Topic: WTF is his diginoise!?

[mikesalvo]

sameple here:
http://www.sendspace.com/file/owrpv9

only a 10 sec. or so sample some sort ofmdiginoise present during beginning/end oif this between song sample. whatb the hell could i be??? cables, mics, JB3???

HELP!!!

[cleantone]

cellphone interference. It would be much louder if it were closer to your gear.

[jamroom]

I'm hearing more and more cellphone interference on taped recordings recently. I always ensure that mine is switch off for the duration - just in case. Not that you can do much about those around you.


EDIT: WTF is a cleephone? 

[aegert]

When we tape at the first row balcony or in the forest we tell everyone to turn them off! or else!

A

[mikesalvo]

no shit. I mean, its annoying, but Im relieved it wasnt my pre or deck or something else

Thats strange. I guess maybe i never got interferenc ewith my Denecke gear. Ive noticed it on my first couple recordings done with my UA5.

thanks ya;ll +t's all around.

[DSatz]

A lot of mass-produced portable recording equipment is made in ways that make it far more vulnerable to radio frequency interference than necessary. This is a somewhat complex topic, but the issue is becoming more and more urgent as cell phones and Blackberries become more and more common.

I've been listening to the official set of recordings from the seminars and other sessions held at the Audio Engineering Society convention this past October. In about half of these recordings you can distinctly hear interference from Blackberries. (On the AES' own recordings!) I also heard the distinctive Blackberry signature in a feed from the U.S. Congress two days ago, when the Federal Reserve chairman was testifying.

For some types of equipment there are fairly simple modifications that would help a lot. I wonder whether the "modders" (whose work seems to be popular here) ever address this issue. It has to do with where and how the shield connection of the incoming and outgoing cables are connected to the chassis of the equipment.

Equipment reviewers for the recording magazines should be testing for what is known as the "pin 1 problem" in any preamps or recorders they review. That way there would be at least a little pressure on the manufacturers to take the problem seriously. Or maybe that's a pipe dream, since the magazines are all supported mainly by their advertising (what we pay to buy our copies pays only a small percentage of their costs) and they never bite the hand that feeds them. But we could at least ask the magazines to do this. It's not hard to test for it.

The "Cables" section of this board is frankly a zoo filled with people making empty claims and counterclaims about the special audio properties of their favorite cables. Cables have an important role in avoiding interference and I rarely see anyone paying attention to that. For example there is a new type of XLR connector from Neutrik which really can help and only costs a few bucks more than the usual kind, but instead people are all focused on their $40/foot silver this or oxygen-free that. Oh, well.

--best regards

[aegert]

I build cables all the time.. It is important to make sure you connect shields to the connectors body.. Most all xlr's have a silver colored tab that you can attach the drain wire to as well... It is critical that the shield extends out to the body or the mic as well I can't speak for active cables as I don't use them..

But for an XLR or Tuchel connection to a mic I always make sure the drain wire or shield is connected to pin 1 for an xlr and to the connector shield pin described... This will make the body of the mic system ground even if it floats. All rf with find its quickest path to ground... For our purposes there is no true real earth ground .. It floats as none of the components are attached to a ground wire to earth. but it will be synched to what ground it for your system.

I have gotten pre-made custom cables from many people.. Invariably I have to rebuild them all as the connections to ground are rarely made.

Some mics are more prone than others to this interference... Look at your mics susceptibility to RFI.. Call the Customer service technical lines and see if they have a recommendations for your mics..

If you really want to eliminate this completely you could build a ball to enclose your mics in side copper screen material and then ground the ball to earth.. But this would probably get you laughed out of the venue ROFL!

When I build audio cables for my home system I build them directional to direct noise where I want it...but that is another conversation entirely LOL

A

[jkbyram]

I've gotta be the luckiest guy on the face of the earth. I've never even heard what this cellphone interefence sounds like (good job on the RFI shielding DPA/Grace/Sound Devices!!)

same for myself and i place my blackberry in my bag while taping all the time. i should leave it off but often forget to leave it in the car or to turn it off.  it makes my computer screen go crazy so i know it is emitting signals.

[pmonk66]

The biggest problem is the text messengers who text set lists to friends and such during shows!

[dean]

I notice the problem much more with my 414s than with my HOs.  Does anyone know, based on the make of each mic, if that's coincidence or if there's a real difference?  I ain't smart enough to know where/how to figure that out.

[aegert]

Different Mics have different RFI rejection capabilities.. Even in the same line..

The CMT44 T powered schoeps had a better RFI spec than did there phantom powered cousins .. Go figure...

But if your gnd pins are not run to the case/ barrel of the mic you will see more RF...

A

[dean]

Different Mics have different RFI rejection capabilities.. Even in the same line..

The CMT44 T powered schoeps had a better RFI spec than did there phantom powered cousins .. Go figure...

But if your gnd pins are not run to the case/ barrel of the mic you will see more RF...

A

Thanks!

[Church-Audio]

I build cables all the time.. It is important to make sure you connect shields to the connectors body.. Most all xlr's have a silver colored tab that you can attach the drain wire to as well... It is critical that the shield extends out to the body or the mic as well I can't speak for active cables as I don't use them..

But for an XLR or Tuchel connection to a mic I always make sure the drain wire or shield is connected to pin 1 for an xlr and to the connector shield pin described... This will make the body of the mic system ground even if it floats. All rf with find its quickest path to ground... For our purposes there is no true real earth ground .. It floats as none of the components are attached to a ground wire to earth. but it will be synched to what ground it for your system.

I have gotten pre-made custom cables from many people.. Invariably I have to rebuild them all as the connections to ground are rarely made.

Some mics are more prone than others to this interference... Look at your mics susceptibility to RFI.. Call the Customer service technical lines and see if they have a recommendations for your mics..

If you really want to eliminate this completely you could build a ball to enclose your mics in side copper screen material and then ground the ball to earth.. But this would probably get you laughed out of the venue ROFL!

When I build audio cables for my home system I build them directional to direct noise where I want it...but that is another conversation entirely LOL

A

I would disagree with your advice about connecting the body of an XLR to ground.. Some audio devices separate chassis ground from Audio ground and connecting the two together actually in "some cases" can cause a ground loop. The problem here is there are no standards.. So there is no 100% correct way to wire a cable for interconnection of gear. Pin 1 connections are often grounded to the case of the mic and that's ok.. But its the other end "the preamp end" where there is no standard and connecting the shell of the XLR can in some cases do more harm then good. Although this problem is mostly an issue with AC powered gear. That's why I personally recommend never connecting the shell to pin 1 on an XLR connector btw when the XLR connector is connected to a device " the devices" ground continues to the shell anyway so your still getting the same effect of ground coverage your just not creating a secondary ground loop in the process.

Chris Church


Chris

[aegert]

Chris I find with my V3 it works just fine.. I would agree int he studio you would want to lift the ground and have one studio ground to eliminate ground loops  but everything I am using is DC battery powered. My only concern is to ensure no leak through the connectors to rf.. To your point if pin 1 is tied to chassis ground and the connectors are not isolated they would inherently be that potential anyway ;-)

Either way they work for my rig...

A :-)

[Church-Audio]

Chris I find with my V3 it works just fine.. I would agree int he studio you would want to lift the ground and have one studio ground to eliminate ground loops  but everything I am using is DC battery powered. My only concern is to ensure no leak through the connectors to rf.. To your point if pin 1 is tied to chassis ground and the connectors are not isolated they would inherently be that potential anyway ;-)

Either way they work for my rig...

A :-)

In an isolated audio ground the chassis is not connected to pin one. If you connect pin 1 to the chassis ground on some units you create a ground loop. If the device is feed by an earth ground or is somehow tied to earth. So if you have a peace of gear that has its pin 1 tied to the chassis there is no need to ground the shell of the XLR connector because as soon as its plugged in to your device its already at the same ground potential by virtue of the connection between the chassis and the XLR connector that is mounted on the chassis it self.

Chris