sound quality with field mixer
 

I was reading some owners' opinions of the Sound Devices 302 mixer, in which they claim that even one mic plugged into the mixer instead of directly into the camera will produce better sound.

I can't figure out the logic of this. I can see how a bad electronic device could introduce noise or distortion, but how can a mixer actually improve the audio quality of a single track?

Re: sound quality with field mixer
 

Because you would be using the Mic Preamps in the SD mixer which are far superior to those in the camera. Then from the mixer you would take a line level in which would produce a signal with less noise.

-Garrett

Re: sound quality with field mixer
 

Thanks, Garrett.

If you compared clips recorded each way, what difference would you hear -- ie, what kind of noise is reduced with the mixer?

Re: sound quality with field mixer
 

You might find this thread I posted over on dvxuser.com of interest. It seems that a mixer doesn't always really improve audio quality in every case. It adds some things that are beneficial, but if you have a pretty decent recorder (camera or not) the main help is in control, not quality.

The thread also includes a short test I did with/without a Sound Devices MixPre between the mic and the camera.

Opinions on this test?

Re: sound quality with field mixer
 

The signal level out of a microphone is tiny. Add a fixed amount of noise (say from cheap preamps in a camera) to that signal and the ratio of signal to noise is small. On the other hand, if you use a great preamp that has a tiny amount of fixed level noise, the signal to noise ratio is much greater.

Now, amplify that high S/N signal with the good preamp and plug that signal into the cheap camera preamp. The camera input signal is now at a much higher level, but the fixed level of noise from the camera is the same as in the first example above. The end result is a much higher signal to noise ratio than you would get without the high quality preamp.

The key points are that the preamp must have a low noise level, and it must also have signal gain.

There are limits to this solution though. Drive the camera with too hot a signal and it will overload and distort. Like Baby Bear's porridge, the signal shouldn't be too hot or too cold.

Re: sound quality with field mixer
 

Don't you mean "much greater"?

Re: sound quality with field mixer
 

Yes, greater. I've edited and corrected the original post. Thanks!

Re: sound quality with field mixer
 

Given equally good technique, would it be right to conclude that an excellent mic plugged into a camera is better than a mediocre mic plugged into an excellent mixer?

Re: sound quality with field mixer
 

OK, I'm pretty new at all this, so someone slap me down if I'm off base here, but...I think in general, yes.

If you don't have a decent mic, nothing else further down the chain can do much about it.

A good Sound Devices-level mixer won't make a mediocre mic sound great. Now, if you have a good mic but a mediocre recorder with noisy preamps, the mixer should make a more noticeable difference. The cleaner, quieter sound from the mixer would probably help keep the mediocre recorder from degrading the audio as much.

Here's a test I did:


In this test I found adding the SD MixPre between the mic (AT 4053b) and camera (Canon XF100, xlr input, 16bit linear PCM) did not substantially improve the audio I was already getting. It's better, but not by much. It's just a touch fuller and smoother, and recording into a laptop @ 24 bit (also in the test) gave a very small further boost. So, I was already getting decent audio and the MixPre did not add very much.

The mixer can get you cleaner sound, better limiters, more control, etc., but it doesn't add audio quality that wasn't there in the first place.

Re: sound quality with field mixer
 

Well here is my take on it there is far too much hype and nonsense about kit for video, otherwise we would be all using oxygen free copper cables and mega bucks mics all the time.

Tv and film sound is not like hifi or recording studio stuff where you spend loads of cash to get that nirvana sound of mics taped on the walls of a room, nonsense.

Great sound for vision can be had by simply plugging a mic into your camera and making sure that you take care and attention to record the cleanest and best audio possible, just buying a mixer and plonking it in the chain will not get instant results its all about how you use your kit and understand it.

That extends to the full audio chain and you are good to know what the process of sound editing and dubbing is beyond what you record on location.

Even thought i have over 30 years in mainstream audio production for TV and film I now use budget kit most of the time and get great results that have been on broadcast productions around the world.

I use sony prosumer stereo mics with mini disc for wild recordings and AT875R and G2 radio mics as my stock kit direct into my HPX301 and 371 cameras, I have just bought a budget TW mixer to add more channels and edit in FCP and dub on a 10 year old digidesign 002 console running pro tools V8.

it's how you use what you have that matters and understanding what you may require in addition to make your location sound the best you can capture, I use auto level all the time on my P2 cameras as it is excellent these days and make sure that my audio gain structure from location all the way thru to delivery is spot on and does not introduce any nasty distortion or unwanted noise along the way.

Yes an expensive pre amp or mixer may improve things but the only way to tell is if I do an A/B comparison so I make sure that the kit I use it set up well and I understand it's limitations so that I get the best out of what I have rather than thinking that I need XY or Z to get better.

Re: sound quality with field mixer
 

A great mic plugged directly into a bad preamp will be noisy no matter what. Maybe you can clean some of the noise from the signal and bury the rest under music and sound design, but that's no fun. It can compromise artistic choice, and you still might end up with a noisy result with dialog that sounds somewhat underwater. The subtleties of the nice mic will be lost under the noise.

A mediocre mic in a good preamp will sound quiet, but the voices might sound dull and/or thin. With good EQ, this can be improved to some degree, but is unlikely to sound great. At least it won't be buried in noise.

In general, I'd lean towards a clean preamp and mediocre (but not bad) mic. A general audience won't complain about dull sounding voices, but they will notice noise and NR artifacts.

On the other hand, the great mic might have a stronger signal than the mediocre one, so that will help mitigate the noise to some degree. Still, the superior preamp probably wins the battle. Not all great mics have high sensitivity, and not all mediocre mics have poor sensitivity.

Re: sound quality with field mixer
 

Consumer mics today are better than many of the pro mics from a decade ago. That's a product of technology trickle-down and mass production in China. So that's no revelation.

Now if you're using the A/D converters of an 002 and getting away with it, well then I'd say you've compromised your sound. The 002 was cheap and accessible because of it, but it's converters were terrible.

I use a digi rack, but I'm using Benchmark A/D converters so I bypass the digi and it's merely a patchbay at that point.

But more to the point of the thread, a good mixer in experienced hands is going to give you control over dynamics that you simply can't get any other way. Through riding the gain and limiters the resulting signal to noise will be far superior to recording straight to the camera.

Re: sound quality with field mixer
 

The one reason that hasn't been mentioned much is levels... a good shotgun microphone might not produce strong enough levels to maximize your dynamic range; my me66 which is known as being relatively hot still sometimes doesn't produce -12dbFS peak levels recording a person speaking relatively quietly from a bit of a distance, and that's with my Sound Devices MixPre. Running it into a camera or recorder directly and the levels are even lower (and therefore noisier).

I'm considering upgrading from the SD mixpre to the 302 partially for this reason, to get a bit more gain.

Re: sound quality with field mixer
 

Jon, is there a way to determine the quality of a camera's preamp without having a mixer to compare it to?

Re: sound quality with field mixer
 

I totally take your point and the kit use inc the 002 is not the best on the market, but it is about getting the job done to budget these days and I have never had anyone comment that the production audio I do is not good enough for broadcast. I don't use the mic amps in the 002 anyway and as all my work is P2 tapeless all the audio stays in the digital domain for delivery so I make sure that my front end audio is squeaky clean, the pre amps on my panasonic cameras are very good and as said the auto gain circuits are very useable and help keep things in spec on location.

TV in the UK is all about compromise these days and before I had the 002 I used AMS Neve DFC and logic 3 consoles that cost up to £500k for my audio dubbing needs.

As for dynamics that is not really relevant for TV production sound as most of it is crushed in the dub to make it sound punchy and match the commercials that are compressed to oblivion. OK film sound may be different but most features dialogue is also compressed and mixed with limited bandwidth anyway.

My daily rates are the same or less than they were ten years ago so that is reflected in the kit I now buy and use, as technology has moved on you don't always have to get the most expensive to get acceptable results.

Re: sound quality with field mixer
 

Yes, but you need some sort of test gear and technical chops to do the measurements.

Probably the easiest way to determine it is to ask questions about specific camera's preamps here a DVInfo. :)

For instance, I've tested Canon DSLR inputs. They are pretty weak and benefit greatly from an external preamp, if not a completely separate recorder.

Re: sound quality with field mixer
 

Interesting discussion. I just tested a new $199 portable recorder with XLR and it did indeed benefit from a high quality mixer through it's line level input. You have to jump to the end, but you can even see the levels drop off in the meters when the line level input is utilized.


In another test that I performed with the Panasonic HPX-170 with a Sign Video portable field mixer, you could barely distinguish the difference through line level. It comes down to how good does it have to sound for your end deliverable? Proper mic technique is going to be the biggest factor in getting high quality audio.

Re: sound quality with field mixer
 

Thanks Guy that new tascam looks very good for the price and I had a sign ENG 44 mixer two years ago, its all down to price and if you use this prosumer kit correctly you can get good results but as broadcast has taken the attitude of using people who know nothing about technology so these days any one with any knowledge of the basics can get broadcast quality sound far better than a self shoot producer director (secretary or media graduate) with the fantastic kit we can now buy at low cost.

I have four audio tracks on my panasonic cameras so have great audio capabilities and even using prosumer gear most of the time it is far better than I used twenty or even ten years ago.

The music industry has been prosumer for 10 years now so don't too hung up on buying industry standard kit to get the best results, its only TV at the end of the day and did you ever encounter anyone asking what mic and console all those classic albums from the 70's and 80's were recorded with?

As said I have used the best for the past 30 years but these days what you can buy and do for the money is a non brainer and at hte end of the day its all about the fact that content is king and to steal the BBC charter remit from 1937 we are here to make interesting content that inspire people and inform, educate and entertain!

We have never had it so good with technology so get out there and make something interesting rather than get bogged down with too much forum bullshit!

Now can anyone tell me what mic and mixer "a matter of life and death was recorded with" or for my all time fave "the thomas crown affair" ???

Go do it, go be creative and be happy with the great times we live in.

Re: sound quality with field mixer
 

Guy makes a good point. The improvement you get with an improved preamp depends on how bad the recorder's preamp is. DSLRs benefit a lot. I have an M-Audio Microtrack II which has balanced inputs but really bad preamps. It also benefits greatly.

A quiet, high-sensitivity mic always helps. Good mic technique keeps the levels strong, so that helps too. A weak signal stresses any preamp and can make a recording through a bad preamp unusable.

This is a weakest-link-in-the-chain situation. Delivery matters too. If you will play this on a mobile phone with earbuds in a bus terminal, the noise can be high and you won't care. Play the same content in a theater and you will care. A lot.

Re: sound quality with field mixer
 

This may have already been mentioned, but...

The 302 also comes with great metering and limiters, which allow you to record at a higher level than if you were going straight into a camera or recorder, where you'd likely have to set the levels and leave them alone, and thus have to set them rather conservatively.

Re: sound quality with field mixer
 

These fine mixers are currently being offered as factory re-furbs on e-bay or can be ordered direct from here:TW Electronic Components — Products

Had a few happy hours setting my first mixer up yesterday, int old days of broadcast we used to do acceptance tests on all audio kit but this seems to have been thrown out the window along with the staff now.


These mixers are very well made and I was able to adjust the limiter threshold and calibrate the outputs and meters with no problems at all, initial tests show that they are very quiet and have some very good features and for the money (I paid £400 delivered for this one:http://www.twelco.hu/LP4S_userman.pdf) I don't think there is anything near it on the market. Even the outputs are transformer balanced and all the switches and pots are very smooth and pro like.


I had a sign ENG44 a few years ago which was a bit of a toy, but this is far superior, arrived in as new condition with a full set of AA rechargeable batteries, two power supplies (sadly two pin euro ones) and a very useable case.


My only criticism is the ballistics of the BBC type PPM meters, they are just re-scaled VU's so are too quick but having said that are still useable for quick gain settings, as the limiters are very good quality they stop any over mod happening and as I have the auto gain set on ch3+4 of my camera all levels can be recorded safely but with plenty of headroom.


Some of the great features are that you can link the inputs for stereo so you only have to use one pot to control the level of a stereo mic or source, you can also get sep outputs for multi track recording straight from the four mic amps and the mix of outputs available inc a video assist are very comprehensive.
http://img.photobucket.com/albums/v6...DSC_0001-2.jpg

Re: sound quality with field mixer
 

I don't see any mention of it, so I thought I'd ask about the Sure FP-33 I have.

How does this unit measure up against other field mixers?

Re: sound quality with field mixer
 

Tom,

The Shure FP-33 was the standard for many years. You'll still see them all over the place at TV stations, production houses and sat trucks. The Sound Devices line (SD-302, SD-442 and its replacement, the SD-552) has become sort of the new standard. The provide some additional features and they are generally a little quieter as well. But the FP-33 is a real workhorse. You can definitely get good audio using that mixer.

Re: sound quality with field mixer
 

I had the first generation FP32, which I took all over the world to many hostel environments, (climatic and civil ) it never let me down... even after having fallen into a stream and we got soaked. I still have it, and have only replaced the master and one of the channel pots since I bought it in 91'. Noisy in a studio environment for sure, but I always liked the warmth of the mic pre's. The FP33 is much quieter, and I'm 'shure' it's super reliable.. I now use an SD however.

Re: sound quality with field mixer
 

Thanks, guys, for the feedback on the Shure. I got mine off Ebay and rarely use it. Most of the time we are running two wireless mics into one of the cameras.

Re: sound quality with field mixer
 

Comparing specs and user reviews of the SD 302 and Wendt X3, I actually prefer the simplicity of the Wendt and don't think the missing features will matter to me in the future.

But I do notice tha SD mixers seem to have much higher resale value. For example, Trew has the X5 in exc. condition for just over $1500, compared to about $2500 new. But the SD mixers sell used for pretty close to retail. I guess the big difference is higher demand.

Re: sound quality with field mixer
 

Okay! I'll ask... Has anyone tested the difference between the preamps on a Canon XF100 compared to a Tascam DR-100mkII?

Re: sound quality with field mixer
 

I can't compare the XF100 to the DR100, but if it's any help, see page one of this thread for a test I did last fall. I tried adding a SD MixPre between my AT 4053b and my XF100 to see if it would get better, cleaner audio. I found that it did not. If I recorded to a laptop with a Mackie usb interface at 24 bit, it was still only a minor improvement.

The interesting part was that I also posted this test over on dvxuser.com and sort of got laughed at. They told me that I had a camera with pretty good audio already - 16bit uncompressed PCM - and so of course adding the MixPre did not improve the audio quality to speak of.

For me, the quality (and simplicity) of recording directly into the XF100 is the best approach. On the other hand, the DR100 is only $330 at B&H, Guitar Center, etc. so it would be easy to get one to try then return.

Re: sound quality with field mixer
 

I think the real issue here is not the equipment, but the users. An understanding of gain structure is critical in digital systems. We now have s/n ratios unheard of in analogue days BUT we have an absolute maximum record level - digital 0 level. Push it off the end of the scale, and it distorts, horribly. This gets coupled with meters that are necessarily fast to catch these means that to avoid distortion, users record too low. The meter ballistics are also lacking the inertia of a moving needle, so the difference between the peak and the average is very wide on the display, and quieter stuff hardly even registers. So if we use a mic direct into the camera, we often for safety deliberately (and often wrongly) record at too low a level. In the edit, we realise the levels are too low, so normalise to recover the full range and up pops the cameras noisy pre-amps. If we go into a proper mixer with better pre-amps, the higher output means the camera gain is lower, so even if we normalise the noise floor doesn't rise too much, because we got the gain structure right. If you MUST add gain, it's always better to do it in the quietest device. However, using a mixer is also a hazard when not using a dedicated sound op because it's easy to get the structure wrong, and have too low an output that you then have to use the noisier camera gain to recover. My favourite is to have the device providing the most gain manually adjusted, but with a limiter to prevent occasional peaks getting through - the flattened output then set to a level top allow sensible gain settings on the camera. Adding a mixer, set up poorly, will compromise the sound in the same way that using an external mixer used well can improve it. All the portable recorders of the Zoom (and others) type produce poor audio when pads are engaged and gain cranked up. No pad and gain set at the bottom is bad,as is full pad and full gain. Both these settings look ok on the meter, but a decent enclosed pair of headphones reveal the distortion/noise issues - somewhere in the middle will be perfectly usable. I've also seen people assume the distortion recorded at the rock gig/nightclub was their fault, when often the distortion was faithfully recorded - being caused by an overdriven sound system. Our ears cannot detect quality so well when their built in compressor is working flat out. Detection of quality and also pitch is severely compromised when the levels are up in the room.

Re: sound quality with field mixer
 

I am a very amature dslr user I bought a Art Dual pre and did some amaturish tests. Have a look and listen if you dare.
https://www.youtube.com/watch?v=eF_v...e_gdata_player

Re: sound quality with field mixer
 

Now if only I were sure that the camera line in really bypassed the camera pre-amp instead of just padding it back down to mic level...........

Re: sound quality with field mixer
 

With the exception of DSRLs, I have never really had a problem with most 'pro' cameras inputting balanced line-level for interviews and such, properly gain-staged and using a quality preamp front end. The primary preamp/mic interaction is normally where noise problems would occur. then again, even if the camera's audio inputs are direct line level, it could have low-grade A/D converters.

Re: sound quality with field mixer
 

Yes, I would suspect that most everything in the camera audio path is relatively low grade. Somehow I don't recall much advertising trumpeting cameras' audio features as a major selling point compared to their video features.

But I guess for voice no major issue as long as you can deliver a clean signal to the camera inputs. Even today's "low grade" is probably better than the "top of the line" of yesteryear.

Re: sound quality with field mixer
 

I had the "lowly" Sony 70U in my possession for a few days, and for a project, recorded some voice over using it as a recorder. Of course it was recording to a video file. I was quite impressed with the very nice sound I go out of my master bedroom closet using the camera.

Edit note: Connected the camera to a Rode NTG2

Re: sound quality with field mixer
 

I like my NTG-2 as well. Voice is fine. Classical music/Piano/Violin on the other hand goes to a separate recorder.