Topic: What caused this buzzing noise on my recording?

[jagraham]

On a recent recording I found a major digital buzzing sound throughout a set. A track is linked below, see at around 20 and 45 seconds in for what I have on my recording. Any idea what this is?

I was running AT-853 cards > STC-9200 > Tascam DR-2D. STC-9200 with a brand new Energizer 9V and set at +15db, line input on the DR-2D set to low gain. I recorded several times later in the week with the same 9V and noticed a little bit of digital noise during quiet parts of a show, but nothing like the buzzing sound here. I don't think the rig was overloaded, as the waveform maxed out around-7db. I don't think any plug was pulled accidentally because the waveform usually looks different for that. I do believe the cable connecting the STC-9200 to the Tascam is unshielded if that matters, and I've been using it for taping for a very long time. Perhaps it's time to upgrade that, but I'm worried there is something wrong with my STC-9200. Anyone have any insight or a suggestion on how to go about troubleshooting which piece of gear might be the culprit? Thanks in advance.

https://www.dropbox.com/s/swqcsxcj3avo2j4/DF%201603.flac?dl=0

[strangerinusall]

That´s typical and intense cell phone buzz.
Avoid any active mobile phone devices close to your recording equipment. Better turn them off.

[vanark]

Agree - cell phone interference.

[jagraham]

Thanks for the quick reply. I've noticed from time to time less intense interference or small digital noises but never anything quite like this. Why would this start happening after I never noticed it as much or as intense as before? Here's another recent recording, is the sound around 2:00 - 2:40 the same thing? Would a better cable or using a battery box instead of a preamp result in less noise? I'm just a little concerned after using the same gear over and over and never having the issue.

https://www.dropbox.com/s/woufacetcr4zok2/trivium2018-07-15t02.at853s.cards.16bit.flac?dl=0

Here's another example, about 8 seconds in...
https://www.dropbox.com/s/dko5kbjmh0vf7fx/jennylewis2018-08-13t15.at853s.omnis.16bit.flac?dl=0

[ilduclo]

Where were phones in your vicinity? I see them all around me at shows, 2’ away or so and have yet to have any issues (knock wood) I use dpa omnis, SP battery box and d50 or m10..hope it isn’t something I run into

[vanark]

Better shielding in the cables and equipment will help, but it is unlikely that a cell phone 2 ft. away is causing the issue. In my experience, the offending cell phone has to be closer.

Can't say if a BB will do better than a preamp - depends on the shielding, I think. The best thing is to keep your own cell phone away from your gear, or off. From what Chris Church conveyed, a lot of the small interconnects are where the shielding is weak. But, I wouldn't count on his gear being particularly well shielded either.

Definitely the same cell phone interference on that Jenny Lewis sample. That Trivium sample, well, not sure I want to turn it up loud enough to here the noise in the music. I assume it is the same.

[if_then_else]

I used to have 2 Church preamps at some point, the STC-9000 and the CA-Ugly.
While I never had any issue regarding cellphone noise with the STC-9000, the CA-Ugly
was highly susceptible to cellphone noise. In other words, it's got to have something
to do with the internal shielding / wiring. And, yes, cellphone noise within a distance of 1.5
to 2m was possible. Of course, switching off your own phone or putting it in airplane
mode would be a smart move.

[relefunt]

I wonder if using “Faraday” fabric such as this one (or larger) or adapting the fabric to line the inside of a gear bag would help. Seems like a harmless and relatively inexpensive intervention:

https://www.amazon.com/FM1-Signal-Shielding-Fabric-Protection/dp/B01M01SXEY/ref=asc_df_B01M01SXEY/?tag=hyprod-20&linkCode=df0&hvadid=198064086842&hvpos=1o1&hvnetw=g&hvrand=7849711395465873879&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9018827&hvtargid=pla-351300477055&psc=1

https://www.amazon.com/RFID-Shielding-Silver-Fabric-Roll/dp/B01JBHY7D8/ref=sr_1_3?s=electronics&ie=UTF8&qid=1535868576&sr=1-3&keywords=Faraday+fabric&dpID=51BifaGcRqL&preST=_SX300_QL70_&dpSrc=srch

(Ah, Michael Faraday, we hardly knew ye)

[georgeh]

I've charged my cell at festivals basically resting on Tascam P2, and haven't noticed interference problems? Maybe better shielded cables?