|
|
Posted by Andy & Kim on 10/07/05 14:52
"Smarty" <nobody@nobody.com> wrote in message
news:iv-dnTLi_8s_CNjenZ2dnUVZ_sidnZ2d@adelphia.com...
> Most if not all of the camcorders do AGC on the audio inputs, and have at
> least 60 to 80 dB of dynamic range. Virtually all the camcorders use
> unbalanced inputs. I have build T-pad attenuators with a simple
> 3-resistor T-network to do precisely what the original post asked for, and
> the attenuators which do around 30 or so dB seem to work just fine.
> Putting in too much attenuation forces the AGC to "gain-up" and crushes
> the SNR by raising the noise floor.
>
> Smarty
>
>
> "Larry J." <usenet2@DE.LETE.THISljvideo.com> wrote in message
> news:Xns96E78BC2755B6thefrogprince@68.6.19.6...
>> Waiving the right to remain silent, "Smarty" <nobody@nobody.com>
>> said:
>>
>>> You will not need equalization, but you do need to attenuate the
>>> line level signal (nominally about 1 millivolt into 47K ohms)
>>> down to a few microvolts (also at the same impedance). Thus an
>>> attenuator / pad of about 30 dB should do it.
>>
>> An even larger pad could be required. Unbalanced live levels are
>> generally -10 to -20db. Balanced can be as high as +8.
>>
>> --
>> Larry Jandro
>> Video Engineering & Equipment Rentals
>> Scottsdale, Arizona, USA
>> [Remove spamtrap in ALLCAPS to reply]
>
>
Thanks for the advise guy's. Smarty could you give me some values of the
resistors I would need for a T-pad attenuator, just as a guide.
Andy
Navigation:
[Reply to this message]
|