noise floor

D

deleuze3

Well-known member
Hi,
i was recording the ambient sound in my dinner room.
I calculate the noise floor in dB.

While recording with a rode lavalier into a sony hxr-nx30, the ambient was going to -42dB

While recording with a rode lavalier into a pcm-m10, the ambient was going to -48dB

I find that these numbers are loud a little bit in terms of room noise floor.

Would i have a lower room noise floor like -60dB if i use a sound devices for example or a more professional setup ?

(maybe its the mic who is noisy too.

What are your thoughts?

Thanks in advance,
have a good day !
 
Are you trying to measure the noise level in your dinner room?
Or are you trying to evaluate noise level in the equipment?
Now are you equalizing the gain settings between the two different types of gear?
You have two equations and about a dozen unknowns.
Nobody can tell anything from such "measurements".

My thoughts are that we don't understand what you are trying to do.
 
I sometimes wonder if this poster just posts crazy things for his own fun.

OP, yes your dinning room will be much quieter if you buy Sound Devices gear.

Hear that SD... Maybe I can get a discount for a shameless plug?

To everyone else the above "test" really says nothing about any of the equipment.

To do what he implies he is testing you would need to calibrate inputs and do it in asound proof room. Even then with out checking a bunch of other variables all you could really say is X appears to be noisier with mic Y. So it's kind of silly to do and it's a spec you can probably find published anyway.
 
I live in an old house so I actually have some noise floors ;~)

I usually stay away from his topics because they tend to be some version of "I recorded sound using brand X orange juice cans and string and then using brand Y orange juice cans and a different string. Which sounds more like a Tram 50 and will work better as a lav?"
 
Noiz2 said:
I live in an old house so I actually have some noise floors ;~)

I usually stay away from his topics because they tend to be some version of "I recorded sound using brand X orange juice cans and string and then using brand Y orange juice cans and a different string. Which sounds more like a Tram 50 and will work better as a lav?"
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Yes, good point. None of his postings have never made any sense. They have all done nothing but decrease the signal-to-noise ratio of this forum.
If this forum has an "ignore list" then deluze3 has earned his place on it.
 
thanks for your replies, thank Rick, i have read the reply on the other thread.
thanks for your patience, understanding to most of you.
Equipment noise, floor noise, ambient, the parameters can be confusing at first.
 
deleuze3,

Really everyone wants to be helpful and there is a huge range of experience and knowledge on this list so generally even very beginner posts will get serious replies. But folks also expect some effort on the posters part to do some basic research and at least not repost variations on the some topic over and over. You have two now that are the same thread, for instance.

Folks will also often cut more slack if we know more about you and what you are trying to do. If it turns out a poster is like a 12 year old trying to get their head around sound folks will gear their responses to that level of experience.

But there have been times when we have had posters who just try and get a reaction with really outrageous posts.

I don't actually think that is you but some of your posts dance right on the edge. And when, as has happened in the past, you post the same question with a small change it starts to put them closer to the edge.

This could be for all kinds of reasons, like english not being your native language, your being really young, sound just being really difficult for you?

I have subjects I never managed to get a decent understanding of so that isn't a knock.

But after many posts by you I still have no idea what you are trying to accomplish. You have many posts with weird mic comparisons, often asking folks which is "better". Why? When people ask you never explain what this is for, what you are trying to do, what your budget is etc.

I'm not saying this to scold you but het bottom line is people are just going to stop responding to your posts. Assuming you actually want opinions, answers to your posts you probably need to address this to some extent.

This is true for some others also.

Let me bring it back to this thread as an example.

The "test" is invalidated in a number of ways as folks have pointed out.
But the real question is what did you want to test?

If it is which will record a cleaner signal, then the question is again why?

Choices for equipment often have more to do with other factors than pure superiority of specs. So WHAT you want to use the set up for is often more important than anything else when deciding which setup is "best".

The second thing is How significant are the results? This also has to do with what you need in the end.

A 2" 24 track recorder is going to sound better than a cassette recorder but you can't haul the 2" deck to the beach to record waves so it doesn't matter if it sounds better.

------


Many "comparison" posts, by lots of different posters, miss the "what I want to use this for" part that is critical to giving a worthwhile opinion about which might be "better".

With out that information it's pretty much a waste of time. Which is why on about 90% of the "which is better" threads the first response will ask what they want to use it for.

It's a two way street on forums. Folks don't have endless amounts of time to answer questions so those that ask better questions get more and better responses. And it doesn't hurt folks to put it up front if they really don't know anything about sound so people explain the terms they use, because it can be confusing.

It is also largely a waste for anyone with out the right lab equipment to try and get actual numbers on anything. I have some of that equipment and I could not generate meaningful numbers and just about anything I would want to test. This is why folks get reminded again and again to use their ears.

Partly it is because what YOU think it sounds like is often the bottom line but it is mostly because people don't have access to the equipment and test stations needed to come up with numbers that are "real". It is VERY complicated to do real testing and bassing anything off numbers that not done properly is, again a waste of time.

I understand the fascination with generating those numbers and I have been the one doing it at times in my life. But take a little (not so little) time and figure your coeficient for error and you will realize that the amount your number could be off by dwarfs and difference in the numbers them selves.

Ask more questions, ask better questions, and better answers will show up.
 
deleuze3 said:
I find that these numbers are loud a little bit in terms of room noise floor.
Click to expand...

- Every room environment has it's own ambient "noise" level, which you may be able to improve by turning off electrical devices or air-circulation fans ( including things like fridges or the furnace fan )

- Every audio recording device ( microphone, mixer/pre-amp, recorder ) has it's own amount of self-noise ( audio noise that had nothing to do with the ambient room noise )

- Better quality audio gear generally has less self-noise than the cheaper stuff, but this may make no difference if the ambient room noise is louder than the self-noise of your equipment.

- Microphone placement is key to obtaining the best quality sound from any microphone

- Monitor your recordings with a good pair of closed-back headphones to ensure you are getting the audio quality you are after

- With careful use of EQ and noise-reduction software you can lower the recorded ambient room noise by 10 dB or more


...It would be helpful if you could post a small WAV file sample of your recording to give us an accurate idea of what is happening with your recording.
 
TheDingo said:
..It would be helpful if you could post a small WAV file sample of your recording to give us an accurate idea of what is happening with your recording.
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On deleuze3 other post, "camcorder sound (juicedlink and xlr interface from the camcorder)" a link was posted (thread #5), hence my reply (#6), on 'acoustical borne noise' ... it gets confusing when the OP (deleuze3) starts another post to continue the same subject.
http://www.dvxuser.com/V6/showthrea...om-the-camcorder)&p=1986518144#post1986518144
 
I think a lot of the recent problems I see in sound are to do with the fact that all too many stills people are trancending their DSLR techniques into video and then think in terms of f stops and exposure latitude.

I see numerous "what are the best settings for this" and how does this sound better than that posts and I think a lot of it as you guys rightly point out is a basic lack of understanding of the fundamentals of sound.

That also gets linked with the dynamic range that is potentially available on modern day digital kit and people start to look at mic noise and how quiet mic amps are in relation to the full range available.

I have rarely considered pure specs in my 35 years in film and TV and most of the time I have a max dynamic range of 20db on most of my final content and at times as little as 4-8db.

Meters tend to be there for indication purposes and to be honest once my brick wall limiters or compressors are calibrated to enable mixing to be subjective without going illegal for delivery I mix with my ears and looking at the gain reduction indicators rather than the overall final mix levels so I get a good balance of dynamic range limiting but always get a balance that suits the delivery medium.

On location I would always just listen to noise floor for a given mic gain and then adjust mic placement to optimise the signal to noise ratio rather than constantly adjusting gains so the noise floor varies too much potentially causing problems once edits are done to a given piece. Doing single camera drama teaches you to match the noise floor rather than the overall dialogue levels but still keeping a reasonable signal to noise ratio.

It is akin to the old days of if you shoot 25 asa at f5.6 you will get a far better cleaner result than 1600 asa at f16 but the fundamental characteristics of the film stock or in the case of the audio recording medium have fewer implications these days of digital recording.

It all ends up being a contradiction though as we have never had technology so good at such a low cost but there seems a lack of basic skills and a wish for instant results without even knowing the limitations and boundaries that are required in the first place.

Remember that most of the dialogue on major films for many years was done on one mic a 405 or 805 (416+816) recorded on a mono reel to reel nagra running at 7.5ips with no noise reduction, the results were then transferred to sep mag 16 or 35mm sound film which probably had a top HF range of 15k and had dolby A or at best SR noise reduction. You probably only had 8-12 tracks of dialogue and the same for FX and music to play with and it was all pre-mixed to free up the mag bays for the next run of finals.

No automation and no virtual mixing and you punch in recorded on the fly to the pre-mix reels level matching as the reels rewound!

Now can anyone actually remember all the specs of this primative kit as I certainly can't but I do remember having to clean and de-mag the heads before each reel was put on for recording!
 
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GaryNattrass said:
It all ends up being a contradiction though as we have never had technology so good at such a low cost but there seems a lack of basic skills and a wish for instant results without even knowing the limitations and boundaries that are required in the first place.
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+1

...I love the YouTube shotgun mic tests where they have the mic positioned 10 feet from the talent.
 
Remember that most of the dialogue on major films for many years was done on one mic a 405 or 805 (416+816) recorded on a mono reel to reel nagra running at 7.5ips with no noise reduction, the results were then transferred to sep mag 16 or 35mm sound film which probably had a top HF range of 15k and had dolby A or at best SR noise reduction. You probably only had 8-12 tracks of dialogue and the same for FX and music to play with and it was all pre-mixed to free up the mag bays for the next run of finals.

No automation and no virtual mixing and you punch in recorded on the fly to the pre-mix reels level matching as the reels rewound!

Now can anyone actually remember all the specs of this primative kit as I certainly can't but I do remember having to clean and de-mag the heads before each reel was put on for recording!
Click to expand...

I came in at the tail end of this. Post had gone digital, editorial anyway, but 1/4" Nagra was still the standard and everything was mixed to 35mm "Mag". We were using ProTools but a high end system only had 16 "voices" so 8 stereo or 16 mono, and the interfaces only had eight outs. We delivered to the stage on DA-88 eight track tapes.

Dialog would be 8 tracks max, ADR also had to fit on 8, but often shared with Dialog so often less. SFX came in in banks of eight, rarely over three banks. Foley was on 24 track 2" tape. Before the DA-88 everything was in blocks of six because that was the max track count on Mag.

Everything would be premixed in food groups, Hard FX, Backgrounds, DX/ADR, Foley was usually only three tracks. I would have to look up some of the old Cue sheets, but not a lot of tracks in general. The mixer had "flying faders" installed so you did have volume automation and in the 80's projectors started being able to rewind. Before that no automation and you couldn't stop a pass with out having to start over from the top of the reel and redo everything. Even so until lateish 80's and fader automation you really couldn't punch in, because you couldn't match levels so it was really a 20 min live performance.

Here anyway about the only thing that went on during rewind is EQ. Mixers found it was easier to EQ dialog when you couldn't understand the words, and that way they didn't waste time.

The Mag machines (Dubbers) were about seven feet tall and maybe three feet square and held two independent recorders (actually doing a search for photos most were just single recorders, but there were dual ones also). You could switch the heads out for different track counts and types of stock. If you want to see some take a look at the "computer" in "Desk Set" the tracy Hepburn film, if I remember correc tly the "tape portion" of the computer are just dubbers. The machine room of the mix stage would have lots of dubbers. Usually they could be patched in to more than one stage so you might have two or three shows going at the same time. A big machine room might have fifty or more cranking away. They disappeared very fast once digital dubbers came in. Wish I had recorded the sound of them but who thought they would disappear so fast.
 
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Wow thanks for that link, what a treat.
BTW only to camera credits, I think they just did a dance.
 
And so it seems... the older I get, the fewer microphones I use.. though my mic collection continues to grow.
 
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