| Electronics > Beginners |
| Unwanted digital noise (Not the standard noise floor) from studio monitors |
| << < (8/9) > >> |
| magic:
--- Quote from: Vildhjarta on November 27, 2019, 11:12:26 am ---I see, i think i might have an improper impression of the hardware available. I always thought that the big and known companies had these things sorted out when shipping their products, and that my case now was an exception, but if these setups usually need fine tuning and not just plug and play i suppose i should do some unorthodox procedures in order to remedy the issue. So, instead of the "okay, there is noise, something is wrong until it disappears completely" i should adopt the "okay, there is noise, optimize every component until it is as minimal as possible" regarding audio gear. --- End quote --- Well, there is something wrong and it should disappear. But the question is what it is. In my opinion you are simply hearing ground bounce of the PC. This is an unavoidable result of noisy current generated by the electronics flowing through the very low but non-zero resistance of ATX ground cables. In my opinion you are unlikely to reduce this noise significantly because you already use a PSU of reputable brand so the cables are probably of similar thickness as in any other reasonable PSU and not some hair-thin POS. And if I am right then you can avoid this noise altogether by using a USB isolator or grounding the audio interface to something quieter than the motherboard. This is what I would try. You can verify yourself that such noise exists: take headphones, touch some metal part of the case (or any other earthed object) with the tip, touch the ground of the headphone jack with a USB cable plugged into the computer. I bet you will hear the same crap. You may also do it with other computers to get a feel of how noisy they are. That Macbook should be quieter, for example. --- Quote from: Vildhjarta on November 27, 2019, 12:21:10 pm ---Might be long shot, but do you think this one could eliminate the noise? https://www.thomann.de/gb/behringer_microhd_hd400.htm --- End quote --- "Passive hum destroyer" - sounds like a pair of transformers so it should work. As for the guitar, the noise should go away if you grab a cable plugged into USB with one hand and wave the other hand over the pickups. That's what my theory predicts, at least. |
| Jan Audio:
--- Quote from: Vildhjarta on November 27, 2019, 02:03:18 pm ---If i were to construct a professional recording studio i might have opted for an analog solution, however; i want to do what i can with my current setup. The soundcard i am using now has a firewire connection and its own power supply. --- End quote --- Do you have another computer to test ? Maybe it works. |
| Vildhjarta:
--- Quote from: Jan Audio on November 27, 2019, 05:17:28 pm --- --- Quote from: Vildhjarta on November 27, 2019, 02:03:18 pm ---If i were to construct a professional recording studio i might have opted for an analog solution, however; i want to do what i can with my current setup. The soundcard i am using now has a firewire connection and its own power supply. --- End quote --- Do you have another computer to test ? Maybe it works. --- End quote --- Tested on a macbook, noise was absent. :) |
| Vildhjarta:
--- Quote from: magic on November 27, 2019, 05:05:15 pm --- --- Quote from: Vildhjarta on November 27, 2019, 12:21:10 pm ---Might be long shot, but do you think this one could eliminate the noise? https://www.thomann.de/gb/behringer_microhd_hd400.htm --- End quote --- "Passive hum destroyer" - sounds like a pair of transformers so it should work. As for the guitar, the noise should go away if you grab a cable plugged into USB with one hand and wave the other hand over the pickups. That's what my theory predicts, at least. --- End quote --- Yeah, i suppose there would be no reason for any grounding to go from the PC to the soundcard if the connection to real ground is broken. Which cures both the symptom (Noise and buzzing) and the issue itself (Ground going from PC through all the equipment and down through monitor power supply) |
| John B:
The solution may be simpler than you think. After months and months of trying to fix basically the exact problem, all it took was a 1 cent cap. Plus some jacks and a die cast case. The issue I had was with this setup: PC + focusrite 2i2 interface --->2 balanced lines ---> MOTU interface + Macbook Pro. The noise I had was exactly as described here: whenever the PC was utilising the CPU or mouse, lots of noise would be present on the MOTU outputs. However, all that was required to cause this was the grounds of the 2 interfaces being connected (ie conductive connection, important to note). The signal lines could be muted or even disconnected and the noise would still be present. I tried a USB isolator. Total waste of time and money. Not only did the PC not recognise the device, the isolated DC/DC supply caused it's own noise on the powered device. I tried (cheap) isolation transformers, whilst disconnecting the ground. This resulted in a very loud distorted 50Hz signal being superimposed on the audio signal. Tried reconnecting the grounds, and THAT sound went away, but the original noise came back. Not only that but the transformers had low frequency attention, distortion, and phase shift etc. They were cheap so that was expected. On a hunch, I tried connecting the grounds capacitively. Well what do you know, it fixed the issue immediately. Turns out there was a constant 78mV DC offset between the grounds. The required capacitance was somewhere around 10nF. With a 2.2nF cap, the 50Hz distorted sound was still there, but sounded different, then with 10nF it disappeared completely. Its odd, it wasn't like attenuation, there was a critical cap value where it just disappeared. So I tried connecting the balanced lines conductively, but connecting the grounds capacitively with a 100nF PP cap. Issue fixed, no need for isolation transformers. |
| Navigation |
| Message Index |
| Next page |
| Previous page |