HPX250: HPX250 - Audio issue when using external shotgun mic.

It seems like this distortion being caused is a result of excessive sound pressure on the microphone in use. This would most certainly cause audible distortion on any recording devise.
I'm not a sound expect by any means, but I would think that it's easier to distort a condenser mic as compared to a dynamic mic, especially a condenser shotgun which is designed to bring sounds that are further away closer, in audible terms ( and rejecting off access sound). I think this is why I was able to replicate the problem with the ME66 and could not with a dynamic mic.

Now My question to you Chris is...

Wouldn't this distortion occur on any camera along with the signal being recorded, because the mic is being overloaded?
The issue in question here is why is it occurring on the HPX250 with the level pots turned down to no gain?
I did another test with the ME66 and did not purposely overload the mic, and the recording was fine with no audible distortion.

It would seem that maybe the preamps in the HPX250 are a little more sensitive than others, maybe 0 gain on the level controls is not really 0 gain.
Not high enough to record a normal signal, but just able to pass through the clipping distortion that occurs on an overloaded microphone?

Certainly microphone choice is critical with any camera depending upon your particular situation, and if in an extremely loud environment it may be wise to choose
a less sensitive mic.

Does this seem Valid?
 
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timbrook2 - What are the problems you have been having with the ME66?

mmaller - I know what you are saying, this was my initial theory but all the sound guys I have spoke to said that shouldn't be the case. The ME66 has a maximum sound pressure of 125db. I'm sure the environment level I was recording in was much less than that as it was much quieter than a typical nightclub and I don't think I'm creating that much sound pressure with my voice when testing. I don't have a proper decibel metre but did just use an app I have on my iPhone and made the same sound into it that I have been doing when testing and it read 90db, again indicating that the mic can't be distorting from excessive sound pressure because its 35db shy of the maximum (I know the iPhone when be accurate but surely its not 35db out). My main concern though is that the levels when recording the venue were around -18db to -12db. When the "electronic distortion" came through it peaked over that, over riding the set levels. The sound in the room didn't rise that much at all, if anything the frequency may have increased. As before, my main gripe is with the camera not blocking that signal when the levels are at zero which all its competitors did. As far as I know, dynamic mics don't require power to run so this could be why you don't get the electronic noise when testing with that. The camera should be able to deal with both though for the level of equipment.

I must stress that everything I say is based on loose knowledge and a bit of guessing/common sense so if I'm drastically wrong in what I'm saying, please feel free to correct me. :)

I'm hoping that I'll get some definitive answers this week from Panasonic etc so I'll keep you posted.
 
This was something that was posted on this same subject on another forum, not sure what you all think.

That sounds like a digital encoding problem to me similar to pixelation on the video side, you can hear the digital bleeping at the end and its unlikely that mic would be making such noises, I would get in touch with panasonic under your warranty registration as it sounds like a faulty component or something is not working right on the camera to encode the audio.
 
The ME66 was creating problems. Intermitting hums and crackles with or without phantom power, with or without battery. We checked it with a second one and it also didnt like the panasonic audio inputs. This was ONLY with the HVX200 and I got rid of it. Since then no more problems with the exact same cables! Your test (I listened to the audio) sounds like the audio hardware after the XLR input is flawed in some way. If the volume is zero nothing should enter....
 
Hi everyone,

I just did a little search on Google about the ME66 being a little hot; I vaguely remembered from years ago that there was an issue with mics that are on the hot side that this can be a problem. I know that the HPX250/AC160/AC130 can use a condensor mic, but one needs to note that it is looking at a max of -40dB. I know that some Sennheisers are at -36dB(hotter than what the camera can handle). So it may well be that a different microphone choice may be in order or a small pad on the output of the mic could be used to bring it back into a useable range.

Best,

Jan
 
Nope, my ME80 does it also. It has less sensitivity than a ME66 and ME416. I was a recording engineer/tech 40 years, and 35 years of DPing and video tech.


I DON'T have a problem with my HPX500, any of my Sony BetaCams, DVcams, JVC's, Canon's,etc.

It's just ridiculous that you would have to pad a Sennheiser shotgun for a XLR input to a video camera. Name me ONE other camera that has this problem.

Sennheisers shotguns are probably the most used shotguns in the world.
 
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Chris Dumont said:
JohnnyD - have you had the same issue with the HPX250 then?
Click to expand...

Yes. The ME80, which I like a lot better,,,AND is less sensitive, can produce that distorted sound, when everything is on manual. It does take a loud sound to make it happen, but it does happen. What's crazy, you can get that clipping even when the manual audio control is on "0", as was described at the beginning of this thread. The resistor pad on the audio pot should ground the hot signal, but somehow there is leakage.

Probably not an issue for many, but I sometimes record in high level environment situations, and I don't want take a chance. Like I said, no problems with my other cameras. And the Sennheiser's are sweet.

It's too bad, I really like the pic of the 250. I need to figure out if I'm going to return the camera, or work with it, by tomorrow.
 
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Let is know what you do. I also use an HPX250 / ME66 combo but haven't noticed any significant issues.
 
JohnnyD said:
The resistor pad on the audio pot should ground the hot signal, but somehow there is leakage.
Click to expand...

My educated guess is that the audio level is set digitally and the pots are simply voltage sources into the CPU. It sounds like what might happen if the input to the audio ADC is overloaded.

Modern technology comes with a whole new set of potential problems.
 
For the purpose of my remarks, I'm going to call the distorted sound, "clipping". Depending on the audio circuit design, it is possible to clip at the input stage before the signal gets to the gain control.

I had a similar experience with a HMC150 when 1) the menu audio setting was -60db (should have been -50), 2) the external audio recorder decided it didn't like it's CF card, and 3) we were shooting a rock guitar amp commercial (think loud) ... also using a neumann U87 and Shure sm57. The audio gain controls were set low, ie between 1 and 2 on a scale of 11. The meters were normal, but some clipping distortion was found in post.

I'm thinking the audio design is similar in the HPX250, and is just a little too "fragile" in the input stage. The easy fix it just to attenuate a strong signal with a 10 or 20 db pad. Also the audio menu setting should be -40db. If I needed perfect audio from a HPX250, I would only run with the gain controls around 5, (12 o'clock on the camera)... or higher to setup correct metering levels. Turning the gain down close to 0 reduces the output (metered) but the input can still clip. Also, FYI, this clipping can be subtle, and hard to detect with headphone monitoring in a loud room.

I have not seen this on my HPX250 because I only record sound from the internal mikes to use for multi cam syncing. All project audio is recorded on a Sound Devices 788T or PIX240 because I specialize in musical events.
 
JohnnyD said:
Nope, my ME80 does it also. It has less sensitivity than a ME66 and ME416. I was a recording engineer/tech 40 years, and 35 years of DPing and video tech.
Click to expand...

Well this is all very odd as the ME80 we have here does not do this at all, in fact at the -40dB setting it actually sounds a little low. Our engineer is reaching out to Sennheiser to see if we can borrow a ME66 to test with.

Best,

Jan
 
Hi Jan,

Thank you for posting on this topic. It seems now that around 5 HPX250's have replicated the original issue I posted about.

Apart from this issue I am having, I think very highly of the camera. Its just a real shame I discovered this as I have lost all confidence in using it to record audio as the distortion I am experiencing is uncontrollable. As I posted before, I ran the same test on Canon's XF305 and a number of sony cameras, none of which replicated the issue I am finding on the HPX250. At the moment, I really feel the camera is not fit for purpose and I really want to come to a solution as soon as possible.

My dealership are reaching out to Panasonic through their supplier as they feel this is a problem with the camera(S).

If you can share anything with us or offer a solution it would be much appreciated, as I'm getting pretty tired of the whole thing now.

Thanks,

Chris
 
An immedidiate solution is like $30 pad to put in between the camera and the mic. Its fast and effective and will work. We still have to go through the process on testing so that will take time, in the meantime, a pad should restore your confidence.
 
JohnnyD;1986140388 What's crazy said:
This sounds reasonable to me. The audio example posted here sounds just like that. Lets see what Jan comes up with, I am also not happy with the sound quality compared to the HVX200, it sounds more digital and brittle from the 250.
Click to expand...
 
Hi all,

For what I know:

This sounds as the same thing with the famous Sony PD-150. With Sennheisser ME series om that camera it occured (only!) at high sound pressure on the mike. It sounded then 'overkilled' while the recording levels 'on paper' looked 'OK'.

I believe some users made attenuators in the mike cable, later on (zo far I remember) there came à modification for The mike inputs. Or just use à different microphone.

Ciao
Seb
 
I had the same problem with my Sennheiser MKH60. When I switched the mic gain setting on the HPX-250 to -40dB and set the -10dB pre-attenuation on the Sennheiser the problem disappeared. Also, an inline pad worked to solve the problem with my original settings.
 
My standard sound kit consists of Sony ECM77s and Sennheiser 416 powered by camera 48v. All working very well with HPX-250.
 
I know I'm coming late to the party but I've had the same experience. About to purchase a HPX250 - waiting for the boss to approve the purchase. We hired a HPX250 for a job in the interim. Used a Rode NGT2 and a Azden 300LT radio mic, there were no problems with the Rode NTG2, the Azden however produced the same audio problems as described here. On the shoot I was constantly turning down the recording levels to the point it was obvious that it wasn't a levels issue. The Azden mic has been used across a range of cameras and has lived a very sheltered life, I'd never had an issue like this before. I have tested the mic and leads on other cameras since and can't replicate the problem I had with the HPX250. Glad in a sense that it "wasn't me" but concerned because I has whittled down the camera choice down to this one. Very keen to hear if there is solution / recall to address the problem. (Note I had to return the camera before I could seriously examine the problem i.e. wasn't able to write down which input / mic / menu audio setting. I also advised the HPX 250 hirer of the issue who said nobody else had reported the problem. Like dfooman we will be sitting on our hands regarding a purchase until this is resolved.
 
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