Please ensure Javascript is enabled for purposes of website accessibility Jump to content

XD-V75 Distortion (again!)


Recommended Posts

Hi,

 

I discovered something fairly alarming this evening...

 

I've posted a few times regarding the distortion (sounds like digital clipping to me) I get with our set of 14 XD-V75 beltpacks. Trying to diagnose the issue has been tricky, and I'd given up to be honest. It seemed completely intermittent, and wasn't helped by the fact that I'm always in different venues, using different combinations of microphone brands, some shows using more channels than others, etc. Initially I thought it was related to the Countryman mics only, but it turned out to affect others too. Then we sent them in to the UK support guys to take a look at, but they couldn't find any problem. Then I thought I'd fixed it by shorting pins 3 and 4 on all the mics. 

 

The clipping only occurs when the talent is singing reasonably loudly (as I've said before red-band Countryman B3s in the forehead position) - I've not noticed it just during dialogue. Receiver normally only has 1 or 2 audio level LEDs lit, and the beltpacks never display the red clip LED when this is happening.

 

I've finally figured it out though. I'm aware that everyone will think this can't possibly be the issue, but I spent a while testing this with different beltpacks, different channels, and it's definitely the cause.

 

Basically, in RF1 I get the clipping. In RF2, they're perfect. Perfectly repeatable by switching backwards and forwards between modes. 

 

Whenever I use 12 channels or less, I always put them in RF1 mode. I've just loaded up the show files for recent shows I've done, and every one when I was using the full 14 channels (so in RF2) didn't have the signal clipped.

 

Everything has the latest firmware loaded.

 

So... any thoughts?! Don?! 

Link to comment
Share on other sites

Well first I doubt you are getting digital clipping. That would make a horrendous sound.

 

So are you saying you can repeat this with a single unit or do you need to be running 12 systems when this happens? What exactly are you plugging the output of the receiver into? I would like to make some tests and see if I can duplicate it.

Link to comment
Share on other sites

Oh it's a pretty horrible sound! I've got multitrack recordings of various shows it's happened on, so I'll put a link up to a short section tomorrow so that you can hear. Sounds digital to me.

 

The set-up during that particular test was 6 receivers powered-on (with 2 pairs of antennas serving 3 each), 6 transmitters powered-on with Countryman B3 red bands connected. 4 were sat on a table (across the room from the receivers), 2 were fitted to cast (on channels 1 and 3). XLR outs from receivers were going into an M7CL on this occasion. The problem was apparent pretty much as soon as they started singing. Unlocked the transmitters, switched them all to RF2... perfect, so we started the show. The following day I tested them again and they were fine, switched one transmitter at random back to RF1 and it started distorting again when I spoke loudly. Back to RF2 and it was fine.

 

So no, I can't definitely say that it happens if you only use a single unit, but I'll certainly test that out next.

 

It seems unlikely that this can be affecting all V75s, because surely we'd have heard more about it on here from other users by now. I did find one other post from someone who had what sounded like the same issue, but they didn't follow it up.

 

Luckily this venue had no WiFi at all, so RF2 was perfectly fine in terms of reception anyway. In busy theatres we'll need to be able to use RF1 to get a full 12 channels working reliably.

Link to comment
Share on other sites

 4 were sat on a table (across the room from the receivers), 

 

 

That might be an issue.  You might be experiencing a "near-far" problem and RF2 mode is just a bit better at handling that.  I've seen shows where they hold transmitters in steel baking pans to help eliminate the problem.  It's usually not as big a problem with Line 6 digital wireless as it is with analog systems, but it can still happen.

 

Maybe you can try the same thing again but put a few feet between transmitters.

Link to comment
Share on other sites

The following day I tested them again and they were fine, switched one transmitter at random back to RF1 and it started distorting again when I spoke loudly. Back to RF2 and it was fine.

An intriguing problem! When you switched that one pack to RF1, were the others still transmitting on RF2? A bit of an unfair test if so as they'll never work correctly like that. Either way, I look forward to hearing the resolution of this one.

Link to comment
Share on other sites

Hi,

 

Don - the transmitters in use weren't close to the receivers, and 4 sat on the table weren't in use, and again weren't near the receivers. I understand what you're saying, but surely that would only affect the RF performance anyway, I wouldn't expect it to alter the audio path. Plus this has happened on several occasions when the positioning has been different anyway.

 

Sheriton - when I was testing with a random pack the following day, only that pack was turned on, so there wasn't anything still using RF2.

 

I've finished the current show now, so when I get a moment, I'll set everything up at home and test a bit further.

Link to comment
Share on other sites

Hi,

 

Don - the transmitters in use weren't close to the receivers, and 4 sat on the table weren't in use, and again weren't near the receivers. I understand what you're saying, but surely that would only affect the RF performance anyway, I wouldn't expect it to alter the audio path. 

 

That's my problem too.  The RF mode doesn't affect the audio path so I'm not seeing how that could be the problem.

 

Just so I'm clear ... you say the 4 sitting on the table weren't in use.  Were they turned on?

Link to comment
Share on other sites

  • 4 weeks later...

Hi Don,

 

I did another show with them over the weekend, so I had time to play around with them a bit more. 100% - if the transmitters are in RF2 mode they never clip and generally run perfectly (there wasn't much interference, plus the antennas were side of stage, so all 14 channels worked reliably without any drop outs).

 

Once I switched to RF1, the first thing that was obvious was a high-pitched whine on some of the transmitters (with or without a mic attached). Some were still silent, but the majority had a whine to some extent. As soon as there was any reasonable level of singing, the various channels started to clip/distort (sounded like digital clipping to me, but I know you're not convinced!) seemingly without any pattern as to which would distort and which wouldn't. Swapping capsules around didn't help - the issue was definitely with the transmitters. I also noticed that if you hold the transmitter in your hands so that as much of the casing as possible is covered, the whine disappears (and it hasn't dropped out of signal).

 

Back to RF2 and the whine was gone, and no distortion.

 

It seems like there has to be at least 3 of the transmitters turned on before RF1 mode causes issues.

 

Any thoughts?! I suspect the answer might be to call in at Line 6 in Rugby one day and demonstrate the issue.

Link to comment
Share on other sites

So when you say digital clipping you mean complete show-stopping explosions ... 100% non usable? There really isn't a "beginning" of digital clipping.  It's either hard clipped or it's not.  There could however be some other type of distortion going on.  You would have to do some kind of THD testing to understand where it begins.

 

You could test this yourself by playing say a 400Hz sine wave into a transmitter and then gradually increasing the level.  There should be well below 1% distortion until you hit the clipping threshold of the input at 6vac p-p (which would be almost impossible using common mics).  Compare this in both RF modes.  It should be visually observable in a wave editor if it is occurring as you are describing it.

 

The other thing I don't clearly see being tested is the receivers.  So if you can get a single transmitter to have the problem then can you switch 3 or 4 receivers to the same channel number and clearly hear the problem on all of the receivers.  That would pretty much rule them out.

 

Other than that, I'm just too far removed from the problem to guess. Can I get a list of the serial numbers of your transmitters? I can back check them to their original manufacturing QA testing.

Link to comment
Share on other sites

  • 3 weeks later...

Hi,

 

My understanding from a previous conversation with Line 6 UK is that they were all manufactured on the same day, and they're some of the very first units. One of the serials is 21D510M6149017701, another is 21D510M6149001038.

 

If I give the UK team a call, are they likely to be aware of the issue? All the transmitters have already been in for repair with them once, and they didn't seem to be aware of any such issues.

 

Thanks.

Link to comment
Share on other sites

  • 4 weeks later...

Hi, I have experienced a similar issue i believe as well.

 

the distortion is not apparent until the input reaches a certain volume, and when testing all of the packs one by one they all seem fine, and due to this it only becomes apparent really during a show in quieter sections, not when apart of a chorus. I have not tested them with all of them running at once as yet but i will do this ASAP this week and determine wether it is a certain pack etc. It is definitely not digital distortion, as this would be far more aggressive, the fuzz or buzz for me is generally softer than the singer and becomes louder and more pronounced as the singer sings louder. And therefore when a show becomes more sparse in its content on a good speaker system the distortion is apparent.    

 

Has this issue been resolved for you as yet? is it an issue with a pack?   

 

thanks

 

Ben

Link to comment
Share on other sites

Hi Ben

 

Which models do you have? Which firmware is installed? Which mode do you have the issues in?

 

On your end ... Checking to see if it happens with just some or all of your systems would be a good idea. Likewise you should check the receivers as well as it could be an issue there. Also does it happen in different venues or just in one?

Link to comment
Share on other sites

Hi Don, all are v75 recievers and a mixture of v55, G90 and V75 packs running in RF1 mode. In the same venue each time, they were running directly over top of a W-DMX and another cheavet wireless DMX for this show and i had no time to make proper space for the Line 6 packs, ie recievers were glowing red when the packs were off :/ not ideal!. They never dropped out, and for 2 rehearsal and 1 show there were no issues at all and then for the other 2 shows i noticed it once for only 1 bar of singing during the show and then in the sound check of another.

 

I have paddles, but have experienced the same issue before i have had paddles.

 

It would be nice if it were just interference as i have a scanner and can ensure they are free of interference and i will be adjusting the settings on the w-dmx unit to work around the line 6 packs next show.

 

Could interference cause this audible disruption?

 

I will do thorough testing tomorrow of all units.

 

Thanks

 

Ben    

Link to comment
Share on other sites

Hello,

 

I have some xd-V55 systems, working in RF2 mode. I find a lot of distortion problems as well when the singer sings loud. First I thought it was because of the microphone (thomann one which are impossible to be used, a lot of distortion!), because using the line 6 one a bit far from the mouth, the problem was not so appreciable. But then I found that with the Line6 mics the distortion was still occurring in some singers with louder voice. It is HF distortion. The signal level in the receiver is just 2 or 3 leds as much. I had to end the gig with some lavalier mics (far placed). 

I've been using now 11 systems. When I used just 5, I didn't realise about this problem, but I can not confirm that it didn't happen because they were used for speech.

I thought it could be because of the output signal level (which is no adjustable in the 55), but I see people have this problem with 75's as well, and I really don't think so.

I'm afraid as well, it is related with the transmission, there is something that I don't know if it is normal. With all the transmitters off, no red transmission leds on (just 2 or so in random devices). When I switch on some transmitters, the others witch are set in different channels. start to show all the red leds on. There occur some drops during the show as well. I feed every receiver with its pair of antennas. 

 

Hope you can give me some advice.

 

Thanks

Josep M. 

Link to comment
Share on other sites

Hi,

 

I've now confirmed the issue exists even with just two of my packs running simultaneously in RF1 (with the others turned off). Anacondaq, it certainly sounds like you have the same problem. Do you also have the high-pitched whine from your beltpacks in RF1 mode? (happens with or without a mic connected)

 

Daniel.

Link to comment
Share on other sites

Hey Daniel

 

So are you saying that the addition of the second unit causes the problem to start and that there is no problem when only a single unit is operating?  As far as the high pitched whine, there was s known issue in a range of production dates.  If that's the case that can be corrected.

 

For everyone else ... these issues may be related or may be individual events and not related.  It's getting hard to keep them straight.  One user says the problem gives away in RF2 mode and another has his problem in RF2 mode.

Link to comment
Share on other sites

Josep

 

It is normal to see red LEDs on the ladder when the transmitters are turned off.  They nearly indicate the presence of some rf on those channel frequencies.  But remember, the Line 6 transmission is digital so interference doesn't cause distortion it only affects the collection of data into the system.

 

It is a possibility that the analog output section of the receiver could be driven to distortion by a very powerful signal.  With V75's the output can be turned down but as you stated this is not an option on the V55 series.

 

If you are operating in RF2 mode you must be able to control the wi-fi in your operating space.  RF2 mode uses only 2 channels to receive the data instead of 4 channels as in RF1 mode so it can leave more empty space for wi-fi to operate.  Its a very usable system but you must have control to ensure no unintended wi-fi is operating.

Link to comment
Share on other sites

Hi Don,

 

I've not had a chance to test just a single unit yet I'm afraid. We had a concert set up on Saturday evening using two beltpacks in RF2 mode and all was working fine. In the interval, I quickly switched them to RF1 and asked the singers to repeat one of the songs they'd just done as a test, and the distortion was then present straight away.

 

I agree that it's hard to diagnose when everyone is reporting different scenarios. I know that I've definitely never experienced the issue in RF2 mode, even using all 14 channels at once. Granted, perhaps that's due to some other external factor, and perhaps the issue can occur in RF2 mode under certain circumstances.

 

Josep - were your units definitely in RF2 and not RF1 when you noticed the distortion?

 

Don, are you able to share what exactly causes the high-pitched whine on the early units? Is it feasible that it could be linked to the distortion issue? I'm curious as to why switching to RF2 gets rid of the whine. Our transmitters are:

 

D510M6149001038
D510M6149025041
D510M6149014847
D510M6149016001
D510M6149001250
D510M6149017817
D510M6149017770
D510M6149014687
D510M6149017701
D510M6149017497
D510M6149017633
D510M6149015028
D510M6149017428
D510M6149022248

 

I did speak to Dietmar on the UK support line, and described the high-pitched whine issue, but no-one there seemed to be familiar with it. They have agreed to open an RMA to have another look at the units, so I'll send a couple of transmitters in this week. 

 

I'm sure we'll get to the bottom of it eventually!

 

Thanks,

Daniel.

Link to comment
Share on other sites

Josep

 

It is normal to see red LEDs on the ladder when the transmitters are turned off.  They nearly indicate the presence of some rf on those channel frequencies.  But remember, the Line 6 transmission is digital so interference doesn't cause distortion it only affects the collection of data into the system. I know, what concerns me is that the leds apear when transmitters in other channels are turned on. When no transmitter is on, no leds shining.

 

It is a possibility that the analog output section of the receiver could be driven to distortion by a very powerful signal.  With V75's the output can be turned down but as you stated this is not an option on the V55 series. Do you think so? because maybe I still can change my units for V75 ones. There were just 2 audio leds shinning in receiver... Is it possible that the headset microphone can not handle so much SPL? (the singer was not shouting).

 

If you are operating in RF2 mode you must be able to control the wi-fi in your operating space.  RF2 mode uses only 2 channels to receive the data instead of 4 channels as in RF1 mode so it can leave more empty space for wi-fi to operate.  Its a very usable system but you must have control to ensure no unintended wi-fi is operating. Ok, other wi-fi signal can cause drops, but constant distortion as well?

 

Thank you very much for answering. I'll try to make myself more clear in red and I'll ask something more: Is the signal transmission better in 75s than in 55s for any reason?

 

Thanks. Josep.

Link to comment
Share on other sites

Hi Josep

 

1- answer is still the same.  The LEDs refer to data not sound and it is normal to see them come on and off.  With transmitters turned off I expect to see them everywhere i go.

 

2-  Headset mics come in ranges for expected performance.  The supplied headset is not really intended for singing but more for speech.  Your singer may well be able to overpower it.

 

3- Wi-fi cannot cause distortion.

Link to comment
Share on other sites

Daniel

 

The "whine" issue was caused by a slightly mis-aligned antenna inside the unit.  The fix is accomplished by adding a small insulating spacer.  I don't know if that is your problem but Dietmar will be happy to check them.  I don't think the RF1/RF2 mode has anything to do with that problem but I can't say for certain.

Link to comment
Share on other sites

Thanks Don - sounds like an easy fix for the whine if that is the cause.

 

Back to the distortion, here's some random short clips from multitrack recordings so that you can hear the problem. Example 1 and Example 2 are from different beltpacks, different receivers, different venue, different day. With Example 2, I then switched all the transmitters to RF2 in the break and we repeated the song before continuing with the rest of the rehearsal. All of the transmitters behaved perfectly after that. Our capsules are a mix of Countryman B3 red-band, B6 blue-band and Sennheiser MKE2 - same issue happens with all. Example 1 is with an MKE2, Example 2 is with a B3.

 

The recordings are pre-fader, so no EQ, compression, reverb, etc. I've normalised the files and saved to MP3.

 

Let me know what you think.

 

Daniel.

 

Example1.mp3

Example2-RF1.mp3

Example2-RF2.mp3

Link to comment
Share on other sites

Unfortunately recordings of someone's performance aren't much help. There is no way to know the quality of the signal. If you had recordings of known test tones then it would be much more help. Also mp3s aren't nearly as useful as wav files because they have been processed by a codec.

Link to comment
Share on other sites

Those examples sound very much the same as what i have experienced, thanks for posting Daniel.  

 

Despite being MP3 and a performer rather than a test tone, the issue we are hearing is plain as day. You can hear how it changes as the vocalist changes dynamic, its almost like some sort of clipping somewhere? We know the pacs have more than enough headroom, and generally the AF out indicators on the receivers only register 2 bars or so at a loud volume, and also it is heard quite clearly at a very reasonable level that should not cause distortion when the receivers output are set at 0db. Also the capsules overloading is ruled out in those examples, and my experience with the issue has occurred with school students "half singing" on DPA 4066's.   

 

I use dpa 4061 or 4066 and have experienced this problem. 

 

latest firmware on everything as well

 

tcc i have not experienced the whine issue, i have experienced a substantial increase in noise on some packs with countryman B3's and Rode HS1's (on 2 of my 10 transmitters only), but with the DPA's the noise is not present at all. Many of mine are second hand, hence the combination of transmitter packs. Not that it makes any difference if not using the eq settings etc. 

 

I shall test my units thoroughly and report back. 

 

Ben

Link to comment
Share on other sites

Hi Don,

 

I appreciate that - those recordings were just what I had available, and they do demonstrate the issue quite clearly. When I get a chance, I'll happily send some suitable test tones to the transmitters and see if I can replicate the problem. I do feel there's enough information in this thread now for someone at Line 6 to have a concerted effort to replicate the issue at your end.

 

Ben, absolutely - the red clip LED on the transmitters doesn't illuminate when the issue is present, and the receivers never get anywhere near clipping based on the LED indicators on the front. I agree that those capsules simply don't overload unless you scream into them right next to the mouth.

 

I would have agreed that it's likely to be heavy RF that causes the problem, but as I said, it's happened now with just two packs and receivers powered on at a show. It was at a church in the middle of nowhere, with no telephones lines, nevermind WiFi.

 

Puzzling...

Link to comment
Share on other sites

It is puzzling.  Have you ever performed an RF sweep?  It is possible some production equipment or some mechanical equipment at the venue could be having an effect.

 

Not to be argumentative because I do want to correct your issue, but there is no what to evaluate what might be distortion in a singer's voice in an empirical manner.  We need to use known test tones.

 

We do lots of testing before a product is released and then ongoing testing to evaluate production runs.   We have done lots of multi-channel interaction testing and have never duplicated what seems to be happening on your end.  What specific test are you looking for?  I can look up the data and let you know.

 

Just curious ... have you ever experienced a problem using the factory supplied mics?

Link to comment
Share on other sites

Hi Don,

 

We haven't, although I've had the same issue in schools, theatres, churches, etc, and I can't think of any common equipment which could have caused interference.

 

I need to spend a good few hours with the receiver racks and transmitters over the next few days and try to work out a more scientific way to reproduce the issue with a given set of test tones. Then any artifacts will be obvious by comparing the original file to a recorded output from the receiver, and that's much more feasible for someone at Line 6 to repeat and evaluate.

 

Clearly there must be some specific set of circumstances in order for the problem to materialise, otherwise you'd have many more customers experiencing the issue. 

 

Most of our systems were TR versions without a mic, but I do have two of the cardiod lavaliers that I can try - I've never used them because they're obviously not suitable for musical theatre anyway.

 

The serial numbers I posted... are they early units? All from the same batch? If touching the transmitter in a certain way, or holding it close to the receivers, results in RF interference affecting the audio output by way of a high-pitched whine, surely it's not inconceivable that it could also be introducing other artifacts during singing..? RF1 presumably generates a lot more RF traffic, especially with 12 channels in use at once, so that could explain why the problem is either non-existant or much less prevalent when switching to RF2.

Link to comment
Share on other sites

Hello,

 

definitely I think I'm not talking about the same distortion as Daniel. I've been checking my units thoroughly and I did not recognze it. In fact, I found no problem with none of the microphones I use. I don't understand why I had so many problems in the gig. Then, the microfones with more sensitivity (thomann's ones) used to distort (a lot, like if the transmition was bad). Testing them myself shouting!!, no problem, even with 10 systems running and transmiting some signal wich was playing on a speaker.

why I did have this problems? as I understood, with this systems when the transmition is not good, drops happen, but not distortion...

Don I leave my email for if my problem is not realted with this forum's. jsala@amanitasound.com. I'd like to know abot 55s vs 75s.

Thank's a lot. 

Josep M. 

Link to comment
Share on other sites

Joseph

 

It is extremely difficult to troubleshoot a problem like you are describing without actually having the having the

Gear right in front of you. On a forum like this you may get some help with hookup or operational issues but if it is a hardware issue it will have to be resolved by the service center.

 

If you think you have a hardware problem then please open a service ticket by clicking on the "contact us" link at the bottom of the page.

 

In order to help here we need a lot more information about your system in addition to more details about how you are operating the wireless units.

Link to comment
Share on other sites

I don't think this is hardware issue, because as I said before, I found no problem testing the 10 systems myself at home. No distortion with any mic. The problems were in the gig. Ok thank's, i'll try it again next gig. By the way, is it possible to program v55 systems in RF1 mode? Thanks again.

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...