Topping DM7 8-Channel DAC Review

[sam_adams]

@WolfX-700's review is up on L7Audio: Measurements of Topping DM7 8Ch USBDAC (googley translated).

 

[nagster]

Maybe why some people are questioning the DM-7 having only balanced outputs?View attachment 218137

Signals can be output from the D10B even with an unbalanced connection.
However, I do not recommend it regardless of whether the ring terminal is connected or not.

Others posted to the D10B thread.

Topping D10 Balanced Review (USB DAC)

It looks (in my case) ,that the onboard switching power supply + 5.65V / -5.6V, which supplies the output analog circuits (3 OA) behind the DAC, fails / does not start ..). That PSU is powered from 5V inputs. The all other onboard sources (3.3V, 1.2V, 1V) start up normally, they are linear (not...

www.audiosciencereview.com

 

[raif71]

All of a sudden multi channel is possible for me.

 

[digicidal]

This assumes you are OK with breaking the copyright protection?

Oh I'm way more than "OK with it"... that's literally the best part! Of course, I'm one of those freaks that will actually re-purchase a game I already own when available on GOG - just to have a version without DRM (which has broken more than one title I've owned). I'd even invite friends over for movie night - without requiring them to show proof that they also own the movie... however, that would require actual friends... so that is a problem.

 

[KSTR]

Signals can be output from the D10B even with an unbalanced connection.

D10B's I/V and output stage is as stripped down as possible -- just one I/V opamp per leg and nothing else. That means there is no rebalancing of the balanced signal to the output GND and that's why in unbalanced connection it has way more distortion and noise than when used balanced as the common mode signal from the DAC chip itself is not factored out. Topping relies on the balanced input of the user gear to subtract out the common mode noise and distortion.
Further, it's not a servo-balanced output, so using a TS shorts the negative leg, not good for specs either.

I would assume the same thing for the DM7.

 

[KSTR]

1. If the naive user employs a mono TS plug, it will short the output.
2. At least one manufacturer has cautioned against loading one leg of the output while leaving the other unloaded citing possible problems for the output stage.
In general, I like to err towards caution when advising apparently naive users.

Yep, this would be true for any signal-symmetric balanced output that is not a servo-balanced circuit or true floating transformer.

In addition, I would imagine (as per my above post) that additionally the DM7 outputs don't have common-mode voltage (noise and distortion) subtracted out because the subtractor/rebalancer is missing (reduced cost and complexity). We need a PCB photo to be sure of this, however.

 

[dualazmak]

Hello @KSTR,

Thank you for your nice technical and educational clarifications.

We need a PCB photo to be sure of this, however.

I fully agree with you. I too wrote the same in my previous post #455 above...

 

[Neftun]

In the simplest case is for multichannel music or movie playback (if you can decode the latter prior to sending it the DAC). Another application is building multi-way active speakers. Then you need 2 or more channels for each speaker.

Forgive my ignorance…

This seem very exciting, but would it decode any multichannel formats? How would one go about that, Dolby or DTS?

 

[raif71]

Forgive my ignorance…

This seem very exciting, but would it decode any multichannel formats? How would one go about that, Dolby or DTS?

use some sort of decoder to convert to pcm before passing to DM7

 

[Trell]

Pavel of OCTO is uncomfortable about my sharing the inside photos in detail because the PCB etc. would be their proprietary know-how and/or patent-protected[?] design, though...)

He can be as uncomfortable as he wants but you can still publish the pictures of your own device unless you’ve signed a NDA, work for him or something.

 

[trcloud]

With the contents available today (Streaming) it really feels like HDMI input and Dolby suite are must-have.

 

[Whoareyou]

Yep, this would be true for any signal-symmetric balanced output that is not a servo-balanced circuit or true floating transformer.

In addition, I would imagine (as per my above post) that additionally the DM7 outputs don't have common-mode voltage (noise and distortion) subtracted out because the subtractor/rebalancer is missing (reduced cost and complexity). We need a PCB photo to be sure of this, however.

I received another response from Topping support
"Balanced to unbalanced will have an impact on performance. It is possible that will work, but there is also the possibility that there will be direct flow."

Any educated guess as to what they mean by direct flow? Yeah, I can just ask them I've now sent followup to support about it and see if I get an explanation that I understand.

 

[Atanasi]

I received another response from Topping support
"Balanced to unbalanced will have an impact on performance. It is possible that will work, but there is also the possibility that there will be direct flow."

Any educated guess as to what they mean by direct flow? Yeah, I can just ask them I've now sent followup to support about it and see if I get an explanation that I understand.

I think it means DC currents due to a DC offset. The midpoint voltage of the balanced outputs is not exactly the same as the unbalanced ground. If the unbalanced input is DC coupled, there will be currents. D10 Balanced also has a small DC offset.

 

[sarumbear]

With the contents available today (Streaming) it really feels like HDMI input and Dolby suite are must-have.

This is a DAC where do you expect the "Dolby suite" will run? You can already run them upstream before feeding to this DAC. HDMI input will increase the cost of the device.

 

[trcloud]

This is a DAC where do you expect the "Dolby suite" will run? You can already run them upstream before feeding to this DAC. HDMI input will increase the cost of the device.

This thing only has USB input. So basically either Multi channel PCM or multi channel DSD DoP with this thing plug on a PC or Mac I assume. Then how much legit muti-channel sources out there to make that happen? Feels like it's targeting people that some how "find" a bunch of multi-channel DSF/DST/DSD-iso files.
On the other hand, please correct me if I am wrong. Most big online streaming service could serve you Dolby Atmos content, through HDMI port, if your streaming device had one that could output Atmos audio format.

 

[nick-v]

Pro version with 4x AES/EBU inputs to compete with Okto Dac8 Pro?

 

[sarumbear]

This thing only has USB input. So basically either Multi channel PCM or multi channel DSD DoP with this thing plug on a PC or Mac I assume. Then how much legit muti-channel sources out there to make that happen? Feels like it's targeting people that some how "find" a bunch of multi-channel DSF/DST/DSD-iso files.
On the other hand, please correct me if I am wrong. Most big online streaming service could serve you Dolby Atmos content, through HDMI port, if your streaming device had one that could output Atmos audio format.

There is nowhere "basically" where you can use such a device. Read the thread and you may learn where else they can be used. Audio is not limited to music streaming.

 

[Sokel]

With the contents available today (Streaming) it really feels like HDMI input and Dolby suite are must-have.

Think of it like a typical internal sound card (without the extra goodie's like mic-in,headphone output and optical which is almost the standard) but external and with a better SINAD (if balanced),nothing more.

There are lot of use cases (some of them unfortunately limited in terms of peace of mind or convenience) as there is for the usual embedded motherboard sound card but with better measurements (even if some of the typical sound cards seem transparent based on their stated measurements so no difference).

 

[MCH]

Think of it like a typical internal sound card (without the extra goodie's like mic-in,headphone output and optical which is almost the standard) but external and with a better SINAD (if balanced),nothing more.

There are lot of use cases (some of them unfortunately limited in terms of peace of mind or convenience) as there is for the usual embedded motherboard sound card but with better measurements (even if some of the typical sound cards seem transparent based on their stated measurements so no difference).

Well, yes, actually something more. This device is almost unique in its class and price range in two very basic and simple things: remote and screen with master volume control.

Such a simple feature allows you to hide all the computers, apps... and just use your multichannel system as if it was another random hifi component. And as a free extra, is not half as ugly as any of the usual suspects interfaces.

So simple but so difficult until now.

 

[Sokel]

And as a free extra, is not half as ugly as any of the usual suspects interfaces.

Not as ugly,I agree,but not beautiful either,far from it as a matter of fact for my aesthetics.
But that's someting completely subjective,not suited for ASR style.