Hum with phantom power and EVF off on A1
 

Hi -

I have been searching for some info on a problem I am having, but I have not had much luck. Basically, when using XLR and phantom power, I have a low level but very noticeable hum when the EVF is off. If I set the EVF to always be on, I don't get the hiss. Same if I close the LCD, or turn it facing forward so the EVF comes on. I don't notice this noise with the internal mic or with my Rode Videomic, and I have not tested without phantom power, but I suspect it is related to phantom power.

Has anyone else experienced this? I just plugged in an XLR mic today for the first time, and my camcorder is only about 2 - 3 weeks old. Any chance I am just doing something wrong here?

I'm new to the xha1 but did you make sure that the switch is selected to mic and not Line?

I just double checked - yes, set to mic...

Is it hum or hiss? I'm confused.

Also, what mic are you using for the xlr connection?

Hi jay,

I haven't used phantom powered mic yet with my xha1. I have a couple of questions for you to clarify:

The mic does require phantom power, right?

Where is the phantom powered mic located?

How long is the xlr cable?

Have you tried another xlr cable?

Is the hum present if the xlr cable removed? or changed to another channel?

I have my evf set to always on......at least you have a remedy....but it sure would be nice to "treat the cause" and not "treat the symptom."

I may have the opportunity to record with phantom next weekend and if so I will do some testing. Hopefully someone who runs phantom power now will be able to test and get you some feedback sooner. I used to run sound for a theatre co, and a constant hum was normally caused by a ground loop or bad cable.

Hi Bill -

I knew someone would catch that :D - I realized I said hiss right after I hit submit. It is a hum, actually....

The mic in question is a Sennheiser ME66...

Hi Michael -

The mic can run on phantom or from a single AA battery. I haven't tried powering from battery yet though, as the one in the mic was dead, and the last AA battery I had in the house seems to be dead as well.

Location doesn't seem to matter - I have tried both a 30 ft. and a 3 ft. cable, and I pick up the hum with the mic on camera and also on a mic stand. I feel confident in saying that the hum does not come from the mic, but rather from the camera's electronics. Incidentally, getting the mic out of the on-board mic holder does miracles for sound - but does nothing to eliminate the hum...

The hum is present on both channels (I can only test one at a time though). I suspect your ground loop diagnosis is correct, but it seems to me that it would have to be internal, since the EVF affects it.

How is the A1 being powered? A/C or battery....

a ground loop though is normally when componants are plugged into 2 different ground circuits.....you are only plugged into one. so i don't think that is it.

Hopefully someone can do some testing for you and see if they have the same issue. I'm kinda leaning towards an internal circuit issue on the camera.

the mic could be picking up camera noise. mine does and the only solution is not using the onboard mic holder.

I was on a shoot yesterday and experienced what I think is the same problem. Setup was the A1 with a Rode NTG-1 channel 1 and a Countryman B6 lav on channel 2. Both connected via XLR. Both mics require phantom power and it was turned on. The hum appeared to be 60Hz on the Countryman but the Rode was clear. The camera was plugged into 110v.

If the interviewee put his hand on Countryman's connection to the cable connecting it to the camera, the hum disappeared. We doused all the lights in the building and hum remained. However, when I unplugged the camera from the wall and ran it on battery the hum disappeared so I did the entire shoot on battery power without further problem. I have not tested the EVF setting.

I don't know for certain if this is related to the OP's issue but it seems to be. I'm going to play with this a bit more in the next few days and will report what I find.

thanks tripp,

I am very curious.

Hi all -

Actually, the camera is on battery power. I will try A/C later today to see if that changes anything.

I get the hum with the mic both on and off the camera, and I am quite sure it is not camera noise - this hum is distinguishable from the various motor noises that come from the camera itself.

It is a very quiet hum, and the volume seems to vary, although that is somewhat subjective. For example, I was trying to see if headphone volume or mic gain had any bearing last night, and I could not hear it over the various sounds that the mic was picking up (like my very noisy PC, or even the refrigerator in the next room). I ended up going to the garage, and it was just audible in there - it seemed louder earlier in the day. The difference could just be me too though, I suppose...

Incidentally, the volume of the hum changes with both headphone volume (expected), and mic gain. Not sure if that has any significance or not.

I think at this point, I may call Canon tomorrow, but I don't think I will be returning it for repair any time soon - I have a couple of things I will be working on over the next couple of months, and don't think I could go without the camera for say, 3 weeks...

This is a different symptom than mine. My hum is not very quiet. It's not loud either but it's reasonably pronounced. So much so that you could not bury under music. The hum would render any audio useless.

I'm going to post my results in a new thread so that I don't hijack this thread or confuse people with two problems.

Can you post a small sample of the hum?

Does it happen with other microphones?

Is it there is the mic is not connected but all other settings are the same?

Are you using manual or auto for audio level control.

OK. I finally got around to doing another test - four tests, actually...

First test was with AC power, both with and without EVF. This was very interesting, because in both tests, I had no hum. Honestly, I expected the result to be the same, especially after reading Tripp's comments. However, I agree that Tripp and I are experiencing different issues, so my results kind of make sense.

The second test was again on battery power. As expected, with the LVF off, the hum was back. I am baffled as to why AC vs. battery would be different, and I would actually expect more noise when running off of AC than off of battery. From the camera's perspective, I just don't see that there could be much of a difference. I mean, the camera is getting a specific DC voltage, right? BTW, I tried with two different batteries - I get hum with both of them. I don't believe my batteries could be weak, as both are new.


Hi Don -

I do have audio from my tests, but I want to re-record it so it is obvious what I am testing. I should be able to get that done in the morning.

I do not have another microphone to test with, unfortunately - in fact, this one is a rental...

I apologize, but I do not quite follow your third question. The mic is connected when I hear the hum - if I disconnect the mic, the hum goes away. I also do not get the hum using the internal mic, nor do I get it using a Rode Videomic attached to the 1/8" mini-pliug, if that helps.

As for the audio level control, I have been setting the gain manually. I can certainly throw in another test to see if auto mode gives the same results.

I should have some samples up some time tomorrow...

You might want to try a trick called, " Lifting the ground".
I've had some hums and hisses before when I had my reference monitor plugged in and connected to my xh-a1.

If you have any other items plugged into your camera, unplug them one by one until the hum goes away. If you find the culprit and it has a 3 prong plug then go to ace hardware and buy a 3 prong to 2 prong adapter and use that to plug the device in. The adapter basically removes the ground loop that could be causing the feedback or hum.

Great sound guy taught me that once and it's saved me on several occasions.

Jay,

I also find it odd that the hum disappears when you plug in the wall power and disappears on battery. Like you, I'd expect the reverse to be true. I cannot wrap my brain around any reason why this might be happening for you.

I think you might want to eliminate the rental microphone as the source of the hum. You could take your kit to the rental house. Explain what's happening and see if they'd let you test some other mics. I think they'd want to know if their mic was faulty.

Scott -

Thanks for the tip - I don't have any external components attached right now, other than the mic and my headphones. However, I will have to remember that for future use...

Tripp -

I think I am going to do that if I can find some time to get down there. Unfortunately, it will take about 2 hours round trip due to traffic, etc. Maybe I an cut out of work early today...

In the meantime, I posted a sample of the hum on youtube:

YouTube - XHA1 hum

It is fairly quiet to me - I have to use headphones, or turn the volume up fairly high to hear it. Of course, the power supply on my PC is fairly loud, so it may be more obvious to those with quieter computers...

Jay,

unplug your pace-maker! just kidding.

Have you tested the setup in the same place every time....have you taken it outside and tested?

I had a hum like that and it was being caused by rf from a ballast.

I'm just shooting in the dark for ya...so don't stand too close to me.

Sounds more like vertical refresh rate spatter than traditional hum. That it changes with LCD orientation makes is sound as though there is a cable or connector that is loose, stressing, or changing position when the LCD panel rotates.

Back a number of years ago with an XL1 I encountered a situation whereas with certain brands of battery there was an increase in nose when using the MA100 XLR adapter. Probably related to the details of the battery internals. But I do not recall all the details at this point. If y0o can try different batteries to see it it changes.

Also, try beg, borrow a different mic, even a cheap XLR SM58 wanna-be from Radio Shack, to se e it it exhibits the noise.

Could hear the noise in the UTube post, but not sure how to down load a bit of the audio so I can look at the frequency spectrum and waveform.

LOL! Come on, I'm not THAT old :)

I have actually tested in my office, in my living room (where I first discovered the issue), in the garage, and finally, today, with the mic in a closet and my camera in my office. It has been too windy and / or rainy to test outside... Maybe tomorrow - the neighbors might think I'm nuts if I am outside recording in the dark...

Thanks for the feedback, Don - one comment though - I get the same results by turning on the EVF from the menu, so it's not really dependent on the LCD position - it really boils down to whether the EVF is on or off. It just so happens that the easiest way to make the problem appear and disappear is by moving the LCD...

The battery comment is interesting, because as I stated yesterday, I do not get the hum when running off of AC power. I would not be surprised if there is a voltage difference between AC and battery, and maybe that is the problem. It would kind of make sense, when I think about it, as I would normally expect more noise from AC power. Maybe AC provides a more stable current under load? I'm afraid I am getting out of my league on that topic though...

I plan on going back to the rental place tomorrow, if I can get away, to see if they will let me test another mic. I will post an update some time tomorrow evening...

Any further progress on addressing this issue?

Hi Don -

Not yet, unfortunately - I've just been too busy. Between the hours at the rental place and my hectic daytime schedule, I am hoping to get down there on Saturday now. In the meantime, I'll be using the mic on Thursday, so hopefully my workaround won't fail me...