radiophonic Posted January 12, 2017 Share Posted January 12, 2017 I've been using a PreSonus Audiophile box and a laptop to make simple stereo recordings of my band for analysing arrangements prior to formal recording. However, I'm getting what sounds like digital noise on the recordings. It takes the form of random HF clicks, unrelated to any dynamic changes in the music and I'm getting it even at low recording levels (although it does become very bad when levels are high - leading me to conclude that it originates in the A/D converter after the mic pre-amp). Has anyone encountered this kind of problem and if so what did you do? I did wonder whether the laptop PSU might be a cuplrit and I'm going to try running off batteries next time (risky). Obviously there are 101 possible sources of RF in the room, but it's not white noise, it's random spikes. Any guesses? Signal chain is as follows: 2 x Dynamic Mic (XY pair) > XLR cables > PreSonus Audiophile USB > MacBook Pro (Running Audacity) Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted January 12, 2017 Share Posted January 12, 2017 I think the problem may lie with Audacity. If I record to Audacity on my iMac I sometimes get clicks like that, especially when the signal approaches 0dB. Try the same setup but recording into GarageBand. Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 12, 2017 Author Share Posted January 12, 2017 [quote name='JapanAxe' timestamp='1484209451' post='3213469'] I think the problem may lie with Audacity. If I record to Audacity on my iMac I sometimes get clicks like that, especially when the signal approaches 0dB. Try the same setup but recording into GarageBand. [/quote] Thanks - that's interesting. I actually have Logic too. I was trying to keep things simple and save some HDD space. Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 12, 2017 Share Posted January 12, 2017 try running off battery, but also try increasing your buffer size. Are the noises there when you export your mixes? Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 12, 2017 Author Share Posted January 12, 2017 [quote name='cheddatom' timestamp='1484211269' post='3213486'] try running off battery, but also try increasing your buffer size. Are the noises there when you export your mixes? [/quote] Yes - it's there in the exports Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 12, 2017 Share Posted January 12, 2017 ...even when you play them on other devices? Sorry, probably seems like a stupid question but it's worth asking I'm not familiar with Audacity but I guess you can access the original audio files? Do they contain glitches? It's a Mac so I don't think the drivers would be out... I can't find a Presonus "Audiophile" online. Is it an "Audiobox"? I just wanted to check if it's powered via USB or an external PSU Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 12, 2017 Author Share Posted January 12, 2017 [quote name='cheddatom' timestamp='1484234151' post='3213804'] ...even when you play them on other devices? Sorry, probably seems like a stupid question but it's worth asking I'm not familiar with Audacity but I guess you can access the original audio files? Do they contain glitches? It's a Mac so I don't think the drivers would be out... I can't find a Presonus "Audiophile" online. Is it an "Audiobox"? I just wanted to check if it's powered via USB or an external PSU [/quote] Yes - Sorry my typo. Audiobox (I have an M-Audio Audiophile Firewire box as well, hence the confusion). One of these: https://www.presonus.com/products/audiobox-usb and Yes it's USB powered rather than PSU. I've used these boxes a lot at work in the past, but not via the internal Mic preamps and I don't recall Audacity giving me any problems on either Mac or PC (several different examples of both) - plus it was for auditory perception experiments so I was paying a lot of attention to avoid even very minor artefacts. The major differences between then and now were 1. Laptop PSU 2. Lots of other audio gear in the room, some of it probably not shielded very well 3. Using the mic preamps rather than the line inputs + outboard pre-amp. Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 12, 2017 Share Posted January 12, 2017 I bet it's the PSU. I have the same at home with one of my interfaces. I just unplug the PSU and let the laptop run off battery. I did have to tweak the power plan to stop it turning off mid take though! Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 12, 2017 Author Share Posted January 12, 2017 (edited) It looks like it's more than one thing. Thee is a low level hash associated with the PSU definitely. Running the laptop on battery gets rid of this. However, that sound is only picked up if using dynamic mics. If I plug a condenser in, it's quiet as a mouse. The major issue isn't PSU related though. Looking at the waveforms close up, tee look to be tiny notches out of them - and it's not a clipping issue. As low as -50 dB there are bits chopped out of the waveform. This seems to be intermittent. I managed to reproduce it with my son singing his made-up songs into a mic (4 year olds are pretty narcissistic fortunately and nowhere near as loud as a band) but I couldn't associate it with being too close to the mic or overdriving the inputs. I'm planning on taping the whole set on saturday and I think I'll use a different machine and try both Audacity and Logic to see if I can narrow things down further. TDK C60s never gave me this trouble! Edited January 12, 2017 by radiophonic Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 13, 2017 Share Posted January 13, 2017 Have you tried it with a bigger buffer? Can you hear these artefacts when you monitor from the interface? Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 13, 2017 Author Share Posted January 13, 2017 [quote name='cheddatom' timestamp='1484302666' post='3214441'] Have you tried it with a bigger buffer? Can you hear these artefacts when you monitor from the interface? [/quote] The buffer is set to 256 (default). I don't usually monitor on phones whilst recording - it's usually a case of set the levels and let it roll, because I'm playing and that's enough to worry about. I cant recall ever having heard artefacts beyond the low level hash that I can I definitely attribute to the laptop PSU though. Another variable I hadn't considered is that I've never had this problem when making 'new idea' recordings - for which I usually use a Mac Mini with much more memory installed (and obviously no nasty PSU either). I can try raising the buffer to 512. The problem with running the laptop off battery is that it isn't a very long lasting one at this point (old laptop too). For the next rehearsal, I think I'm going to use the Mini + a single large diaphragm condenser rather than the 2 dynamics / XY approach. It means sacrificing stereo, but the inherent noise floor will be far lower and it is much less prone to interference by design. It's probably a more robust recording method overall - I just wish I could afford two of em! Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 13, 2017 Share Posted January 13, 2017 get it in the right place and mono should be fine I wonder whether it's just the laptop running out of power? On Cubase there's a meter that shows CPU and Disc usage. Is there anything like this on Audacity? Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 13, 2017 Author Share Posted January 13, 2017 [quote name='cheddatom' timestamp='1484306921' post='3214497'] get it in the right place and mono should be fine I wonder whether it's just the laptop running out of power? On Cubase there's a meter that shows CPU and Disc usage. Is there anything like this on Audacity? [/quote] No - although I can monitor power draw and CPU use elsewhere. It happens when powered from the PSU though, so unlikely to be that IMO. My guess is some combination of memory, buffer and noisy PSU. There pretty clear notches out of the wave-forms, implying missed or wrongly interpolated samples. Quote Link to comment Share on other sites More sharing options...
cheddatom Posted January 13, 2017 Share Posted January 13, 2017 Sorry, when I said "running out of power" I meant running out of RAM or CPU capability If it was a PC I'd be going on about drivers etc but AFAIK the audio drivers on macs are rock solid Quote Link to comment Share on other sites More sharing options...
radiophonic Posted January 13, 2017 Author Share Posted January 13, 2017 No problem. This has been a really useful conversation. Not sure I've got to the bottom of it but I know more than I did. Plus I now have some very funny recordings of my 4 year old son singing improvised songs, as test recordings! Quote Link to comment Share on other sites More sharing options...
Zombie1965 Posted January 15, 2017 Share Posted January 15, 2017 [color=#282828][font=helvetica, arial, sans-serif] increasing your buffer size should solve the issue[/font][/color] Quote Link to comment Share on other sites More sharing options...
.gif.9ad672bb8b84505709f76b39c8c256ec.gif)
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.