Re: Digital / Analogue Voice Recorder

thanks for that very in depth reply....

.....I'm having problems with kids/neighbours from 22-00pm evening to as
late as 01-30am in the morning - screaming /shouting/ banging etc...

trying to monitor this as evidence....

Any ideas as to mic/recorder setup ???

I've got a couple of Shure SM58's - one of which I set up directly
(realtime) into my PC (using Cool Edit Pro) - that was far to noisy.....

This little analogue Olympus micro cassette does the job and captures some
stuff OK but s/n ratio is not good.. Filtering in Cool Edit
takes out some detail...

any ideas welcome from others in this forum....

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

<dpierce@xxxxxxxxxxxxx> wrote in message
news:1135951937.467760.120390@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Advid wrote:
>> ...does a Digital Voice Recorder (dictaphone ect) have a better signal to
>> noise ratio than an analogue voice recorder ???
>
> Not necessarily.
>
>> ie NO tape hiss as there is no tape (or moving parts) ....
>
> The tape hiss has nothing to do with moving parts. The tape hiss
> exists because there are random variations in the orientation of
> the magnetic particles on the tape.
>
> But tape is but one source of noise, and there are many others,
> some are irreducible.
>
> There's noise inherent in the electronics themselves, whether
> the recording method is digital or analog. There is noise intrinsic
> in the microphone (probably one of the major sources of noise
> limiting low-level reocrdings.
>
> And while tape-based recorders have tape noise, a digital recorder
> must/will also have noise, whether it is the signal-correlated
> quantization noise resulting from a bad implementation of the
> analog-digital conversion stage, or it's the uncorrelated noise due
> to dithering.
>
>> I want to use one to monitor very low external noise levels....
>>
>> My Olympus analogue/tape device records OK but there's too
>> much hiss and background noise - I have to filter it out using
>> PC software....
>
> As long as you insist on using these little voice recorders, which
> are NOT designed for the purpose, you're going to be stuck with
> the noise problem.
>
>> Just wondering if digital would produce better sound levels.....
>
> No, not intrinsically.
>
> What you need to understand is that the noise levels are dependent
> in both analog or analog units, by the amount of storage available
> and the amount of time you want to record. THat may seem surprising
> and not at all intuitive but, in fact, the amount of storage or the
> amount
> of data, whatever ytou want to call it, sets the limits of the dynamic
> range you can capture, all other things being equal (like bandwidth).
>
> It means that if you have tiny little tape cassettes with not much tape
> in them, you have to run the tape very slowly, and tiny tapes at low
> speed have lots of noise, becuase there's not enough data storage
> to capture wide dynamic ranges (that means difference between loud
> and soft signals) well. If you want to record soft sounds, you can't
> record loud, because the loudspegnals would overload the tape
> and severely distort. If you want to record loud, you can't record soft
> becuase of the inherent tape noise.
>
> Implement it in digital, and you have the same problems: low data
> storage (memory) means that you can't assign a lot of bits to the data,
> and you end up with the same limitations as analog.
>
> This is why low-noise recordings are made, in the analog world, with
> wide tape passing at relatively high speeds past the tape heads. It's
> why low-noise recordings are made with digital recorders using high
> sampling rates and wide samples widths with lots of memory.
>
> Now, add to that the fact that most of these little voice recorders
> are
> most assuredly NOT designed for what you have in mind: they are
> designed for just the opposite: high sound levels and limited signal
> bandwidths. They're designed to be heald a few inches away from the
> mouth while someone is speaking in a clear, normal level. The
> desitgners deliberately don't care about noise, in fact, to make them
> as small and as cheap as possible, they make design compromises
> which make the noice worse. They don't for example, use a high-
> frequency erase or bias signal, which leaves the noise on the tape
> worse than it otherwise could be. But it's not important for what they
> are used for.
>
> If you want to record very low sound levels, you need equipment suited
> to the task. That means low-noise microphones, that means quiet
> electronics with a carefully configured gain structure to maximize gain
> and minimize noise (two conflicting requirements). An Olympus voice
> recorder, digital or analog, or a digital dictaphone is about the worst
> choice for such a purpose. Getting rid of your analog one and
> replacing
> it with a digital one is NOT likely to make much difference. If, for no
> other reason, the microphones used are pretty awful, they're noisy
> becuase they don't have to be quiet, and quiet microphones can be
> as large or larger than the entire recorder AND will cost MUCH more
> than the entire recorder.
>


.

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