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Old July 3rd, 2010, 11:28 PM   #1
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XLR mic output to camera 3.5mm impedance

I'm in need of a connection between the mic output and the camera mic input.

The mic output is from a Sennheiser ME66/K6 which uses XLR connections to a JVC HD7 that has a 3.5mm, or 1/8" mic input.

The Sennheiser K6 specs say:
Nominal impedance is 200 ohm,
Minimum terminating impedance is 1kohm, and the
Maximum output voltage is 2V.

The specs for the video camera are silent except to say the input is 3.5mm and the JVC support person wasn't knowledgeable about this.

Part A: The main concern at the moment is I need to buy a patch cord or adapter to go between the two items and I there is a concern about impedance mis-matching and what this might cause in the way of hum, buzz, or volume problems - if any (is this a concern or not).

Part B: Another concern is with the overall length of the mic system (which hasn't arrived yet so I don't know if this is really a problem or not). Mic + K6 + any XLR adapter (if the adaptor would go on the aft end of the K6). I don't have the K6 yet (should arrive in a few days) so I don't know what the aft end is looks like. I'll be needing a good windshield for wind (on a sailboat) so this shouldn't be getting in the field of view. I don't want to have a blimp or zeppelin due to the shear size and awkwardness, not to mention cost.

I also reviewed a previous post about right-angle XLR adapters on April 2, 2010.

Anyone have some thoughts about the impedance concern?
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Old July 4th, 2010, 03:46 AM   #2
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Hi John.............

What you need is a Balun (balanced XLR to unbalanced 3.5 mm) into the camera.

For reasons that escape me entirely, the B&H web site "denies all knowledge" of such a device that costs anything below a zillion dollars and has a footprint smaller than a Volkswagen Camper Van, but hey, I just don't speak Yank.

If someone can find the relevant link, it's a simple plug in at the camera end which should sort the impedance and balance mis - match, and allow pretty long cable runs, as it will be balanced till it gets to the camera.

As for the mic itself, well, it's not a ME67, which is a mother, and no mistake. I solved my ME67 problem with a Rycote CCA adapter (which they no longer do) but I think there are a number of companies doing similar or better systems that will move the front end of long mic's rearwards on the camera, thus reducing the chance of it appearing on wide shots.

Judicious use of the "Search" at the bottom of the page should throw up numerous links.


CS
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Old July 4th, 2010, 04:04 AM   #3
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This may be useful:http://www.dplay.com/dv/balance/balance.html
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Old July 4th, 2010, 06:05 AM   #4
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Lots of issues to deal with beside just impedance and a simple off-the-shelf patch cord is not likely to solve them. In fact, impedance per se isn't much of an issue as most modern mics are low impedance and work fine into modern solid state mic inputs. But wiring from a balanced mono XLR into an unbalanced stereo TRS requires attention to what pin on the XLR goes to what connection in the 3.5mm plug. People sometimes go to the music store and get a XLR->TRS cable and then stack adapters to get the 1/4 on the cable to go into the 3.5mm on the camera but that is an approach that is doomed to serious L/R phase problems, sending the mic signal to both left and right channels but in opposite phase to each other. You also need a blocking capacitor to prevent the camera's 'mic plug-in power' from getting back up the cable to the mic. All in all, your best bet is to use a converter box such as a Beachtek or JuicedLink (I prefer the Juiced as it is a true mixer) that takes the XLR mic and converts it properly to feed a 1/8 camera input.
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Old July 4th, 2010, 09:25 AM   #5
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As Mr. House stated, the impedance is not particularly an issue. I would take steps to block the DC "plug-in power" from feeding back into the microphone (which has its own power).

I have a page on my website showing how to interconnect between XLR and 3.5mm mic connectors, and also discusses the DC blocking issue: Camcorder Mic Adapters
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Old July 4th, 2010, 10:04 AM   #6
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Good morning everybody. I now have a headache!!!

I made the post last night and really hoped for "an easy fix", or better yet, "that's no problem". However, my worst fears have materialized. Well, almost. Maybe the worst fear would be "there's no way this will work".

As they say, "Don't ask the question if you don't want to hear the answer."

Chris: A Balun? Never heard of that before! So I learn something new every day. I did an Internet search for "Balun" and - wow! Seems the whole world knows about this except me! There are all kinds of articles, pictures, diagrams, etc. for a balun. Not only that, there are ununs, "unbalanced to unbalanced". So now I actually learned two things. (wonders will never cease)

By the way, Chris, I hitch hiked around New Zealand (Invercargill to Cape Reinga) to and visited your beautiful city of Dunedin. Had an interesting experience hitch hiking across Cook Strait to Wellington as a volunteer crew on a sailboat. Memories I'll have forever.

Have to break now for breakfast. To be continued.......
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Old July 4th, 2010, 11:17 AM   #7
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Quote:
Originally Posted by John Nantz View Post
I made the post last night and really hoped for "an easy fix", or better yet, "that's no problem". However, my worst fears have materialized. Well, almost. Maybe the worst fear would be "there's no way this will work"..
HUH? The answer is very nearly trivial. The only thing that keeps it from being trivial is a 50-cent capacitor. Those BeachTek and JuicedLink boxes are nice, but they are not indispensible. If you are looking for a low-cost, simple and yet completely functional solution, a simple adapter cable (XLR on one end and 3.5mm on the other end) will do exactly what you need.
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Old July 4th, 2010, 01:03 PM   #8
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Reply: Part II

Just finished writing a reply part II to everybodys comments and it got "lost" - apparently it timed out? or something. I'm exhausted so this version will be much shorter, and faster.

Gary Nattrass: That was a really good link. I read the first few pages of the article but I'll have to go back and read it again. There is so much to digest. The devil is in the details and that's what I'll have to deal with.

In a way it would be nice if there was a little video of a "clock" that would let one know how much time is remaining before the reply to thread gets zapped.

I'm familiar with electromagnetic interference from other endeavors but audio for video is a new area for me and there is much to learn.

Steve House: Lots of issues to deal with .... is what I'm finding out. Yesterday I came across a Sennheiser "XLR to mini" adapter, CL 100 at Partfinder > CL 100 and wonder if this might work. Price-wise it is just under $50 US vs. many cheaper models on the Internet in the realm of $10 US. I'll try writing them to see what they have to say. I'm wondering if it would incorporate a blocking capacitor or diode, or if that is something that I'll have to deal with at this end.

By the way, that you said about the Music Store is exactly what I just experienced. They wanted to sell me a XLR to 1/4" adapter and then a 1/4" to mini adapter.

Richard Crowley Reply #5: I've seen pictures of small rectangular "boxes" that seemed to incorporate what you're talking about. Saw them when searching for Chris' "Balun". This looks like something I can make up if I can find the "box" part to hold everything to begin with.

By the way, what program did you use for your drawings? I've been looking for a program to make electrical diagrams, and possibly house plans, but I've gotten sidetracked on so many things. The lastes "side track" is video photography and several things I want to do with it. What ever happened to good ol' "point-and-shoot"? This is turning out to be WORK. Argh!

Richard Crowley #7: Now that I've had to re-type my whole reply I see your Reply #7. If all it turns out to be is the capacitor then, you're right, that makes it a lot easier.

Now to copy all this before I hit the "Send" button! [and it's a good thing I did!]
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Old July 4th, 2010, 01:13 PM   #9
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Richard (Reply #5) - wiring diagram

In my zeal to get the previous post out the door before being timed out I forgot to mention about your wiring diagrams on the link in your post.

Since my mic is MONO, and I assume "balanced", and since the camcorder mic is 1/8-inch (3.5mm) stereo, I assume the top, or first, wiring diagram would be the proper one to go with, right?

Thanks,
John
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Old July 4th, 2010, 02:24 PM   #10
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Quote:
Originally Posted by Richard Crowley View Post
HUH? The answer is very nearly trivial. The only thing that keeps it from being trivial is a 50-cent capacitor. Those BeachTek and JuicedLink boxes are nice, but they are not indispensible. If you are looking for a low-cost, simple and yet completely functional solution, a simple adapter cable (XLR on one end and 3.5mm on the other end) will do exactly what you need.
Having checked that the Canon HV-30s that I use have no microphone power supplied though the 1/8 stereo jack MIC input (they use the 'Advanced Accessory Shoe' connection for that), I am quite happily using a simple XLR to 3.5mm TRS cable I made up without a capacitor in the circuit.

Pity the JVC manual doesn't say one way or the other. Better to include the capacitor where there's any doubt, but the soldering can be a bit more fiddly as you say.
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Old July 4th, 2010, 03:14 PM   #11
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Quote:
Originally Posted by John Nantz View Post
...
Steve House: Lots of issues to deal with .... is what I'm finding out. Yesterday I came across a Sennheiser "XLR to mini" adapter, CL 100 at Partfinder > CL 100 and wonder if this might work. Price-wise it is just under $50 US vs. many cheaper models on the Internet in the realm of $10 US. I'll try writing them to see what they have to say. I'm wondering if it would incorporate a blocking capacitor or diode, or if that is something that I'll have to deal with at this end.

By the way, that you said about the Music Store is exactly what I just experienced. They wanted to sell me a XLR to 1/4" adapter and then a 1/4" to mini adapter.

...
Nope, the CL100 is totally different.

The music store's solution would result in signal hot being placed on the left channel while signal cold goes to the right channel, the same signal but phase inverted with respect to left. If the two are mixed to mono, a common occurance in video at many stages along the chain from camera to viewer, the two cancel each other out and completely dissappear, When heard in stereo, a voice will be outside the speakers rather than centered between them. When heard on a surround system, they may even flip from the front channels into the back
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Old July 4th, 2010, 10:06 PM   #12
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Thanks Everybody for all the good information

There is a LOT of very good information about how to adapt the mic cable to the camera mic-in. A significant amount of this is over my head at the moment but I have a good resource - a retired FAA electronic Tech who is also a musician (with mics and amps) that can help decipher all this.

Seems this will be a bit of a project getting it all figured out but doesn't look like it will be a budget-buster.

Thanks again for all the input.
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Old July 17th, 2010, 11:16 PM   #13
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UPDATE: went with a JuicedLink CX211, but more info.....

After doing a lot of checking around and exploring all the options, I finally decided to bite the bullet and go with a JuicedLink system to solve the XLR to 3.5mm mini (1/8") plug and balance problem. This was done with great reluctance.

The JuicedLink form factor is something that I really didn't like. I much preferred the BeachTek and Studio 1 shape to fit better under the camera. Also, there is no rubberized antiskid where the camera attaches.

For those who are also trying to deal with the XLR mono to 3.5mm plug, Studio 1 sells an adapter for $29.95 at this link: XLR Adapter Cable to 1/8" 3.5mm Transformer Balanced Cable It has a built-in capacitor which was talked about as a requirement. Hopefully the XLR mono to mini connections are "standard".

Now, onward to the next problem: finding a cardioid mic to complement the shotgun mic.
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Old July 18th, 2010, 09:43 PM   #14
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John,

Consider a Bogen 357 or 577 adapter between camera and preamp. It makes it quickly removable, but more importantly, it stiffens the whole thing up. I haven't tried the 577. I use the 357.
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Old July 19th, 2010, 12:12 AM   #15
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"Acquisition" takes on another meaning

Thanks for the suggestion, Jon. You know, this is going to be continuous process of "acquisition" for awhile. Actually, the "All Things Audio, Everything Audio, from acquisition to.....", I think, meant acquisition of audio signal. In my case, though, it's more along the lines of equipment for the moment. At least until the "missing link" JuicedLink shows up.

Right now my tripod is a really old 35mm one that is 50 years old. It isn't the age so much but it wasn't designed for really good stability. There is no cross-bracing for the legs and the head is a simple two-way tilt and swivel and it doesn't work very well for panning. A better tripod is on my list but probably not right away. I need to do some research on it and I haven't even started.

Checking out the quick release you mentioned, though, revealed some nice Bogen tripods that are much better than the one I have at present. Tripod recommends will likely be in a post in the future - under "acquisition"!
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