ALERT: good spdif input 24/96 DAC for only $40 (with measurements) - diyAudio
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Old 9th May 2014, 03:42 AM   #1
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Default ALERT: good spdif input 24/96 DAC for only $40 (with measurements)

I have been exploring the realm of the "low cost DAC". This is the second DAC that I am reporting on.

Now here we have a real contender - the "Little Bear Decoder v1.08". This is a 48kHz/96kHz spdif input DAC using a DIR9001 spdif receiver IC and the CS4398 D-to-A chip. The output is run through a 5532 op amp to provide low pass filtering and to buffer the output. The quality of the board seems to be high and good quality parts are used in critical areas.

I performed some measurements on this DAC using an M-Audio ProFire610, ARTA/STEPS and REW. For these measurements, the signal path begins in software, goes to the 610 spdif output port, into the DAC, and then back into an analog input port of the 610. Software can then evaluate the analog input (for distortion, frequency response, etc.). This signal path also permits me to do A/B testing (after level matching) of the 610's internal DAC and the external DAC using the 610's routing software.

I have attached the measurements I obtained. At both 48kHz and 96kHz the distortion levels are low and more or less input-level independent. I also took a spectrum of the DAC output for a 1kHz test tone, showing distortion products and the noise floor, both of which are very low. Keep in mind that the distortion spec for the analog input of the M-Audio Profile 610 that I am using to measure this DAC is 0.002% distortion (at 1kHz -1dBFS) and -108dB S/N ratio (A-weighted). Essentially the "Little Bear" DAC is approaching the measurement threshold of my equipment.

This is an exceptional product, especially given that I purchased it for $40 including shipping to the USA. Power is supplied via a single 12-0-12 VAC input, and a transformer is included by the seller (115VAC or 230VAC primaries are available). Once you connect the transformer the unit is ready to run.

If you are looking for an SPDIF input (only) DAC then this is really one that performs far above its price level.

Ebay link:
HiFi Digital to Analog Coaxial Decoder DIR9001 CS4398 96kHz 24bit DAC Converter | eBay (or search under "Decoder DIR9001 CS4398")
Aliexpress link:
Little Bear DAC on Aliexpress.com




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Last edited by CharlieLaub; 9th May 2014 at 04:08 AM.
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Old 9th May 2014, 05:09 AM   #2
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and... how does it sounds?
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Old 9th May 2014, 03:18 PM   #3
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It sounds like a good deal.
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Old 31st May 2014, 08:01 PM   #4
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I just bought, and received, three more of these DACs. I need four DACs for an upcoming project, and wanted to test one of these first before buying the others.

I'm happy to say that the other three measure just as good as the first one. You get very low distortion for the price. The Ebay seller is nice and a transformer for your mains voltage is included by the seller.

If you need spdif input (not USB) then this is a really great option.
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Old 4th August 2014, 06:07 PM   #5
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FYI - these are again listed on Ebay by the seller:
HiFi Digital to Analog Coaxial Decoder DIR9001 CS4398 96kHz 24bit DAC Converter | eBay
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Old 4th August 2014, 07:20 PM   #6
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Quote:
FYI - these are again listed on Ebay by the seller:
That is because I asked the vendor to list them, so that I could buy three
The boards look nice. I too am going to use them with nanoDIGI.

Thanks for the heads-up.
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Old 5th August 2014, 04:15 PM   #7
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I just got my Little Bear DAC via AliExpress, and the hateful thing doesn't work. The power coming in from the little transformer is good, and I get the power LED. I tried both jumper settings (48Khz $ 96Khz) and with two different CD players. After much gnashing of teeth, I got the bloody thing to make some noise, but it is extremely quiet and distorted. Basically I can only faintly make out certain drum beats.

Any ideas for a fix/troubleshooting? For $35, it's not worth shipping back to China so I haven't even contacted the seller. I did notice an 'Error' jumper/pins. What does this do? Anybody have a schematic?
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Old 5th August 2014, 04:25 PM   #8
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Here are my suggestions: The first thing I would do is contact the seller. I would not jump to the conclusion that you need to "ship it back to China"... You could have a bad board, or could have something connected wrong, etc. Also, don't go messing with the jumpers. There is no need to move them from the default position for the correct operation of the board - it handles all rates of 96kHz and below as is. Also, the "bloody thing" cannot be "hateful" - you can only project your own feelings onto it. So relax! Disapointing, yes, but it's not the end of the world...

I can only add that all four of mine work perfectly.

Ask the seller to help you fix the problem and give them an opportunity to do so.
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Last edited by CharlieLaub; 5th August 2014 at 04:28 PM.
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Old 5th August 2014, 04:41 PM   #9
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CharlieLaub,

Thanks for the advice. I tend to write like I talk, with lots of exaggeration and expletives. I post so rarely that I tend to forget that text is a poor substitute for conveying one's intents.

I have contacted the seller once before (to as for a Schematic), but got no response (through the AliExpress web site). Perhaps I should try other means of contact.

Thanks again.

p.s. Do you have a schematic?
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Old 5th August 2014, 04:54 PM   #10
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I don't have a schematic. I'm not all that surprised that the seller is not sending you one. It's likely that they are a reseller and don't have it. But even if they do, by releasing the schematic of a successful board to anyone they run the risk of someone else copying it. This is the nature of business in China I believe. Perhaps the very reason that you did not get a reply is because you asked for the schematic. I would just stick to the nature of the problems you are experiencing and give the seller a chance to make it right.

The same seller is listing the item on Ebay:
HiFi Digital to Analog Coaxial Decoder DIR9001 CS4398 96kHz 24bit DAC Converter | eBay
You could try there if contact through AliExpress is not productive. The seller has always gotten back to me in a day or two. Keep in mind the date in China is about 2/3 of a day ahead of you.
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