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Old 15th May 2011, 11:26 AM   #1
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Default DIY ADC around?

Hi,
did anyone try and build a DIY analogue-to-digital converter that surpassed at least entry level and mid-priced solutions in soundcards or external studio gear?
I have the faint feeling that one might do better than that what's in my RME ADI-2. I have, however, rarely seen DIY-efforts in this area.

Rüdiger
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Old 15th May 2011, 06:08 PM   #2
Nisbeth is offline Nisbeth  Denmark
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The only one I know of: AD24QS and DA24QS - Audio ADC and DAC, 24 Bit / 192 kHz

/U.
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Old 15th May 2011, 08:47 PM   #3
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Quote:
Originally Posted by Onvinyl View Post
I have the faint feeling that one might do better than that what's in my RME ADI-2.
Better than yours?
Quote:
Dynamic range AD: 110 dB RMS unweighted, 113 dBA
THD AD: < -110 dB (< 0.00032%)
THD+N AD: < -104 dB (< 0.00063%)
Crosstalk AD: > 110 dB
You are dreaming...
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Old 16th May 2011, 03:01 AM   #4
qusp is offline qusp  Australia
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yeah not a chance, you might be able to improve the analogue section of your rme somewhat, but the rme gear is pretty superb and rocksolid
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Old 16th May 2011, 03:23 AM   #5
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PCM4222EVM.

The appnote contains schematics and BOM for this, so you could DIY it. However its not a trivial exercise if you have no experience with low noise digital circuits. The typical ADC performance exceeds the specs that SoNic has quoted (123dBA dynamic range for example, THD+N -108dB). If you're really serious about performance you can do better still by designing your own digital filter rather than using theirs.
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Old 16th May 2011, 04:01 PM   #6
qusp is offline qusp  Australia
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yes, the typical adc listed spec does, but typical real world performance may not be that easy. possible, but better to just improve the analogue section of what he has already imo, because adc real world performance will depend heavily on the quality of the mic-pre and analogue input section. then you also have the interface, software driver etc. the rme is renowned for driver stability, rugged build and as a bonus you can use it standalone

Last edited by qusp; 16th May 2011 at 04:03 PM.
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Old 16th May 2011, 05:00 PM   #7
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Exactly. The specs are someting, implementation is where the truth is.
He might improve the input stage using better components, but that's it.
PS: Another product that has better ADC performance (for less money) is EMU1616:
Quote:
Analog Line Inputs
Type: servo-balanced, DC-coupled, low-noise input circuitry
A/D converter: AK5394A
Level (software selectable):
- Professional: +4dBu nominal, 20dBu max (balanced)
- Consumer: -10dBV nominal, 6dBV max (unbalanced)
Frequency Response (20Hz-20kHz): +0.0/-.03dB
Dynamic Range (1kHz, A-weighted): 120dB
Signal-to-Noise Ratio (A-weighted): 120dB
THD+N (1kHz at -1dBFS): -110dB (.0003%)
Stereo Crosstalk (1kHz at -1dBFS): < -120dB Analog Line Outputs
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Old 17th May 2011, 03:23 AM   #8
qusp is offline qusp  Australia
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yeah the emu stuf is good value, but the interface cant touch patchmix
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Old 29th July 2011, 02:01 PM   #9
Frex is offline Frex  France
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Maybe mine ?
(You have probably not well used the topics search engine...)

Frex
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Old 7th October 2011, 03:38 AM   #10
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I just started a project dubbed the OpenNGADC, or Open Next-Gen Analog to Digital Converter.
The basic idea is to create an open source pcb around the Arda AT-1201, which spec wise betters any commercial ADC out there, or course this is yet to be heard. I am not one for numbers, but I do want to push the capability of the open diy audio community.

It offers DXD output as well as 256fs (12.288Mhz) Delta-Sigma, 1 or 6-bit. And a better DNR than pretty much any part out there, feel it's worth a shot, even if I can't find a single report online as to how it sounds.

Currently working on the gerber files, I want to develop this as a community project, just have to find someone willing to help.

The name was chosen just to have something unique, could do better, but there are more important things than a name.

-Alex
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