Gear / Technical Help > Post-Processing, Computer / Streaming / Internet Devices & Related Activity
Trying to figure out what caused these intermittent spikes/pops
billydee:
I recorded for three days straight (about 10 hours a day) at a recent bluegrass festival and upon beginning to process the four channel recordings I found that my two aud channels contain intermittent audible and visible spikes. Each performance was about 45-50 minutes in length and each set of aud tracks has anywhere from one to half a dozen of these mystery spikes.
The spikes are there all three days and are only missing in a couple of the sets. They show up duiring music and also in between sets.
AND, the spikes seem to be predominant in the right channel, not so much the left.
The two soundboard channels have no issues. I tested the mics at home this past weekend and ran them two hours straight with no issue/no spikes.
The mics are a set of Teac ME-120s, 48v phantom modded. I had the mics mounted on a t-bar on a wooden beam about 12 feet off the ground, running to my Tascam DR-70D thru 50ft long XLR cables. I used the mics with different cables three times previously since they were modded, no spikes/no issues.
I powered the deck using a heavy duty extension cable that was plugged into a power rack at the soundboard.
I've attched a some examples of the spikes in Audacity.
Any thoughts appreciated, it's a real mystery to me at this point.
dyneq:
Have you checked for dirty XLR pin contacts? I use Caig to clean/lube my plugs/jacks, but high % alcohol works fine.
Or, is it possible that there is an intermittent break somewhere on the cable? I know it's 50', but in order to find those, you need to flex the cable during recording or pause/recording with headphones on. Start at the terminated ends, then flex each cable as you listen.
billydee:
--- Quote from: dyneq on May 02, 2017, 02:09:55 PM ---Have you checked for dirty XLR pin contacts? I use Caig to clean/lube my plugs/jacks, but high % alcohol works fine.
Or, is it possible that there is an intermittent break somewhere on the cable? I know it's 50', but in order to find those, you need to flex the cable during recording or pause/recording with headphones on. Start at the terminated ends, then flex each cable as you listen.
--- End quote ---
I did not check or clean the cable ends, but will next time for sure. I also did not check to see how the files looked prior to the end of the week as I would have caught the issue sooner and been able to adjust.
And I've been unable to test the cable as they were loaned to me for that weekend by a friend, who lives an hour away.
He's aware of the issue and will test it when he can.
Thanks
morst:
--- Quote from: billydee on May 02, 2017, 10:52:06 AM ---I powered the deck using a heavy duty extension cable that was plugged into a power rack at the soundboard.
--- End quote ---
Did you meter the A/C? Sounds like it could be dirty power (intermittent low voltage) causing your phantom power to turn off and on again.
billydee:
--- Quote from: morst on May 02, 2017, 03:40:44 PM ---
--- Quote from: billydee on May 02, 2017, 10:52:06 AM ---I powered the deck using a heavy duty extension cable that was plugged into a power rack at the soundboard.
--- End quote ---
Did you meter the A/C? Sounds like it could be dirty power (intermittent low voltage) causing your phantom power to turn off and on again.
--- End quote ---
I did not meter the A/C and have no experience doing that. This was in a theater that "should" have reliable power but you never know I guess.
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