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SMSL SU-8 Version 2 Balanced DAC

badyard

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Hi, need some help. recently got the su-8 and noticed a weird behaviour.

If i'm on balanced cable connected to my amp and i switched the input from usb to optical while music is playing on the current input, there will be an extremely loud boom and subsequently no sound is coming out.

This does not happen if i connect the su-8 via unbalance cables. Has anyone else experienced this?
I suspect you have the old version 1.0 or 1.1 pcb, with the old 1.2 firmware.
The popping sound you hear it's a problem they've fixed in the current revision units.
If you've got the old unit I suggest you to return it and make sure you get the last version.
 

yeaster

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I suspect you have the old version 1.0 or 1.1 pcb, with the old 1.2 firmware.
The popping sound you hear it's a problem they've fixed in the current revision units.
If you've got the old unit I suggest you to return it and make sure you get the last version.

thanks. other than opening it up, do you know how can i tell the difference between version 1.0 or 1.1 pcb?
 

Ultrasonic

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That's an inherent benefit of a balanced end to end signal path, less noise. Although it is to mention that the noise levels even with the unbalanced connection are so low, to the point it hardly makes a noticeable difference anyway.

I think you misread what I wrote there: the unbalanced noise (other than mains peak and harmonics) appears LOWER than balanced - the opposite of what you, and I, expected. This is across the whole frequency range.

Edit: apologies, you didn't misread, I wrote the wrong thing! I'll edit my first post.
 

badyard

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I think you misread what I wrote there: the unbalanced noise (other than mains peak and harmonics) appears LOWER than balanced - the opposite of what you, and I, expected. This is across the whole frequency range.

Edit: apologies, you didn't misread, I wrote the wrong thing! I'll edit my first post.

If you meant that the "overall" noise appears to be higher in the balanced graphs, the slight increase you see I assume is probably due to the additional paths the signal has to run in a balanced design. It's a bit of a compromise in this case, mains noise wasn't much to begin with so you don't get much better results with balanced, but if you had to run longer cables, or you have other external sources of noise the difference would be much more noticeable.
 

badyard

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thanks. other than opening it up, do you know how can i tell the difference between version 1.0 or 1.1 pcb?
Unplug it from the power then plug it while holding the button near the display, you should see the firmware version.
If says 1.2 it's the old, 1.3 it's the last.
 

pantag

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I answered that above. The issue with using shared mode/kernel stack is that everything gets resampled to one sample rate. This is not optimal for playing different sample rates. There is also other processing that can impact the measurements. Audibly the impact is small to non-existent.

This is very helpful, thank you. One last question i have is around the sample rate and bit depth. What is the best option to select with WASAPI, for FLACs that can be 16bit or 24bit and max rate 192kHz? Will WASAPI down/upsample?
 

yeaster

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Huh...that's new i guess... Where and when did you get your SU-8 from? Can you open up the cover and tells us the board revision? Just 4 screws at the bottom and the cover pops up.

It shows the board revision as 1.2.

Edit: I'm guessing now that firmware v1.6 is causing the issue then.
 

Ultrasonic

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If you meant that the "overall" noise appears to be higher in the balanced graphs, the slight increase you see I assume is probably due to the additional paths the signal has to run in a balanced design. It's a bit of a compromise in this case, mains noise wasn't much to begin with so you don't get much better results with balanced, but if you had to run longer cables, or you have other external sources of noise the difference would be much more noticeable.

I wanted to make a distinction between obvious mains noise and the noise at other frequencies, but I think you understand me now.

Is this effect possibly an indication/result of the DAC not being inherently balanced, but rather an additional step at the end producing the balanced signals from an unbalanced one?

I do take your point about the major point being reducing/preventing larger mains noise spikes though.
 

badyard

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Is this effect possibly an indication/result of the DAC not being inherently balanced, but rather an additional step at the end producing the balanced signals from an unbalanced one?

No, because a balanced design does not reduce component related "self noise", but reduces considerably external noise which might be caused by electromagnetic interference.
Additionally the pcb design and components are suggesting a balanced end to end signal path.
 

Ultrasonic

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No, because a balanced design does not reduce component related "self noise", but reduces considerably external noise which might be caused by electromagnetic interference.
Additionally the pcb design and components are suggesting a balanced end to end signal path.

I was looking for a reason for balanced outputs to increase noise. So what are the "additional paths the signal has to run in a balanced design" that you referred to? I was following on from this, naively thinking they wouldn't exist is an inherently balanced design.

I realise we're talking about differences in very low level noise. The only reason I was looking at this is because I assume I ought to use balanced connections given I have the option, but there will be additional cost to me vs sticking with unbalanced,and I just spotted that balanced wasn't better in all ways as I'd expected. Preventing/reducing mains noise is I'm sure the more important consideration though.

(I've now ordered an SU-8 BTW, to hopefully be delivered on Friday.)
 
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amirm

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This is very helpful, thank you. One last question i have is around the sample rate and bit depth. What is the best option to select with WASAPI, for FLACs that can be 16bit or 24bit and max rate 192kHz? Will WASAPI down/upsample?
If you use WASAPI, the sample rate (and bit depth) will be automatically selected to match the content which is what you want.
 

badyard

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So what are the "additional paths the signal has to run in a balanced design" that you referred to?
In this case we have 2 ES9038Q2M stereo DAC modules, one is generating two identical Left channels the other two identical Right channels, then the signal path continues in this fashion. If it was an unbalanced design it would have been only 2 channels in the signal path.
 

badyard

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The only reason I was looking at this is because I assume I ought to use balanced connections given I have the option, but there will be additional cost to me vs sticking with unbalanced,and I just spotted that balanced wasn't better in all ways as I'd expected. Preventing/reducing mains noise is I'm sure the more important consideration though.

I personally think that in a professional or enthusiasts product at least a balanced connection (not end-to-end design) should be mandatory.

However the main benefits to the enjoyment seems to come from the fact that Left and Right channels each have their own signal path, which can also be the case with certain unbalanced designs, but then not all of this unbalanced designs have a balanced connection.

So to sort this out I'll say go with balanced if you are unsure and you have a limited budget but you really care about the sound.
Granted, i'm sure there are unbalanced designs which can perform better that this one to a certain degree, but this way you'll save money and potential hassle with unwanted noise in your system.

Also get Proel Bulk cables or other professional affordable cables if you don't have money to throw at hyped audiophile cable brands.
Avoid cheap unknown alternatives and you'll be good!
 

Jaimo

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Placed my order for a SU-8 with Shenzhen on Feb 8 and it's still in "processing". Looks like they are badly backlogged. Not sure if it applies to me but the website now say's that shipping is currently on Feb18 for SU-8 orders - Even with Chinese New Year considered, this is a long delay when added to shipping time to North America and pushes my expected delivery date close to a month from order. - Will update if anything changes...
 

richpjr

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Placed my order for a SU-8 with Shenzhen on Feb 8 and it's still in "processing". Looks like they are badly backlogged. Not sure if it applies to me but the website now say's that shipping is currently on Feb18 for SU-8 orders - Even with Chinese New Year considered, this is a long delay when added to shipping time to North America and pushes my expected delivery date close to a month from order. - Will update if anything changes...

Not sure about Canada, but you can order from Amazon (form Shenzhen) in the US and have it in 2 days.
 

pantag

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Placed my order for a SU-8 with Shenzhen on Feb 8 and it's still in "processing". Looks like they are badly backlogged. Not sure if it applies to me but the website now say's that shipping is currently on Feb18 for SU-8 orders - Even with Chinese New Year considered, this is a long delay when added to shipping time to North America and pushes my expected delivery date close to a month from order. - Will update if anything changes...
Same here. Placed my order a couple days ago and it is still processing. The banner that you see for Feb 18th, does not only apply to the SU-8. It is even on the front page of their site. I guess it is just backlog from the Chinese New year closing in combination with holiday shopping and of course, hungry Americans shopping for DACs. :)
 

Jaimo

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I didn’t see any option for shipping from the US when I checked out. What with the China tariffs I would have expected the US price to be higher. This way Canadians seem to be billed for the tariff and also hit with slow shipping. Still, the price is very good.
 
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