Jump to content

Recommended Posts

Last week on a job, 2 talent were driven down a track to walk back towards camera. Signal was patchy on the drive but as soon as they got out of the vehicle I had them clear as day, distance was 400 yards. Txs(900 LAs) set at 50mW placed in chest pockets, dipoles mounted in bag. The location was the countryside with no RF interference.

In urban environments I've gotten 100 yards + in line of sight situations with dipoles mounted in front of bag (no elevation) and Txs at 50 mW.

My 2 cents

Trev

Link to comment
Share on other sites

  • Replies 95
  • Created
  • Last Reply

Top Posters In This Topic

Constantin - Come on my friend, i have a pair of ears and a brain in between.

Of course, and I don't doubt that at all. I didn't mean to insinuate anything else. I had really only been wondering if you'd set-up some sort of test to find out what happens in the frequency spectrum with each of these systems. It's not that difficult to do.

I was perhaps a bit surprised by your findings, since many people here rave about the audio quality of the Zaxcom systems and for you they are last.

Link to comment
Share on other sites

The amount of times I have seem people walk out of a cinema because the didn't like the sound of radio mics and preferred a different brand.............

Sent from my Nexus 4 using Tapatalk 2

Thankfully, that is not our measure of quality. If it were, we'd all be working with that Zoom on a boom
Link to comment
Share on other sites

I understand that JustinRoss's tests are unscientific, but in truth no one on this forum except Larry, Glenn and Howy (and possibly G Trew) are really set up to do any really "scientific" measurements of wireless performance anyhow.  We all accept that the situation is very complex.  But all the garden-variety soundie has to go on is their direct experience, really, and I think all of us, in the face of bonafide scientific proof of something related to our gear that contradicts our direct experience would take that proof with a grain of salt and probably do more direct testing, imperfect as it is.   We ultimately have to make choices and then put considerable money where our mouths are over them, and at that point most of us want some alignment between what our brains and our guts are telling us.

 

philp

Link to comment
Share on other sites

We do test wireless range when we introduce a new product. Zaxcom wireless at the same power level as FM wireless will provide on average 85 to 90 percent of the range of the analog system. With the introduction of Zaxcom 125mw transmitters operating range is not an issue. These transmitters easily cover a football field and are used during every NFL game.

Audio quality when tested with test equipment verifies the vast differences in audio quality between the Zaxcom system and all FM transmission systems. Our web site has the results of a multi tone test demonstrating the clear difference between systems.

Some people like tube sound over solid state, some like vinyl records over cd, and some like companders, noise reducers and fm distortion over hard wire quality wireless. We should not debate if chocolate is better than vanilla. Vanilla is clearly the better choice. ;-)

Glenn

Link to comment
Share on other sites

i was there for the tests Vin is mentioning, and they were my zaxcoms that we used.

when we were doing the listen tests, we put DPA 4063's on every transmitter we could, though i cant recall if we had a 4063 or a 4061 or a 4071 on the lectro, and i also had a 4063 going through an ambient eumel for comparison.

the wisycom and the audio wireless sounded very similar to the hard wire. the lectro had less ambience, which i am guessing is due to the smart NR, but i must emphasise the guess part as i never got a chance to turn it off.

the zaxcom didnt sound as good as i was expecting, though on my last film, there was a mic i wasnt happy with so i may have some gremlin that i need to chase down - or i may be subconsciously looking to defend the vast amounts of money i have spent on zaxcom radio mics. 

 

for the walk tests, the zaxcom at 125mw was about the same as the lectro we had - an smdb at 50mw, but the audio wireless and wisycom were far and away the best. but these were fairly unscientific tests and the receivers were differing distances away from my 788 that was being used for monitoring, so receivers susceptibility to rf can be taken into consideration, as well as the fact that each test we did had only 2 tx running, and we didnt change frequencies or swap who was wearing the tx. though in all cases, line of sight improved matters vastly - though we all know that to be the case.

Link to comment
Share on other sites

" Imho people should stop obsessing with range "

yeah, but not gonna' happen...

When I spend thousands of Dollars on any piece of equipment I'm going to be obsessing about Every aspect of it. How much weight you put on each aspect is another question.

+1 Philip and Glenn above

Link to comment
Share on other sites

" I'm going to be obsessing about Every aspect of it. "

OK, however typically there are a couple of factors complicating the  obsessing:  the laws of physics, and unreasonable expectations.

 

speaking of obsessing,  the TV broadcasters spent a lot of time and $$ obsessing over range during the conversion to digital transmission, and that included a lot of increasing power to retain similar coverage.

Link to comment
Share on other sites

Zaxcom wireless at the same power level as FM wireless will provide on average 85 to 90 percent of the range of the analog system. 

 

Is this tied up with the digital wireless has no intermod idea Glenn? My thinking is that "digital wireless" still has to use an analogue radio wave to carry its digital data stream and those waves must still interact with others and cause intermodulation products in the RF realm. Its just that it is manifested as a total drop in signal as the error correction gets past its limit rather than being manifested as audible artefacts of intermodulation like an analogue system would with its analogous audio. Thus a digital system seems to have less range as it drops out at the point where an analogue system would be just starting to give, possibly liveable, whooshes and splats.

 

Hhhmm I'm mixing up intermod with pure range a little there but I guess it is all mixed up in real life.

 

This is a meandering thought of mine not the knowledge of an expert as you can tell!

 

Thanks

 

Stuart 

Link to comment
Share on other sites

[snip]

 

Digital so no intermodulation

[snip]

 

Hi Rado,

You might want to try this: Place two digital transmitters two feet apart at a distance of four feet from a spectrum analyzer. Set the carrier frequencies 1 MHz apart and look for a large spur 1 MHz below the low carrier and 1 MHz above the high carrier. These are the third order intermodulation products. My prediction is that you, as we did, will see regular levels of IMD with digital transmitters. You can move the transmitters closer and farther from the analyzer antenna to prove the IMD is between the transmitters and not in the analyzer front end. If the IMD tracks the carrier level in dB for dB it is the transmitters; if the IMD moves two or three times faster than the carrier level, the IMD is in the analyzer and invalid.

Since this is a quick and dirty, not to say loosey goosey test, we have found an hardwired test that can be done in a formal, repeatable manner. See this ITU document page 14:

http://www.itu.int/dms_pubrec/itu-r/rec/sm/R-REC-SM.1446-0-200004-I!!PDF-E.pdf

We are playing with it now and will have some numbers in a week or so. What will be most interesting is a comparison of the ITU test with the open air test to see if we can make the bench act like the real world.

Best Regards,

Larry Fisher

Lectrosonics

 

Link to comment
Share on other sites

" My thinking is... "

it is much more complicated than that..

it is physics...

it isn't easy

Yep.

 

Just started reading the article linked to by Larry about IM of digitally modulated signals being linked to the makeup of the digital signal. Kind of makes sense when you type it out loud. More stuff to learn. Bugger.

Link to comment
Share on other sites

Hi Rado,

You might want to try this: Place two digital transmitters two feet apart at a distance of four feet from a spectrum analyzer. Set the carrier frequencies 1 MHz apart and look for a large spur 1 MHz below the low carrier and 1 MHz above the high carrier. These are the third order intermodulation products. My prediction is that you, as we did, will see regular levels of IMD with digital transmitters. You can move the transmitters closer and farther from the analyzer antenna to prove the IMD is between the transmitters and not in the analyzer front end. If the IMD tracks the carrier level in dB for dB it is the transmitters; if the IMD moves two or three times faster than the carrier level, the IMD is in the analyzer and invalid.

Since this is a quick and dirty, not to say loosey goosey test, we have found an hardwired test that can be done in a formal, repeatable manner. See this ITU document page 14:

http://www.itu.int/dms_pubrec/itu-r/rec/sm/R-REC-SM.1446-0-200004-I!!PDF-E.pdf

We are playing with it now and will have some numbers in a week or so. What will be most interesting is a comparison of the ITU test with the open air test to see if we can make the bench act like the real world.

Best Regards,

Larry Fisher

Lectrosonics

Larry,

I have not done a spectrum analyzer test but from my own experience having 6 people in a metal paint booth some tx frequencies 2mhz apart, I don't see any difference or signs of intermodulation.

To be fair with proper frequency coordination I have not had issues with lectrosonics gear when it is only me. But working non coordinated events with bunch of mixers at the same location it becomes a problem...

But again in my line of work range, or even sometimes physical presence is not my main concern.

For the last one year I have never worried about drop outs or a challenging shoot. I have made it work in situations where six sound mixers are needed with six separate sound bag recorders.

In fact last week I bang my head in the middle of a walking scene. I let the director know over the com that I need a few minutes to recuperate. 10 minutes later I walked half a mile away where the scene was still going. later on I just pulled the sound from the transmitters.

So range does not bother me since in extreme situation I don't rely on the air to deliver the final audio.

Also I don't miss stopping a scene to adjust gain on a transmitter.

Before I use to worry about sudden dropouts, extreme unrealistic range and tx limiter distortion. Now I don't.

Link to comment
Share on other sites

I must say working in an organized environment with trained actors , everything I mentioned above is more of an extra feature, but in reality tv it is anecessity.

 

I find it preferable in reality TV to let producers know that it's a necessity for sound to be monitored for quality/mic rustle/mics fallen off etc by a professional experienced sound recordist and for content by a production member. If either is not right then we needn't have bothered. (apart from that pesky subtitle button they seem to have found...)  

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share


×
×
  • Create New...