strange SMSL M500 high 3rd harmonic

[Dmaumau]

@amirm @WolfX-700 and guys, Is it possible to verify this problem with an osciloscope ?

I have a 2 channel 50MHz Tektronix 1052b osciloscope and I made this tests

My M500 has SW 1.7 and HW 1.3

FFT 1KHz both channels

FFT 1KHz Left Channel Only

FFT 1KHz Right Channel Only

The only thing that bothered me is that i´ve read about the left channel and I could reproduce this in both channels.

I´m measuring the rca outputs, dac connected to a windows PC thru USB and a windows tone generator.

Is this right ?

 

[Dmaumau]

No thoughts at all ?

Were my ideas of measurement THAT stupid ?

 

[JSmith]

Tektronix 1052b

https://www.testequipmentdepot.com/tektronix/pdf/tbs1000b-series_datasheet.pdf

Need advice on gear to measure DACs, amps and headphones.

Hi, I would like to have some guidance on making my measurement rig for measuring DACs, amps and headphones. Of first priority is DACs because I believe I have most of the necessary gear and I have been able to personally design the tones needed to measure the same. I personally feel that audio...

www.audiosciencereview.com

DAC noise observation on Oscilloscope

Hi, I am trying to observe some DAC points on an oscilloscope. It is a sigilent 200MHz scope. Probe is correctly compensated and set at 1x. CH1(yellow) is connected to the GND stub on the scope CH2(pink) is connected on the DAC XLR output (between pins2,1) The DAC is powered on but there is...

www.diyaudio.com

To test for this issue you need to run 2 different frequencies on the L/R channels to simulate stereo. It won't show using the same L/R or a channel at a time.


JSmith

 

[Dmaumau]

Now we are going somewhere.

Thanks @JSmith

 

[Dmaumau]

Hi guys,

First of all I would like to thank @SMSL-Mandy for all the support and for sending me the programming tool to solve the problem with my M500.

The instructions are very clear and the process went without hickups.

The only thing to mention is that I could not flash the M500 using my Windows 11 PC.

I received the message that the file could not download to the M500 several times.

Switched to another PC with Windows 10 and it worked the first time.

 

[Deleted member 46664]

@amirm @WolfX-700 and guys, Is it possible to verify this problem with an osciloscope ?

I have a 2 channel 50MHz Tektronix 1052b osciloscope and I made this tests

My M500 has SW 1.7 and HW 1.3

FFT 1KHz both channels

FFT 1KHz Left Channel Only

FFT 1KHz Right Channel Only

The only thing that bothered me is that i´ve read about the left channel and I could reproduce this in both channels.

I´m measuring the rca outputs, dac connected to a windows PC thru USB and a windows tone generator.

Is this right ?

That waveform looks like it might be clipping ... try turning the signal generator's output volume down slowly... as you pass under the clipping boundary the harmonics should go away.

 

[snubbers]

Apologies for bumping this one..

I've recently bought a second hand M500 (v1) and sadly my brief research prior to purchasing for reviews did not unearth the 3rd harmonic issue.

The unit hardware/software versions are HW 1.3 / SW 1.7 and looking at this thread and people's upgrading of firmware if the v1.7 software had the fix for the 3rd harmonic issue applied or not? I suspect not, but wanted to check, I've reached out to @SMSL-Mandy anyway, and don't mind a bit of DIY programming if needed! (We make products with STM32F439's in so have plenty of the ST-Link SWD/JTAG USB interfaces lying around!)

Obviously my ears probably couldn't tell the difference, but you know pyscho-acoustically just knowing of an imperfection often has your mind listening out for things it really shouldn't!

 

[JSmith]

I've reached out to @SMSL-Mandy anyway, and don't mind a bit of DIY programming if needed! (We make products with STM32F439's in so have plenty of the ST-Link SWD/JTAG USB interfaces lying around!)

The M500 needs to be opened up to perform this update unfortunately... they will probably ask you to send it to them or a local distributor for update. Or they might send you the JTAG device, if you mention you are capable of and prepared to do same.


JSmith

 

[snubbers]

The M500 needs to be opened up to perform this update unfortunately... they will probably ask you to send it to them or a local distributor for update. Or they might send you the JTAG device, if you mention you are capable of and prepared to do same.


JSmith

Thanks!

Fingers crossed!

 

[jpgolding]

I bought my M500 in October 2021 from Amazon, so presumably it is of a late enough batch to have the updated firmware with the 3rd harmonic issue fixed.

These are the results from REW, with RCA outputs on the DAC connected to the 3.5mm line-in on my PC's soundcard.

I note all the harmonics are higher than on other people's measurements (presumably this is due to the soundcard not being of "audiophile grade") but there doesn't seem to be a difference between the left and right channels.

Forgive me if I've made some basic noob errors, but do you think I can rest assured that my M500 is all good?

 

[Laserjock]

I bought my M500 in October 2021 from Amazon, so presumably it is of a late enough batch to have the updated firmware with the 3rd harmonic issue fixed.

These are the results from REW, with RCA outputs on the DAC connected to the 3.5mm line-in on my PC's soundcard.

I note all the harmonics are higher than on other people's measurements (presumably this is due to the soundcard not being of "audiophile grade") but there doesn't seem to be a difference between the left and right channels.

Forgive me if I've made some basic noob errors, but do you think I can rest assured that my M500 is all good?

Is this mono? Problem was with different levels (stereo) signals.

 

[jpgolding]

Is this mono? Problem was with different levels (stereo) signals.

The problem is that REW will only allow me to measure either the right or left channel output, not both at the same time.

If I'm overlooking something then excuse me, and please point me in the right direction.

Is it safe to assume that all new M500s sold since SMSL acknowledged the problem, have the fix applied?

 

[Laserjock]

The problem is that REW will only allow me to measure either the right or left channel output, not both at the same time.

If I'm overlooking something then excuse me, and please point me in the right direction.

Is it safe to assume that all new M500s sold since SMSL acknowledged the problem, have the fix applied?

You would think so but wouldn’t trust them.

 

[Laserjock]

Thanks!

Fingers crossed!

Get it done?

 

[aerochrome2]

Lurker reporting in, it sure if it’s of interest but I’ve been ok with my 500 for a while, the form factor is perfect just don’t like what I’m reading and it’s not good for my chakras! I spoke to Amazon today after purchasing in 2019! Said very briefly “scam, op amps not the same, measurements lie”

Was offered a full refund from Amazon instantly

Was the easiest return ever so not sure if it’s on a list of products the CS reps referred to and allowed the late return

How did you do this exactly? I just got shut down in chat with an Amazon rep for a unit from December, 2020 since I was over 2 years out. They say they escalated internally twice and I was denied.

 

[aerochrome2]

40 is max. At 30it is nowhere near their spec performance. In my case as far as I remember I need to turn volume down to 20 to have acceptable thd behavior.

Does it matter if I have the volume bumped elsewhere in the chain? I.e., if I have my streamer/pre-amp or amp turned up to compensate, but keep the SMSL at 15 or 20, does that work?

 

[Nikkel]

Correct me if I'm wrong, so this issue only reveals itself in "Pre" mode rather than "DAC" mode via RCA only...?

Got a SU-9 in Oct 2020 and I'm in South Africa

 

[Veri]

Correct me if I'm wrong, so this issue only reveals itself in "Pre" mode rather than "DAC" mode via RCA only...?

Got a SU-9 in Oct 2020 and I'm in South Africa

The problem should be in the DAC programming so if it's fixed it's fixed on all outputs really.

 

[Nikkel]

I received the jtag update tool from @SMSL-Mandy, thank you kindly but no instructions... Anyone here that could help please?

I have a SMSL SU-9

 

[Qusk]

Hi,

What settings should I use in REW to test this correctly? My numbers doesn't seem right.

Setup for testing:

M500 -> USB -> PC
M500 -> RCA stereo to 3.5mm -> PC line-in