Defeat Plug-in Power at DVinfo.net

Daniel Favand · April 18th, 2010, 09:39 PM

I have a

* Sony HDR SR1
* Phonic mixer with various inputs.

I can use the mixer to mix mics and other sources to the camera, but I always get a hiss on the camera. (I have tried it, it does work without overloading the camera.) The automatic gain control is turned off. Could this be a problem with plug-in power from the camera mic-in? If so, how do I defeat it? Or is that even the issue? My output options are 1/4" Headphones jack or a mono output from the main L or the main R 1/4" jack. Both have their own level control.

Thanks in advance for your thoughts. I've been searching the net and these forums for hours, but I haven't found anything conclusive, or cheap. (A Beachtek is out of the question, budget-wise.)

- Daniel

Richard Crowley · April 18th, 2010, 09:58 PM

Seems unlikely that the plug-in power would be implicated in the hiss. I suspect something else is the cause of your symptoms.

Do you get hiss on your tracks when the Phonic mixer (unidentified model) is NOT plugged in to your camcorder? Exactly how are you managing to get a (presumed) line-level output from your mixer into a mic-level input on your camcorder? Are you using an attenuator of some kind? Or are you just really cranking the levels down to accommodate the difference in levels?

Daniel Favand · April 19th, 2010, 06:32 AM

I borrowed an iKey recorder today, so I will be experimenting to find out if I get the hiss without the camcorder.

No, I don't have an attenuator, I am just cranking down the levels on the Phonic 1002a.

Thanks,
Daniel

Richard Crowley · April 19th, 2010, 07:11 AM

You didn't say whether you get the hiss with the mixer disconnected, but I suspect you don't.

Cranking down the line-level output of ANY device to get mic level is practically GUARANTEED to produce the kind of symptoms you are complaining about. The equipment was just not made to be operated like that and you are demonstrating WHY.

Battle Vaughan · April 19th, 2010, 06:34 PM

I once had a similar situation -- more of a 60 hz hum, actually--- with a Canon HV20, running on its AC adapter (which is not grounded) and the mike input into an audio distribution preamp ... problem was a ground mismatch between the grounded amp and the ungrounded power supply ... running the camera on battery it was ok... or running the camera without the audio input, was also ok....possibly a ground loop with your mixer?

April 18th, 2010, 09:39 PM	#1
Daniel Favand Tourist Join Date: Mar 2010 Location: Clinton, PA Posts: 2	Defeat Plug-in Power I have a * Sony HDR SR1 * Phonic mixer with various inputs. I can use the mixer to mix mics and other sources to the camera, but I always get a hiss on the camera. (I have tried it, it does work without overloading the camera.) The automatic gain control is turned off. Could this be a problem with plug-in power from the camera mic-in? If so, how do I defeat it? Or is that even the issue? My output options are 1/4" Headphones jack or a mono output from the main L or the main R 1/4" jack. Both have their own level control. Thanks in advance for your thoughts. I've been searching the net and these forums for hours, but I haven't found anything conclusive, or cheap. (A Beachtek is out of the question, budget-wise.) - Daniel

April 18th, 2010, 09:58 PM	#2
Richard Crowley Trustee Join Date: Aug 2007 Location: Portland, Oregon Posts: 1,238	Seems unlikely that the plug-in power would be implicated in the hiss. I suspect something else is the cause of your symptoms. Do you get hiss on your tracks when the Phonic mixer (unidentified model) is NOT plugged in to your camcorder? Exactly how are you managing to get a (presumed) line-level output from your mixer into a mic-level input on your camcorder? Are you using an attenuator of some kind? Or are you just really cranking the levels down to accommodate the difference in levels?

April 19th, 2010, 06:32 AM	#3
Daniel Favand Tourist Join Date: Mar 2010 Location: Clinton, PA Posts: 2	I borrowed an iKey recorder today, so I will be experimenting to find out if I get the hiss without the camcorder. No, I don't have an attenuator, I am just cranking down the levels on the Phonic 1002a. Thanks, Daniel

April 19th, 2010, 07:11 AM	#4
Richard Crowley Trustee Join Date: Aug 2007 Location: Portland, Oregon Posts: 1,238	You didn't say whether you get the hiss with the mixer disconnected, but I suspect you don't. Cranking down the line-level output of ANY device to get mic level is practically GUARANTEED to produce the kind of symptoms you are complaining about. The equipment was just not made to be operated like that and you are demonstrating WHY.

April 19th, 2010, 06:34 PM	#5
Battle Vaughan Trustee Join Date: Nov 2008 Location: Miami, FL USA Posts: 1,505	I once had a similar situation -- more of a 60 hz hum, actually--- with a Canon HV20, running on its AC adapter (which is not grounded) and the mike input into an audio distribution preamp ... problem was a ground mismatch between the grounded amp and the ungrounded power supply ... running the camera on battery it was ok... or running the camera without the audio input, was also ok....possibly a ground loop with your mixer?