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Best spec ADC Chip currently.... ??

SoZo

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Apr 21, 2020
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Have an older interface looking to upgrade, whats the supposedly best spec chip and who is using it to it's full potential in a multi channel converter ???
 
How many channels is multi channel, and for what purpose? The answer will be quite different for surround use vs. active crossover for example.
 
Looking for the best A/D for my recording studio, anywhere from 2 - 32 channels for a sonic upgrade
 
Maybe the Merging technologies gear. They make some impressive claims.

https://www.merging.com/products/interfaces/specifications


They tell which chips they use here:
https://www.merging.com/products/interfaces

https://www.akm.com/content/dam/doc.../audio-adc/ak5578en/ak5578en-en-datasheet.pdf

So look for others that use the AKM AK5578 chips. The chips are around $15 in quantities of few dozen. So probably only very expensive gear will have them.
Beat me to it on the Merging stuff. I've used it in a mastering context before and it's very impressive how clean it is.

Also - I would not just be concerned with the specs of the A/D or D/A chips, but also the circuit design around them. Even very cheap chips have quite respectable performance, assuming the circuit design is good.
 
Also TI PCM4220 and PCM4222. Datasheets show very flat frequency response with extremely low passband ripples, also deeper filter attenuation and lower noise floor at ultrasonic range than the top AKM chips.
Those are the only audio ADCs I've been able to test myself or find graphs for that have no discernible modulator noise below 50 kHz. Whether or not that matters is another question.
 
so my current A/D Apogee 16x specs

THD+N: -110 dB •
Dynamic range: 120 dB A weighted

is it worth upgrading for 4db ?
 
Maybe the Merging technologies gear. They make some impressive claims.

https://www.merging.com/products/interfaces/specifications


They tell which chips they use here:
https://www.merging.com/products/interfaces

https://www.akm.com/content/dam/doc.../audio-adc/ak5578en/ak5578en-en-datasheet.pdf

So look for others that use the AKM AK5578 chips. The chips are around $15 in quantities of few dozen. So probably only very expensive gear will have them.

They just talked about their new dual-gain architecture, mind-blowing figures
The Anubis shares the same design as well btw

looking forward to their update manual to have a peak into the block diagram

 
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Wow.. yea looked at Merging before but not much if any better previously to what I had. This though is what I was looking for.... Using all 8 channels x2 of the A/D for best SN ratio etc..
 
Well Sound Devices does use a pair of DACs to record directly into 32 bit float. I think they claim an effective 142 db dynamic range plus you won't ever get clipping. I think the base circuitry is something like 110 db SNR so good, but not quite SOTA. Great for on location stuff so you never mess up the levels.
 
The AK557x ADCs themselves are 32-bit integer already, regardless actual DNR specs.

Basically the floating point approach is just an array of ADCs (or a multichannel ADC) recording at different levels. The old Sony PCM-D100 used a similar approach -- recording two copies at the same time, but with a difference of 12dB. Of course, it only supports 24-bit integer and DSD.
https://www.solidstatesound.co.uk/sony_pcm-d100.htm

While 32-bit float "only" has 25 bits of precision, don't forget it wins 32-bit integer when sample values (yes, sample values, not the overall level of the whole file) are below -42.1442dBFS (7 bits below full scale) and above 0dBFS (integers will clip). Floating point on the other hand always store 25 bits of data within the ~1500dB range. Since no combination of ADC, mic and preamp can achieve 25 bits of instantaneous dynamic range, the floating point approach is much more sensible.

2L for example has a raw DXD vs DSD comparison page here:
http://www.2l.no/hires/DXD-DSD/index.html
Look at the highest peak level of the raw DXD file, it is -12dB, and stored as 24-bit integer. That means the whole file, being integer, only has a maximum bit-depth of 22, and in quieter portions the bit-depth is even lower. In terms of RMS it is about -35dB, so only about 18 bits. Very compressible with flac (~35.5% of original). Typical normalized 16/44 flac (1411kbps) often only has a ratio of about 50-80%.

bitrate.PNG


Not criticizing anything in terms of audibility, just want to clarify the technical details.
 
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hi bennetng, that was very informative

im wondering if you have seen the Sound Devices patent for their triple ADC that claims 168 dB of dynamic range?

https://patentimages.storage.googleapis.com/a7/6b/f5/77e31e68cca8b7/US9654134.pdf

Their implementation in the Mixpre-II series states 142dB of dynamic range in the ADC section. That series uses 32-bit float files. In your opinion would such a setup theoretically perform better writing to 32-bit fixed? The EIN of the unit is -128dBU which both float and fixed can contain.
 
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