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Author Topic: Trying to figure out what caused these intermittent spikes/pops  (Read 1803 times)

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Offline billydee

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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.

Offline dyneq

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #1 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.

Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #2 on: May 02, 2017, 02:17:17 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.
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

Offline morst

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #3 on: May 02, 2017, 03:40:44 PM »
I powered the deck using a heavy duty extension cable that was plugged into a power rack at the soundboard.

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.
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #4 on: May 02, 2017, 04:06:44 PM »
I powered the deck using a heavy duty extension cable that was plugged into a power rack at the soundboard.

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.
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.

Offline vanark

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #5 on: May 02, 2017, 08:05:21 PM »
Are you using an approved card in the DR-70D?
If you have a problem relating to the Live Music Archive (http://www.archive.org/details/etree) please send an e-mail to us admins at etree(AT)archive(DOT)org or post in the LMA thread here and we'll get on it.

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Offline barrettphisher

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #6 on: May 02, 2017, 09:21:10 PM »
Should have used the schoeps instead....
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #7 on: May 02, 2017, 09:44:18 PM »
Are you using an approved card in the DR-70D?
No. Although I used two different cards and the spikes appeared on both of them.
I have an opportunity to run the mics in a live setting later this week, although not with the same cables nor power source.

Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #8 on: May 02, 2017, 09:45:57 PM »
Should have used the schoeps instead....
Thanks barrett, you beat skaggs to the punch this time!  ;)

Offline vanark

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #9 on: May 02, 2017, 09:56:55 PM »
Are you using an approved card in the DR-70D?
No. Although I used two different cards and the spikes appeared on both of them.
I have an opportunity to run the mics in a live setting later this week, although not with the same cables nor power source.

There are at least 500 posts in the 70D threads about using non-approved cards and spikes in the recordings. I hope you aren't going to be recording something you care about.
If you have a problem relating to the Live Music Archive (http://www.archive.org/details/etree) please send an e-mail to us admins at etree(AT)archive(DOT)org or post in the LMA thread here and we'll get on it.

Link to LMA Recordings

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Mics: AKG C480B/CK61, CK63 | Church Audio CA-11 (cards) (with CA UBB)
Pres: <empty>
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #10 on: May 02, 2017, 10:09:42 PM »
Are you using an approved card in the DR-70D?
No. Although I used two different cards and the spikes appeared on both of them.
I have an opportunity to run the mics in a live setting later this week, although not with the same cables nor power source.

There are at least 500 posts in the 70D threads about using non-approved cards and spikes in the recordings. I hope you aren't going to be recording something you care about.
Couple things Rory, could it be possible that the spikes were only on two of the four channels?
And, I can't for the life of me find the exact same cards as detailed in the approved list. Every one I find is just slightly off from a number perspective.


Offline vanark

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #11 on: May 02, 2017, 11:15:59 PM »
I don't own a 70D, but since the spikes are due to write errors and it is writing two different files, I can see how it might only be one file. But I suggest you post in that thread to get feedback.

Sorry to hear about the trouble finding approved cards. Too bad they won't update the list. I have a 60D that I'm prefectly happy with and always wanted to try the 70D, but these problems scared me away.
If you have a problem relating to the Live Music Archive (http://www.archive.org/details/etree) please send an e-mail to us admins at etree(AT)archive(DOT)org or post in the LMA thread here and we'll get on it.

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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #12 on: May 02, 2017, 11:39:16 PM »
I don't own a 70D, but since the spikes are due to write errors and it is writing two different files, I can see how it might only be one file. But I suggest you post in that thread to get feedback.

Sorry to hear about the trouble finding approved cards. Too bad they won't update the list. I have a 60D that I'm prefectly happy with and always wanted to try the 70D, but these problems scared me away.
Thanks for the reply Rory.
I guess I should have only used it with an approved card but finding the exact ones online is daunting so far. And part of me worries that there's some other reason for the spikes. But after reading in the DR-70D threads a bit, I see that others have had similar issues with the spikes.

And like you I've had 100% success with my DR-60 but struggle with the stereo 1/8" input and the fact that the slightest bump sometimes causes problems with it. So here I am giving the 70-D a whirl.

Offline morst

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #13 on: May 03, 2017, 12:04:39 AM »
Are you using an approved card in the DR-70D?
No.
OH dang. I should have known.

Only use cards from Trashcan's short official list.  :-X
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Offline Gordon

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #14 on: May 03, 2017, 09:40:18 AM »
I can't for the life of me find the exact same cards as detailed in the approved list. Every one I find is just slightly off from a number perspective.


I'm using one of these

https://www.bhphotovideo.com/c/product/824139-REG/SanDisk_SDSDXPA_016G_A75_Extreme_Pro_16_GB.html

Ran it a handful of times without issues.  If you notice it says MFR # SDSDXP-016G-A46.  The only difference between that and the one on the list is the "-A46" at the end.  If you notice on the list NONE of the cards have the additional letter/number at the end.  So it leads be to believe it's the exact same card and from what I found just has to do with the packaging.

Unfortunately they are out of stock but it says "more on the way".  I preordered another one so I have an extra.
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Offline 8Afractal

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #15 on: May 03, 2017, 05:52:54 PM »
Cables and connectors are # 1  likely cause, of course.

Don't discount electrical noise from cell phones, fluorescent lighting, air handlers, blowers, electric doors, subways, golf carts, alien craft, etc.
Close walk-bys with nylon clothing can create static pops as well. 
Don't let gals in spandex swing on your mic pole.          (was going to make this gender inclusive, but wasn't sure how to word it)
« Last Edit: May 03, 2017, 05:55:02 PM by 108 Ohms »
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #16 on: May 04, 2017, 04:35:17 PM »
I'll have a chance tonight to at least find out if it was the mics causing the problem. I'll be running sbd/aud for the Black Lillies and be using different cables, running battery power and be using the DR-60.

Offline morst

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #17 on: May 05, 2017, 10:00:02 AM »
Don't let folks in spandex swing on your mic pole.          (was going to make this gender inclusive, but wasn't sure how to word it)

FTFY^^
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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #18 on: May 05, 2017, 06:42:05 PM »
Don't let folks in spandex swing on your mic pole.          (was going to make this gender inclusive, but wasn't sure how to word it)

FTFY^^

Well that was too easy!   Thanks
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #19 on: May 06, 2017, 11:28:51 AM »
I'll have a chance tonight to at least find out if it was the mics causing the problem. I'll be running sbd/aud for the Black Lillies and be using different cables, running battery power and be using the DR-60.
Well, in a 2hr and 15 min recording there was one "spike", about 90 mins in. Different deck, different cables, different power, different venue, same SD card and same mics.  :shrug:

But I did get an approved card (for the DR-70D) finally so I'll be using that recorder next time out.

Offline jbell

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #20 on: May 10, 2017, 09:50:31 AM »
What mics??  Sounds like they could be the problem.
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Offline Life In Rewind

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #21 on: May 10, 2017, 11:04:27 AM »
Its a DR-70D - Gotta be the card - here's the thing - the corruption can happen with sets that were fine.

Example - Using an unapproved card - I recorded one show - and it was fine.

I recorded another show and it had spikes - and then - the previous show also had spikes that weren't there before.

And then the card failed wouldn't work in camera - so I think the unapproved cards can not only make bad recordings - but they also can get screwed up in the 70D.
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Offline billydee

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #22 on: May 10, 2017, 12:37:24 PM »
What mics??  Sounds like they could be the problem.
The mics are phantom power modded Teac ME-120's (essentially Nak CM300 clones).

I asked the person that did the mod and based on what they know and the spike samples I sent, they suggested the spikes could be caused by environmental noise, i.e., EMI picked up on the cable and that the spikes are completely untypical of a bad jfet or capsule.

He also suggested that to be sure I do an equally set up test in the same venue using one of the phantom modded mics and a similar battery powered mic. I do have a pair of the same mics that were not phantom power modded, but the chances of running a test like that in the same venue in the near future is nearly impossible for various reasons.

One thing I did not mention in the last recording update is that I did use one of the same "not-approved" SD cards in the Black Lillies DR-60 recording, and that same card had been used in the DR-70 recordings with multiple spikes. And I think this gets to the most recent point made by Life in Rewind.

Offline rumbleseat

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Re: Trying to figure out what caused these intermittent spikes/pops
« Reply #23 on: May 13, 2017, 12:26:47 PM »
This is a taper's worst nightmare.  I feel your pain!

I suggest trying to take EMI interference out of the list of possible culprits.

Neutrik makes and XLR connectors that "eliminate" EMI on the cable.  You only need one connector on the cable - at either end.
Most put the EMC connector on the Male end - the end that attaches to your recorder/preamp.

The downside is that these connectors are pricey and more difficult to solder and install than standard Neutrik XX connectors.

http://www.neutrik.com/en/xlr/emc-series/nc3mxx-emc
« Last Edit: May 13, 2017, 12:29:17 PM by rumbleseat »
AKG C480B CK61 cards >  Canare L-4E6S with Neutrik EMC > Tascam DR-680 MKII > memories

 

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