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Old July 15th, 2011, 02:57 PM   #1
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AX2000 captures card writing noise with external mic

This is very strange. I connected an Azden SMX10 to my AX2000 using a couple of RCA to XLR adapters and a short 3.5mm to dual RCA cable, since the Azden is 3.5mm. I did this because as anybody who owns the AX2000 knows, the sound quality in the built in mic is pathetic, worse than even a cheap consumer camcorder.

So I got obviously better quality from the Azden, but with one big problem: it captures the noise from the camera writing onto the card, to the point where it's unusable. I'm not talking raise the volume of the home theater all the way up audible, I'm saying that at normal voice speech level, you can hear it. Not terribly so, but still to the point where it's a nuisance. It's like a high pitched noise that is one second long, every other second. And the weird thing is that this happens whether the microphone is sitting on the shoe, on the holder with the clamp, or even if I move it around as far as the cable will go.

It took me a while to realize where it was coming from, at first I thought it could have been something in that particular room, so I went around the house while recording, and also outside. This noise is noticeable even outdoors, along with the noise of all the critters typical of this time of the year. I even put my ear half an inch away from the compartment that holds the two memory cards and I can hear the high pitched noise coming from there.

Even weirder, the built in mic doesn't make this noise at all, even if I record in a silent room, with the levels on manual and the highest they will go.

Then, I put the SMX10 in the other camera I own, the Panasonic AG-HMC40, and this annoying noise is not present at all, even when raising the volume really loud.

So I'm puzzled. Is this a noise present because of the XLR adapters and extra cabling, or is it that the AX2000 has this terrible defect and even if I buy an expensive XLR mic for it it will still capture the noise of the card writing?

Can anybody else that owns this camera and uses an external microphone tell me if this is a design problem with the camera? Because if any external microphone will make that noise, I'll have to sell this camera ASAP.
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Old July 15th, 2011, 04:24 PM   #2
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Re: AX2000 captures card writing noise with external mic

This is not a design defect in the AX2000. It might be a manufacturing defect (warranty issue) or there might be something wrong with your microphone hook-up.

One point that I am not clear about. Do you hear the noise every time you record regardless of whether you are using the Azden or internal mic, or is this noise present only when you use the Azden? I got the impression that there was noise only when using the Azden mics, but maybe you meant to say that the noise was continuous but only the Azden mic picked it up. If it is continuous, I would suspect there is something wrong with your particular camera and it should be covered by warranty.

I say it is not a design defect because I have never heard any such noise from my NX5 which I have been using for well over a year now. When I first got it, I used my NX5 with SD cards alone while I waited for the FMU units to finally start shipping, I have continued to use SD cards for the dual (back-up) recording capability. I have never heard any sound emanating from the SD card slots. I frequently use shotgun mics with with NX5. Sometimes, I use the Sony mic that came with the camera, but mostly I use an AT 877 in the mic holder. Sometimes, I've had two AT877 shotguns on stands and feeding into the camera while recording concert footage. This includes footage of a concertmaster/violinist with very acute hearing. Never heard any whining noises or high pitched pulses from the SD cards or slots, nor was any picked up in the recording.

So, the fact that you are getting regular high pitched pulsing from the back of the camera makes me think that there is something wrong with your particular camera, then there must be something wrong with your Azden mic or something wrong with the cabling you are using.

If you are hearing the highpitched pulses only when using the Azden mic, I would strongly suspect a problem with your cabling rig or the mic itself. I may be wrong, but isn't the Azden supposed to have a very narrow stereo pick-up pattern aimed entirely forward? Unless the room is very quiet, a normal shotgun is unlikely to pick-up noise from the the back of or from behind the camera.

On the left side of the NX5 there are audio routing swtiches. I am guessing the AX2000 has the soame ones. (If not, then disregard this paragraph). If you have the Azden SMX10 connected, but switch both channels to internal mic, does the noise go away? If you then switch one channel to the Azden, does the noise come back? Does anything change if you swap which channel is internal and which the Azden? If so, then you definitely have a problem with your cabling or one of the channels in the Azden.

If the noise is present only when you are using the Azden, I would troubleshoot the connections. I'm not familiar with the Azden mic, but I believe it uses a single battery (probably an AA) for both mics. Is that correct?. If so, look at the mic/line switches (the ones immediately behind the XLR plugs). Are both both set to "mic" or or is one (or both) set to "mic+48v" (phantom power.) If you have them set to phantom power, the noise might be coming from your camera's battery which is right beside the SD slots. Switch to "mic" and see if the noise goes away.

Regarding the test with your HMC40, you did not say if you had Panasonic's optional XLR adapter or had plugged the Azden into that camera's 3.5 mini-stereo mic jack. If you were using a straight-in 3.5mm connection, it seems that the problem is most likely in your 3.5 mm to RCA adapter.

On your 3.5mm to RCA adapter cable, is the 3.5mm plug a mono (one ring) or stereo (two rings) plug? If it is stereo, do you know if Azden's plug uses standard wiring or has some proprietary set-up? Does Azden make a 3.5mm stereo to dual XLR adapter for this mic?
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Old July 15th, 2011, 04:52 PM   #3
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Re: AX2000 captures card writing noise with external mic

Let me correct my last comment. I just realized your adapter cable must have a 3.5 mm female socket rather than a plug. Can you tell if your adapter cable has a stereo or mono socket? Look at the RCA plugs. If the RCA plugs are the same color, you have a mono splitter. You need a stereo splitter (one RCA plug will be white or black while the other will be red.) If you have been using a mono adapter, see if a stereo one makes any difference.
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Old July 15th, 2011, 05:42 PM   #4
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Re: AX2000 captures card writing noise with external mic

Hi Jay, yes, like I put in my original post, the noise is not picked up when I switch to the internal mic, even setting the gain as high as possible. I had posted this as a follow up to a thread I had started on the audio forum about finding a way to use the Azden SMX10 with this camera since the Azden is 3.5mm and this camera doesn't have that input, which resulted in the two adapters and cable I mentioned in the original post.

Somebody there replied that this is a consequence of breaking the balanced audio with the adapters and the cable, and that if the camera causes electronic interference like this one apparently does, then the microphone will pick up that interference while an XLR microphone will not. It makes sense that this is more an electronic interference than something the microphone picks up acoustically, because even moving the microphone around doesn't change the volume of the noise, even extending it as far as the cable will go.

I doubt that my camera in particular is defective, although anything is possible, but very unlikely. I bet your NX5 does the same noise, but you haven't noticed it because normally nobody would put their ear half an inch away from the card compartment. Please do that (while the camera is recording, otherwise you won't hear anything) and let me know if you can hear it.

My need for using these adapters with the SMX10 is that apparently the cheapest stereo XLR shotgun mic is over $400, which is way too much for me right now, and the built in mic is a piece of crap. My consumer Canon HF100 has a mic ten times better, as well as my Panasonic AG HMC40's mic. So I wanted to have something that was at least decent for a while until I could afford a true stereo XLR shotgun mic, because while I can get a mono XLR mic for $130, it has the problem that it's not stereo. Besides, I want to get a mono directional mic for situations when I will recording only voice, but probably a $130 wouldn't be too good anyway.
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Old July 15th, 2011, 05:53 PM   #5
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Re: AX2000 captures card writing noise with external mic

Quote:
Originally Posted by Jay West View Post
Let me correct my last comment. I just realized your adapter cable must have a 3.5 mm female socket rather than a plug. Can you tell if your adapter cable has a stereo or mono socket? Look at the RCA plugs. If the RCA plugs are the same color, you have a mono splitter. You need a stereo splitter (one RCA plug will be white or black while the other will be red.) If you have been using a mono adapter, see if a stereo one makes any difference.
Yes, this is a stereo female 3.5mm input that goes out to two RCA male plugs, each of which connect to an adapter that has a female RCA and a male XLR that goes into the camera. It's not a mono splitter, in fact I tested that it's stereo by moving around from side to side while talking.
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Old July 15th, 2011, 11:36 PM   #6
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Re: AX2000 captures card writing noise with external mic

1. Could you please confirm for me that your camera always makes the same noise when recording regardless of which mic you use? I mean, it produces the same high pitched pulsing when you record and the SMX10 is not connected by any kind of cable, right? (I do understand that you hear the noise in captured video only when the audio came through SMX10.
2.The other forum is this, right?

I need a very cheap stereo XLR mic

If so, I think you have misunderstood what Chad Johnson and Steve House were telling you there. In fact, it seems that Steve was asking you the very same questions I asked you. (We will now have a 10 second pause to marvel at what I have learned from years of reading Steve's posts. Wow!)

3. Seriously, I do not read anything in that other forum where Steve or anybody else even hinted that your problem was a result of the SMX10 using balanced output. What you have done with your jury-rig of cabling is take the UNBALANCED mini-stereo plug from the Azden and patch it into XLR connectors which are, by definition, "balanced." Sometimes jury rigging works well (and then we call it a "hack") sometimes it does not (which is when we say, "Oh well, time to try something else.")

Do you understand that mini-stereo is not a "balanced" output. When we speak of "balanced" outputs we are talking about electrical balance. We are not about talking about balancing right and left stereo channels. If you want to understand the vocabulary better --- although you don't need to understand it to fix your problem --- read here: Balanced audio - Wikipedia, the free encyclopedia

4. I cannot see where you responded to my question (and Steve's) about your camera settings when running the Azden mic.

(a) Have you verified that you are not feeding phantom power to the Azden? A simple yes or no will let us eliminate or focus on this as a possible problem.

(b) Does you camera record the pulsing noise when you switch between channels using the left-side audio routing controls as I suggested? (I though that the AX had them, but maybe not.) That helps focus on or eliminate cabling as the possible problem.)

5. Your camera makes noise, mine does not. I've shot several hundred hours of video standing next to the camera, with my right ear about 6 to 8 inches away from the card slots in my NX5. I've shot hundreds more using earphones while recording through various shotgun and wireless mics plugged into the XLR sockets on my NX5. I have reference monitors for audio monitoring in my editing room. I also check audio with excellent headphones. I have excellent hearing accoding to last year's hearing tests. (Paying attention is different matter, of course!) I have never once heard or picked up the noise you describe. Let me point out that the AX2000 has been shipping for what, 15 - 16 months now? I did a quick internet search. The only reports I could find about whining and pulsing noises were about fan noise in some of Panasonic's hard drive cameras that folks were comparing with the Ax2000.

Now, I have just tested my camera. Since it is hot here today with air conditioners running and since we have a mini-Sturgis rally going on (the Red Lodge Iron Horse Harley Rally with, count-em, two stages with live bands for 10,000 Harley bikes; oh the joy!) I went down into my basement. Closed all the doors. Turned out all the lights (no noise from any ballasts, don't you know.) Unplugged the freezer. It is realllyyyy quiet down there. I waited five minutes for my ears to adjust to the quietness. (My wrist watch can be read in the dark.) I started recording with my NX5. I put my ear right up against the card slots with the card slot door open. Not a sound from the SD cards.

6. So, what this tells me is:

(a) You have an ax2000 that produces a high-pitched, pulsing sound that doesn't seem to have turned up on anybody else's AX or NX cam. Kinda seems very probable that your camera is either defective or has gone bad, doesn't it?

(b) The only time this noise is a recording problem for you is when you are using your inexpensive Azden SMX10 microphone with a patchwork of cabling of unknown provenance to try to adapt that mic for use on a camera that was designed for other kinds of mics. Many people (myself included) have used other XLR mics without these problems. Logically points to your mic as a problem, doesn't it?

Ultimately, this issue seems (at least to me) to be less about the camera that than it is sorting through your priorities. Seems to me that the obvious solution for you is dumping your AX2000, Of course, since other AX and NX cams are not known to make the noises you have run into, you would need to disclose that your camera makes unusual noises. But, at least then you could move on to a camera you can use with the consumer grade 3.5mm socket that the Azden mic was designed for.

Actually, if you've had your camera for only a short time, you are probably still under warranty and you might be able to return it to to Sony or whomever you bought it from. You might get most of your money back, that way. Although, these days, many places will charge a 15% to 20% restocking fee. But even with a restocking fee, you would be getting more than you could get trying to sell a used AX which produces unusual noises when recording.

Last edited by Jay West; July 16th, 2011 at 12:45 AM.
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Old July 16th, 2011, 12:27 AM   #7
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Re: AX2000 captures card writing noise with external mic

Something else to add. Apparently, you told Steve House you did not want to try listening to the "card nose" with the Azden disconnected from the camera. This seems like such a basic step in troubleshooting. Please don't tell me that you cannot imagine why it would make a difference. Please understand that, when I say "disconnected," I mean completely and entirely removed from the AX. No cables in the XLR plugs. No nothing.

What we are trying to figure out here is whether you have one problem or two:

Do you have a camera that is making noises that other AX and NX cams do not make? (Seems like you do but until you test it without the Azden connected to it, we will not know for sure.)

Is the Azden SMX10 suitable for use with an AX even if it was designed to put out high-pitched pulsing sounds? Seems not since even hypercardoid mics normally do not pick up internal camera sounds from a nearly a foot back of the business end of the mic.
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Old July 16th, 2011, 12:50 AM   #8
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Re: AX2000 captures card writing noise with external mic

Jay,

I was in the middle of typing the answers to all your questions, several paragraphs actually, when I thought about doing a new short test to answer one of the questions and I realized what the problem was. It was the card. Perhaps it is because the original card was 32 GB and the card I tried now is 16. Or perhaps it's because the 32 GB card is a class 4 and the 16 GB is a class 6. To be certain of that exactly I will have to gather all my cards and run more tests.

Here's what happened: I put in a Trascend 16 GB class 6 card and when I press rec with the headphones connected to the camera, I don't hear the chirping noise from earlier today. I take the headphones off, I put my ear one inch to the card compartment, and I can't hear a thing. That made me realize right away that most likely it was the card. So I pull out the Trascend, and I put in the Kingston 32 GB class 4 card I had use earlier (or maybe it was the other one, since I have two of those that are identical) and the moment I press rec, the chirping is back. I switch to the internal mic and the chirping is gone, although taking off the headphones, I can hear it with my ear if I put it right against the card compartment.

So when I have some time available I will format a few different cards to see if the reason for the chirping is due to the card being class 4, or because it's a 32 GB, or even because they're different brands, although I never had a problem with any of them. My guess would be that it's the class, since class 4 is the minimum accepted, so I think the camera might have a harder time between buffering and transferring to the card, and thus creates that interference. Of course it might be something else completely.

Regardless of this particular problem being solved, I will probably have to get even a cheap XLR mic, because even without the annoying noise, I can still hear this artificial background hum that seems to me might be caused by trying to mix unbalanced audio with balanced inputs. It's not a terrible noise, certainly it would be lost in a crowded room, but it's not present with the camera's internal mic, even though the Azden has a far better overall audio quality than the AX2000 internal mic. And this background hum is not present when I use the Azden with the Panasonic camera with its 3.5mm input. For now I'll probably go with the MXL FR-304, and then if business gets better, upgrade to something better in the future.

Thanks a lot for taking the time to reply in such detail and even test this for yourself, I really appreciate it.
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Old July 16th, 2011, 10:51 AM   #9
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Re: AX2000 captures card writing noise with external mic

The hum you hear in the earphones can have several sources. Not getting hum with other cameras rules out the microphone. The way to quickly sort out the other two likely culprits is to make a short recording and check the footage on the computer. If you hear the hum iin when playing back on the computer, the most likely culprit is the cabling. (Might be the cables, might be the multiple connections, all likely when going from unbalanced to balanced. It just takes a slight mismatch in a cheap connector to result in a bad fit and hum.) If you hear the hum in the earphones while recording but do not hear it when played back from a computer, then you've either got a noisy earphone pre-amp or else it is something in the connection to the earphone jack.
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Old July 16th, 2011, 11:26 AM   #10
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Re: AX2000 captures card writing noise with external mic

It's not the headphones. Like I put in my previous post, the hum is not present when I switch to the internal microphone. That rules out the headphones. Unfortunately I don't have any other external microphone to test this with at this time, but I'll know for sure when I order a real MXL microphone.
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Old July 16th, 2011, 12:36 PM   #11
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Re: AX2000 captures card writing noise with external mic

Actually, it only suggests that the headphone connection or headphone preamp might not be the problem. But, it does not absolutely rule it out. Different mics have different output levels so you might hear hum with one and not with another. The idea is to confirm that it is the mic cabling that is causing the problem. All you need is a ten second clip for testing. If you hear hum through your headphones with a particular mic and also hear the hum when you play a recorded clip through your computer, then you have absolutely ruled out the possibility of a problem with the earphone jack on the camera..
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