Hi Ellis:

That is an interesting issue. If you ever do the math, please let us know your answer. I'm not sure 
there's any natural transient acting in an actual room that can rise much faster than that, but what 
about electronic instruments? Even with a sharp drum hit, there is some slowing of the wave front in 
air, plus whatever small physics issues are involved with the microphone itself, plus whether the 
mic preamp can catch the rise time in the first place, including the electroncs inside a condenser 
mic, if that's used. Going backwards in this thread, it could be that a muted trumpet close to a mic 
that can capture the attack would be the ultimate test for the whole system, both digital and 
analog. I remember my father saying that many lab tests of audio gear were useless because they 
weren't addressing real-world situations, but pulse tests were very useful because, as he put it 
"things in front of microphones definitely pulse," and produce voltages and currents very similar to 
what lab equipment can simulate. His beef about sine-wave tests was that only flutes tend to produce 
sine waves "and anything worth its salt" should have low or no distortion with sine waves.

-- Tom Fine

----- Original Message ----- 
From: "Ellis Burman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, October 25, 2013 10:50 PM
Subject: Re: [ARSCLIST] $1K DSD recorder

> Not only what listening environment outside of an anechoic chamber has 120
> dB dynamic range, but also what recording environment?  I'd imagine the
> breathing of the musicians would be well above that!
> True, a mic pre-amp is a much more demanding application for an op-amp than
> a line-level buffer.  Still, I'd be more concerned with the slew rate
> limits of the 5532.  In my mind, the whole idea of DSD is to capture
> transient information (at least that's what I hear with DSD or higher
> sample rates, or direct-to-disc recording for that matter.)  I haven't done
> the math though - maybe 9V/uS is fast enough, even at 5.6 MHz sample rate.
> Ellis
> On Fri, Oct 25, 2013 at 4:19 PM, Tom Fine <[log in to unmask]>wrote:
>> You two are more expert than I, but I think a 5532 is fine in this
>> application because you have built-in level limits by the nature of digital
>> zero. So as long as you can design your analog sections to accomodate low
>> distortion at digital zero (and leave a few dB headroom for over-sample
>> problems with rate and format conversions), then I'm not sure what audible
>> differences there would be in using a designer chip. Aren't the designer
>> chips more appropriate for mic preamps or inside condenser mics?
>> With the high-resolution formats in the download world, I'm starting to
>> see marketing again based on crazy claims of dynamic range. Benchmark, a
>> company that can stand on its reputation, showed a new power amp at the AES
>> Convention. Their marketing hook is that they can demonstrate something
>> like a 120dB range from their noise floor to whatever distortion figure
>> they find objectionable. But, what listening environment outside of an
>> anacholic chamber has 120dB dynamic range? And what music that provides any
>> pleasure needs 120dB dynamic range? It's not good for your ears to be
>> exposed to 120dB above silence, but no one seems to talk about that. I
>> remember the dynamic range claims with early digital, which definitely had
>> a lower noise floor than any tape recorder. The problem was, when there was
>> sound, it often wasn't as good as the sound coming off the allegedly noisy
>> tape.
>> -- Tom Fine
>> ----- Original Message ----- From: "Paul Stamler" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Friday, October 25, 2013 6:48 PM
>> Subject: Re: [ARSCLIST] $1K DSD recorder
>>  On 10/25/2013 4:28 PM, Ellis Burman wrote:
>>>> But it's funny how manufacturers are still touting the NE5532 op-amp.  I
>>>> used them over 25 years ago in my designs for Quad Eight.  They're fine
>>>> (a
>>>> lot of legendary consoles used them - Neve, Quad Eight, SSL, etc) but
>>>> there
>>>> are many better op-amps available now.
>>> Yes, the good ol' 5532  has been surpassed in many ways by more recent
>>> designs -- but for an excellent balance of low noise and clean performance
>>> *at low price*, it's hard to beat.
>>> Peace,
>>> Paul
> -- 
> Ellis
> [log in to unmask]
> 818-846-5525