Topping DX7 - DAC and balanced headphone amplifier
Dec 14, 2018 at 12:25 AM Post #347 of 468
So, I just got mine a week ago, and... it's dead now. Well, in the least, it's completely stopped being recognized by my PC as a USB device. Optical in still works. I don't have another system to test it out on, but there's nothing that hints me toward it having anything to do with my PC. I can say that it's not the cable. Very excited to test out their customer service, which I'm sure isn't going to at all be a huge hassle. While I wait their response, however, I'm cracking mine open to see how bad the heatsink problem is. Hugely bummed out by this; I don't really have the money to throw around on expensive crap that stops working in a week. Sounded good for that week though. :grimacing:
I am sure you have tried this, but just in case... Disconnect the DX7S, uninstall the Topping drivers, reinstall the drivers, reconnect the DX7S... Maybe it's something as simple as that...
 
Dec 14, 2018 at 12:28 AM Post #348 of 468
Question to DX7(s) owners, when i set it to DAC+HP mode so I can control
volume on DX7s, as I listen headphones at -38DB or so, its DAC output is to low.
But, if I turn it up for external AMP, then the headphone that connected would be too loud.
So, what do you people do about this mode, I want the HP plug in, so I don't have
to plug/unplug every time I change to DAC+HP mode.
Is it possible? or it is either dac or HP never the dac+hp?
Then, the dac+hp mode seems not practical at all, is it?
 
Dec 14, 2018 at 12:39 AM Post #349 of 468
I am sure you have tried this, but just in case... Disconnect the DX7S, uninstall the Topping drivers, reinstall the drivers, reconnect the DX7S... Maybe it's something as simple as that...
I originally wasn't using the Topping drivers at all, as it seemed to work fine out of the box with Win10. I did try installing them once the problem arose (at first Windows still recognized the device but it wasn't outputting sound, then it completely stopped recognizing it), but the drivers couldn't detect a connected device either. As it is, there's nothing else to try uninstalling and reinstalling, and it's not even showing up on the Windows Device Manager, so I can't do anything in there either.

To update on breaking it open, as expected the heatsinks did not have any thermal pads or paste, though unlike some other reports here they at least weren't loose. I don't know enough about circuitry w/r/t DACs and amps, but it would seem weird to me for just the USB to not work as a result of the heatsink problem, especially when it works in DAC + Amp mode through optical. Some of the soldering is pretty garbage, but the actual USB port's soldering seems fine.

I did try plugging it into my laptop without any luck, but to be fair, it is a Linux machine and I wouldn't expect it to work without the level of tinkering that I'm not really in the mood to do.

I'll keep messing around and hopefully stumble across a solution because I really don't want to ship this thing back to China, but for the time being I'm pretty convinced it's a hardware issue.
 
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Dec 14, 2018 at 12:54 AM Post #351 of 468
Question to DX7(s) owners, when i set it to DAC+HP mode so I can control
volume on DX7s, as I listen headphones at -38DB or so, its DAC output is to low.
But, if I turn it up for external AMP, then the headphone that connected would be too loud.
So, what do you people do about this mode, I want the HP plug in, so I don't have
to plug/unplug every time I change to DAC+HP mode.
Is it possible? or it is either dac or HP never the dac+hp?
Then, the dac+hp mode seems not practical at all, is it?
I have never found an output level that would work for both headphone out and DAC out.
 
Dec 14, 2018 at 1:02 AM Post #353 of 468
I've used both of mine heavily without issues, maybe you got a dud:frowning2: I'd definitely try the firmware flash though and see if anything populates in device manager.
 
Dec 14, 2018 at 1:02 AM Post #354 of 468
Okay, so after four (probably unnecessary) computer restarts and taking the whole thing apart, it started working again? When I plugged it back in after having it disassembled, I noticed that the sample rate on the display read "---kHz". The whole time it was not working it was stuck at "44.1kHz" even though it shouldn't show a sample rate when it's not connected to a PC. Sure enough, once I reconnected the USB cable the sample rate display updated as you'd expect and it once again was being recognized by the PC. Very peculiar; I'm guessing it fully losing power caused it to reset whatever was going on to make it frozen in the way it was. I don't know what version of the firmware this shipped with, but I'm going to update it now.
 
Dec 14, 2018 at 2:19 AM Post #356 of 468
Okay, so after four (probably unnecessary) computer restarts and taking the whole thing apart, it started working again? When I plugged it back in after having it disassembled, I noticed that the sample rate on the display read "---kHz". The whole time it was not working it was stuck at "44.1kHz" even though it shouldn't show a sample rate when it's not connected to a PC. Sure enough, once I reconnected the USB cable the sample rate display updated as you'd expect and it once again was being recognized by the PC. Very peculiar; I'm guessing it fully losing power caused it to reset whatever was going on to make it frozen in the way it was. I don't know what version of the firmware this shipped with, but I'm going to update it now.
Yay!
 
Dec 14, 2018 at 4:08 AM Post #357 of 468
Okay, so after four (probably unnecessary) computer restarts and taking the whole thing apart, it started working again? When I plugged it back in after having it disassembled, I noticed that the sample rate on the display read "---kHz". The whole time it was not working it was stuck at "44.1kHz" even though it shouldn't show a sample rate when it's not connected to a PC. Sure enough, once I reconnected the USB cable the sample rate display updated as you'd expect and it once again was being recognized by the PC. Very peculiar; I'm guessing it fully losing power caused it to reset whatever was going on to make it frozen in the way it was.
Yes, the same has happened to multiple others. Sometimes the USB inputs freezes up, and disconnecting all power (including the USB and power cables) for 10s or so can fix it.

Question to DX7(s) owners, when i set it to DAC+HP mode so I can control
volume on DX7s, as I listen headphones at -38DB or so, its DAC output is to low.
But, if I turn it up for external AMP, then the headphone that connected would be too loud.
So, what do you people do about this mode, I want the HP plug in, so I don't have
to plug/unplug every time I change to DAC+HP mode.
Is it possible? or it is either dac or HP never the dac+hp?
Then, the dac+hp mode seems not practical at all, is it?
I used the DAC+HP mode all the time because then it functions as a DAC and preamp into a separate power amp. But then I don't have headphones connected. DAC+HP is definitely a misnomer for this mode.
In DAC mode the rear outs are at full volume, in HP mode they are off. When using the external amp, do you need the DX7s's volume control at all? Are you switching back and forth between the DX7s and the external amp or something like that? Otherwise I'd indeed switch to DAC mode for the external amp and to HP mode when listening with the DX7s. It should remember the volume level.
 
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Dec 14, 2018 at 9:09 AM Post #358 of 468
Yes, the same has happened to multiple others. Sometimes the USB inputs freezes up, and disconnecting all power (including the USB and power cables) for 10s or so can fix it.


I used the DAC+HP mode all the time because then it functions as a DAC and preamp into a separate power amp. But then I don't have headphones connected. DAC+HP is definitely a misnomer for this mode.
In DAC mode the rear outs are at full volume, in HP mode they are off. When using the external amp, do you need the DX7s's volume control at all? Are you switching back and forth between the DX7s and the external amp or something like that? Otherwise I'd indeed switch to DAC mode for the external amp and to HP mode when listening with the DX7s. It should remember the volume level.
Obvious reason to have the DX7S volume knob control the DAC output is if using the DX7S as a preamp.

The reason I know of to use the DX7S volume control for DAC output when it is connected to an external amp is if the DX7S output voltage swing would cause clipping in the amp... an example of this is the MD THX AAA 789... if the 789 is at the highest gain setting the DX7S output voltage swing at 0dbfs is too great - the DX7S output needs to be set to -6dbfs in that case.

But, yeah, HP+DAC is at best a misnomer. In reality it is well intentioned, but given that no setting is useful in both cases and thus is dangerous to your headphones and hearing it is ultimately a bad design choice - that mode should be something like “DAC-V” for variable DAC output and should not also drive the headphone output.

But, hey, given the 10 ohm output impedance on the headphone out on single ended and 20 ohm on Balanced, only high impedance, or planar, headphones should be used... I see the headphone outputs on the DX7S as a pretty useless/limited feature if you own a decent amp with sub-1 ohm output impedance.
 
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Dec 14, 2018 at 10:39 AM Post #359 of 468
Obvious reason to have the DX7S volume knob control the DAC output is if using the DX7S as a preamp.

The reason I know of to use the DX7S volume control for DAC output when it is connected to an external amp is if the DX7S output voltage swing would cause clipping in the amp... an example of this is the MD THX AAA 789... if the 789 is at the highest gain setting the DX7S output voltage swing at 0dbfs is too great - the DX7S output needs to be set to -6dbfs in that case.

But, yeah, HP+DAC is at best a misnomer. In reality it is well intentioned, but given that no setting is useful in both cases and thus is dangerous to your headphones and hearing it is ultimately a bad design choice - that mode should be something like “DAC-V” for variable DAC output and should not also drive the headphone output.

But, hey, given the 10 ohm output impedance on the headphone out on single ended and 20 ohm on Balanced, only high impedance, or planar, headphones should be used... I see the headphone outputs on the DX7S as a pretty useless/limited feature if you own a decent amp with sub-1 ohm output impedance.
True. For transparency, I'd rather use a lower gain setting in the amp than use the DAC's volume control, but that is a legitimate use case. It could also be useful to volume match another source for A/B comparisons.

For me as well, the DX7s is primarily a DAC with some added convenience functions that can be useful, but to get the most out of the DAC section, use an external amp.
 
Dec 14, 2018 at 2:27 PM Post #360 of 468
Thanks you all who answer my question.
I will remember not to use dac+hp mode, I mostly use it as dac or drive my headphone.
Just exploring the mode for possible usage.
 

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