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SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A
SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A
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Old 20th January 2016, 07:35 PM   #1
hlooman is offline hlooman  Canada
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Default SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A

Hi all,

Haven't seen this one around on the forum so I thought to give it a shot.
Been on the forum for a couple of years but haven't contributed yet and thought now is a good time
I've been playing around with a couple of SD card FLAC players for a while now and ran into this one on eBay:

Finished Digital Turntable Lossless Music Player Ape WAV MP3 AK4495 DAC | eBay

Decided to buy it and see how it can be modded to sound any decent.

Click the image to open in full size.

After opening up, the player shows a modular approach. The SD card section is based on the ESS Crescendo II soundbar chip. I spoke with my contacts in ESS to get confirmed that this chip is actually real and capable of doing FLAC decoding on the fly.

Click the image to open in full size.

The ESS chip reads SD cards and USB sticks, clocks the data through it's built in DSP blocks, which at this point should be all 32bit wide audio path.
Apparently this is also where it decodes FLAC up to 24bit 192ksps and does digital volume control.
Via i2s and spdif the resulting digital audio is available.
Seeing the small smd crystal oscillator that clocks the whole thing, I'm thinking there may be something to optimize here.

The second pcb is the i2s AK4495 and power supply board.

Click the image to open in full size.

First thing I had to do was a checkup of the infamous dipswitch that controls the filtersettings of the AK4495 and of course the dipswitch design flaw is present in this board. Removed and replace by 2 jumpers.
Second thing, check the level of pin 5, the SSLOW signal. Luckily this is connected to GND already, so disabled.
The SSLOW signal makes the filters extend their roll off for use at lower than 44.1 kHz sampling frequencies, if I'm interpreting the datasheet correctly, page 28:

http://www.akm.com/akm/en/file/datasheet/AK4495EQ.pdf

The next thing was checking the output circuit. They used a double opamp by JRC, the MUSES8920
I'm not familiar with that chip at all, I'm definitely going to experiment changing it for something else.

The output is connected via 22ohm resistors, thank goodness no crapacitor in the output... BUT because they apparently used 5% resistors or something there was 45mV DC offset in one channel and 16mV in the other. Not so good.
My mod shows a 47K5 fixed resistor / 50K trimpot pair over each DAC output resistor to level away the DC offset. See the image above.

I have to say my first impression, after the mods, is quite positive. I am going to do a lot of listening now and prepare a list of further mods to improve the way the thing sounds.

By the looks of it, there is room for improvement in the decoupling, power supply, clocking and output filter.

Never a dull moment

I'm curious to know if there's anyone out there that already has done something with a unit like this.

Cheers, Hans.
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Old 22nd January 2016, 09:13 PM   #2
hlooman is offline hlooman  Canada
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The player has now been playing for almost 2 days and I've been doing some first impressions listening to it.

First immediate thing I noticed using the headphone is that the channels are reversed on the 3.5mm headphone output! Annoying... The line outputs are connected OK however.

Studying the decoupling of the DAC chip itself revealed an interesting mod:
The VREFH and VREFL for both channels are decoupled with 100n ceramic parallel to a 22uF elco. According to an article on hifiduino - https://hifiduino.wordpress.com/2014...rita-4490-dac/ - there's something to be gained by the value of the decoupling capacitors there.

Click the image to open in full size.
(image courtesy of hifiduino)

I paralleled 2200uF/35V to it and that has made some good changes to the lower midrange and bass.

Click the image to open in full size.

Next mod will be focusing on the output opamps, the one currently in there is the MUSES8920 which I'm still not familiar enough with the have a feel how it sounds like compared to other opamps out there.

I have ordered some other dual opamps, such as the OPA2604 and 2134 and might build a couple double SO8 SMD->single DIP8 contraptions to test other single opamps

Since the AK4495 is voltage out compared to current out, it could be that other than my usual goto workhorses such as the OPA627 might shine here...

Any recommendations from the field?
I'm going to shoot an order in with Digikey this Monday

Cheers, Hans.
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Old 24th January 2016, 04:14 AM   #3
abraxalito is offline abraxalito  United Kingdom
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I'd not trouble yourself swapping out the opamp, that MUSES has decent enough specs on paper. You could though increase the impedances of the networks surrounding it (Rs and Cs) as when I did this on my WM8741 player it improved the low frequency dynamics a lot. If you can identify which of the recommended output circuits in the AKM datasheet is being used, I can calculate some new R and C values to try.
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Old 24th January 2016, 04:25 AM   #4
Bigun is offline Bigun  Canada
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SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A
Can you also plug in a USB hard disk ? (Probably a really dumb question but what the heck)
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Old 25th January 2016, 06:50 PM   #5
hlooman is offline hlooman  Canada
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Quote:
Originally Posted by Bigun View Post
Can you also plug in a USB hard disk ? (Probably a really dumb question but what the heck)
Not a dumb question at all...
I was more focused on playing from SD card but intrigued by this option I connected a 1TB external USB disk and it does show the file structure no problem, however, when I try to play a FLAC file from it the player freezes.
I will experiment a bit more to try get this going because that would turn it into a neat low cost music server...

Cheers, Hans.
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Old 25th January 2016, 08:45 PM   #6
hlooman is offline hlooman  Canada
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Turns out it was harddisk related. Might be something to do with the filesystem.
Connected an older 160Gb Freecom USB drive and it plays the first 24bit 96kHz wav file it found without a problem.
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Old 28th January 2016, 11:47 PM   #7
mill23bay is offline mill23bay  Canada
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I am a newbie when it comes to your mods, but if your results are what you want and you are happy, then maybe I will get the unit you are working on and very carefully do what you are doing without that magic smoke that makes my eyes water.
Thanks hloorman
PeterC
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Old 24th March 2016, 06:49 PM   #8
Jogi is offline Jogi  Germany
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Hans,
any news on this project?
It looks quite interesting, especially regarding the possibility of adding another dac, for example the Soekris. Should be a nice one box solution, if the Scard Player is up to task soundwise.
Playing via computer and USB is surely very convenient, but I guess SD sounds better.
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Old 2nd April 2018, 06:28 PM   #9
acidbrain is offline acidbrain  Netherlands
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SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A
Bought a DV20A as well. Slightly different than Hans his version, powersupply for the SD/USB has been moved to the i/o board itself. Now i'm trying to identify the oscillator on the i/o board. It's a 4 "legged" SMD verion, brand : KSS and maybe it's a 27 MHz version ?? I will add a picture, a sharper one once i'm back home again.
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Old 4th April 2018, 08:56 PM   #10
acidbrain is offline acidbrain  Netherlands
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SD Card Memory FLAC/WAV 192/24 player - ESS crescendo II - AK4495 - DV20A
Is this a 27MHz oscillator ?
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