janneman said:
Jan,
one techincal query,
when designing a 2 pole low pass filter, how critical are the real values used when compared to calculated values, that will affect the cutoff frequencies, and more importantly the phase.
this is most critical when one is using discrete comps rather laser trim SMDs.
any comments, I think you have some experience in this area.
Hi David,
I'm curious about all the new DACs. I'd look forward to your opinion about this one.
I've read some of your other posts with interest. It's good to hear that someone actually likes the sound of some of the new DACs. I would hope that some of the new digital technology actually sounds as good or better than non-oversampling DACs. Especially, since I don't know of any non-oversampling DACs for Hi-Rez audio. I can't quite imagine a multichannel home theater processor made with those old old technology DACs.
My hope is that in the future, there's will be a multi-channel processor project here, which will decode and convert every conceiveable format including SACD, DVD-Audio, PCM, 16/24/32 bit 44.1-192KHZ , LPCM, MLP, Dolby True HD, DTS HD Master etc. Will have every conceivable input. SPDIF, optical, HDMI, USB ETC. . .
Have tube and transistor output stages. Be modular. And anything else I've forgotten to include.
This way one project could be built and improved upon by anyone looking make a DAC project. To me this would be better than everyone building many different projects.
I'm curious about all the new DACs. I'd look forward to your opinion about this one.
I've read some of your other posts with interest. It's good to hear that someone actually likes the sound of some of the new DACs. I would hope that some of the new digital technology actually sounds as good or better than non-oversampling DACs. Especially, since I don't know of any non-oversampling DACs for Hi-Rez audio. I can't quite imagine a multichannel home theater processor made with those old old technology DACs.
My hope is that in the future, there's will be a multi-channel processor project here, which will decode and convert every conceiveable format including SACD, DVD-Audio, PCM, 16/24/32 bit 44.1-192KHZ , LPCM, MLP, Dolby True HD, DTS HD Master etc. Will have every conceivable input. SPDIF, optical, HDMI, USB ETC. . .
Have tube and transistor output stages. Be modular. And anything else I've forgotten to include.
This way one project could be built and improved upon by anyone looking make a DAC project. To me this would be better than everyone building many different projects.
labjr said:
I'm working on a company project that uses a 32 bit DSP in front of a Delta Sigma DAC. It has or will have, the Dolby library, ethernet 802.11 & 802.3, and finally HDMI 1.3. Don't even ask what the licensing costs are.
We have been poking around with wireless HDMI. It works very well. HDMI is great since it overcomes a lot of recording company concerns about pirating since DRM is a component of the spec.
The older DAC chips are simplier and more DIY friendly. Delta Sigma got a bad rap (partially deserved)in the earlier versions.
-David
janneman said:
There is still a lot of out of band noise. Although AKM definately does the best job of reducing it. Filtering is still required, and my own experience has had greater success with active filtering to provide more drive to reduce cable sensitivity.
To your point I have seen successful implementations with some Delta Sigma DAC's like the WM8740 with just passive filtering, but the DAC was integrated with a preamp and another had special cabling.
-David
Re: Re: Re: 32-bit DAC
The AK4397 is very nice and all, but there is no reason for 32 bit resolution. The noise floor of 120 dB still swamps everything beyond 20 bits. You would need 256 DACs in parallel to even reach noise floor of 144 dB, which is the limit for 24 bits.
If I'm not mistaken, most sigma delta DACs use a switched capacitor filter.
You got that right.
janneman said:
The AK4397 is very nice and all, but there is no reason for 32 bit resolution. The noise floor of 120 dB still swamps everything beyond 20 bits. You would need 256 DACs in parallel to even reach noise floor of 144 dB, which is the limit for 24 bits.
janneman said:
If I'm not mistaken, most sigma delta DACs use a switched capacitor filter.
dw8083 said:
You got that right.
TheShaman said:
They need to get a new version of the laws of physics out.
Let us ignore thermal noise entirely; there is a fundamental limit from quantum mechanics, given by Planck's constant. This about 6.6x10^-34 Js. If we take a a 0.6microsecond time period (from the sampling rate), the fundamental noise uncertainty energy in a sample is 10^-27J, so the noise power is about 10^-21W
If we set the reference power level at say 1mW (0dBm) this is -180dB. Applying the basic 6dB per bit rule, we find that the maxiumum resolution, for this sampling rate and reference level, is 30bits.
So the claimed figures can be shown to be pure and simple marketing BS.
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