Echo when using Lav + Boom/Handheld

[PhotoScout]

I recently purchased a Sennheiser AVX Wireless System (Lav) and would like to integrate it into my workflow (This is my first lav)

When doing on camera narrations or test-interviews, I notice an echo on the recording if I use the lav in conjunction with a handheld or boom setup.
Is there a way to avoid this, or can I only use one mic at a time?

(Also, I notice that there is a slight delay in my headphones while monitoring between what the talent says and what I hear, is this normal?)

 

[graywolf]

Radio mic's do have a slight delay. That is probably what is causing your echo too.

Usually, when using wireless mic's the shotgun is only used to record a scratch track in the camera.

Not what you wanted to hear, because it means once you go to wireless, you really need 2 to 4 of the expensive things. I found out that with just one, I am pretty much limited to a single speaker. It does work nicely for narrative on walk around videos, you wear the mic and talk about what you are taping. I picked up some of those dirt cheap close out wifi wireless mentioned in another thread (unfortunately, no longer available for $10 each) and am working at getting them setup with my equipment.

However, do note that I am a hobbyist, the pro's here may give a different answer.

 

[ggrantly]

You don't mention what you are recording to nor how you are listening. Is the echo heard while recording or in your editor? I haven't encountered this as an issue but some camera headphone outputs have a slight delay, but both tracks should be in sync when you listen in the editor.

Using both a boom and lav for an interview is very common and allows you to choose to use whichever sounds better.

I wonder if what you are hearing is room echo recorded to your boom mic? What does the boomed track sound like when the lav is turned off? Does this occur always, or just in the room you were using?

Grant

 

[videoshot]

Hi PhotoScout, what's you're hearing is the delay coming from the Sennheiser AVX Wireless System,unfortunately it works this way, it has some frame delay,I think it's about 1 or 2 ! and i think it's because of the way this AVX works with WIFI radio!your boom is going directly to the canon in so no delay there! It (AVX) have delay also vs other radio mics I have from Sony. I have two of them (the AVX) and never had a problem but only this annoying Echo!
Regards
Sam

 

[paulears]

Digital radio mics have latency due to the analogue to digital conversions - but analogue wireless doesn't!

You have 19m/s of latency - which sadly, is noticeable. Of course it's totally curable by slipping the timeline forwards to sync the analogue and digitals sources together. So it isn't echo, it's just a digital delay, and fixable fairly simply. One of the hazards of digital kit. 10ms or less usually goes by without noticing - although if you blend analogue and digital together even a small delay makes the horrible hollow sounds we hear all too often.

As pros - we should be precise with descriptions - echo is when the delay is long enough that a hand clap becomes two! Less than this is reverberation if it's multiple reflections, or in digital systems, latency - as in simple processing delay.

 

[Rick R]

Yes, that particular system has a longer than usual latency delay (as Paul stated, 19ms). It can be easily advanced in post though since it's linear. AFAIK, the top shelf digital wireless systems from Zax and Lectro are about 2-3ms.

 

[ggrantly]

Didn't know about the delay in that Senn digital system. Do other digital systems have similar delay? I have only used G2 G3 systems (analogue) and never encountered that.

 

[cpreston]

As somebody else mentioned, you never mix a wireless feed with a boom feed on the same track. Well, sometimes I will let a little boom feed into a mix when I need a touch of ambience to make the wireless sound more natural. In fact, mixing multiple wireless is also not going to get you the best sound. It's a one source process.

The wireless delay probably isn't a huge deal for online video. Many cameras don't even have particular good sync on their in camera sound and people don't notice. What will drive you up the wall is monitoring with a delay.

 

[brettsherman]

Using both a boom and lav for an interview is very common and allows you to choose to use whichever sounds better.

I used to do that. But I never used the lavalier, so I stopped using it. Either boom only (wired or wireless) for me, or wireless lavalier only when there is a logistical reason for it. Camera mic as backup for both situations. When one man banding it's helpful to eliminate unnecessary equipment.

 

[cpreston]

I used to do that. But I never used the lavalier, so I stopped using it. Either boom only (wired or wireless) for me, or wireless lavalier only when there is a logistical reason for it. Camera mic as backup for both situations. When one man banding it's helpful to eliminate unnecessary equipment.

Same here. Everybody expects a hidden lav in addition to a boom for interviews. Personally, I only recommend a lav when somebody will be moving around or the director wants an inordinate amount of head room. A properly positioned hyper will almost always sound better than a hidden lav and is generally just as close to the talents mouth as a lav in an interview with a normal amount of headroom. You skip so much headache if you don't wire up every person you have to interview. I've gone so far as to set up a stereo boom mount with two hypers so that the producer is getting the two sound sources they feel they need. The worst is when the editor doesn't even bother to separate the sources and you end up with a hard pan of the lav and the boom to each channel. But now that wireless mics are common, people expect you to use them.

 

[Joshua_G]

As mentioned above, it's quite common practice to use both lav and boom mic. However, each should be recorded on a separate track. In post, the better sounding track is chosen.

 

[Noiz2]

You have two things going on and to some extend they are canceling.
First and what you are probably noticing is that the more electronics and processing the signal goes through the longer it takes to make it out the other side. Cheaper wireless have generally longer delay times.

The second thing is that sound travels a LOT slower than light. So if that Lav was wired you would see the lave showing up first by a small amount. Not a big issue with a boom but if you are shooting say a concert, the direct feeds from the stage will show up significantly sooner than any house mics.

The big takeaways are that you need to keep separate mics on their own channels, and you almost never want to mix mics together if you haven't done a real sound post and had someone get the mics in phase with each other.

So while it is common to shoot a lav and a boom, you are going to choose one or the other in post and not mix them.

 

[davefisk]

As others have said, the AVX has a delay, and that's probably what you are hearing. I don't use that system with anything else like a boom or other wireless systems. All digital wireless have a slight delay, but the high end stuff it's not noticeable because it's so small.

Just do the lav on one track and the boom on another track and pick in post which one you like the best. I've done this a bunch, and even using high end lavs (for sit down interviews I did hardwired...no need to use wireless), I always ended up using the boom.

 

[ryanjf]

While it is common to choose between a lav and boom in post, there have been many cases where I presented the re-recording mixer with both channels (phase aligned) so that she/he can mix them together. Sometimes the lav adds the body of the voice while the boom gives it a sense of real space (without reverb) and movement. As long as they're not phasing, do whatever sounds good!

 

[graywolf]

So while it is common to shoot a lav and a boom, you are going to choose one or the other in post and not mix them.

Well if they are on separate channels, and he can shift one in post, it is possible to mix them.

However, I think you pro's would usually record the wireless mic's into a recorder and use the shotgun as a scratch mic into the camera to get the number of channels you would need for more than a couple of mic's.