I have the 1985 Robert W. Adams AES paper too about the 18bit ADC , it speaks about the 18 bit burden using different conversion techniques ~ I can upload / send.
anthonybisset said:
What’s your objection to sigma-delta? I don’t like it because it tends to make natural acoustic music sound like a digital synthesizer. What I hear sounds sliced, diced, chopped, and homogenized. The sound is too smooth and the complexity and subtle variation in timbre and texture is missing. On the other hand, if I were making music with synthesizers, as it appears you are doing, I don’t think I would be able to identify the sonic signature of a sigma-delta DAC. That said, I think a good multi-bit sigma-delta ADC/DAC combo with no intervening conversion would be very good; probably the next best thing to amplifying and listening to the microphone feed. My objection to sigma-delta comes mostly from the castrated dynamics of a 1-bit data stream (DSD/SACD) and from the application of FIR filters, which replace each sample with a weighted average of many surrounding samples, to convert the format and sample rate. AFAIK, most recording studios these days are using multi-bit sigma-delta ADCs. After that, the signal goes through multiple digital conversions and filters and that’s where I think most of the damage is done.
anthonybisset said:
It’s unfortunate the term non-oversampled (NOS) usually implies no reconstruction filter (NRF), as well. I believe a properly designed analog reconstruction filter does a better job of removing the HF sampling noise without distorting the signal then do amps and speakers. In other words, a filter in between nothing and a brickwall. Whenever I hear a NOS/NRF DAC in a high-resolution audio system I can hear a cloud of white noise that envelops the music. Sometimes the noise is obtrusive and sometimes it is barely noticeable but it always there.
whatsup said:
Hello
Since you eard a cloud of white noise, it's mean that there is harmonics quite under 20khz.
Did the non-os Dac using a 20khz low pass filter was without that
cloud of white noise ?
I'm thinking to made a non-os Dac using TDA1541 and a I/V op-amp with a 3rd order 20khz low pass bessel filter.
Thank
Gaetan
abzug said:
Hello
I know that Bessel have slow slope but they are the best for transient response.
Any suggestions ?
Thank
Gaetan
gaetan8888 said:
Either that or I can 'hear' >20KHz or I am otherwise aware of the HF noise.
gaetan8888 said:
Among my collection of DACs is an Audio Note 1.2 NOS that uses an AD1865. It includes a LP filter and I don't 'hear' any white noise. Some time ago I auditioned an Audio Note 3.1x; the latest generation that has no formal LP filter other than a transformer, or so I understand. With it the HF noise was hard to ignore. The same with a Scott Nixon DAC I heard in a different system. Often I don't consciously hear a cloud of white noise but I get a very strong sense that something is wrong with the sound. For example, I also have an 8xTDA1543 NOS/NRF DAC. With it I don't notice any white noise, per se, but I get very uncomfortable listening to it.
The OP, being in Japan, might want to track down the Sony CX20018, a late 80's vintage pre 1 bit ADC. 192kHz may prove a bit ambitious though.
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