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Topping M50

Fleuch

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If you use the M50 with input (other source device) via Bluetooth or USB, then the M50 no longer acts as a player (source device) but only as a bridge. There are no more player functions, therefore no EQ functionality. In this mode, the M50 is just an interface converter.

What would be the point of going into the M50 with a USB source device and then connecting a USB DAC to the M50?

According to Topping's description, you can connect a USB storage device and a USB DAC to the M50 (player mode including EQ function) at the same time and play the music files from the USB storage device on the DAC.
If it is possible to go into the M50 with a USB source (USB HDD, USB Flash Drive, or SD card) and output to a USB DAC, the M50 would replace a PC/Mac in the music file path, with a device that, hopefully, has its design specification based on sound audio principles. There may be other ways to achieve the same objective, but most alternatives seem to be particularly expensive.

The USB connections on a PC/Mac are notoriously noisy, particularly the power rails, since the power supply in a PC/Mac is unlikely to be optimised for stability. For example, there is a possible problem of a voltage difference between the 0V rail on a PC/Mac and the 0V rail on a USB DAC, or the CPU demand causing a dip in the 5V rail. These mght not be major problems but are a potential source of noise at the input to the USB DAC.

The table for input/output in the user manual for the M50 states: USB Storage Devices/HDD/TF card IN [can output to] Bluetooth; USB-OTG OUT; SPDIF/IIS OUT. Great, connect to the USB DAC using the USB-OTG connector as output.

The connection diagram for the USB Storage Device/HDD/TF card indicates a USB HDD or USB Flash Drive as input to the USB-OTG connector with the output taken from HDMI/OPT/COAX USB cable. Without the M50 available "on the desk" to investigate the menu settings to configure the input/output options, the manual seems to lack clarity when it is necessary to state how this combination of input/output is configured.

The user manual also shows file formats APE, WAV, FLAC and mp3 are "CUE supported". Hopefully this means that CUE files can be used to control playback, rather than having to select each track as part of a playlist. There is no further explanation of what "CUE supported" means.

Lastly the user manual states the HiByMusic app can be used as a control point. As the M50 is DLNA certified it should be possible to use any app that complies with the DLNA standard, such as Bubble, shouldn't it?

To summarise, all of these points suggest that there is a need to improve clarity in user manuals and not leave any aspect of the operation of a device to interpretation. Otherwise the M50 does all I want it to do, but it would be fantastic if Topping provided Amir with a production sample to see how the M50 stands up to rigorous testing.
 

Roland68

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If it is possible to go into the M50 with a USB source (USB HDD, USB Flash Drive, or SD card) and output to a USB DAC, the M50 would replace a PC/Mac in the music file path, with a device that, hopefully, has its design specification based on sound audio principles. There may be other ways to achieve the same objective, but most alternatives seem to be particularly expensive.
Almost every Raspberry PI achieves this functionality with the free Volumio version, e.g. a Raspberry Pi Zero 2 W for around €16, or with a power supply unit and housing for less than €50. Even with a 5" touch display you pay less than € 100. However, that would also work with a mini PC or board with an Atom processor or an older MAC Mini for € 50 - 150. Comfortable operation via APP, web browser or (touch) display.
The USB connections on a PC/Mac are notoriously noisy, particularly the power rails, since the power supply in a PC/Mac is unlikely to be optimised for stability. For example, there is a possible problem of a voltage difference between the 0V rail on a PC/Mac and the 0V rail on a USB DAC, or the CPU demand causing a dip in the 5V rail. These mght not be major problems but are a potential source of noise at the input to the USB DAC.
The dirt or noise that you mean comes from various components, including displays, DC step-up or step-down converters, various switching regulators, processors, various ICs, power supplies, etc. However, this is present in all devices, even (or especially) in mobile ones DAP with battery.
However, this is not a problem with more modern and well-designed DACs, as these devices do not use the 5 volt supply voltage from the USB port. You can easily test this by isolating the + contact of the 5V power supply on the USB connector with a piece of adhesive tape. With older or poorly designed DACs, you can separate the + line of the 5V USB power supply and supply it with an external power supply.

0 volt is 0 volt, even with different devices. You probably mean the different potential of the individual devices, which can be equalized via the ground line of a supply voltage if the design is poor. But that's exactly what shouldn't happen.
In the ideal case, each device is grounded via its mains connection, which is used for equipotential bonding. With devices connected to each other via USB, assuming the right design, this compensation can also take place via the shielding of the USB cable.
 

Fleuch

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Ground loops can occur simply because the 0V rail is relative to each device, so 0V on a PC/Mac is not necessarily the same 0V at the DAC, particularly when power is supplied from different mains outlets.

At the same time the switching noise within a PC/Mac or RPi can impact both power rails. Perhaps a Topping M50 will never be on the want list of some folk but it is a better proposition than a Limetree bridge at around €750, or having to juggle the components of an RPi arrangement, together with the uncertainties of coding and making the individual components work as a whole. Replacing a PC/Mac with an RPi does not meet the need for an audiophile grade digital transport, which removes a standard PC/Mac or RPi from the music file pathway.

Voltage fluctuations on the power rails will also impact the signal levels transmitted on the USB cable, which will not be mitigated by cable shielding. Reclocking and galvanic isolation are expensive solutions to cleaning up a digital signal.

By the way, I have a USB cable with a small connector to connect/disconnect the 5V power line. SBooster offered a USB plug-in that only passed through the signal lines. The Topping HS01 also has a similar function, but a small connector in the cable is much cheaper.

If all modern DACs were well designed there would be absolutely no need for Amir to continue to test device performance.

This is moving well away from discussion of the Topping M50, which is the thread topic, and really is more approriate to a different conversation.
 

kchap

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At the same time the switching noise within a PC/Mac or RPi can impact both power rails. Perhaps a Topping M50 will never be on the want list of some folk but it is a better proposition than a Limetree bridge at around €750, or having to juggle the components of an RPi arrangement, together with the uncertainties of coding and making the individual components work as a whole. Replacing a PC/Mac with an RPi does not meet the need for an audiophile grade digital transport, which removes a standard PC/Mac or RPi from the music file pathway.
I have 3 Raspberry Pis, all installed in a metal case - for cooling, all using standard USB PSUs and all connected to USB DACs. I have no problems with hum and noise. A Raspberry Pi, an X86 PC, a MAC and very likely, the computer chip is inside the M50 can all meet the needs of "audiophile grade digital transport"; software being the main issue as opposed to hardware.

The reason for the lack of interest is not the performance of the M50 but rather the Raspberry Pi, the X86 PC and the MAC seem to be more versatile and a RPi or Celeron SBC would be similarly priced.

Voltage fluctuations on the power rails will also impact the signal levels transmitted on the USB cable, which will not be mitigated by cable shielding. Reclocking and galvanic isolation are expensive solutions to cleaning up a digital signal.
The mention of reclocking seems to indicate a misunderstanding about the current generation of Asynchronous USB DACs. AUSB DACs do not use the recovered I/C clock to synch the master clock. The master clock, in control of the DAC, runs independently of the recovered clock and is therefore independent of the upstream host's clock.

This PDF: USB Audio is possibly a bit dated but it gets the concept across with a bit more detail than my following summary.

In ASUB mode the I/C data is written to a buffer at a rate determined by the recovered clock. Under control of the master clock data is read from the buffer and passed to the DSP/DAC. When the buffer sizes reaches a point where overflow could occur the USB controller sends a message to stop sending. If the buffer lower limit is reached the controller requests additional data.

Any jitter caused by time and frequency distortions or noise are removed as the buffer is always being read at a constant rate regardless of variations in the write rate. The concept of the DAC controlling the data rate is also used with I2S DACs. This means that I2S DACs can perform as well as but no better than AUSB DACs.
 

Berwhale

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At the end of the day, Topping made this nifty thing because a certain amount of folks wants to play local files at best.
I'm among them, for sure.

Yes, especially if you already have the rest of the stack (currently driven by a CCA blu tacked under the table)...

IMG_20220502_162958 (Small).jpg


1651505550653.png
 

Berwhale

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wrote to Topping support on some q's rasied here, attaching their reply


View attachment 201323

guessing the EQ works on external HDDs

That's strange, why would it work with a 4TB HDD, but only a 256GB flash drive? I think it's highly likely that the unit will support higher capacities of both microSD and USB flash drive, but they just haven't tested them.
 

Fleuch

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At the end of the day, Topping made this nifty thing because a certain amount of folks wants to play local files at best.
I'm among them, for sure.
Quite agree, my requirement is to play local files without a computer in the music file pathway. Also quite surprised to find there is no power supply "in the box", only a USB to OTG cable to connect with a phone charger.
 

Berwhale

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Quite agree, my requirement is to play local files without a computer in the music file pathway. Also quite surprised to find there is no power supply "in the box", only a USB to OTG cable to connect with a phone charger.

Perhaps Topping want to shift more of the P50 Linear PSUs? The P50 has sockets to power a D50s, A50s and M50 (mine is currently powering a D50s/A50s and Chrome Cast Audio).
 

Fleuch

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I have 3 Raspberry Pis, all installed in a metal case - for cooling, all using standard USB PSUs and all connected to USB DACs. I have no problems with hum and noise. A Raspberry Pi, an X86 PC, a MAC and very likely, the computer chip is inside the M50 can all meet the needs of "audiophile grade digital transport"; software being the main issue as opposed to hardware.

The reason for the lack of interest is not the performance of the M50 but rather the Raspberry Pi, the X86 PC and the MAC seem to be more versatile and a RPi or Celeron SBC would be similarly priced.


The mention of reclocking seems to indicate a misunderstanding about the current generation of Asynchronous USB DACs. AUSB DACs do not use the recovered I/C clock to synch the master clock. The master clock, in control of the DAC, runs independently of the recovered clock and is therefore independent of the upstream host's clock.

This PDF: USB Audio is possibly a bit dated but it gets the concept across with a bit more detail than my following summary.

In ASUB mode the I/C data is written to a buffer at a rate determined by the recovered clock. Under control of the master clock data is read from the buffer and passed to the DSP/DAC. When the buffer sizes reaches a point where overflow could occur the USB controller sends a message to stop sending. If the buffer lower limit is reached the controller requests additional data.

Any jitter caused by time and frequency distortions or noise are removed as the buffer is always being read at a constant rate regardless of variations in the write rate. The concept of the DAC controlling the data rate is also used with I2S DACs. This means that I2S DACs can perform as well as but no better than AUSB DACs.

The point I was making is that the USB output connector on a PC/Mac/RPi is inherently "noisy" or "dirty" and may not provide stable 5V and 0V power rails or signal levels, partly due to the power supply not being implemented to the high standards of audio equipment.

The dirt or noise that you mean comes from various components, including displays, DC step-up or step-down converters, various switching regulators, processors, various ICs, power supplies, etc.

The reasons for the noise, which would be carried through to the USB connector, are identified in this post.

However, it is disappointing that the basic power configuration for the M50 is to connect it to a phone charger, as there is a USB to OTG cable "in the box", which is unlikely to have sufficient reserve to handle power rail demand and fluctuation any better than a PC/Mac/RPi. Perhaps it is a Topping ploy to increase the sales of the P50 linear power supply rather than supply an SMPS to match the requirements of the M50. If designed with care the noise on the USB connectors on the M50 should "quieter" than those found on a PC/Mac/RPi

There are number of YouTube videos which demonstrate the problem of connecting a computer into an audio system through a USB link. An example is youtube.com/watch?v=einxGsiuwso which targets ground loop noise but also demonstrates computer generated noise.

Like any YouTube video it can only be taken at face value and it is open to the viewer to accept or to reject the content.

At the end of the day, Topping made this nifty thing because a certain amount of folks wants to play local files at best. I'm among them, for sure.

For me the M50 is a "nifty device" for "folks [who] want to play local files"; not everyone wants or needs the "versatiity" of a PC/Mac/RPi arrangement.
 
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F1308

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I am wondering what point is there...

Designing such a device in 2022 and go limiting to '"up to 256 GB" the capacity of the TF card and Flash disks.

An extremely wrong decision.

Went to buy, refrained doing it.
 

Saponetto

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Maybe I'm wrong, but afaik its USB OTG input allows hard disks up to 4 TB.
Nothing changing the world, but at least a good collection of DSF files can be hosted as well.
 

F1308

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Maybe I'm wrong, but afaik its USB OTG input allows hard disks up to 4 TB.
Nothing changing the world, but at least a good collection of DSF files can be hosted as well.
How can you tell, please ?
 

Berwhale

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1651700300742.png
 

Berwhale

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The manual also mentions connecting to wifi, but doesn't go into the details of how a password would be entered...

1651700446500.png
 

aka

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I'm going to try one and swap out my SqueezeBox Touch. I can't get the SBT to consistently connect with Apple Music - even though the LMS software community is fantastic - I'm always trouble shooting. On again/off again. This might be just the ticket. I've had great luck with Apos in the past. 45 day return window. We'll see...
 

Stickler1

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I got one. For one major reason. When the internet goes out here in ComCrapLand you cannot stream or even operate most streamers. I have six and none of them do. And the home made RasPi is about on a par. With all the add ons it's about the same price. This keeps on playin', even DSF And it has the holy grail - shuffle.
 

F.van Dijk

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I got one. For one major reason. When the internet goes out here in ComCrapLand you cannot stream or even operate most streamers. I have six and none of them do. And the home made RasPi is about on a par. With all the add ons it's about the same price. This keeps on playin', even DSF And it has the holy grail - shuffle.
Can you tell us someting about the sound quality vs the pi or oders?
 
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