> However, David's comment about preserving the phase response at high freq=
uencies
> also has merit.
Hi Greg,
Yes, the phase response could be an issue at very low sample rates, such as=
at 22.05 kHz, as David explained. However, at a sample rate of 44.1 or 48 =
kHz, the roll-off of the anti-aliasing filter is already sufficinetly far a=
way from the upper limit of the human hearing curve. In addition to that, t=
he AAF in modern sigma-delta converters are usually FIR filters that probab=
ly do not affect the phase response.
Regards,
Raimund
>
> This is not a concern of many people, but some of us have a need for it.
>
> Best,
>
> Greg O.
>
>
>
>
> ________________________________
> From: Avocet
> To:
> Sent: Sun, January 6, 2013 7:33:58 PM
> Subject: Re: [Nature Recordists] Re: Olympus LS-14 initial thoughts
>
> =C3=82=C2=A0
> > Even people who hear well, as I understand it, rarely hear 20K. So,
> the question is, why should a preamp be called on to amplify
> frequencies above 20 K if nobody can hear it? I frequently see
> references to magnitudes above 20K; I'm guessing this is purely techno
> babble.
>
> Max,
>
> An interesting point. When my son was in his early teens, he could
> hear 21kHz. When I was working, my ears rolled off between 15 and 16
> KHz, and at 72, I brag about still hearing a bit up to 13.5kHz.
> (Rodent squeaks) However, on general recordings I can hear when
> frequencies at the top end are filtered out.
>
> I reckon what we lose is the phase response, and if I sample at
> 22.05ks/s, I can clearly hear the difference. I think we need these
> high frequencies to maintain the HF phase and transients.
>
> Another danger with limited frequency responses is cross-modulation,
> which can be high at the limits of the frequency specs. I may not he
> able to hear 15kHz, but if there is cross-mod distortion up there
> because an amplifier is close to its limits it could becomes audible
> making the recording sound rough.
>
> If you listen to the tweeter end of commercial recordings, it is often
> just mush up there. I'm happy at recording at 44.1ks/s as it is CD
> compatible, but a case can be made out for 48ks/s or 96ks/s for high
> quality masters.
>
> David
>
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce
>
>
>
>
>
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