Review and Measurements of Topping DX7s DAC and Headphone Amp

[March Audio]

Iirc Archimago or someone else did exploratory time-domain analysis of ringing with real audio signals, the conclusion was it could be an issue for badly mastered material with lots of clipping.

Yes that makes absolute sense as with clipping we have essentially square waves

 

[amirm]

At clipping there is so much distortion I am not sure anything else matters.

 

[gvl]

At clipping there is so much distortion I am not sure anything else matters.

But, but.. The clipping you hear can be different from the clipping that the mastering engineer heard! That's not pure.

 

[xevman]

So i just bought a Stax energizer and connected it to the DX7s I noticed if the DX7S is connected to my PC via USB it causes a horrible ground loop. If I connect it with an optical cable the ground loop disappears. Is there any detriment to the performance in connecting it via optical?

 

[gvl]

So i just bought a Stax energizer and connected it to the DX7s I noticed if the DX7S is connected to my PC via USB it causes a horrible ground loop. If I connect it with an optical cable the ground loop disappears. Is there any detriment to the performance in connecting it via optical?

Depends on the quality of the optical output on your PC but likely not an issue especially considering DX7s uses ESS chips that run in async mode. Optical has a limit of 96kHz sampling rate typically, so if you get your hands on some hi-res material above that you'll need to down-sample. You might be able to mod your USB cable to get rid of the noise - check the D10 thread.

 

[xevman]

You might be able to mod your USB cable to get rid of the noise - check the D10 thread.

I've tried modifying USB cables in the past to no avail. It seems that if there is any sort of physical electrical connection between my DAC and PC and my amp the trouble starts. I'm fairly certain the optical implementation in this DAC is rather good given Amir's measurements where done via SPDIF (not sure if via toslink or coax though) so I assume I should be ok, I just wanted to check. Don't really care for DSD or super high sampling rates. 24/192 over SPDIF ought to be enough for anybody.

 

[gvl]

Don't really care for DSD or super high sampling rates. 24/192 over SPDIF ought to be enough for anybody.

Toslink maxes out at 24/96, typically. Coax is up to 24/192 indeed.

 

[xevman]

Toslink maxes out at 24/96, typically. Coax is up to 24/192 indeed.

Toslink does 24/192 on the DX7S just tested it and it accepts the incoming 192khz sampling rate.

 

[gvl]

Toslink does 24/192 on the DX7S just tested it and it accepts the incoming 192khz sampling rate.

Cool, some DACs and sources can do, I guess there is progress after all. Usually it is up to 24/96 via optical.

 

[Vosya]

Here are the filter responses to a white noise source.

The graph of the filter response "Mode1: apodizing fast roll-off filter" looks better for me, than the "Mode5 : linear phase fast roll-off filter."
This is strange, since in the ES9038Q2M Datasheet both the graph and the numerical values (Stop band < –120dB vs. Stop band < –80dB) are better at Mode5.

P.S. Is it possible for you to do the same research for Topping D50 DAC?

 

[amirm]

P.S. Is it possible for you to do the same research for Topping D50 DAC?

I can. Remind me if I forget a few days from now.

 

[derp1n]

Is it possible to do a 1kHz sine FFT (like your newer APx555 reviews include in the dashboard) with the latest firmware (18G) applied, please? The results I posted here are surprisingly poor, so I'd like to validate my results against someone with proper test gear and measurement experience.

 

[ripvw]

ordered remote from AliExpress on 6/28 - never arrived. They are now stating that the product was returned because the address was wrong - their fault - they supposedly shipped it out again last Thurs...

just ordered it from Amazon through ShenzhenAudio - same people I got the DX7s from - if I end up with 2 remotes I'll let you know

 

[derp1n]

Is it possible to do a 1kHz sine FFT (like your newer APx555 reviews include in the dashboard) with the latest firmware (18G) applied, please? The results I posted here are surprisingly poor, so I'd like to validate my results against someone with proper test gear and measurement experience.

Never mind about this. There seems to be something more fundamentally wrong, either with my unit, my measurements, or the design.

From the single ended RCA output with the unit powered off, I'm still getting the same (high) levels of noise:

Above is with the unit powered off via the rear main power switch. Just the power cable and the RCA outputs connected to the soundcard's line input.

...with the power cable disconnected, the noise disappears as expected.

I'm wondering if I've got a faulty unit, or is the DX7s power supply/filtering inadequate? Note that this noise doesn't show up in the dac1541 measurements I ran at the same time, so it's not inherent to my local power supply (or the dac1541 is dealing with it properly).

 

[Vosya]

I can. Remind me if I forget a few days from now.

I think it's time to remind...

 

[amirm]

I think it's time to remind...

Slave driver. Did I say sometimes you have to remind me twice???

 

[Vosya]

Did I say sometimes you have to remind me twice???

Reminding is mach easier than doing. I can do it.

 

[amirm]

Reminding is mach easier than doing. I can do it.

Here you go: https://www.audiosciencereview.com/...asurements-of-topping-d50-dac.2403/post-94424

 

[derp1n]

No comment from @amirm on my measurements

 

[amirm]

No comment from @amirm on my measurements

I wanted to replicate them before commenting. Right now, I am smoking some ribs so that takes priority.