[sdiy] move over you 32 bit DACs ...

Roman Sowa modular at go2.pl
Fri Feb 4 11:06:06 CET 2022


It's funny how the idea is described as undoable and useless in the 
patent itself:

"As described above, if both mantissa DAC 6 and exponent DAC 9 have 
16-bit accuracy, a low level distortion is obtained as shown by solid 
line A in FIG. 4. In practice, however, a low level distortion cannot be 
achieved because 16-bit accuracy of exponent DAC 9 cannot be obtained. 
[...] In particular, it is very difficult to achieve high accuracy in a 
range where the level of analog output is small. Consequently, 
sufficient adjustment of resistors in the exponent DAC 9 is practically 
impossible, so the actual accuracy obtained is about 10- to 12-bits."

Roman

W dniu 2022-02-04 o 10:01, Mikko Helin via Synth-diy pisze:
> I don't know what you are talking about but now as this patent is
> expired you could use two of those 64-bit DAC's (or whatever), one for
> the mantissa and one for the exponent:
> https://patents.google.com/patent/US4951054A/en
> 
> On Fri, Feb 4, 2022 at 10:39 AM Vladimir Pantelic via Synth-diy
> <synth-diy at synth-diy.org> wrote:
>>
>> On 04.02.22 09:21, Mattias Rickardsson wrote:
>>> You're right, 64-bit is overkill after all.
>>> 32-bit μ-law will do.
>>
>> or maybe part mantissa, part exponent?
>>
>>
>>> Den fre 4 feb. 2022 00:46Ben Bradley via Synth-diy
>>> <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> skrev:
>>>
>>>      I want to see the microphone/transducer that picks up 194dBSPL with
>>>      any reasonable degree of fidelity.
>>>
>>>      On Thu, 3 Feb 2022 at 17:48, Mattias Rickardsson <mr at analogue.org
>>>      <mailto:mr at analogue.org>> wrote:
>>>      >
>>>      > True, Harry!
>>>      > And mono will do... So why is it stereo?
>>>      >
>>>      > /mr
>>>      >
>>>      > Den tors 3 feb. 2022 22:10Mr&MrsAccount <hbissell at wowway.com
>>>      <mailto:hbissell at wowway.com>> skrev:
>>>      >>
>>>      >> Yes you will need 64 bits, but only once...
>>>      >>
>>>      >> Harry
>>>      >>
>>>      >>
>>>      >> ________________________________
>>>      >> From: Mattias <mr at analogue.org <mailto:mr at analogue.org>>
>>>      >> To: Brian <brianw at audiobanshee.com <mailto:brianw at audiobanshee.com>>
>>>      >> Cc: Synth <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>>
>>>      >> Date: Thursday, 3 February 2022 3:52 PM EST
>>>      >> Subject: Re: [sdiy] move over you 32 bit DACs ...
>>>      >>
>>>      >> Brian Willoughby <brianw at audiobanshee.com
>>>      <mailto:brianw at audiobanshee.com>> skrev:
>>>      >>>
>>>      >>> Speaking of jet engines, I went to an AES talk where someone
>>>      explained that 24 bits is enough to span the dynamic range from  the
>>>      softest sound that the human ear can pick up, all the way to the
>>>      pressure wave (of 2 atmospheres?) a couple of miles from an atomic
>>>      blast. That convinces me that I don't need to search for a 32-bit
>>>      DAC, much less a 64-bit DAC.
>>>      >>
>>>      >>
>>>      >> 2 atmospheres... Sounds a bit like you're referring to the
>>>      loudest possible sound in air, 194 dB?
>>>      >> 24 bits won't take you to more than 144 dB. And since even 32
>>>      bits give a futile 192.6 dB, it seems like the next level will be
>>>      needed: 64 bits. ;-)
>>>      >>
>>>      >> /mr
>>>      >>
>>>      >
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