Posted by Arny Krueger on 08/13/07 20:40

"Mark & Mary Ann Weiss" <mweissX294@earthlink.net> wrote in
message news:oh2wi.211786$u82.135144@fe09.news.easynews.com
>>> In general, I have had a high degree of respect for you,
>>> based on your demonstration of audio knowledge on
>>> USEnet,
>>
>> Thank you.
>>
>>> however, in this case, I think you're being too
>>> forgiving of this horrible digital recording system.
>>
>> I haven't forgiven anything - its just that the scale
>> used in the page being referred to does use a
>> signficiantly expanded dB scale.
>
> It's a realistic deviation for measuring cheap $29 PC
> sound cards, which are mostly flat to within +/- 2dB over
> 20-20K. This expensive camera, which doesn't sport 1/8"
> phone jacks, but real phantom powered XLR jacks, can't
> even stay within the deviation of the cheapest, most
> awful computer sound card. This isn't analog tape
> recording, where bass response depends on the amount of
> iron in the recording head--it's a DC-coupled A/D
> converter that someone mucked with to make it AC-coupled.
>
>
>
>>>> The actual -3 dB point is about 130 Hz. The rolloff is
>>>> hard to judge because of the expanded scale, but does
>>>> not seem to be overly rapid. Not all that great, but
>>>> about an order of magnitude better than you have been
>>>> mislead to believe.
>>
>> On second glance, the roll-off appears to be about 12 dB
>> per octave.
>
> Whatever we agree it to be, it's still abnormal for a
> digital recording system on ANY device.


I note that your tests of the Canon HV20 (which I just acquired) put the -3
dB point at about 45 Hz, which is obviously a lot better than 130 Hz.

I notice that another Sony camera you tested rolled off at about 110 Hz,
suggesting to me that Sony considers a rolled-off bass like this to be part
of their house standard.

>>> RightMark is intended to measure digital audio systems,
>>> hence, anything more than +/-0.1dB is objectionable
>>> deviation across the 20-20kc bandpass.
>>
>>
>> While 30 dB down at 20 Hz is kinda of a lot for a hi-fi
>> system, its not bad by say live sound standards.

> Most live sound systems are flat to 45Hz.

One could hope. IME reality is more like 85 Hz, which is about what it takes
to handle a typical male voice without excessive degradation.


>> If the digital recording system in question is optimized
>> for ENG, then flat response to 20 Hz is not required at
>> all.
>
> Yes, but they should give the operator the ability to
> turn off the filter.

Given that modern cameras seem to be option-rich, this seems like a
reasaonble approach.

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