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SMSL SU-8 Version 2 Balanced DAC

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SMSL answers sales questions but does not answer any obstacles or technical questions.
Topping, on the other hand, responds sincerely to the consultations from our users.

I think your SU-8 V2 symptom is probably a USB firmware issue. There are other problems with SU-8 V2.
However, regarding SU-8 V2, SMSL is no longer aggressive and I don't think there is any hope for improvement.
Yeah that's what I suggested to them, USB drivers, firmware, etc. No response unfortunately.
 

phoenixsong

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Thanks for the replies guys. This is my first stand alone DAC and have nothing to compare it to, but I like it. I use its XLR outputs to my amp, playing Tidal through my laptop and phone. I also dig the remote functionality. My only issue right now, is wanting it to do the decoding instead of my Oppo 93 for disc playback, still working on that.. Also looking for a nice streamer with ethernet to handle Tidal and the like.
I think you'll find this really helpful: SACD on blu-ray player, as digital input to external DAC? How? | Headphone Reviews and Discussion - Head-Fi.org (head-fi.org)
(The guy's even using the same model of player as you)
 
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Update for those who responded and are interested. I set my Oppo to bitstream prior to turning on the SU-8, which I didn't do last time and it is now playing as it should, with the dac in the SU-8 doing the decoding.
 
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viper414

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Your report is very informative and valuable.
The XLR output pop noise problem is also common to the M500's XLR output.
If you connect the M500 directly to a power amplifier that does not have an input volume via XLR, a large pop noise will occur. When I connected the XLR for the first time, I was surprised by the loud noise.
I was thinking of replacing the M500 with the SU-9 because of this, but I'm worried that the SU-9 may be the same after seeing your report.
Yes I have similar worries too with these DACs now. The Quality control doesn't seem that high. The price is right and sound is great(also measures extremely well) but these are problems we will not get with the Branded models that may measure less but also receive less issues.
 
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Reading about the pop noise being talked about, I am wondering how things are being powered up to get that popping noise? Are you turning on the DAC first, then insuring its volume level is turned down, then powering up the amplifier afterwards?
 

mononoaware

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SU8v2 user reporting back too, zero issues here except the occasional light pop when turning on. I've had the unit almost since release of the v2 version, probably 2 years now? Granted I have mine at fixed bitrate since I don't care for anything beyond 16/44. Here's hoping that it lasts me 20 years because I see absolutely zero reasons to change it.

Editing post to add that I use mine exclusively via the XLR outputs via a professionaly made (NOT expensive but made by a professional) Y splitter on Mogami Multi cable (which is designed for balanced Y splitting) and Neutrik connectors, one split going to my SP200, another one to my JBL LSR305 Mk1 monitors.
Hi I would like to add to this,

I also report zero issues for years using XLR outputs of SU-8 V2.
Setup: Source (constant Bit/Sample rate) > Optical cable > SMSL SU-8 V2 > XLR cables > Studio Monitors
I have noticed a very quiet pop when changing the "filter" and "sound color" settings, but I only changed these settings in the beginning when testing them.
I leave the settings to default: "Fast Linear" Filter + "Standard" Sound color, and for years now I only control "volume" (no pops) and "on/off" (no pops) (Sequence: SU-8 is first on and last off).
It has been a flawless device, until I recently tried the RCA outputs for the first time.

Setup 2: Source (constant Bit/Sample rate) > Optical cable > SMSL SU-8 V2 > RCA cables > Monoblock Power Amplifiers > Speakers
Everything in the chain is identical to first setup except from RCA cables and after.

So this is the issue which happens only on RCA outputs.
1. "Power on" the SU-8, it takes a second to remember/show last used input (optical), and then shows volume when it is ready.
2. "Power on" the Monoblock Amplifiers --At this point before anything is played from the source there is no noise in the signal (same silence as XLR output)--
3. "Play" audio (song) from source (optical), then after song ends or I stop the audio --At this point there is constant audible noise in the signal, I can hear it from the listening position after the song ends, and I can even hear it in quiet passages of songs--
The best way I can describe the noise is high pitched "coil whine". Keep in mind it is quiet from listening position, so with busy loud songs I can sometimes forget it is there, but I can hear it in quiet/silent passages.
Adjusting the volume up or down has no effect on the level of the noise, it is always constant and same level of noise.

Summary:
- XLR outputs: controlling only "volume" and "on/off" sequence, the SU-8 is silent and works as expected.
- RCA outputs: same conditions as XLR. Before source is "played" the signal is silent, but after source audio is played there is constant audible "whining" noise in signal.
I can power cycle everything to reproduce the issue.
I am using optical input connection so that should rule out any noise from the source.
Edit: just now I considered it may be ground loop related since noise is on RCA outputs but not XLR.
I will do more troubleshooting tomorrow...

The SU-8 V2 "XLR output" is great (no pops when adjusting volume and correct on/off sequence), but the SU-8 V2 "RCA output" has noise issues.
I did not realize until I used the RCA outputs for the first time.

-

V1 Measurement (RCA 60hz/120hz noise, XLR shows same noise)

As noted, I powered the D50 using a Samsung charger I had laying around. Let's compare that to SMSL SU-8 using its unbalanced output:


We see fair bit of power supply noise at 120 Hz and other harmonics of mains 60 Hz. We take a 4 to 5 dB hit in SINAD (signal above distortion+noise).

There is fair bit of interest in balanced outputs of the unit so let's see how that did:



Distortion climbs unfortunately reducing SINAD to 86 dB.
V2 Measurement (RCA 60hz/120hz noise, XLR No Power-supply noise)

Measurements
Let's start with our unbalanced dashboard:


This is some 8 dB improvement in SINAD/distortion relative to original review sample! Let's see how our previously problematic balanced output performs:
 
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mononoaware

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Update after further troubleshooting with noise in RCA outputs...

Turned the DAC then Amplifier's on as explained above in my first post, confirmed the signal was silent, and then left it on for ~1.5 hours, and then confirmed again the signal was dead silent.
Then I proceeded to play music, then after source playback the "coil whine" noise was present again.

It seems to be when using Optical (Toslink) input, the SMSL SU-8 V2 when first turned on has a standby/sleep mode as it waits for a digital signal.
And when left alone after "power on" the RCA outputs are deactivated or simply not outputting any signal (maybe someone with a voltage measuring device can confirm this).
As soon as signal is sent to the DAC by Optical (Toslink), the SU-8 wakes up from sleep and proceeds to do D/A conversion and output via RCA (in this case the problematic output).

I suspect this "coil whine" noise in the signal is the SU-8 being very sensitive to the power it is receiving or simply "power supply" noise in the DAC when using RCA outputs.
After this I did re-arrange the power sockets of all connected devices, I connected just the Monoblock Power Amplifiers to another wall socket.
The "coil whine" noise in the signal was still present in the signal after playback, it could have been quieter, but I think that is just due to listening for it at a different time of day.
- just a reminder: the XLR outputs have none of the noise issues which are experienced with RCA outputs.

Noise through RCA is audible from near-field listening position depending on audio content (audio with higher dynamic range seem to reveal the noise).
Only solution I can think of is getting/putting another DAC in the system and using it just for RCA outputs.
Currently I will accept that this is a minor flaw of the SU-8, which was priced very reasonably to begin with given it's features.
 
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AnalogSteph

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What exactly were you connecting to the RCA outputs? I'd suspect some possible common mode (ground loop) issues that just happened to make this power supply related noise audible.
 

mononoaware

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What exactly were you connecting to the RCA outputs? I'd suspect some possible common mode (ground loop) issues that just happened to make this power supply related noise audible.
The SU-8 V2 RCA outputs are connected directly to Monoblock Power amplifiers (maybe unconventional).
I am using Optical (Toslink) connection to the SU-8 input.

I have heard from some others that recommend against connecting SU-8 direct to Power amplifiers, due to the SU-8 sending voltage spikes (which manifest as audible pops) when changing certain settings on the DAC (bit/sample rate, filter setting, sound color setting).
I only control on/off and volume, which are free from this "popping" issue, so I have never run into this problem.

I read your post yesterday, and planned on trouble shooting again today so I am posting now to give you more up-to-date information.

I read in another forum about a person also experiencing "noise" in their system coming from the speakers, and about half-way through the thread they mentioned that they had a device plugged in with no ground pin on the power socket, so they removed that and the noise went away (apparently this was not the end to their solution due to their options etc).
Today I checked all the plugs and I did have one device without a ground pin.

So what I did is plugged every single plug with a ground pin into the same "power board" -> going to one wall-socket.
Then plugged the device without ground pin into its own separate wall-socket.
(Please advise if this is the correct method to eliminate ground loop).

Well the result is. . . the noise is still there.
The noise is the same amount in volume as when just the Monoblocks into a separate wall-socket, which I tried previous to this method.
I would appreciate any input you could give. . .
 
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mononoaware

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One more observation, with everything else left on and turning just the source off, the noise stops.

The source is a Apple TV being used as a streamer.
So if the source is connected with optical, and switching it off stops the noise, one would conclude it is the source power supply introducing noise into the power circuit.
(Maybe it is in fact not the SU-8 power supply noise I am hearing)

But the source is already plugged into its own separate wall-socket.

Just to repeat myself none of this noise gets through when using the XLR outputs of SU-8 V2.
 
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Celty

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No noise with XLR does tend to steer your search toward ground loop issues. As Amir has stated, those can be devilish to track down and resolve.
 

mononoaware

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No noise with XLR does tend to steer your search toward ground loop issues. As Amir has stated, those can be devilish to track down and resolve.
Yes for now I am concluding the power supply inside the streamer is directly causing the noise, and there is not much I can do about it.
(I have read many examples where the noise is from a computer with a large power supply)

But I am aware even small AC power supplies (wall warts) can start making a very high pitch whine from the device itself just from long use/old age.
So I imagine something similar is happening with the streamer, only it is not audible directly from the device itself, but through the nearby speakers.

I will do some more online research and update if I do find out anything new.
 

mononoaware

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Hi everyone,

Just thought I should clear some things up.

Noise directly from device (switched on in isolation):
- SMSL SU-8 V2: with ear to DAC constant quiet whine, silent from listening position.
- Apple TV 3 streamer: with ear to ATV, silence.

Noise from ATV -> Optical -> DAC (SU-8 V2) + Monoblocks connected to speakers - all switched on
- XLR outputs: silence from speakers.
- RCA outputs: “coil whine” like sound from speakers, audible from listening position (when nothing is playing, during quiet passages in audio).

Temporary fix: With everything else on, Turn off the ATV. The noise stops.

-

At first since the SU-8 switched on in isolation makes a coil-whine noise (quiet auxiliary sound from device itself), I first assumed this is the same noise coming from the speakers when using the RCA outputs from DAC.

But after further troubleshooting and understanding of the components, it is most likely a ground loop due to the ATV acting like a switch for the noise.

The “coil whine” noise coming from the speakers sounded that way because the speakers used single Fostex FE103NV drivers which when given a pure/un-colored signal produce little to no low-frequencies. This is what must have taken away the typical low-frequency “hum & buzz” associated with ground loop noise, making it sound more like a high pitched whine through the speakers.

Plugged all other components into the same power board into a single wall socket and there is still noise.
Then tried plugging only the ATV to every single other Wall power socket in the room and there is still noise.

So current conclusion is still:
Only use the SMSL SU-8 V2 for its XLR outputs.

A better description of the noise coming through the speakers is like the “ringing” you hear after an extremely loud noise.
It is audible from listening position as soon as the ATV is switched on (playing AirPlay wakes it up from standby) and depending on the dynamic range of the audio content. A way I found to check this is by listening to music that fades away slowly at the end.

Currently it seems like the only option to connect to Monoblock RCA inputs is to get a decently built Streamer/DAC/Pre-amp like the Yamaha WXC-50, and connect the RCA pre-outputs to the Monoblock Power Amplifiers.
 
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Andrii

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Guys, please forgive me for my English and ask for your help. I purchased SMSL SU-8 V2 and it does not work with a remote control. Rather, he can work, and then stop and I do not know what to do about it. What was done: 1. Batteries are new and inserted correctly (I tried to change the batteries) 2. When you click on the remote button, the remote control sensor is lit on all buttons except A, B and C 3. The remote control can work (and works correctly), but then it simply turns off and does not respond at all. After a while, it can start working again (I can not understand regularities). If someone came across such a problem, tell me whether there is a way to solve
 

mononoaware

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Guys, please forgive me for my English and ask for your help. I purchased SMSL SU-8 V2 and it does not work with a remote control. Rather, he can work, and then stop and I do not know what to do about it. What was done: 1. Batteries are new and inserted correctly (I tried to change the batteries) 2. When you click on the remote button, the remote control sensor is lit on all buttons except A, B and C 3. The remote control can work (and works correctly), but then it simply turns off and does not respond at all. After a while, it can start working again (I can not understand regularities). If someone came across such a problem, tell me whether there is a way to solve
I suggest a factory reset.
This can be done as follows:

1. Turn off power at wall switch.
2. Wait 1 minute.
3. Hold the “device” power button (only 1 button) on SU-8 and keep holding while turning on power (with other hand) at wall switch, keep holding until SMSL logo shows on DAC, then let go of button.

Then with remote, before any other button, press C button once.

Even with future use try not to press A, B, C button again.

In case of main power cut, remote can stop working, I press C button once and remote works again.

Use “remote” power button to turn DAC into standby (on/off) and it should work smoothly.
Only when main power is cut you have to press C button again.
 

Andrii

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I suggest a factory reset.
This can be done as follows:

1. Turn off power at wall switch.
2. Wait 1 minute.
3. Hold the “device” power button (only 1 button) on SU-8 and keep holding while turning on power (with other hand) at wall switch, keep holding until SMSL logo shows on DAC, then let go of button.

Then with remote, before any other button, press C button once.

Even with future use try not to press A, B, C button again.

In case of main power cut, remote can stop working, I press C button once and remote works again.

Use “remote” power button to turn DAC into standby (on/off) and it should work smoothly.
Only when main power is cut you have to press C button again.
Thank you for your answer, MononoaWare. I forgot to specify, Factory Reset I did several times and it does not help. Once the remote earned when I turned off a couple of minutes, but after a while I stopped working again. I have a couple of questions: 1. If the bullets are sent to the camera to the camera and press the buttons A, B and C, the glow of the sensor is visible (I see a response from all buttons, but from these - no) 2. How long should be pressed on the C button?
 

mononoaware

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1. If the bullets are sent to the camera to the camera and press the buttons A, B and C, the glow of the sensor is visible (I see a response from all buttons, but from these - no)
The A, B, C buttons just program the remote for SMSL DA-8, SH-8, SU-8 devices.
You do not need to point remote when pressing these buttons.

2. How long should be pressed on the C button?
Just quick press as with other normal remote button.

-

If you are still experiencing problem after factory reset. I think maybe the remote control is faulty, or the receiver (camera) in the SU-8 DAC.

First I suggest you ask for replacement remote control as it is lower cost and easier fix.
If problem continues, I think you may need to return SU-8 and buy another.
 

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