Serious failure in DAC SMSL SU-1

[Firulais71]

Good afternoon, everyone.

A few months ago, I purchased an SMSL SU-1 DAC, which I've integrated into my main audio system. This system includes the following components:

1- A Windows 10 PC that stores and plays FLAC, WAV, and DSD files. I primarily use Foobar2000 for playback.
2- A Yamaha AX-497 analog amplifier (transistor-based).
3- A set of Onkyo E-83A MKII stereo speakers.
4- Corresponding audio cables.

Component Connections, the system is connected as follows:

1- From the PC to the DAC using the original USB A/USB C cable that came with the DAC.
2- From the DAC to the amplifier using RCA cables.
3- From the amplifier to the speakers using #14 audio cables.

For the first three months, the DAC worked perfectly with excellent audio quality. The equipment installation and cabling in general are permanent; that is, since I installed everything and properly connected the cables, I have NEVER touched, moved, or manipulated them. However, yesterday, suddenly, while listening to music, the volume dropped almost completely. It's nearly inaudible, and the distortion is horribly bad. I have to turn the potentiometer all the way up to barely hear anything, and to top it off, the distortion is terrible.

Tests: I performed the following troubleshooting steps:

1- I replaced the original SMSL USB cable that connects the PC to the DAC, trying two other high-quality USB cables I have at home, and the problem persists.
2- I used a different USB port on the PC to connect the cable that powers the DAC. I performed this test with the original SU-1 cable and the other two USB cables, and the problem persisted.
3- I repeated the tests described above using another PC and a laptop as the audio sources for the DAC, and the problem persisted.
4- I connected an optical audio/Toslink cable between the main PC and the DAC, while maintaining the PC's USB connection to power the DAC. I even tried all three USB cables, and the problem persisted.
5- Without disconnecting the optical cable, I tried powering the DAC using cell phone chargers connected to a wall outlet. I ensured the voltage was always 5V with an amperage of 1A and 2A. I tested three different chargers with the three available USB cables, and the problem persisted. 6- I tried two different amplifier inputs, AUX and CD-DVD, connecting the RCA cables from the DAC to them, and the problem persists.

Obviously, I made sure that the USB or optical input was always selected on the DAC when appropriate, and the correct audio input was always selected on the amplifier.

The only thing I haven't been able to check are the RCA cables connecting the DAC to the amplifier, but I doubt that's the problem. The cables are excellent quality; I built them myself with high-quality components. I've been making my own cables for decades, and I've never had a problem like this. However, tomorrow I'm borrowing a couple of sets of RCA cables to do one last check.

Finally, to rule out the possibility that the problem is the amplifier, the speakers, or the speaker cables, I tried connecting a CD player to the amplifier using a jack-to-RCA cable. And the equipment works perfectly, as I mentioned above. I've also ruled out any problems with the main PC or the other two computers used for these tests.

So, given the circumstances, and since everything points to the problem being the DAC, at least until I borrow some RCA cables tomorrow, have you seen this issue with the SMSL SU-1? Is there anything I can do? I bought the DAC months ago on AliExpress, and the warranty has already expired because, in my region (Latin America), the warranty is only 30 days.

I would be very grateful for any helpful comments.

Best regards.

 

[Redacted]

Your testing looks good.
Sounds like the DAC has failed.
My guess is no chance of a repair or replacement out of warranty....
I got a Topping DX1 when they first came out, which is similar to the SU-1 (it has been great on my PC), and now there is a new Mk II version out, you may find people selling their DX1's on eBay etc.

 

[RandomEar]

Definitely sounds like a failed DAC. If you've got a multimeter, I would just open the SU-1 and check all the voltages. There appear to be test points for every one on the board and they are labeled, which is nice.

If they are all present, I would check if the audio signal coming into the op amp (LME49720, close to the RCA jacks) still looks good - this would need a scope, though.

 

[Firulais71]

Your testing looks good.
Sounds like the DAC has failed.
My guess is no chance of a repair or replacement out of warranty....
I got a Topping DX1 when they first came out, which is similar to the SU-1 (it has been great on my PC), and now there is a new Mk II version out, you may find people selling their DX1's on eBay etc.

Hey man, thanks for the quick reply. Tomorrow I’ll run one last test with the RCA cables I’m borrowing; if the problem persists, I’ll assume the DAC is faulty. My final attempt will be to take it to a friend who knows electronics to see if he can fix it. If not, I’ll have to buy another one, as you recommended. Cheers.

 

[Firulais71]

Definitely sounds like a failed DAC. If you've got a multimeter, I would just open the SU-1 and check all the voltages. There appear to be test points for every one on the board and they are labeled, which is nice.

If they are all present, I would check if the audio signal coming into the op amp (LME49720, close to the RCA jacks) still looks good - this would need a scope, though.

Yes, I feel the same way. In a few days, I’ll take it to someone with more expertise to measure the values and -if possible- fix the issue; otherwise, I’ll have to buy a DAC from a higher-end brand. Best regards from Peru.

 

[Joe Smith]

Lots of good inexpensive choices out there...Fosi Q6, Schiit Modi, JDS Atom 2, etc. All of those have proven quite reliable for me.

 

[JSmith]

A few months ago, I purchased an SMSL SU-1 DAC

Hey, where from... locally, any consumer protections? 2 months is not acceptable... needs to be replaced or repaired. Should have a 1 year warranty.


JSmith

 

[Redacted]

Hey, where from... locally, any consumer protections? 2 months is not acceptable... needs to be replaced or repaired. Should have a 1 year warranty.


JSmith

Should have, but the process of returns to an Ali X vendor (even they accepted returns now) is horrendous. Ask me how I know!....

I bought a small device that was not what it claimed to be in in the web description. I asked for a return on what Ali claimed was "100 day free return". They said 'sure' and told to send the item back in the post - to China and they refund cost and postage on receipt. The cost of doing this with a tracked service was more than the item was worth, and TBH, I doubt it would work, so I made a complaint to my credit card company, who eventually refunded me the £18. Not the money, the principle was the point - what a pain though. Ali have been ok on a few other returns but I'm more cautious about buying anything from them them that costs more than £25 and then there is the worry of fake stuff. Amazon on the other hand, I have used since they first had a UK presence, and never had an issue with a return. eBay is OK too, but you may pay for postage for a return, but in the UK (not international post) it's not too bad.

 

[ATTI]

the volume dropped almost completely. It's nearly inaudible, and the distortion is horribly bad

This looks very much like a malfunction of output op-amp or it's power supply - dual rail dc-dc module. Stock op amp is LM49720 but you can put here mostly any popular dual operational amplifier in soic-8 case to test. DC-DC dual rail module you can find by words DC-DC A0512S module. It is not expensive and not hard to try to change.
At first measure both positive/negative 12V at testpoints between DC-DC module and op-amp, also check two 5V rails at capaticors around another ic (marked blue).

 

[Firulais71]

Hey, where from... locally, any consumer protections? 2 months is not acceptable... needs to be replaced or repaired. Should have a 1 year warranty.


JSmith

Hi bro, AliExpress's warranty and return policy for orders bound for Latin America is a disaster. For us -I live in Peru- we only have 15 days to initiate a return in the event of a defect or malfunction; either way, it’s a very short window (almost a scam). I believe it’s a year for Europe. Anyway, that ship has sailed for me; my only options now are to either repair this piece of junk (hopefully that's possible) or buy a DAC, one of better quality than SMSL this time.

That old saying really holds true: "you get what you pay for, if you buy cheaply, you pay dearly".

Grettings

 

[Firulais71]

This looks very much like a malfunction of output op-amp or it's power supply - dual rail dc-dc module. Stock op amp is LM49720 but you can put here mostly any popular dual operational amplifier in soic-8 case to test. DC-DC dual rail module you can find by words DC-DC A0512S module. It is not expensive and not hard to try to change.
At first measure both positive/negative 12V at testpoints between DC-DC module and op-amp, also check two 5V rails at capaticors around another ic (marked blue).

Pal, thanks a lot for this technical information. In a few days, I’ll take the DAC to a friend who is an electronics expert so he can diagnose it; he has the necessary equipment at his office to take the relevant measurements. Hopefully, we can identify the fault and it turns out to be repairable.

Your information will be a huge help, it gives us a starting point. Thanks again.

 

[Firulais71]

Should have, but the process of returns to an Ali X vendor (even they accepted returns now) is horrendous. Ask me how I know!....

I bought a small device that was not what it claimed to be in in the web description. I asked for a return on what Ali claimed was "100 day free return". They said 'sure' and told to send the item back in the post - to China and they refund cost and postage on receipt. The cost of doing this with a tracked service was more than the item was worth, and TBH, I doubt it would work, so I made a complaint to my credit card company, who eventually refunded me the £18. Not the money, the principle was the point - what a pain though. Ali have been ok on a few other returns but I'm more cautious about buying anything from them them that costs more than £25 and then there is the worry of fake stuff. Amazon on the other hand, I have used since they first had a UK presence, and never had an issue with a return. eBay is OK too, but you may pay for postage for a return, but in the UK (not international post) it's not too bad.

I can confirm what you're saying, bro; AliExpress's return policy is a disaster, at least for Latin America. I just commented on that below. Best regards.

 

[Nutul]

Return policy is different from warranty period...

 

[Firulais71]

Return policy is different from warranty period...

The panel in the completed order or purchased product, only offers two options: "add to cart" or "returns/refunds."

And if I open a dispute from the main menu:

It takes me to the same screen where, once again, I can only choose between "add to cart" and "returns/refunds"; and, for Latin America, there is NO way to open a dispute, request a return, or claim a warranty -whether due to a defect or any other reason- once 15 days have passed since receipt.

Perhaps the warranty period is longer in your region, and that is why you think it works the same way in the rest of the world.

Regards.

 

[Nutul]

of course it does offer only those two options. If you didn't like the product within 30 days you could have sent it back and you'd have been given the refund.
Now, you actually bought it. This is when the warranty kicks in (one month less than the ordinary - in Europe - 2 years).Within the warranty period, if your unit fails, you are entitled to send the unit back to the seller (or to a local vendor, but this is not your case, as I can understand). They will either fix-and-return it, or replace it with a new one (depending on what comes out to be less expensive on their side, of course).

Now, it all depends on where you bought the unit. If it is AliExpress, for instance... you're going to suffer some PITA... if it is Amazon, I think they do have warranty policies.

 

[Firulais71]

of course it does offer only those two options. If you didn't like the product within 30 days you could have sent it back and you'd have been given the refund.
Now, you actually bought it. This is when the warranty kicks in (one month less than the ordinary - in Europe - 2 years).Within the warranty period, if your unit fails, you are entitled to send the unit back to the seller (or to a local vendor, but this is not your case, as I can understand). They will either fix-and-return it, or replace it with a new one (depending on what comes out to be less expensive on their side, of course).

Now, it all depends on where you bought the unit. If it is AliExpress, for instance... you're going to suffer some PITA... if it is Amazon, I think they do have warranty policies.

The warranty offered by AliExpress and its sellers for Peru is a disaster; they only allow 15 days to activate it if the product arrives with a factory defect or fails within that two-week window, and I made my purchase four months ago.

As I’ve already explained, it is IMPOSSIBLE for me to open a dispute to claim the warranty; my only remaining options are to repair the item or buy a new one.

 

[Redacted]

Return policy is different from warranty period...

I think we all know that, but one issue is how you get a warranty honoured in some countries.

 

[Roland68]

The panel in the completed order or purchased product, only offers two options: "add to cart" or "returns/refunds."

View attachment 547691

And if I open a dispute from the main menu:

View attachment 547693

It takes me to the same screen where, once again, I can only choose between "add to cart" and "returns/refunds"; and, for Latin America, there is NO way to open a dispute, request a return, or claim a warranty -whether due to a defect or any other reason- once 15 days have passed since receipt.

View attachment 547697

Perhaps the warranty period is longer in your region, and that is why you think it works the same way in the rest of the world.

Regards.

I would report the problem to the retailer first; if that doesn't work, try contacting customer support via chat.

Based on your description, the fault lies with the 5V to +/- 12V DC/DC converter in the SU-1—a component known to fail frequently in this unit. Just mention the issue and point them to the forum.

If none of that works, you can try contacting SMSL directly, as a lifespan of only four months is unacceptable, even at this price point.

 

[DSJR]

My SU1 is nearly two years old now, but only gets limited use, being totally disconnected when not in use. I think we all have to accept that bargains like this are landfill if they fail, as they usually have to go back to China and from 'the west,' it's extremely expensive to return. Sad state of affairs but I believe that's the way it is.

May be worth checking the power supply to the dac, as glitches there may take something out internally. No idea how expensive these add-ons are, but SBooster used to do inline extra-smoothing boxes for (years ago) not silly money which may help improve the quality of the supply and smooth out any potential nasties - maybe...

 

[Roland68]

My SU1 is nearly two years old now, but only gets limited use, being totally disconnected when not in use. I think we all have to accept that bargains like this are landfill if they fail, as they usually have to go back to China and from 'the west,' it's extremely expensive to return. Sad state of affairs but I believe that's the way it is.

May be worth checking the power supply to the dac, as glitches there may take something out internally. No idea how expensive these add-ons are, but SBooster used to do inline extra-smoothing boxes for (years ago) not silly money which may help improve the quality of the supply and smooth out any potential nasties - maybe...

You're slightly mistaken about the SU-1; aside from that DC/DC converter, it is actually a very robust device.
That specific converter is indeed the common point of failure in the SU-1. However, it can be relatively easily replaced with a high-quality DC/DC converter costing €3–7—one that will likely last for the next ten years.
Things like power smoothing boxes or other unnecessary gimmicks won't help in this case.