attenuation vs. lower levels

M

mccutch

Member
I have a 4073a feeding a canon xh-a1.

Is there any advantage to using the 20 dB attenuation on the back of the camera for basic dialogue? (and setting a normal recording level)

Or should I just set my levels lower and go with no attenuation?

To my ear it sounds the same.

best
jeff
 
I'm assuming you are connecting the mc directly to the camera and not using an external mixer.

And assuming you have the mic input level set for mic level, I would NOT use a 20db pad if you can still achieve a good level by potting down. If the mic is WAY overdriven and you can't bring the mic to a decent level before you run out of pot, then I might use the pad.

I would always be hesitant of adding any in-camera pads. Especially if I didn't absolutely have to.

Other may disagree
 
Right on - generally, well designed analog amplifiers have less distortion, better signal to noise ratio, etc., with less amplification. For your example, the difference may not be perceived by most with your configration, other configurations or subsequent regenerations will be happy with fewer stages of attenuation and applications (white noise is cummulative).

Save the attenuator for situations when you *must* pad the volume, such as when you're only feed is at line level (mixer out, etc) and your recording device needs a mic level input.

Is the 4073 signal output really all that hot?
http://webcheckout.academyart.edu/handbook/sound/4073.pdf


Regards, Michael
 
the 4073, which i got a few weeks back is quite sensitive. Compared to my at835b longer shotgun, its about 3fold.

This is great in a sense because literally every mutter from the talent's mouths are heard no problem, but unfortunately the price comes at picking up loud levels of ambient noise at the same time ( we shot under and overpass mind-you )
 
mccutch - there is a distinct difference between pads on mics and pads on cameras(which I or the other regulars here can explain if you dont know).

The pad on camera versus potting down, though, is a different sensitivity level of the same thing - setting the gain the camera does or doesnt apply to incoming audio. Sometimes even 0 is too much, and this is when you can engage a pad to get the audio back into a workable range.

Tim
 
timapter said:
mccutch - there is a distinct difference between pads on mics and pads on cameras(which I or the other regulars here can explain if you dont know).
Tim
Click to expand...
Yes, please explain.
 
a pad on a microphone gives you the option to change the way the mic outputs audio right from its input - all mics have a maximum volume they can record up to undistorted, thereafter you start getting overmodulation. as the volume increases, this becomes worse until the mics diaphragm breaks (like popping your eardrum).

if you attenuate on the mic, you can record clean audio even in high SPL environments, and sets levels appropriately down the signal chain.

if you attenuate on camera, you are changing the levels of whats coming in, but obviously not the content - if your MIC is distorting because of high levels of SPL, you will simply record the distorted signal at a more managable level.

hope that clarifies.
 
sorry that was a bit of a trick question.

sorry that was a bit of a trick question.

timapter said:
a pad on a microphone gives you the option to change the way the mic outputs audio right from its input
Click to expand...
When I was a first year Recording Engineer student (30 years ago) that was one of the questions on a test, which incidently I got wrong.

A diaphram reacts to an input source the same regardless of the attenuation pad. The pad merely lowers it's output signal to a more manageable level for the channel mic pre. The reason why you pad the mic and not the console input attenuator is (a) there is an optimum operating level for any given input pre and (b) it is a proper engineering technique to always improve your signal path at the head of the chain. Likewise, an engineer will usually insert a high pass filter from the mic before he reaches for the channel strip unless that strip has favored characteristics.

A studio condensor's spec sheet provides a maximum input level for this reason.
Also note that microphones with a -10db attaching capsule, such as the Octava MK-012 are situated at the end of the body independent of the diaphram.
 
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Oh boy, we're entering the engineering chalk-talk dimension. Okay, back 30 years ago when vacuum tubes were still king, we used to talk about "class A" amplifiers which theoretically provided a linear output based on the input; say a 10x amp would yield: 10 volts out with 1 volt in, 11 volts out with 1.1 volt in, = 9 volts out with .9 volts in, etc. Of course, if the input signal varied from .1 to .3 volts, those amps didn't provide exactly 1 to 3 volts out, ergo a distorted signal. Fortunately, with today's transistors and integrated circuits, differential amps, phase loops, superior capacitor dialectrics, etc, audio fidelity has made tremenendous improvements.

Generally, audio engineers will set their mixers so the faders are set to 0 - that's the point where the mixer's amplifier provides the best fidelity. Perhaps one of our techie types here could give some guidance on the optimum setting for your Canon xh-a1

Regards, Michael
 
sound chaser is of course quite right, and Im not pretending to be a hard core technical wizard on this - just a simple explanation to help the general public.

it IS true that a distorted signal FROM MIC can be remedied with a attenuation pad - you will notice that the oktava's signal flow is DIAPHRAGM - PAD - PREAMP.

Im sure you technical guys can give more technically accurate data (Im more interested in the results! :))

Cheers,
Tim
 
True, but if there is already a mechanically related distorsion from the mic (diaphram) no pad can remedy that no matter where in the signal chain it is placed.
 
More good points

More good points

Agreed about the evils of overpowering the mic's diaphram cannot be remedied by electrical attenuation. That's why many wedding videograpthers will place an insensitive drum mic in front of the DJs speakers at the reception (versus using a more sensitive voice mic). Anyway, sorry if we're all going off-topic here.

Regards, Michael
 
i am not an expert on this at all, but i did some tests with my sennheizer 416 mounted on my xha1. i tried using the attenuator with higher levels and then without attenuator with lower levels. when listening to the records on fairly good speakers later i heard that the record done with attenuator and higher levels picked up less camera-operation noise... how come? other than this i am not sure about the use of attenuator, but i had the impression that it was something to be used in situations with very loud sound, like concerts for instance...(?)

at the same time, can anyone give me tip on how to actually achieve the best possible soundtakes with sennheizer mkh416 mounted on the mic.mount on xha1?
 
teupaksa said:
i am not an expert on this at all, but i did some tests with my sennheizer 416 mounted on my xha1. i tried using the attenuator with higher levels and then without attenuator with lower levels. when listening to the records on fairly good speakers later i heard that the record done with attenuator and higher levels picked up less camera-operation noise... how come? other than this i am not sure about the use of attenuator, but i had the impression that it was something to be used in situations with very loud sound, like concerts for instance...(?)

at the same time, can anyone give me tip on how to actually achieve the best possible soundtakes with sennheizer mkh416 mounted on the mic.mount on xha1?
Click to expand...

One of the uses for the attenuator in the camera is to lower the level of an extra hot mic. Another is to lower the mic level in a high SPL situation while in a very high SPL it is better to use the pad in the microphone itself if it has one. One of the factors to bear in mind is where the various actions or attentuation and/or amplification is taking place. Presenting too hot a signal from the mic at the camera inputs can overload the preamp. The camera gain control is AFTER the inputs but the pad is BEFORE the inputs. Using the pad can reduce the high signal before it has a chance to cause overload and clipping. Not using the pad and reducing the recording gain doesn't prevent problem that occur earlier in the chain and only lets you record the distortion at a proper recording level.

As for not picking up as much camera noise when using the attenuator and increasing the gain, I'm at a loss to explain that one. It should be a wash since those sounds should be fairly low level anyway.
 
how about getting the audio from the board does it need to be padded? i always turn the attn in the A1 becouse it distorts easy but i find the sound muffled and i pick the levels on the post.
 
teupaksa said:
i am not an expert on this at all, but i did some tests with my sennheizer 416 mounted on my xha1. i tried using the attenuator with higher levels and then without attenuator with lower levels. when listening to the records on fairly good speakers later i heard that the record done with attenuator and higher levels picked up less camera-operation noise... how come?
Click to expand...

Any attenuation will not stop a diaphram from overloading, they are downstream. Pads also add noise as the s/n ratio will go down by the amount of the pad (i.e. 10dB pad worsens the s/n ratio by 10dB). Why? the noise floor of the mic does not change but the input signal (gain) is reduced. Additionally the pad will have an affect on the frequency response (depending on components and circuit used) and that could be why you hear a difference. Pads are there for two reasons, the in mic pad is there to protect the front end of the mic (FET/tube, whatever), the pad added to the end of a mic is there to protect to front end of the preamp. Ideally you want to use a mic that has a higher max SPL so it never goes into distortion. Use a pad only if you have no way to move the mic or make changes to the source to keep the mic from overloading or to keep your micpre from overloading. Bottom line is pads add color and noise to the signal...

You should be able to adjust the output of the board to keep it from overdriving your recording device or camera pre's.
 
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