Hi

Just to correct
Dynamic range is approx 6dB per bit
ie 16 Bit = 96dB dynamic range (In Theory)
24 bit = 144dB dynamic range       -"-
Random thermal noise kicks in around -128dB
So don't get too hung up over headroom on noisy sources

Cheers
-pm 

-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Tom Fine
Sent: Wed 10 Mar 2010 21:51
To: [log in to unmask]
Subject: Re: [ARSCLIST] Disc EQ in the digital domain

Hi Eric:

The way I interpret this is, under typical conditions if you do a FLAT
transfer of a grooved disk at 24-bits, and then EQ in the digital realm
(EQ = compensate for the recording curve), you end up with more or less
CD resolution as far as bit-depth. And if you went with a conservative
transfer level, where peak level upon EQ compensation is somewhere
between -6dBfs and digital zero, you then are right in the realm of CD
resolution (6dB equalling about 2 bits, so net bits are about 16). Is
this a correct interpretation?

-- Tom Fine


----- Original Message -----
From: "Eric Jacobs" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, March 10, 2010 4:28 PM
Subject: Re: [ARSCLIST] Disc EQ in the digital domain


> On Wednesday, March 10, 2010 8:44 AM, Jim Sam wrote:
>
>> On Tue, Mar 9, 2010 at 6:42 PM, Eric Jacobs wrote:
>>
>>> Transfering FLAT will cost you about 6-7 bits of dynamic
>>> range - an audible loss.
>>>
>>
>> 36-42 dB*?  ~10-12 is more like it, which is two bits max.
>> That leaves 22 bits, which is more than adequate.
>
> Hi Jim,
>
> Just a thumbnail calculation on word length loss for two common EQs:
>
> RIAA boost = 19.27 dB @ 20 Hz
> RIAA cut = 19.62 dB @ 20,000 Hz
> RIAA dynamic range lost = 38.89 dB
> RIAA approximate word length loss with FLAT EQ transfer = 6.5 bits
>
> NAB boost = 19.85 dB @ 20 Hz
> NAB cut = 21.52 dB @ 20,000 Hz
> NAB dynamic range lost = 41.37 dB
> NAB approximate word length loss with FLAT EQ transfer = 6.8 bits
>
> To the extent that fractional bits exist.  <smile>
>
> Keep in mind that this is word length loss due to a FLAT transfer,
> where the bass boost is lost, and extra headroom is needed to
> accomodate the lack of treble cut.
>
> Eric Jacobs
>
> The Audio Archive, Inc.
> tel: 408.221.2128
> fax: 408.549.9867
> mailto:[log in to unmask]
> http://www.TheAudioArchive.com
> Disc and Tape Audio Transfer Services and Preservation Consulting
> 

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