[Mellowship]

Hello,

Just got this lousy cheap DAC from AE (12 USD), based on the SA9023 and ES9018K2M. My idea was to use some components that were left over from another project and put it in a cheap wooden box with proper panel RCA sockets. Also, I was looking for something that was powered from USB only.

Suprisingly, the thing I was most afraid of - the USB noise - does not apply with this device. It's dead silent. So, I don't need to worry with that part of the circuit. The sound is about fine... It does the job, no hypes... I wish it was a little more "natural" or "warm"....

As I will be unsoldering the PCB lousy RCA and jack sockets, I was wondering if, with a little more work, I could mod a thing or two on the audio path. I was thinking about better caps.

(note: I have plenty of space in the box I'll be using, so I accept suggestions for bigger caps. I only need thorough info about the caps I will need to substitute - I can use a soldering iron but I don't have theorical knowledge of electronics and such)

Can you please take your precious time to help me out on this?

Below are pictures of the thing:

It works...

The board


Detail of the output section


Below


Thanks!

 

[HiGHFLYiN9]

Nice price given the photographs. One thing you could try is swapping out the Op-amp (currently you have an Analog devices AD823). Unfortunately it's not socketed so you'd have to desolder and resolder. That would make the greatest audible difference. With the caps, I can't see the brand name. The purple sheen leads me to believe they are Panasonics (they'd be marked with an "M" in a little square, Matsushita is Panasonic's Japanese name). If so, you can leave them, Panasonic caps sound good. If they're some no-name brand, you could try Elma Silmic IIs. Look up "RFS" at Mouser and you'll see the various values. Remember you can always go up with voltage rating but never down You can also bypass the electrolytics with small film caps. Try Wima or Nichicon 0.1uf polypropylene film caps mounted on the other side of the board. Film caps are usually rated for much higher voltage than general electrolytics, so the lowest you may find is 63v or 100v (or 250v in some cases). Polypropylene caps generally sound better than polyester, but polyester is much smaller in form factor typically if room is an issue.

Have fun!

EDIT: also, you can try adding an Audioquest Jitterbug inline with the USB. Great little device if you have $50 to spare.

 

[Mellowship]

Nice price given the photographs. One thing you could try is swapping out the Op-amp (currently you have an Analog devices AD823). Unfortunately it's not socketed so you'd have to desolder and resolder. That would make the greatest audible difference. With the caps, I can't see the brand name. The purple sheen leads me to believe they are Panasonics (they'd be marked with an "M" in a little square, Matsu****a is Panasonic's Japanese name). If so, you can leave them, Panasonic caps sound good. If they're some no-name brand, you could try Elma Silmic IIs. Look up "RFS" at Mouser and you'll see the various values. Remember you can always go up with voltage rating but never down You can also bypass the electrolytics with small film caps. Try Wima or Nichicon 0.1uf polypropylene film caps mounted on the other side of the board. Film caps are usually rated for much higher voltage than general electrolytics, so the lowest you may find is 63v or 100v (or 250v in some cases). Polypropylene caps generally sound better than polyester, but polyester is much smaller in form factor typically if room is an issue.

Have fun!

EDIT: also, you can try adding an Audioquest Jitterbug inline with the USB. Great little device if you have $50 to spare.

Thank you so much!

If the size of the opamp was the same as a socket, I would put a socket there and swap them, but it's small. And the AD823 is not that bad...

So, those two 220 uf 16 v caps are not Matshush_ita, but some cheap chinese ones. That's the place to start. You're telling me that if I take those of I can put some polypropylene caps of different capacitance? I have a couple of gigantic 4.7 uf 400v MKP "audiophyler". Do you think these would do a good job there?

 

[HiGHFLYiN9]

You're telling me that if I take those of I can put some polypropylene caps of different capacitance? I have a couple of gigantic 4.7 uf 400v MKP "audiophyler". Do you think these would do a good job there?

No you can replace the electrolytics with the same value, but on the bottom of the board have a bypass film cap. Bypassing capacitors means having a second capacitor connected in parallel. Here's an example of someone bypassing electrolytics on the bottom of a PCB with Wima film caps.

Here's a great article on the subject: http://www.gammaelectronics.xyz/ax_05-2005_capacitor-bypass.html

 

[UnknownAX]

That looks like some impressive bang for the buck! The AD823 is impressive considering the price, no reason to swap it out. Seems to have some pretty sizeable CLC power supply filtering too, explains the lack of noise. If you had issues with power supply noise I would've suggested polymer capacitors but apparently there's no need.

 

[Mellowship]

No you can replace the electrolytics with the same value, but on the bottom of the board have a bypass film cap. Bypassing capacitors means having a second capacitor connected in parallel. Here's an example of someone bypassing electrolytics on the bottom of a PCB with Wima film caps.

Here's a great article on the subject: http://www.gammaelectronics.xyz/ax_05-2005_capacitor-bypass.html

Thank you!

Mouser is a great store but in my country they charge 20 euros for shipping... And I can't find good brands on physical stores around. Are caps from AE legit?
And what about those I have already here? Could I bypass the board caps with axial polypropylene 4.7 or 3.7 uf 400 v caps using twisted pairs of cat5?

 

[HiGHFLYiN9]

Use Tayda Electronics - https://www.taydaelectronics.com/ - Amazingly low prices, cheap shipping and legitimate parts. They carry WIMA and other various capacitors.

You can bypass using those big caps, but it's not going to be pretty, and you have some fly leads you'll want to ensure don't short anything on the board. You'll also want to secure the caps to the board somehow (or secure the board and caps to a base) otherwise the weight could tear off of the solder pads while handling. Personally I wouldn't, but you could

 

[Mellowship]

Use Tayda Electronics - https://www.taydaelectronics.com/ - Amazingly low prices, cheap shipping and legitimate parts. They carry WIMA and other various capacitors.

You can bypass using those big caps, but it's not going to be pretty, and you have some fly leads you'll want to ensure don't short anything on the board. You'll also want to secure the caps to the board somehow (or secure the board and caps to a base) otherwise the weight could tear off of the solder pads while handling. Personally I wouldn't, but you could

Thank you. I will test with the big caps and listen to any differences in sound. If I hear nothing I will order the small wimas.
And trust me, I ain't gonna fool around with sloppy jobs. Got a lot of retractable sleeves!
I will keep you posted on my advances

 

[duo8]

I have this exact same one.
It came in with a cap installed wrong so I had to replace it, while I was at it I also replaced the other 10uF caps that are installed in the slot marked "47uF".
There are still a few caps with the wrong value though. I didn't even check the resistors.
Also the silkscreening on the voltage regulator and opamp is just printed on, those components may be fakes, idk.

 

[Mellowship]

I have this exact same one.
It came in with a cap installed wrong so I had to replace it, while I was at it I also replaced the other 10uF caps that are installed in the slot marked "47uF".
There are still a few caps with the wrong value though. I didn't even check the resistors.
Also the silkscreening on the voltage regulator and opamp is just printed on, those components may be fakes, idk.

Mine seems to be ok in that respect. Only problem detected was the inversion of the red/white RCA sockets, but since I'm going to unsolder them...

 

[technicus]

Hello everyone! How is this project going/sound with the bypass caps installed? I'm pretty sure I found this exact guy on AE and am interested in a USB DAC like this for my headphone amp kit and this might work.

 

[Mellowship]

Hello everyone! How is this project going/sound with the bypass caps installed? I'm pretty sure I found this exact guy on AE and am interested in a USB DAC like this for my headphone amp kit and this might work.

Hi there. Still waiting for parts coming in the slow boat from China. I will post pictures and impressions as soon as the soldering iron gets hot.

 

[duo8]

Hi there. Still waiting for parts coming in the slow boat from China. I will post pictures and impressions as soon as the soldering iron gets hot.

Why not just buy them locally? Caps aren't hard to source.

 

[Mellowship]

Why not just buy them locally? Caps aren't hard to source.

Local stores in Portugal only have generic low quality parts. Even good RCA plugs are hard to find.

 

[technicus]

Local stores in Portugal only have generic low quality parts. Even good RCA plugs are hard to find.

Plus, they have VAT so the higher quality stuff would cost more plus that 23%, is it? So, buying better from China for less, and even after shipping is way cheaper for our EU friends.