Topic: Line-In or Mic in - reason for choice?

[Mike Rivera]

I'm curious about using the Mic input versus the Line-In input when using stealth Mics and a Battery Box.  I'm using a Sony D-50, Giant Squid omnis, and Sound Pro (9v) BB.  I'm not lookign for ultimate sound quality here (obvious by my equipment) - I'm just having fun.

I've read (in the SP BB manual) that I should try to use the Line-In first and if there's enougn gain, it would be a cleaner recording than using the Mic in.  I'm not sure why. 

If the Line-In also adds gain (adjustable via the Record Level knob), why would the gain here be cleaner than the Mic input gain?  Does the D-50 have two amps (a clean on for the Line-In and a higher-power but not a clean one for the Mic input) - or is there just less amplifiation in the Line-In circuit, so there's less distortion?

Can anyone explain?  I tried searching and saw similar recommendations, but real reason as to why.

-Mike

[ozarkbilly]

hmmm, I'm interested in the answer to this as well.  Waiting on the experts....

[Brian Brock]

look at it this way: the ad converter accepts a certain level of signal.  A mic level signal is generally lower than a line level signal, actually the signal produced by a mic element itself is many many times lower than a line level signal, but the battery box will boost it, I guess.

So, the mic signal needs to be boosted to reach given level.  Gain circuitry always adds noise - whether or not you are applying gain - especially in devices like the pcmd50 that use IC op-amps.  The line input could conceivably be just a coupling into the AD converter.  The battery box has boosted it once already, so, if you have enough level at that point to get a decent level going into the AD converter, why run it through the extra circuitry?

hope that helps

[DSatz]

Normally in miniaturized equipment such as this, there is a dual-purpose input stage whose gain is controlled by the Mike/Line switch, followed by a stage whose gain is controlled by the record level knob. (The microphone and line-level inputs might be on separate sockets or they could be on a shared socket.)

Item #1 to consider--if you find that you can get close to 0 dB (full scale) levels by connecting your microphones to the line inputs--is that your microphones are evidently putting out relatively high signal levels, which might (depending on a whole host of variables) overload the input circuit of your recorder if you switched it over to "microphone."

However, if that's not the case--if you really have the luxury of a choice because both settings work without causing overload--then you reach item #2: There's likely to be some difference in the amount of preamp noise which gets recorded in the "line" setting versus the "mike" setting. But you have to make that comparison yourself on a case-by-case basis; the outcome isn't the same for all equipment. It's possible in some cases that a recording would have less noise in the mike setting, that it would have less noise in the line setting, or that there would be no audible difference in noise level between the two settings.

The equivalent noise of your recorder's input circuit is likely to be lower via "line in" than via "mike in," but if you choose the "line in" setting, you'll have to turn the gain knob up farther--and that may actually make everything noisier than it would have been if you'd used "mike in" with a much lower setting of the gain knob! And even if there might be a clear difference in a special quiet room, maybe the noise in any actual recording environment swamps the difference. It all depends.

If that seems like a non-answer, it's because the only way anyone can give you a more definite answer would be either (a) to use your recorder and microphones in the environments you typically record in, or (b) to go all the way over to the technical side and hash out all the specifications of your microphones and recorder--and then we'd still need an estimate of the maximum SPL and noise levels that occur in the recording venue.

[spyder9]

You definitely get better Dynamic Range using Line-In as opposed to Mic-In.  Agreed on SPLs and noise handling.

[Church-Audio]

The other thing to remember is on a mic input like others have said here is more sensitive. They design them like that because they know your mics electrical output is somewhere around -35 to -50 db range. So they automaticly add 20db or so to a mic inputs gain structure using buffer amps, these are little amps are ahead of the digital volume control on some decks..

The problem with using a mic input is sometimes the output from your mics can get up to -18 db or so. This creates a problem for the mic input buffer amps that were expecting a signal of -20 so what ends up happening is you get distortion because even before you have a chance to attenuate the signal the main buffer amp ahead of the digital attenuation/mic gain stage is being overloaded. So using the line input is much better because it already expects to see a signal of anywhere from -10 to +4 db depending on the deck. So its ready for your -18 signal and will not overload as ea-sly. Sony has now added a feature on some of there MD recorders that fixes this problem of buffer amp overload by introducing a signal attenuation or pad at the mic input. They call it high sensitivity / low sensitivity. But it does help with the distortion issue. The other issue is one of bias voltage your mic input just does not have enough juice to run some mics properly so a separate battery box or preamp can be a good idea.

Chris

[ozzyzak]

I use the line in as much as possible.  I use an R-09 recorder and using the plugin power with my mics is very noisy.  A lot of hiss and things like that.  I've noted that the line-in gets much more range and is quieter, so I just run the mics through a battery box and go.

[Dede2002]

I use the line in as much as possible.  I use an R-09 recorder and using the plugin power with my mics is very noisy.  A lot of hiss and things like that.  I've noted that the line-in gets much more range and is quieter, so I just run the mics through a battery box and go.

That's exactly what I used to do with my R-09. Right now I'm using a Marantz PMD 620 and it's Line In is way less sensitive than the R-09's. Even with a loud, really loud band, you have to set you Rec Level up to -9 or -8 to peak around -12db to -6db! I'm using Mic In but I'm considering a preamplifier purchase. The Marantz has a unity gain setting around -9 ( that's what I'm told), so I think a pre would be nice.