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SMSL M400 Balanced USB MQA DAC Review

MakeMineVinyl

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View attachment 85725
The filter is before the opamp. The two resistors and transistors are for muting fuction.
Are we talking about the same device even?:facepalm:
Unless I'm entirely missing something, there are two capacitors which go to ground after each resistor, ignoring the muting transistors (FETs). This would create a 2 pole filter if this is what's going on. They could be for click suppression in muting too, but unless we tear the unit apart, we'll never know. They could also be resistors, but why would they use this style SMD resistor when all the others are a different style? In any event, if they are using these series resistors to avoid loading the opamp outputs, they're choosing higher values than they need to do. There is a 'pole' created by the capacitor in the summing stage, but not knowing its value, its impossible to determine where in the frequency band this is effective.
 
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JohnYang1997

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Unless I'm entirely missing something, there are two capacitors which go to ground after each resistor, ignoring the muting transistors (FETs). This would create a 2 pole filter if this is what's going on. They could be for click suppression in muting too, but unless we tear the unit apart, we'll never know. There is a 'pole' created by the capacitor in the summing stage, but not knowing its value, its impossible to determine where in the frequency band this is effective.
If you look at the trace it's simply a differential amplifier with 2nd order filter. There's only resistor after the output.
 

MakeMineVinyl

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If you look at the trace it's simply a differential amplifier with 2nd order filter. There's only resistor after the output.
If there's a 2 pole filter, it goes from pin 6 of the 1611, this being a single opamp rather than a dual. In any case I'm not curious enough to tear mine apart to resolve it. ;)
 

JohnYang1997

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If there's a 2 pole filter, it goes from pin 6 of the 1611, this being a single opamp rather than a dual. In any case I'm not curious enough to tear mine apart to resolve it. ;)
One cap is from Vin+ to ground another is in the feedback. I can measure mine for you tomorrow if you want.
 

MakeMineVinyl

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One cap is from Vin+ to ground another is in the feedback. I can measure mine for you tomorrow if you want.
There are undoubtedly rail bypass caps, probably 0.1uF. If you want to dig in, I'd be curious to know exactly what's going on. I'm just not curious enough to tear apart my brand new DAC. In any event, I use the XLR outputs for listening and the RCAs only for secondary use when I want to dub a digital file to an analog tape machine. :)
 

JohnYang1997

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There are undoubtedly rail bypass caps, probably 0.1uF. If you want to dig in, I'd be curious to know exactly what's going on. I'm just not curious enough to tear apart my brand new DAC. :)
Screenshot_20201002-022501.jpg
These are the ones that caused the issue.
The yellow ones are of course rail bypass.
 

Veri

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Don't fight guys ;D this is all way over my head lol.

Enjoying the discussion though!
 

Harmonie

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I enjoy their enjoyment too,
it's funny to read their comments and look at the pictures, I feel reading a comics at the age of 3 (or maybe 4).
 

JohnYang1997

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"Caused"?

So it means it was fixed, if so then the PCB changed in any way?
That's the point of the discussion yesterday. He made measurements with no issues at higher than 44.1khz sample rate. I do not know what really happened. I am only sure the cause for the phenomenon I measured.
 

pinky-me

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To open the dac you need to remove all screws from the bottom (including the ones under the rubber feet) and connectors on the back (except the Bluetooth antenna). Then the entire top and sides lift up and you need to pull 2 flat cables out (bigger one has a latch) as well as the antenna connector. Pretty easy.
 

MakeMineVinyl

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I just did some RTA sweeps of the filters in the M400 at 44.1kHz and at 96kHz. The uppermost magenta and orange are at 96kHz (the limit of my ADC) with the 'sharp' filter and 'low dispersion' filters (the 'short' variations of the filters measure identically to their 'non-short' versions). The yellow, also at 96kHz, is the 'slow' filter which is what I use for listening. The filters which roll off a bit above 20kHz are all at 44.1kHz sampling rate. The cyan one is the 'super slow' filter. What is interesting is the notch in the cyan and magenta 'slow' filters and the lesser notch in the 'low dispersion' filter (green). I don't know if these notches in response are an artifact of my measurement, but I tend to doubt it. I upsample to over 384Khz in Audirvana on my computer, so I will never see this behavior. Anyway, interesting.

SMSL M400 Filters.jpg
 

MBWORLDZ

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Hi there, I am new to this. I do have the questions with the MQA, may be some of you can help me answer it. I don’t want to use any of the PC or Roon setup. Just want to stream directly through my Tidal or Quboz from Android or Ipad devices.

Right now I have the Cambridge CXN V2, which this unit doesn’t support MQA at all. I want to know if I add a MQA Decoder on the top of it, would it decode Full MQA using the hardware to get 24bit / 192khz. or even higher.

Here is the setup, can someone let me know if this work?

Cambridge CXN V2 ---> Digital Out (Toslink/Coaxial) --->
SMSL M400 DAC or Topping D90 (Line Input) ---> Then Coaxial RCA out ---> My Amp (Coaxial Input)

Will it work?

What I know is if I use Digital Coax or Toslink connected from Cambridge to the MQA dac, it will bypass the decode from Cambridge and use the new MQA Dac to decode. But I want to know if this will work for full MQA decode and give me 24bit / 192khz when using either above MQA DAC.

Any feedback will be great. Thanks.
 

Jimbob54

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Hi there, I am new to this. I do have the questions with the MQA, may be some of you can help me answer it. I don’t want to use any of the PC or Roon setup. Just want to stream directly through my Tidal or Quboz from Android or Ipad devices.

Right now I have the Cambridge CXN V2, which this unit doesn’t support MQA at all. I want to know if I add a MQA Decoder on the top of it, would it decode Full MQA using the hardware to get 24bit / 192khz. or even higher.

Here is the setup, can someone let me know if this work?

Cambridge CXN V2 ---> Digital Out (Toslink/Coaxial) --->
SMSL M400 DAC or Topping D90 (Line Input) ---> Then Coaxial RCA out ---> My Amp (Coaxial Input)

Will it work?

What I know is if I use Digital Coax or Toslink connected from Cambridge to the MQA dac, it will bypass the decode from Cambridge and use the new MQA Dac to decode. But I want to know if this will work for full MQA decode and give me 24bit / 192khz when using either above MQA DAC.

Any feedback will be great. Thanks.

No- will not work. You dont cast from the phone to the CXN- you tell the CXN to look at the Tidal stream . You cant cast Tidal Masters (MQA) . Nor does the CXN built in Tidal app receive the MQA files.

You could use your phone into the USB of the CXN and use the Tidal app to do the first MQA unfold and output up to 24/96 to the CXN. Or likewise plug a PC/MAC running the Tidal app in via USB and do the same. I believe the CXN will pass through the full MQA file out of its optical/ coax digital out if you send it from a PC and adjust the pC Tidal app settings to not do the software decode. But I might be wrong on that.
 

zjx1017

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I got mine with discount price at 600$ from ShenzhenAudio website last week.i wonder where that 400$ one bought from
 

Googolbyte

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800$ is quite a regular price, you may have some discount from time to time.
400$ id an incredible price. Did you get it new in a sealed box ?
Where ?

I got mine straight from Amazon, and it was definitely new and sealed in the box.
 

ethanhallbeyer

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got mine with the fix... $600-something shipped during recent sale... never saw for $400 on amazon... you have your invoice?
AC637E73-B834-4565-8447-29A59813D4F7.jpeg
 
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