[Top] [All Lists]

Re: Homebrew Recorder

Subject: Re: Homebrew Recorder
From: "Avocet" madl74
Date: Fri Jun 1, 2012 8:32 am ((PDT))
> A digital limiter would be post conversion, therefore missing the
> point of a limiter entirely, which would be to avoid crashing the
> ADC. It would need to be analog to be of any use.


Not if you over-sample. Two bits extra give you 12DB more headroom,
for instance. There is a 24 bit ADC onboard, so use it and select the
most appropriate 16 bits to record. That's still 78dB S/N ratio after
dithering. That would suggest the input sensitivity settings could be
in 6 dB stages. As I said, if recording at 24 bits, there is no excuse
for overshooting the ADC. Theoretically 24 bits (138dB range) actually
means you don't need a record level control, but no ADC can be that

> if you have gain selectable at 10 db intervals over a 60 db range, i
> see no need for gain trimming at all.


I'd need a headphone output mini mixer to hear how the stereo image
was forming. +/- 1dB shifts the centre image noticeably. So that may
be where to put the gain controls. The settings would be saved as slow

We are thinking right out of the box here. How about digitising
everything coming in and doing everything else by DSP? Which 16 out of
24 bits were recorded would be set by the output monitoring controls
preserved in the slow metadata. The cost base would then shift to
software writing, so make this open source. Too revolutionary? :-)


David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU