Community: Message List - XD V-75 TR system strange interference!

Re: XD V-75 TR system strange interference!

support@line6.com — Wed, 30 Jan 2013 00:23:47 GMT

Your taking the time to post that "follow up" may prove really valuable for others suffering "strange interference", ...so many thanks!

First of all, I cannot emphasize strongly enough the importance I also attach to Don Boomer's sage recommendation that you switch ALL of your transmitters to operate in the (far more robust) four-frequency-diversity "RF1" mode.

Now to the vexed issue of (...ahem) undergarment support.

Don is (as ever) absolutely correct as far as the pristine excellence of all audio once it's actually in an XD-V system's transmission path, but I'm sure he'll agree when I say that his comments really only apply AFTER the analog audio has actually been bit-mapped.

Which brings me back to another vexed issue that I touched on earlier, ...the problems I've repeatedly experienced with the unbalanced wiring from DPA's (otherwise superb) miniature microphones.

I'm referring to the fact that ANY waveforms fed into the beltpack's TA4 connector's "+ and -" will always be transmitted with the utmost fidelity.

If those waveforms happen to contain a proportion of the transmitter's own encoded RF signal (in the case of the support garments in question, reflected from adjacent underwiring metalwork and induced into a length of unbalanced mic cable) ...then that's what will be heard.

Hence my earlier recommendation ("Point 1" of "two things to check" in my very first reply to this discussion) regarding the care I've found that needs to be taken in dealing with excess cabling from DPA mics.

As I also mentioned earlier, anyone can easily experience the "racket" of such accidental induction by plugging an un-terminated length of XLF to TA4 mic adapter cable into a Line 6 beltpack and then listening to its receiver's output.

A variety of "bunching, bending, grabbing" and "moving alongside the beltpack" manoeuvres will then yield a truly impressive array of "soundscapes", ...some of which may well prove useful for a future audio work.

So, matchlessly natural that the sound of DPA miniature mics may be, it's been my oft-repeated experience that the nature of their cabling means special care MUST be taken with their fitting, especially to such iconic figures as the operatic "knight in chain mail" and/or the buxom "fair damsel" whose hand he seeks.

"Arise, Sir James ...and may thy Noble Quest grant thee and Sir Donald the just peace that thou desirest."

Re: XD V-75 TR system strange interference!

support@line6.com — Tue, 29 Jan 2013 16:11:21 GMT

I see a couple of points in your post that concern me.

You are using the mics even though the scan shows full interference bars on the channels you are operating on? That is risky, especially in RF2 mode. I would suggest switching to RF1 mode.

Interference ... even if the performer's costume is causing interference, that interference cannot become audio in the radio. We send a code in the header of every digital packet and when the receiver receives anything that does not have the code then it does not make sound. And if that reception is "audio" that doesn't pass either as your are still in the digital world. I can't say for certain, but the most likely cause is a mechanical one. Did you also try swapping transmitters?

Re: XD V-75 TR system strange interference!

support@line6.com — Tue, 29 Jan 2013 12:29:27 GMT

Right!! Late follow up to my orignal post!!

The Panto went well!! Had to substitute the weird mic with a UHF unit but here's the thing!!

On down time between peformances we obviously tried swapping packs, headsets, Lapel mics, receivers and still the same problem on only the one person!!!!!!!!!!!! thinking she was somehow electricly charged!, yes i know strange conclusion but realy had no other explenation i gave up and just used a uhf sennheiser and problem solved.

Now i'm on another production with all 8 XD75's all still in mode 2, this new venue is a school with every channel on the scan feature Full on the wifi!!! Networks everywhere!!!!

But with the rack on the stage and local P180 antenna on stage all was fine.

Now here is the strange thing. One pack was attached to the back of a womand bra as i did in the last production i did, and again that same noise!!! Moved the transmitter to her waist and a belt to hold the pack on and all was fine!!

So i'm thinking that the metal in the bra's are somehow creating a interferance field?

has anyone else had a simlar situation??

I must admit i still havn't tried changing the RF mode.

Re: XD V-75 TR system strange interference!

support@line6.com — Sun, 13 Jan 2013 23:31:21 GMT

Me too. I've yet to experience a more natural-sounding or versatile range of miniature microphones than DPA's, including their newest "d:fine".

"On the road", my only two concerns have been

The price of (and the occasional connection problem with) their microdot screw-on system and
That their amazing bass response can yield feedback "surprises" in the event that adequate subsonic roll-off has been overlooked.

I'd be very surprised if the age of the "culprits" was to blame, as some very old "originals" are still on the air every night here, sounding exactly as they did when first unpacked.

However, I seem to remember that two sensitivities were on offer when the range was introduced about ten years ago, so perhaps you've three of the lower sensitivity version among yours.

Re: XD V-75 TR system strange interference!

support@line6.com — Sun, 13 Jan 2013 22:47:11 GMT

Thanks for all the help and suggestions! We have had a few rehearsals now within the v75's and so far they have been fine! Looks like 3 of the dpa headsets were causing the weird interference I was talking about.

I'm thinking it's down to the mics been old, not had the time to do more research into the problem to be honest.

As soon as I changed them for some Chinese specials off eBay I got much better results although a sound quality dip.......

Still a few more runs then the shows.

I also re-located the rack to FOH so the directional Antenna were facing directly towards the stage. I had them back stage, mainly moved the rack so I could see the signal levels etc.....

By the way I'm using all 8 with the 8 way distro and active antenna's.

I will get to the bottom of the dpa problem when I have more time.!!! Still impressed with the sound!

Re: XD V-75 TR system strange interference!

support@line6.com — Fri, 11 Jan 2013 17:13:27 GMT

Re: Audio Meter LEDs

Maybe a little different than you might be used to. Think of it as 4 LEDs and not 5. The top one on V75 (not V70) indicates clipping and is red. So "normal would be 2 or sometimes 3 LEDs lit green while giving you proper headroom.

Re: XD V-75 TR system strange interference!

support@line6.com — Fri, 11 Jan 2013 02:49:43 GMT

Oh, ...and very much "by the way"...

I find that the "Audio" LED column on the front panel can't be interpreted as any form of "meter", but has the effect of being more of an "audio activity" indicator that's ideal for quickly locating a given source of "splatting", intermittent disconnection or other such heart-thumping annoyance that's been created at the on stage "business" end.

Re: XD V-75 TR system strange interference!

support@line6.com — Thu, 10 Jan 2013 23:58:26 GMT

I reckon you needn't bother with a cap instead of a zener, ...as the actual method of blocking DC back to the input would seem to be irrelevant and everything else in your wiring would seem to be exactly as you and I would expect.

In the event that you're listening at a very high "critical evaluation" PFL level on headsets, then maybe you are right in thinking that your perception of the unbalanced mic-induced noise floor is (dare I say it) "too critical".

However, if you feel you really must have extra gain at that input, (and if you have the time to do so) I think you'll need to at least double the value of that "pull-up" resistor to about 20 or 30kΩ.

An earlier discussion related to such a "gain-maker" (albeit for a Shure headset) can be found here: http://line6.com/support/thread/70314?tstart=180

If it was me, I'd prefer the extra headroom and so would leave the values as they are, ...UNLESS there was a need for absolutely pristine individual multi-track recordings for later album-related re-mixing and/or overdubs.

Even then, it's my experience that the "Norm" setting of the superb adaptive processing that Line 6 calls their "Dynamic Filter" performs a "clean-up" that's more than adequate for most applications.

I just hope that you've enough rehearsal time remaining to try it, although enabling just the "Norm" setting ("live", at the receiver/s) would almost certainly pass un-noticed in "the house".

Re: XD V-75 TR system strange interference!

support@line6.com — Thu, 10 Jan 2013 09:47:25 GMT

As an aside, I'm always amazed by the harmonic variety and shattering loudness of the digital "storm" that I can induce from my TA4 to XLF mic cables when they're left un-terminated.

However correct location of the cable once the mic's connected invariably yields the pristine audio that I've come to expect from my XD-Vs.

As you've tried other combinations, it looks like the amazing Don Boomer's right "on the money" yet again, so your suggestion of a Sennheiser replacement would seem to be the only practical way to get on the air, unless these guys can either lend you a replacement or know of someone who hires them out:

http://www.studiospares.com/mics-wireless/line-6-xd-v75l-lavalier-wireless-system/invt/301160/?VBMST=line%206%20XD-V

Re: XD V-75 TR system strange interference!

support@line6.com — Thu, 10 Jan 2013 23:19:49 GMT

Right I had some time this evening in the theatre to get my head around the problem. Im thinking I'm adding too much gain at the desk end, with all the transmitters active the interference is apparent on all but very quiet.

I made all my DPA's connections on the TA4's by copying the pins in the Microdot to TA4 adaptor that was with one I had laying around.

Pin 1 ov

Pin 2 10k to a Zener then to pins 3,4 with the hot soldered between the Zener and resistor.

Had a play tonight changing the resistor values, not much difference, had no caps to try replacing the Zener with a cap. Next thing to try.

Reason I'm trying all this is even with a powerfully singer wearing a headset the receivers VU led display only flashes on the first 1-2 LEDs!! Is this normal or should I be getting a hotter signal?

So adding the extra gain at the mixer might be why I'm hearing this noise?

Guess I will just try some more configurations on the TA4 to get better results.

I still get a good sound from each receiver but think I should be getting more into the transmitters!