Audio recorder questions

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kevinkt

Active member
I'm a complete audio noob so please excuse my questions. Here we go.

1) Are mixers able to record sound too or are they just fed into the external audio recorder?
2) Is the pre-amp the key to noise-free sound? If not, what is?
3) Is pre-amp and mixer the same thing? If not, what's the difference?
4) Don't recorders like the zoom h4n and tascam dr-100 have pre-amps?

Thanks!
 
kevinkt said:
I'm a complete audio noob so please excuse my questions. Here we go.

1) Are mixers able to record sound too or are they just fed into the external audio recorder?
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No, mixers take signals from multiple sources, adjust levels and perhaps apply equalization, perhaps combining the signals with signals from other sources, and then send them on to a separate recording device. They don't record, though at least one mixer on the market (Sound Devices 552) does incorporate a basic 2-track recorder in its features.

2) Is the pre-amp the key to noise-free sound? If not, what is?
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Clean preamps are part of getting noise-free sound but also quality mics, a well designed recorder, etc contribute. The recording chain is only as good as its weakest link.

3) Is pre-amp and mixer the same thing? If not, what's the difference?
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A single box called a 'mixer' usually has two sections internally, a preamp section that receives the signals as they come in, amplifying and shaping the signals, and then a mixer section to handle routing and combining the signals coming from the preamp section. Thus "mixers" have preamps as part of their circuitry but add other functionality such as limiters, equalization, etc as well. Mixers, well, mix ... allowing you to route a mic input to either the left channel output or the right channel output or some combination of the two either singly or in combination with signals from other mics or even line level sources. But preamps are also available as stand-alone devices, ampifying and shaping a single mic's signal before handing it off to a separate mixing console and recorder. While there are some small, battery-powered, stand-alone preamps such as the Sound Devices MM1 available for field use, the stand-alone variety is usually found in the rack along with equalizers, reverbs, etc in a music recording studio.

4) Don't recorders like the zoom h4n and tascam dr-100 have pre-amps?
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Technically yes. Any device that accepts mic level inputs has a preamp to raise the very feeble signal coming from the mic to the levels used by the device's internal circuitry. How good they are in inexpensive consumer devices is another matter. Your $20 generic computer soundcard has a preamp on its mic input but I'd hate to compare its quality to some $10,000 per channel stand-alone boutique preamp such as might be found in a major music label's recording studio.
 
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A followup question that I have.

So is it always better to use a good pre-amp or mixer with an external recorder instead of the camera's recorder (let's say using a tascam dr-100 recorder and a canon t2i camera), even if you're using an agc disabler like the juicedlink dt454?
 
kevinkt said:
I'm a complete audio noob so please excuse my questions. Here we go.

1) Are mixers able to record sound too or are they just fed into the external audio recorder?
2) Is the pre-amp the key to noise-free sound? If not, what is?
3) Is pre-amp and mixer the same thing? If not, what's the difference?
4) Don't recorders like the zoom h4n and tascam dr-100 have pre-amps?

Thanks!
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A basic mixer just mixes, but many mixers come with preamps and digital interfaces.
All the parts together lower the sound, of which a really quiet mic make the big difference, unless you plug it into real junk. Preamps are a lot quieter nowadays, and so are mics. A Sennheiser MKH 40 or 20 will give you really quiet sound because the output is strong as well as the self noise, but there are many choices, Look for a self noise figure of 10-12 dBa
As far as preamps, look for a self noise of 129.5-132. A properly engineered preamp will have this spec. Many of the so-called "top of the line" preamps will not spend the extra $25 in parts to get to this spec. A simple upgrade from Audio Upgrades will get you this spec. However, that isn't the whole story. Some pres don't match too well with the mics, and some pres use hybrid designs that are super quiet, high output but have a slightly lower spec, like the RME FF 400. AD conversion will make a small difference as well, although most converters now do a reasonably good job. It is worth noting that that last little bit of noise will be buried in most ambient acoustics. But, quiet is quiet :)
 
kevinkt said:
A followup question that I have.

So is it always better to use a good pre-amp or mixer with an external recorder instead of the camera's recorder (let's say using a tascam dr-100 recorder and a canon t2i camera), even if you're using an agc disabler like the juicedlink dt454?
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I'd hestitate to say 'always' as a generic statement comparing ANY recorder and ANY camera combination but since you specifically mention a DSLR, and DSLRs as a class are notoriously weak in the audio department, I'd say that double system is usually the way to go for best results. Of course, that assumes you do the rest of the job correctly as well, most importantly placing the mics properly for the situation. A $100 consumer toy mic boomed into the proper position 18 inches over and in front of the talent and connected directly into the camera is likely to sound better than a $2500 Schoeps CMIT mic feeding a $4000 Sound Devices recorder, if the mic is kept mounted on the camera back 15 feet away from the action .
 
Steve, pretty much nailed it. I would add that things like the JuiceLink don't "disable" the AGC, they overwhelm it with noise (it's I believe a sign wave but noise in the sense of something you don't want and should later remove). I have heard bad things about the sound and you are still going through all the same bad audio circuits in the DSLR. Dual system is a much better option (in general) but is also more complicated.
 
Noiz2 said:
Steve, pretty much nailed it. I would add that things like the JuiceLink don't "disable" the AGC, they overwhelm it with noise (it's I believe a sign wave but noise in the sense of something you don't want and should later remove). I have heard bad things about the sound and you are still going through all the same bad audio circuits in the DSLR. Dual system is a much better option (in general) but is also more complicated.
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To add one thing (and I've become an unwitting evangelist) for dual-system sound it's hard to beat pluraleyes. Send a scratch track to the camera, record sound somewhere else (hopefully something better) and then use Pluraleyes to sync in your favourite NLE. Used to be FCP only, apparently now it's no longer the case. It works shockingly well. It takes more time in post than a well-thought out timecode-centric workflow, but sometimes the cost and complexity of timecode gear goes beyond certain production levels (often where some DSLRs are being used.)
 
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