cable A. It works. Attach USB 2.0 flash memory 2 to computer USB 2.0 port through extension cable B. It works. USB extension cable A is one of those wind-up affairs. USB extension cable B is standard, specfically rated for USB 2.0. |
#70
Posted to rec.audio.pro
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USB hum/noise isolation?
And does that happen with both the Behringer interface and the Alesis used
as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. |
#71
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. Nothing attched to the interface but the computer? |
#72
Posted to rec.audio.pro
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USB hum/noise isolation?
On Mar 20, 2:07 pm, "Arny Krueger" wrote:
"StudioDog" wrote in message oups.com And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. Nothing attched to the interface but the computer? Again, no. I can remove everything down-stream of the Behringer UCA202 interface and listen through the unit's headphone output. The noise is present as soon as I boot Cubase. |
#73
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com On Mar 20, 2:07 pm, "Arny Krueger" wrote: "StudioDog" wrote in message oups.com And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. Nothing attched to the interface but the computer? Again, no. I can remove everything down-stream of the Behringer UCA202 interface and listen through the unit's headphone output. The noise is present as soon as I boot Cubase. So, how far to the nearest radio transmitter or other strong EMI source? |
#74
Posted to rec.audio.pro
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USB hum/noise isolation?
"StudioDog" wrote in message
oups.com... And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. Then it cannot be a problem in both interfaces, I'd say. No ground loop either. The thing that puzzles me most is that it starts the moment you start up Cubase. It does not make sense. The only thing I can think about is that when Cubase is not active, neither sound interface is active and cannot pick the noise from some unknown nearby source. Does the noise change when you move things aroud physically? Try to turn the Behr and the Alesis in all three axes, just to see if the noise is some interference picked up by the circuits. Meindert |
#75
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USB hum/noise isolation?
"Arny Krueger" wrote in message
. .. "StudioDog" wrote in message oups.com On Mar 20, 2:07 pm, "Arny Krueger" So, how far to the nearest radio transmitter or other strong EMI source? Thought about that too, but why is it only present when Cubase is started? meindert |
#76
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USB hum/noise isolation?
So, how far to the nearest radio transmitter or other strong EMI source?- radio transmitter? 5 Km, maybe? there's nothing in the house that is an obvious culprit, or I would have found it already. the studio is on a separate electrical circuit in the house...there may be a power cable in the stud space adjacent to the cable conduit passing through to the computer (PC tower is in separate room to combo control room/ recording space), but I've also tried setting up with the computer in the same room, no extensions. Still get the noise. |
#77
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USB hum/noise isolation?
On Mar 20, 10:30 am, "StudioDog" wrote:
On Mar 20, 12:48 am, "w_tom" wrote: I understand what you're saying, but is it possible we're talking about different cables? Is there a difference between a USB 1.1 cable and a USB 2.0 cable? I have not found any twisted pairs in the cable I'm dissecting. All four coloured wires in my cable are singles, made up of mutli-stranded steel-coloured wire. It's a USB A male to USB B male cable, btw - probably came with the Alesis mixer, which is USB 1.1. USB is actually three different types - low speed, full speed, and high speed. First two are USB 1.1. Only low speed cables can have signal wires untwisted. Also "color used for the cable assembly is vendor specific". Only three colors are 'recommended': white, grey, or black. Another should have known this. Just another reason why I did not state a color; was specific about twisted verses non-twisted wires. USB cables use a A series (more square) and a B series (more rectangular) plug. Low speed cables (without twisted pair wires) only have a B series plug and must be attached to the USB device. Only Full speed and High speed cables are detachable. Both must have twisted pair signal wires. If no twisted pair wire, then the cable will act like an antenna; inject noise into the device. Cable must have twisted pair AND if must have a bare 'drain' wire. No way around that fact. If cable is not twisted pair, well, try the experiment anyway to learn. Disconnecting the untwisted wires should not cause loss of signal in direct contradiction to what another has posted. Cables that violate USB standards: extension cables with both a male and female A or B type plug. Cables with untwisted wires that are detachable. Detachable cable without a drain wire inside. Cable without the USB icon molded into every connector. USB cables can exist with any color wire inside as quoted above from a USB standard. If cable is not twisted pair, well, try the experiment anyway to learn. Disconnecting the two untwisted wires must not cause what another has posted for reasons not relevant here. But be very concerned if this cable has USB icon markings on connectors and no twisted pair inside. That is an absolute violation for detachable cables. |
#78
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USB hum/noise isolation?
On 20 Mar 2007 20:26:03 -0700, "w_tom" wrote:
If no twisted pair wire, then the cable will act like an antenna; inject noise into the device. Cable must have twisted pair AND if must have a bare 'drain' wire. No way around that fact. We've gotten pretty far afield, but it might be interesting, in the general context, to note that twisting doesn't have much effect where the dimensions are small WRT a wavelength. The purpose of twisting is to "average" the geometries of the twisted conductors, allowing a differential receiver to ignore a better "average" of an imposed hum field. Turns out that this train is on another track (and God help the passengers) but maybe some airing of ground loop issues will be useful generally. Unfortunately, not specifically. (Insert frowny-face emoticon.) All good fortune, Chris Hornbeck |
#79
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USB hum/noise isolation?
On Mar 20, 2:07 pm, "Arny Krueger" wrote:
"StudioDog" wrote in message oups.com And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. The noise comes through either interface as soon as I boot Cubase. Nothing attched to the interface but the computer? I have the same problem. I run Reason 3.0 and Cubase SX3, an Alesis Multimix8, and an EMU Xboard 61 USB controller. As soon as I boot up either program-- seperately or using ReWire-- the hum starts with nothing connected to the inputs. Here is the interesting bit. If I play with the sample rate in Reason the pitch of the sound changes. If I play with theASIO buffer size in the driver (ASIO4all) the hum becomes more modulated as the buffer size gets larger (i.e. the hum begins to pulse). When I listen to music through the Alesis using iTunes the hum is not there. StudioDog, does any of this reflect your experience? This suggests a problem with the mixer's USB data input-- maybe a bad D to A conversion on the input stage? |
#80
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USB hum/noise isolation?
On Mar 24, 8:10 am, wrote:
On Mar 20, 2:07 pm, "Arny Krueger" wrote: "StudioDog" wrote in message roups.com And does that happen with both the Behringer interface and the Alesis used as output device? Meindert Yes. Thenoisecomes through either interface as soon as I boot Cubase. Nothing attched to the interface but the computer? I have the same problem. I run Reason 3.0 and Cubase SX3, an Alesis Multimix8, and an EMU Xboard 61USBcontroller. As soon as I boot up either program-- seperately or using ReWire-- the hum starts with nothing connected to the inputs. Here is the interesting bit. If I play with the sample rate in Reason the pitch of the sound changes. If I play with theASIO buffer size in the driver (ASIO4all) the hum becomes more modulated as the buffer size gets larger (i.e. the hum begins to pulse). When I listen to music through the Alesis using iTunes the hum is not there. StudioDog, does any of this reflect your experience? This suggests a problem with the mixer'sUSBdata input-- maybe a bad D to A conversion on the input stage? I'd like to put up my hand at this time to say I've been experiencing the same annoying problem with My Nehringher xenyx 1622 mixer. I get a high pitched whine with a beeping on top. I was trying to figure out what was going on and noticed that the mouse light was flashing at exactly the same rate as the beeping. Is this a clue? I was hoping this usb thing was going to cure these problems, not introduce more...... No difference when I use my old NEC laptop. It's still there. Can't believe these things could be pumped out with this inherent problem on all units. Is there anyone out there who is using these usb interfaces successfully? |
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