What db for recording lav to Tascam DR100

[lolage]

Hi

I'm going to use a lav for an interview tomorrow, but just playing with the setup and I'm noticing a lot of background noise, especially when I come to around -12 db. Sounds OK when its -20db but I presume this is too low?

What db should I be aiming for?

Cheers.

 

[st599]

The decibel is a relative measure. So signal A can be 6 dB lower than signal B, but a signal can't be 6 dB.

Without knowing what you're measuring against (something like SPL-A, SPL-B, R128 etc.), no one can answer.

 

[Chappers]

-20db may sound OK as far as background noise is concerned , but when you boost it up to a more acceptable level in post you may still find that the noise is still there.

If you have background noise, it's going to be recorded, whatever level you record at.

 

[st599]

-20db may sound OK as far as background noise is concerned , but when you boost it up to a more acceptable level in post you may still find that the noise is still there.

If you have background noise, it's going to be recorded, whatever level you record at.

By boosting the noise, you'll add the noise of the amplifier to the original signal.

We still need to know what dB scale is used to say what levels to use. I'd imagine it's either FS where you'd peak at minus 10 with an average a few dBs down or SPL-A where you'd be peaking in the low 70s?

 

[nigelbb]

By boosting the noise, you'll add the noise of the amplifier to the original signal.

What amplifier? The rues are totally different for analogue & digital recording. In the old analogue days we always made sure that the peaks just kissed into the red. With digital you should record at a much lower level & should never allow the signal to clip. With digital recording once the signal is there you can boost the level in post without adding any amplifier noise. With my Tascam DR100 I will typically record at -20dB or -30dB.

What do you mean by background noise? Maybe your microphone is noisy?

 

[st599]

What amplifier? The rues are totally different for analogue & digital recording. In the old analogue days we always made sure that the peaks just kissed into the red. With digital you should record at a much lower level & should never allow the signal to clip. With digital recording once the signal is there you can boost the level in post without adding any amplifier noise. With my Tascam DR100 I will typically record at -20dB or -30dB.

What do you mean by background noise? Maybe your microphone is noisy?

Sorry, but you're wrong.

You will have a signal to noise ratio in your initial recording. By boosting the signal, the very best you can hope to achieve is to maintain the same signal to noise ratio. This won't happen as when you amplify a signal in the digital domain, you add quantisation noise.

So if you have a signal peaking at minus 30dB(A) and add 20dB of gain, the noise floor will increase by at least 20dB.

Even if you try and remove the Johnson and Shot noise from the recording in post, you will add artefacts which, by definition, are noise.

 

[nigelbb]

My advice is correct. I said in the old analogue days we always made sure that the peaks just kissed into the red. With digital you should record at a much lower level & should never allow the signal to clip. In my experience using a Tascam DR-100 (which the OP is enquiring about) that lower level is -20dB or -30dB. The signal then can be boosted in post to the required levels which may be 0dB, -6dB or -12dB depending on the mix. It's crucial not to allow digital recordings to overload & clip as there is no way to recover the data it's just like blowing highlights in a photograph.