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Old December 6th, 2001, 10:05 PM   #1
rcumpton
 
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XL1 Microphone Hum

I began experienceing a microphone hum on my brand new XL1 right out of the box. The on-board mic is picking up mechanical vibration from the transport motor. Now, I know there have been posts discussing the nuisance hum from the zoom motor - but to clarify - I'm talking about a relatively loud, constant hum that is present as long as the unit's drive motor is spinning. When I sit the camera on my desk with the motor on, I can even hear a hum caused by vibration between camera and desktop. Is this normal?

I learned by accident that if the tape's erasure prevention tab is set to "save" instead of "record", the XL1 drive motor is switched off. When the motor is not on, there is absolutely no hum (thus confirming the source of the hum). I have not quantitatively measured the hum (say, via oscilloscope, yet) but can definitely say that it is extremely distracting and not acceptable for even the most amateur home videos.

I've scoured the internet, including this forum, and have not found one mention of the constant mic hum that I'm experiencing; only the zoom motor hum. This leads me to believe that my drive motor must have some problem that is causing the excessive hum. Can anyone give me some insight on your XL1 audio experiences? Is this hum normal? I'm considering sending my camera into a service center for inspection if this turns out not to be "normal".


FYI - for any other souls obsessed with bad audio.... I discovered something interesting, I think. I've tried to dampen the vibration/hum by experimenting with various sound-absorbing materials placed between the mic barrel and holding clamp; everything from foam tape to toilet paper - and none had any significant effect. Not even grabbing and squeezing the holding clamp by hand seemed to appreciably lessen the hum. Then, by accident, I lightly squeezed the mic's foam windscreen with two fingers (one on each side of the mic) and noted that the hum almost disappeared completely! (Forgive my excitement; pretty heady stuff for an engineer). What this indicates (I think) is that foam windscreen has a natural frequency close to that of the motor vibration, that is, it tends to resonate at the drive motor vibration frequency. I've also noticed that the foam windscreen is not glued to the microphone. Although snug on the mic, it is still free to "rattle" or vibrate against the microphone, and apparently exacerbate the hum. Wonder if Canon ever considered applying an adhesive between the windscreen and mic barrel - or using a different material? Any counter theories out there?
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Old December 6th, 2001, 11:08 PM   #2
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You shouldn't use something like a desk as a tripod for just this reason. It will pick up vibes, etc. and/or bounce them into the mic. I know, because I was thinking the same thing one day until I realized what was happening.

I think I remember a demonstation in school about putting your ear on one end of a yard stick and a spring-type of watch on the other and.... you could hear the watch, because of the vibes.

One possible way around this is to put the cam on some softcover book or better - a cloth to dampen the sound/vibes.

All this is assuming a normal camera w/out major transport problems.
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Old December 7th, 2001, 02:53 PM   #3
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Lightwave Systems MM-XL1 Mini-Mount

Hi there!

I have noticed the same problem on two XL-1s cams I checked out before I bought mine (and the one I bougth shows it, too), and figured it was normal. Thus, I started looking around for solutions. I found out that Lightwave Systems makes the Mini-Mount, a polymer mic damping device for the XL-1 that has been added to the Canon productline in the US. I ordered it at B&H for approx. $170.--

The Mini-Mount almost completely eliminates the hum (which I think comes from vibrations of a not perfectly balanced head assembly). So far, so good.

While it works well, the Mini-Mount can be a nuissance, depending on the camera bag you have. I have the Tamrac XL-1 bag, and the XL-1 won't fit in the bag with the Mini-Mount attached. I have to remove the mic when putting the cam away. I got used to it, but it can be annoying when you want to get the cam quickly out of or into the bag.

But other than that I can highly recommend the product...

Cheers,

Ron
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Old December 7th, 2001, 04:16 PM   #4
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Notorious XL-1 hum problem. Generally the Lightwave System's MiniMount XL-1 reduces this noise nearly to undetectable. It works better if you get the System Isolator.

The funny thing about the XL-1 is that the noisest side of the cam is the right side.

Nathan Gifford
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Old December 8th, 2001, 02:47 AM   #5
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System Isolator

IMHO, the System Isolator is poorly designed.

- The cable from the viewfinder assembly to the camera body is under quite a bit of tension when the System Isolator is installed.

- Further, I hardly noticed a difference compared to using the Mini-Mount alone. This is easily tested when using the System Isolator alone, without the MiniMount.

- When using the XL-1(s) with the System Isolator and an MA-100 or MA-200, the viewfinder assembly will be too far forward for comfortable shoulder mount shooting.

-And the System Isolator further exacerbates the Tamrac bag problem, particularly when the XL-1(s) is used with an MA-100 or MA-200.

FWIW,

Ron
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Old December 8th, 2001, 07:11 AM   #6
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Back a long time ago a number of XL1 users found that if they tighten the mic mount screw too much noise would be coupled to the mic. A looser screw setting lessened the coupling.

Tamrac makes two bags for the XL, and the newer model is larger. Does it still have a fit issue with the lightwave?
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Old December 8th, 2001, 07:56 AM   #7
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Tamrac 2248 vs. 2249 bags and Lightwave Products

Hi there!

I have the new Tamrac bag, the 2249 (which fits the XL-1(s) with the MA-100 or MA-200 attached). The problem with the Lightwave Systems' Mini-Mount is that the whole camera rig becomes about 2 inches taller, thus no longer fitting in the bag.

I think the 2248 bag is quite similar, but shorter, so it wouldn't fit in there, either.

So buy your bag after you buy the Mini-Mount, not vice-versa :-(

Cheers,

Ron
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Old December 10th, 2001, 09:07 AM   #8
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I really wished Canon would have made the mic cable about 1 to 1.5 inches longer. That's all the length the mini-mount needs. I really wish there were a better way to mount that critter w/o the SI (System Isolator).

Without the SI you really just cannot mount the mic correctly. You have to be careful about whether the mic is in the field of view (the MM MiniMount has to be inserted backwards). Not only that but it is hard to seat the acoustic sock (which works extremely well) fully.

Yep! A little longer mic cable would help.

Nathan Gifford
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Old December 10th, 2001, 09:19 AM   #9
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Howdy from Texas,

I had been under the impression that the XL1S had longer cables for the mic and EVF, however apparantly this is not the case.

Re: the System Isolator, it is supposed to move the entire EVF assembly forward to *increase* shoulder-mount comfort, and I find this to be the case. The other advantage is you can flex the EVF assembly a few degrees left or right with the SI attached... it is no longer so delicate.

Giff is correct, with the MM you really need the SI as well.
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Old December 17th, 2001, 07:12 PM   #10
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Yes, Chris. The XL1s mic does have a longer cable than the XL1. I now have one of each, but have not purchased the Lightwave system isolator yet.
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Old December 19th, 2001, 11:29 AM   #11
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It really sucks to pay some much for a camcorder then have to find ways to fix it right out of the box. Sony seems to have the same problem. How come you can go buy a $500 camera and not have these problems. In my search for a new camcorder, my thought right now is what is the problem with Canon and Sony?
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Old December 20th, 2001, 09:38 AM   #12
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Howdy from Texas,

Thanks to rcumpton for verifying that the mic cable is now a bit longer for the XL1S. My next question, I guess, would be to ask if the EVF cable is a bit longer as well.

The reason why I thought these were the same length as before is, I've handled them at the Canon USA booths at tradeshows and didn't notice a difference. But those are demo units which go everywhere, and probably have older mics and EVF's.

To Zimvg304, look at it this way, $500 cameras *do* have that problem, and much worse. However $5,000 for a nice camera is actually very cheap when you look at the history of semi-professional video. Audio has *always* suffered as a result.

I'm thankful that Les Drever, when he was still alive, had the foresight, expertise and capability to develop his LightWave Systems components for the XL1 and other DV camcorders, effectively eliminating the problem. If it weren't for him, we'd all have to live with the motor noise.
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Old December 20th, 2001, 03:54 PM   #13
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EVF Cable on XL1S

Hi Chris,

If the EVF cable on my XL1S was any shorter it would not work at all with the System Isolator. Therefore, I suspect that it was not lengthened on the new model.

Someone should come up with a simple molded adapter with a male EFV connector on one end and female on the other. If it were only an inch long or even less, it would solve the tight cable problem and maybe make someone a few bucks at the same time.

Same thing for the mic cable. Just make a short extension cable. Maybe even switch the left and right so that the mic could be mounted with the cable pointing down instead of up. Seems like a simple solution that just needs a home.

Ed Frazier
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