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XD-V75 Distortion (again!)


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Excuse me for my poor english. I meant to set them up in RF1 mode. As I so in the pilot's guide you can switch the mode in the transmiter. Do you have to do something in the receiver? or it recognises RF1 mode automatically? As long as I use just 12 systems is it better to work in RF1 mode?

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The receiver automatically detects which mode you're transmitting so you don't need to change any settings there. RF2 mode was implemented to allow users to work around the presence of wifi traffic without causing undue interference. RF1 is much more robust but tramples all over wifi. As long as you don't need to avoid any wifi channels, RF1 is a better bet. (Having said that, I don't think you can avoid any wifi channels whilst using as many as 12 channels in RF2 mode anyway).

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There are reasons to use RF2 mode.  But you must be in command of the Wi-Fi in the venue to be successful with it.  Most users cannot guarantee that so RF1 mode will work better for them.

 

That said ... yes you can mix any XDV/Relay devices up to 14 channels in RF2 mode however only V75's can be assigned to channels 13 & 14.

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Hello, 

 

last weekend I've been testing my system again.

I have the same problem in RF1 mode as other users kindly posted. The same distortion (digital artifachs...) which is not present in RF2 mode. I've been using different mics including Line 6 headset and lavaliers. It's exactly the same distortion. I think it is more present as more transmitters are working, because in the sound check, it was not present or it was not easily appreciable. This problem disappears in RF2 mode.

 

Apart from that, in any mode, I had the same problem that I found the gig before. A lot of distortion appear when all the 11 v55 systems are working at the same time. Specially with thomann mics which are more sensible, but I'm sure it is not a microphone problem, because when I test it alone, there is no problem at all (I have to make a big effort so that it distorts, and the distortion that appear is not so terrible). The systems with Line6 mics have a worse behaviour as well, the sound is not so clear, it seems compressed and a bit distorted.

With all the transmitters off, almost no RF red leds were shinning. The receivers were placed at 2 meters in the side of the stage, with no wall or curtain in between.

 

I've been using 5 systems a lot of occasions and they performed excellent, and started to find problems now with 11 systems.

As I understand, it have to be a V55s problem that V75s doesn't have, because otherwise, other friends in this forum would complain as well.

Do v55s perform somehow worse when a lot of systems are required at the same time?

Thanks a lot.

 

Josep.

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As you stated before, the systems work when you are at home but have problems at the gig.  That would seem to suggest that the wireless units themselves are working properly but that you have a system related problem at the gigs.  That can be very difficult to trace.  I'm confused a bit as to why the problem seems to happen only in RF1 mode and not RF2 mode.  So when you have tried the two modes is it side to side at the same venue at approximately the same time?

 

It's easy to test for distortion on a test bench with a known signal but difficult to understand exactly what is happening with a singer.  I'm wondering if something is getting into the mics themselves from the transmitters and that signal is then just being passed through.  If it were possible to test a spare channel with a sine wave (about 400Hz of medium level) running through it while all the other channels are operating.  Record that channel for a period of time and then analyze it for problems.

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I'm sorry you didn't understand me. The systems work in the gig as well but each one alone, or a few units at the same time. the problems appear when working all at the same time. 

The distortion that appears in RF1 mode and not in RF2, is this kind of artifacs that Daniel posted. It's not on a sine wave, but I think it is clear with a voice as well. As I said I think it is more present as you increase the number of systems at the same time, because I didn't noticed checking one system alone, but I'll check. Yes, I tried the two modes at the same venue.

This doesn't represent a problem for me, because I can work in RF2 mode.

 

The other distortion which is not mode dependent is just distortion, as if the microphone was clipping.

 ""I'm wondering if something is getting into the mics themselves from the transmitters and that signal is then just being passed through"". Can it happen when a lot of systems working at the same time but not when this unit works alone?

 

I can make the sine wave test, but I just have 5 days for returning this systems wich I can not work with. Now my options are:

1. change the v 55s for v75, hopping I'll have no more this problems.

2. buy more line6 mics and try all the systems with the same mic, and see what happens.... (just in case you tell me the transmission quality is the same in both systems V55s and V75s).

or return them because they have some hardware problem.

that's why I'm asking your advice, and the differences between the systems. I can not wait for the next gig and having this problems again.

 

Thanks.

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Hi all,

 

I'm hoping to get time to do a more scientific test with set signals next weekend so that we can try and narrow down exactly what the issue is. I'll do recordings with varying numbers of transmitters switched on to see if that makes a difference.

 

Josep, mine are V75 units, so swapping to those is unlikely to improve the situation for you.

 

I personally still think the problem occurs with increasing RF traffic, which is probably why switching to RF2 mode fixes it. Most buyers seem to be either handheld users or guitar users - both probably only using a handful of channels, and I'd imagine that's why there are few reports on the forum. There are actually a few other times when this has been mentioned in threads, but it's always either been dismissed as user error, or the original poster hasn't followed it up afterwards.

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Most buyers seem to be either handheld users or guitar users - both probably only using a handful of channels, and I'd imagine that's why there are few reports on the forum.

 

I'm not sure that's entirely true. I've seen a number of people posting that they've had good results on theatre shows (beltpacks) with 14 sets. I've only used six at a time thus far (always RF1; along with 12 G3 transmitters) and have never experienced this distortion issue. I'm still very interested to get to the bottom of it though.

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Are you using low sensitivity DPA mics? Normal sensitivity are not best for musical theatre in my experience.

 

And are you sure you are not having the issue in soundcheck? Sometimes kids don't give you the same amount of energy in soundcheck as they do with an audience (as I am sure you are aware). 

 

Do you have any Countryman B3's you could try it with (red ring for low sensitivity)? the distortion sounds like it could be the mics not having enough phantom or current.

 

I do not think this has anything to do with RF. 

 

How are you powering the receivers? Are they all on when you test in sound check? 

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Hi Steve,

 

Thanks for the reply. It definitely happens with red band B3s - mine are all red band low sens versions. It does it with the blue band B6s as well (very low sens).

 

Interesting theory regarding the current - that might explain why it can be intermittent, and perhaps doesn't happen in sound check when the batteries are straight out of the packet. Could it also be the case that the transmitters draw more current in RF1 mode because of the extra RF being generated? That could explain why switching to RF2 fixes it.

 

Any specs available for how much juice the V75 transmitters are able to supply to the connected mic?

 

I'm away at the moment, but I'll investigate further once I get back. The receivers are all just mains powered from the originally supplied adaptors.

 

Thanks,

Daniel.

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OK after a little listening party we have some theories, but they are only theories. The main one is the sound you here may be the error correction at work. There are a few things you can do to manage that:

1. Use RF2 mode which has improved error correction response.

2. Minimize the need for error correction by minimizing the distance between the transmitters and the antennas.

 

If your show were on a broadway stage or tour they would be doing their best to keep the distance down to less than 50 feet and possibly even 30 feet. That is with $8000/channel wireless that is very capable of 300+ feet. Think of it as headroom. 

 

If the receivers are in RF2 mode you can use the RF Performance page on the receiver (Page 6), to monitor the actual errors and drop outs. this is best done by going to page 6, then turning the encoder clockwise to get the errors and dropouts stats. This counter will reset to zero when you cycle the receiver power. It works in close to real time so it is an excellent tool to use for aiming antennas etc. You can use a spare receiver if you have one to monitor your lead during run throughs and performances if you like.  Let us know what you find.

 

Steve

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Hello Steve, I'll try to answer:

I don't have any DPA, but the theory could have sense, because I find the distortion much more important when the mic is more sensitive. I found problems in a channel with a thomann mic that disapeared using a lavalier Line6 mic (or even a headset one). More sensitive mic produced more distortion, but the receiver was not clipping and as I said before, using this mics alone was very difficult to make them distort. Always speaking about both modes, not about the RF1 mode distortion.

 

Sorry, during the soundcheck, I meant with few transmitters on. With them all on, the problems occurred as well. 

I made them shout during the soundcheck till they thought I was crazy. Not so wrong...

 

I power each receiver with its transformer, all together in the same plug. I had them all on during the soundcheck.

 

I'm sorry I'm not focusing my explanations in the RF1 problem wich you are dealing with, but the distortion that I found is much bigger and as I said is not mode dependant. 

Thank's Steve, I found It could be related with the mics sensitivity as well, that's why I decided to use Line6 mics in every channel. What was puzzling me as well is that the units with Line6 mics didn't perform as well as I was used to. I keep on posting.

 

Josep

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  • 1 month later...

Hi,

 

I think I have the problem somehow solved, or at least more controlled.

 

Sorry I don't focus on the RF1 problem. The only thing I can say is that I have it as well, at least when I use 11 units working at the same time, I don't know if it occurs with just one unit.

 

Swapping to the problems that I had working in RF2 mode, I have to say that they disappeared. Now I'm using line6 and Beyerdynamic mics in each channel, and 11 systems in an almost clean wi-fi environment, performed perfectly.

 

So I think that the theory about high sensitivity mic was ok. I don't know why they produce distortion (kind of artifachs) when used in a lot of systems at the same time, without signal clipping leds in the receiver. I can use this cheap mics with a few systems at the same time with no problem, though.

 

So thank you very much for your advise, and hope this information can be useful for you.

 

Josep.

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Hi Guys, Im just chiming in again after a few more shows running these units.

 

Last show i eliminated a wireless DMX unit that was seriously flooding the 2.4ghz spectrum with information on all channels, and i only had a few sound checks where this bizzare distortion presented itself and it was not as pronounced as it has been in the past. I never noticed it during the course of a show. Switching channels on the belt pack that had the issue did not stop the problem. I notice this as a problem when there are many people on stage, ie when a performer is sound checking just before or whilst vocal warm up is taking place on stage. 

As usual it becomes more pronounced with a greater input into the mic, and nothing in the chain is anywhere close to clipping.

 

I have a scanner that i use for UHF radio mic's as well as 2.4ghz, and i plugged in all of the line 6 frequencies for each of the 12 RF 1 channels (4 for each channel) and used the best 9 of these. Being able to see the 4 frequencies signal levels made channel selection a lot easier and safer.

 

Is Intermodulation a consideration for these systems? I always presumed that it was not as the set channels are intended to work with one another. 

 

The error correction theory sounds plausible, and i guess if this were the case the only way to test this is if there were an option to bypass it however i imagine that it is an integral part of the system and this would not be possible.   

 

The only way i see to improve this is more control of the RF environment, and more 'headroom' for the receivers. Perhaps an RF Venue 2.4ghz CP Beam would help, i currently use 2 p180 antennae. 

 

I often have my line 6 rack right beside Sennheiser G3 units, all are using remote antenna's that are correctly spaced, close to a minimum of 1 meter. Could having the receivers next to one another have any adverse effect?

 

Thanks

 

Ben

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It looks like you issue is likely related to some incompatibility of the Beyer mics and the Line 6 transmitters. I'm wondering if the Mics have some powering requirement ( maybe current consumption) that is causing them to produce the artifacts which are then transmitted by the wireless systems.

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I've still not had much of a chance to play around further, but I'm due to use about 12 channels for a show next week, so we'll see how it goes!

 

I'd rather fix the whine issue here than send all the packs in to the service centre - Steve/Don, do you know where this spacer gets inserted to stop the whine? Is it to stop the little round metal post from conducting between the RF board and the main board?

 

Thanks,

Daniel.

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Unfortunately it's not a "user" repair and must be done by our service center.  I believe it also involves swapping out a couple of resistors as well as a spacer.

 

Usually the whine is not audible unless you put your hands near the antenna (which detunes the antenna) and makes it worse.

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Also, The whine issue has never been a problem when im using DPA 4061's and the packs are in waist straps, It is still there but only audible in headphones.

 

But when i use DPA 4099 on them on say softer instruments like cello, double bass or acoustic guitar the whine issue packs are quite bad. This is due to the lower output of the 4099, and the 4099's are much nosier or their own as well. 

 

They are fine on the packs without this issue. I have one that whines particularly worse than the other two as well.  

 

Ben

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Hi Don,

 

Ah I see. Shame the service centre didn't fix the issue the first time all the packs were sent in, but nevermind! I'll get them all sent back after Christmas when things calm down.

 

Most of mine whine all the time, even when you're not touching the pack at all. It does get significantly worse when you touch near the antenna or input jack though.

 

I agree it's less of an issue on higher-output mics (the Line 6 lav included), but on low-sens Countryman B3s/4060/MKE2s it can be heard during quieter passages.

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  • 2 weeks later...

Hi again, i had a thought. Could the whine issue and the distortion be correlated? 

 

My brand new packs are perfect, and the 

 

I have sent 3 packs with the whine in for service, and another 2 that are very noisy. They have not heard of either of the issues but hopefully they can figure it out.

 

Ben

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Hi,

 

That was my feeling given that Don says the whine fix may involve changing some resistors. I guess that might explain why more people aren't encountering the issue - if it only affects early units.

 

I've been using all 14 in RF2 mode this week with various mics, including several scenes with all the mics on stage at the same time. No distortion problems at all, and luckily there was no WiFi in the building anyway, so RF2 mode worked fine. The whine was noticeable on quite a few of the transmitters, so I still need to send those in to the service centre in Rugby for the fix, although when I spoke to them last, they didn't know of the issue or what the fix is.

 

Like Ben, the new pack I bought has no whine whatsoever.

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  • 2 weeks later...

Could you have an issue with your mic pre's ? How much headroom do you have in your gain stage ?   Also how about your antenna setup  I havent seen yoiu mention what kind of antenna configuration you are using... are you using the provided cables?   Do you have Phantom Power on?   I find sometimes my XD-V35's get a hum if phanom power is on with SOME PA's .. 

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