Topic: 722 noise?

[ts]

Had my first experience with some noise on my 722. It was indoors, so I don't think it can be blamed on heat. It happened mostly during middle of one track, isolated to about 3 seconds during that track and I guess it could be classified as digi-noise, whatever that is. Also happened during opening act. Closing act was fine. Could this have been cell phone noise? Something else? Anything that can be done to prevent it from happening again? Sorry for not being more specific, but ask away, maybe I can pin it down a little better.

[MattD]

1 channel or both?

[terrapinj]

can you post a sample?

[morningdew]

A sample sure would help.  But my money is on a cell phone.

Is a tap tap tap with a flutter like sound...kind like thffpt, thffpt, thffpt in rapid sucession maybe at a rate of 3 times per second?

[ts]

A sample sure would help.  But my money is on a cell phone.

Is a tap tap tap with a flutter like sound...kind like thffpt, thffpt, thffpt in rapid sucession maybe at a rate of 3 times per second?

If I knew how to post a sample I would .

It sounded like both channels, but looking at the wav form appears to be stronger in left, with some in the right channel. And the noise is not a pop or tap, more like basic digi noise()in rapid sucession. I'm stumped.

[ts]

tony check out the sample I posted in this thread to hear what cell phone interference sounds like:

http://taperssection.com/index.php?topic=44616.0

thansk tim. that's not the noise I got. The noise repeats, but sounds different than that.

[ts]

have you done a hard drive repair / format recently?  how full was your drive? 

since it's in both channels, it's probably not a cable issue. 

what were you running?  jw 460s > v3 > 722?
[/quot

Only format. maybe needs drive repair?

No V3 in the line. mics>722.

[ts]

too large. how do I convert to mp3?

[terrapinj]

you can always use www.yousendit.com as well and then post the link here

[ts]

I have the file, it's 5.6 seconds and 930kb. how do I just convert it to mp3? so I can post the sample?

[terrapinj]

I have the file, it's 5.6 seconds and 930kb. how do I just convert it to mp3? so I can post the sample?

what did you use to split the file? you may be able to save directly to mp3 from that program, if not grab dbpoweramp its a great converter

[ts]

I have the file, it's 5.6 seconds and 930kb. how do I just convert it to mp3? so I can post the sample?

what did you use to split the file? you may be able to save directly to mp3 from that program, if not grab dbpoweramp its a great converter

cdwav. then I converted to shn and still to big

[terrapinj]

I have the file, it's 5.6 seconds and 930kb. how do I just convert it to mp3? so I can post the sample?

what did you use to split the file? you may be able to save directly to mp3 from that program, if not grab dbpoweramp its a great converter

cdwav. then I converted to shn and still to big

you can save directly to mp3 from CDWave

[ts]

trying this

[Rick]

That's definitely a cell phone

Same thing happens on my computer speakers when my phone is about to go off

[nickgregory]

yup, cell phone

[terrapinj]

damnit, i was hoping the 460s>722 would be protected from cell phone interference...

[ts]

That's what I thought. I think it was someone at the board. Wasn't me. Anyway of getting rid of it in post?

[ts]

thats just ratdog.

 

[wbrisette]

That's RF / Cellphone as folks mentioned. Ask any sound mixer in LA what they dislike most about the 7xx series recorders and the first thing they all mention is how susceptible they are to RF. That's why there is a big issue with the wireless mics and the 744 on the set. Most TV and film crews have moved to wireless mics and the RF interference with the 744 is horrible.

Maybe a lead lined bag will help in the future. 

Wayne

[thegreatgumbino]

So how common is RF with the 722?  Is everyone with a 722 on the board having issues?

[thegreatgumbino]

Good to know.  Thanks, Moke!  I've been toying with the idea of selling the V3 and grabbing a 722, but this thread worried me.  +T

[terrapinj]

i've never had any issues either (knock on wood) and I have sent/received text messages while standing right next my rig thinking the 722 wasn't succeptable to cell phone interference. i'm a little worried now  that sample was clearly cell phone 

[WiFiJeff]

I have also taped about twenty concerts this year with my 722, lots of cell phones in the room often ringing at inopportune moments where the audio ring was hard to edit out, but have never experienced any of the weird noise referenced above. 

Jeff

[ghellquist]

Ask any sound mixer in LA what they dislike most about the 7xx series recorders and the first thing they all mention is how susceptible they are to RF. That's why there is a big issue with the wireless mics and the 744 on the set. Most TV and film crews have moved to wireless mics and the RF interference with the 744 is horrible.

Now, I don´t spend much time aroung the sound mixers in LA, in fact I´ve never been in that town. But I was under the impression that the problem with 744 and radio mics was not that the 744 was effected, but instead that it can produce radio interference that disturbs the radio receiver, quite the other way round. Is this what you have heard as well?

As for my experience, I have had zero issues with cell phone interference with my 722.

Gunnar

[ts]

Could it have been my phone. It was on but not in use. I had my bag on top of the seat directly behind me and my phone was in my back pocket, which would have put it inches away from the 722. But no calls were made to me that night.

[kgreener]

fwiw this sound is similar to what i hear when my Blackberry is too close to my computer speakers, or when i'm in my car with my JB3 serving as an mp3 player via the car stereo.

http://taperssection.com/index.php?topic=67991.msg911085#msg911085

i don't think these pda's, cellphones, etc are discriminate of the recording device, i.e. i don't think it's the 722's fault, this seems to be happening on all kinds of recording devices (MT's, Marantz, JB3's, etc) and it's just happening more & more each day.

[ts]

My wife says she did call me during RD's set to see if SCI was getting close. So I'm assuming thats what did it. No noise during SCI. An awesome set to. Shine on You Crazy Diamond for Sid. Here's my SCI torrent: http://bt.etree.org/details.php?id=27278.

[it-goes-to-eleven]

Knock on wood, no 722 issues for me.  Not all cellphones are equal.  The blackberry and nextel seem to be the worst in the US due to the frequencies used.

FWIW, they were selling metal mesh bags pre 9-11 that you'd put your bag into and lock when flying. The idea is that the metal mesh secures otherwise unlockable bags.  Maybe the mesh could be incorporated into a faraday cage for a bag?

I don't think anyone here has tested whether quad cables reject the noise better (or even sound better/worse) than non-quad but we have discussed it. I know that some of the teflon-silver cables are not quad, fwiw.

[(((KB)))]

Just curious, what mic cables are you using?

-K

[ts]

Just curious, what mic cables are you using?

-K

I'm using Silver Serpents from mic bodies to 722, 12 inches in length, and AKG mk46 actives from caps to mic bodies, 3 meters in length. I see what your getting at.

[wbrisette]

But I was under the impression that the problem with 744 and radio mics was not that the 744 was effected, but instead that it can produce radio interference that disturbs the radio receiver, quite the other way round. Is this what you have heard as well?

Yes, the RF leakage on the 7xx series seems to be more on the output side of the house, mainly from the battery area and various parts of the case (or at least that is what Lectrosonics found). However, RF leakage is a two-way street. I use to work for a company that built the testing gear for  radiated emissions and radiated immunity, and it's very rare that you have just one, usually if you have poor emissions, you have poor immunity. And as you might suspect, where you fail in one test is usually where you fail in the other. In the case of the 744, according to the tests Lectro ran, the 7xx series isn't out of FCC limits, but they aren't going to set any records in this area either. Jon Tooles is recommending to all mixers that they move their radios and wireless units as far away from the 7xx as possible.

This is why mixers have a love/hate relationship with the device at the moment.

Waynee

[hammerhorror]

I am an ENG sound mixer / Cameraman for my day job. The cable choice seems to make a HUGE difference in determining if your audio will be affected by RF interference or not.

I know that Nextel phones and Blackberry's both affected my sound bag until I switched out my cheap mogami cables with my bumblebee silver clad cables. Now I never have a problem with cell phones whatsoever.

The problem is trying to find out which cables succesfully block RF. I know that my bumblebee cables do.

Hope this helps.

-John

[thegreatgumbino]

Normally the shield is not attached to the xlr connectors on mic cables.

   Since when? 

Here's some info from the following link regarding not connecting the shield:  http://www.taperssection.com/reference/pdf/DIY_CableDiagram_Rane.pdf

"A common solution to these noisy hum and buzz problems involves disconnecting one end of the shield, even
though one can not buy off-the-shelf cables with the shield disconnected at one end. The best end to disconnect
is a matter of personal preference and should be religiously obeyed; choose inputs or outputs and always lift the
side you choose (our drawings happen to disconnect the input end of the cable -- the output of the driving unit). If
one end of the shield is disconnected, the noisy hum current stops flowing and away goes the hum -- but only at
low frequencies. A one-end-only shield connection increases the possibility of high frequency (radio) interference
since the shield may act as an antenna. Many reduce this potential RF interference by providing an RF path
through a small capacitor (0.1 or 0.01 microfarad ceramic disc) connected from the lifted end of the shield to the
chassis. The fact that many modern day installers still follow this one-end-only rule with consistent success
indicates this and other acceptable solutions to RF issues exist, though the increasing use of digital and wireless
technology greatly increases the possibility of future RF problems.
If you've truly isolated your hum problem to a specific unit, chances are, even though the documentation
indicates proper chassis grounded shields, the suspect unit is not internally grounded properly. Here is where
special test cable assemblies, shown in Figure 3, really come in handy. These assemblies allow you to connect
the shield to chassis ground at the point of entry, or to pin 1, or to lift one end of the shield. The task becomes
more difficult when the unit you've isolated has multiple inputs and outputs. On a suspect unit with multiple
cables, try various configurations on each connection to find out if special cable assemblies are needed at more
than one point."

FWIW, the BBee's I owned did have the shield connected to the xlr on both ends.  I think the only time you see it not connected is in an unbalanced cable, but YMMV.

[wbrisette]

I am an ENG sound mixer / Cameraman for my day job. The cable choice seems to make a HUGE difference in determining if your audio will be affected by RF interference or not.

Here is what Larry at Lectro found:

On the 744T we checked (emphasis, on the one we checked), we found no
RF on any of the in or out connectors, power inputs, you name it. Any
wire or cable connection was effectively RF dead. This was actually a
disappointment, since if a connector was the culprit it would be easy
to build in a filter for that connection. What we found was RF leakage
around the battery compartment and some radiation from other parts of
the case. The battery compartment area may be the main offender and
other radiation from the case just a secondary effect.

-=-=-=-=-

Seems that the cables aren't the issue with the 7xx series.

Wayne

[terrapinj]

FUCK!

just realized I picked up a couple seconds of cell noise while stealthing moe on Tues night, mod 460 (ck1x/mk46) > 722

i was the only taper too, its only a couple seconds but still - FUCK im gonna be really paranoid now about cell phones

[Genghis Cougar Mellen Khan]

I am an ENG sound mixer / Cameraman for my day job. The cable choice seems to make a HUGE difference in determining if your audio will be affected by RF interference or not.

Here is what Larry at Lectro found:

On the 744T we checked (emphasis, on the one we checked), we found no
RF on any of the in or out connectors, power inputs, you name it. Any
wire or cable connection was effectively RF dead. This was actually a
disappointment, since if a connector was the culprit it would be easy
to build in a filter for that connection. What we found was RF leakage
around the battery compartment and some radiation from other parts of
the case. The battery compartment area may be the main offender and
other radiation from the case just a secondary effect.

-=-=-=-=-

Seems that the cables aren't the issue with the 7xx series.

Wayne

They didn't find any RF leakage on any of the connectors, that doesn't rule out the possibility of a cable being the culprit.  It's entirely possible mic cables could act like monopole antennas.

Generally it's probably a good idea to keep a cell phone as far away from any recording device just to be safe.

I say do a test run, place the cell phone close to the 7XX, start recording, call it and see if you get interference.

try: just 722 no cables attatched
            722 cables but no mics (cables vertical as if you were running them with a stand)
            722 cables and mics

It might not have even been your phone, but it's worth testing.

[terrapinj]

is it possible that the active cables may be the culprit?

so far Tony and I are  the only ones here that seem to have had interference with the 722 and we were both running the mk46 cables

[nickgregory]

is it possible that the active cables may be the culprit?

so far Tony and I are  the only ones here that seem to have had interference with the 722 and we were both running the mk46 cables

maybe.  I run the 4022s and havent had an issue, but it could be a construction difference between DPA and Schoeps

[terrapinj]

is it possible that the active cables may be the culprit?

so far Tony and I are  the only ones here that seem to have had interference with the 722 and we were both running the mk46 cables

maybe.  I run the 4022s and havent had an issue, but it could be a construction difference between DPA and Schoeps

Schoeps 

give us some credit Nick we have better taste than that. mk46 are AKG active cables

[nickgregory]

is it possible that the active cables may be the culprit?

so far Tony and I are  the only ones here that seem to have had interference with the 722 and we were both running the mk46 cables

maybe.  I run the 4022s and havent had an issue, but it could be a construction difference between DPA and Schoeps

Schoeps 

give us some credit Nick we have better taste than that. mk46 are AKG active cables

my apologies

[it-goes-to-eleven]

Anyone have any mfgr info on the mk46 cable?

[Genghis Cougar Mellen Khan]

Interesting read, something to give consideration.

RF Susceptability in microphones:
http://www.audiosystemsgroup.com/RF_in_Microphones.pdf

Cheap, but it might help!

http://cgi.ebay.com/20-pcs-Clamp-On-Ferrite-EMI-RFI-Suppressors_W0QQitemZ320008966145QQihZ011QQcategoryZ15051QQcmdZViewItem

http://media.digikey.com/PDF/Data%20Sheets/TDK%20PDFs/ZCAT%20Series.pdf

Other related articles:
Understanding and eliminating RF problems.
http://www.audiosystemsgroup.com/Ferrites-Ham.pdf
http://www.audiosystemsgroup.com/AESPaperNYPin1-ASGWeb.pdf

[mhibbs]

So how common is RF with the 722?  Is everyone with a 722 on the board having issues?

I haven't heard it on mine, and I've definitely had my blackberry on at many shows in the last year and been standing close and had no issue.  Mine is Cingular GSM (I'm guessing providers can differ due to the different technologies).  It makes a ridiculous amount of racket next to my monitors on my DAW and anywhere near my laptop speakers but doesn't bother my home Snell's or the radio in my Tahoe either.  Regardless, I've been turning it off for the last month or so after reading so many posts about RF interference.  Going to test at home and see if I can't cause it at some point when I have some time...just to see how close it really has to be.

Mitch

[terrapinj]

picked up a little sample of cell noise agian last night at CSNY

mod 460 (ck1x/mk46) > 722

i believe it occurred when i remembered to turn off my phone right at the end of the 1st song, not devestating but its clearly there 

[musicsherlock]

cellphones should be banned in concert environments.

But what would we do during the Power Ballads?

[kidtexas]

is it possible that the active cables may be the culprit?

so far Tony and I are  the only ones here that seem to have had interference with the 722 and we were both running the mk46 cables

Speaking entirely out of my ass, I can't imagine active cables would help the situation at all.  After all, your sticking a long (most likely unbalanced) cable in between the capsule and the mic body, meaning any noise that enters at that point in the system then gets boosted up by the electronics in the mic body, etc.  It's a point of entry that mics without active cables just don't have.

Not to say they are the problem, but in my mind, it could hurt.  Though in my experience, I've gotten cell phone noise in just about every system I've put my cell phone up to if I positioned it right.  I've never tried on my 722 since I just turn off my phone.

[ts]

picked up a little sample of cell noise agian last night at CSNY

mod 460 (ck1x/mk46) > 722

i believe it occurred when i remembered to turn off my phone right at the end of the 1st song, not devestating but its clearly there 

Yep, my guess is it's the cheesey active cables. My only experiences with the noise is with those actives. I have found some noise on an earlier recording. Brief, but there. No noise on any of my V3>722 recordings, using Bumblebees.

Can a better cable be used in those actives?

[cshepherd]

Our old rig had cel phone interference issues pretty regularly, to the point of frustration.  We were running km 184's>>V2>>ad1000>DA-P1 with Harmonic Tech cables.  After switching to Van den Hul cables, cel phone interference has never been an issue, regardless of rig setup.  I've run 184's>V2>ad1000>SV3800, 184's>V2>722 and 184's>722 with VdH cables.  We've tried to induce cel phone noise after shows and have never heard it come through on the recording.

Chris

[it-goes-to-eleven]

Can a better cable be used in those actives?

With that in mind I asked what cable was being used but nobody ever replied...

The circuit is a very important part of noise rejection. So cable alone may not make a diff.

[thegreatgumbino]

It's the AKG mk46 active cable.

[F.O.Bean]

wow, very interesting read, ive personally taped prolly about 30 sets w/ my 722 since getting it in june and i have not heard anything out of the ordinary, thats using bumblebee mic>v3 cables and regular/silver interconnects going from v3>722

gotta be those active cables