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Digital converters

Dumdum

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I have put it in here as there isn’t a specific section for it...

I use a topping D10 as a usb to optical and coax output converter, I am curious as to why when measuring the devices as DACs is it not easy to then plum the output into the audio analyser and measure it’s digital output also?

I am curious as to why and how I am hearing extra detail, a higher, more defined soundstage and better sound quality in my car from digital vs analogue into my dsp... the freq response is more or less identical give or take the odd 0.1db but that could be variations in the pink noise used for the measurements

I Have recently sent a spare D10 to a friend in Holland and he heard the exact same thing

is there a reason you don’t measure the digital outs on these devices?
 

JeffS7444

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First thought that popped into my mind was to be careful not to set analog input levels too high lest you cause clipping in the DSP unit. Also, what sorts of corrections is the DSP performing? Large boosts can be problematic.
 
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Dumdum

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First thought that popped into my mind was to be careful not to set analog input levels too high lest you cause clipping in the DSP unit. Also, what sorts of corrections is the DSP performing? Large boosts can be problematic.
There is zero clipping in the dsp, In other words we know our onions, and both signals come out the amplifier end with the exact same frequency response to a microphone, it is very clean with both and a good way from clipping, this is a car that does sound quality competition, and my friend from Holland has been Dutch Emma champion for years and years
The how I’m looking for is in the form of measurements

The only other variable is the input adc that’s used on the analogue into the dsp which is listed below...
 

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Dumdum

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The D10 coax out has been measured here.
I have seen that I think, thanks... but surely thats not the only thing you can measure with usb to digital converter? I can’t be the only one that would use the device how I do...

surely a digital connection has a freq response for example, does the output compare to the input from usb? Is something lost?

I don’t really know much about digital signals if I’m honest... I’m curious to see if there’s a better usb coax converter?
 

Eetu

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I have seen that I think, thanks... but surely thats not the only thing you can measure with usb to digital converter? I can’t be the only one that would use the device how I do...

surely a digital connection has a freq response for example, does the output compare to the input from usb? Is something lost?

I don’t really know much about digital signals if I’m honest... I’m curious to see if there’s a better usb coax converter?
With digital there's no frequency response deviation, the bits are just passed along so to speak.

Not sure what your setup is though, can you share some details? When you're using the D10 as a usb->coax/toslink converter, you're letting the dsp handle the D/A-conversion. What DSP are you using and how did you connect it before?
 

RayDunzl

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REW -> USB -> D10 -> Optical -> Audio authority 1177A switch -> Optical -> Focusrite Optical Input -> Focusrite USB Output -> Another instance of REW

1592063460791.png


Probably meaurement error/artifact here for the frequency response, since the sending REW and the receiving REW are two different instances:

1592064476805.png
 

RayDunzl

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surely a digital connection has a freq response for example, does the output compare to the input from usb? Is something lost?

Does your web browser's screen display suffer poor frequency response from its digital connections?
 

pozz

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I am curious as to why and how I am hearing extra detail, a higher, more defined soundstage and better sound quality in my car from digital vs analogue into my dsp... the freq response is more or less identical give or take the odd 0.1db but that could be variations in the pink noise used for the measurements
It's not the FR for sure.

If you're sure you aren't overloading the analog inputs, I would guess that the gain structure and staging causes digital to be a bit louder overall.

Measuring the digital outs isn't that important other than to make sure they aren't broken. It's just an information stream after all.
 
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Dumdum

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It's not the FR for sure.

If you're sure you aren't overloading the analog inputs, I would guess that the gain structure and staging causes digital to be a bit louder overall.

Measuring the digital outs isn't that important other than to make sure they aren't broken. It's just an information stream after all.
Gain structure is identical between the two, the only gain that is adjusted is the analogue only gain to match digital vs analogue

The dsp will take an 8v input so it definitely won’t get overloaded by 2v

gain structure is identical between the two as it was the same dsp with the same settings, and the exact same output level between the two, I literally matched the input gain of the analogue input on the dsp so if you put 1khz in one from the exact same source (a file on an iPhone) both analogue and digital would provide 92db for example, all the eq, levels, time alignment were identical, I just connected the topping with both analogue and optical and was able to switch in ms from the front of the vehicle via the director whoch

how can it be a bit louder overall if the measured output (with a umik-1) is exactly the same (as I say in some places it’s 0.1db quieter, some it’s 0.1db louder, ie you overlay the measured freq response of one over the other and they overlay (I measured it to ensure that it wasn’t just what you say with pink noise from the same source)

the speaker locations are fixed as it’s an installed system in a car

but switching between one to the other the stage physically jumps upwards, you can do it blind and it’s obvious, and it’s the exact same source
 

Eetu

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Gain structure is identical between the two, the only gain that is adjusted is the analogue only gain to match digital vs analogue

The dsp will take an 8v input so it definitely won’t get overloaded by 2v

gain structure is identical between the two as it was the same dsp with the same settings, and the exact same output level between the two, I literally matched the input gain of the analogue input on the dsp so if you put 1khz in one from the exact same source (a file on an iPhone) both analogue and digital would provide 92db for example, all the eq, levels, time alignment were identical, I just connected the topping with both analogue and optical and was able to switch in ms from the front of the vehicle via the director whoch

how can it be a bit louder overall if the measured output (with a umik-1) is exactly the same (as I say in some places it’s 0.1db quieter, some it’s 0.1db louder, ie you overlay the measured freq response of one over the other and they overlay (I measured it to ensure that it wasn’t just what you say with pink noise from the same source)

the speaker locations are fixed as it’s an installed system in a car

but switching between one to the other the stage physically jumps upwards, you can do it blind and it’s obvious, and it’s the exact same source
I feel like I'm missing something here but seems like you prefer the built-in DAC of the dsp over the D10. And with analog in there's also an additional A/D conversion inside the dsp degrading the signal..?
 

pozz

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how can it be a bit louder overall if the measured output (with a umik-1) is exactly the same (as I say in some places it’s 0.1db quieter, some it’s 0.1db louder, ie you overlay the measured freq response of one over the other and they overlay (I measured it to ensure that it wasn’t just what you say with pink noise from the same source)
If I understand you right you have a D10 feeding your DSP with both analog outs and digital outs, and you're switching between the two? If you measure the electrical output of the DSP with a voltmeter you may find your answer there.
 
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Dumdum

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I feel like I'm missing something here but seems like you prefer the built-in DAC of the dsp over the D10. And with analog in there's also an additional A/D conversion inside the dsp degrading the signal..?
With analog there is another 2 conversions you are correct...

but the digital source will also pass through the same dac, and I am reading that the topping is an excellent dac and measures well... so is it the input adc that sucks?

however if that’s the case why did my friend also come to the exact same conclusion as me, he has a different dsp to me (I run the helix dsp.3 and get runs a mosconi 8-12 aerospace)

im not looking to argue technical points as I don’t know enough to even contemplate that as you may have all seen and I’m sure have chuckled at my lack of knowledge

I basically want to know how I can distinguish between one digital source vs another, so my topping via optical sounds different to my friends £30 usb Chinese digital converter from eBay...

in which case how do you measure what the differences are, and if you can how do I then know before buying if another usb to digital converter has more detail or sounds different... if digital is different how does my topping sound different to the other device if plugged into the same input on the same system
If I understand you right you have a D10 feeding your DSP with both analog outs and digital outs, and you're switching between the two? If you measure the electrical output of the DSP with a voltmeter you may find your answer there.
if the output of the amps and identical speakers are identical the output level of the dsp is identical as the output level is identical

if you set the volume at wherever you like there is more detail in the digital source, listen to cymbals and the decay is more life like, music sounds more lifelike

you keep saying it’s output level related... I’m saying it’s not that... as for speakers to output the exact same db level the input voltage to the amplifiers must be the exact same... unless your saying somehow you can have different input levels for the same output levels with a fixed gain structure...
 
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Dumdum

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So regarding the digital source vs analogue it may be the dsp input adc that makes the difference

Anyway, perhaps I versed my first post badly, I am after a way of comparing digital converters... I have used a different usb to digital converter and the result was very different to that from the topping... if its digital what are the measureable parameters that can explain this, as using the same source they sound very different, and the topping wins out... but digital either works or it doesn’t? How can they sound different? Same tablet, same usb c hub, same original file, different detail levels

short of sending amir my dsp and a topping D10 I’m not sure how I can find an answer to my question...
 

BDWoody

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So regarding the digital source vs analogue it may be the dsp input adc that makes the difference

Anyway, perhaps I versed my first post badly, I am after a way of comparing digital converters... I have used a different usb to digital converter and the result was very different to that from the topping... if its digital what are the measureable parameters that can explain this, as using the same source they sound very different, and the topping wins out... but digital either works or it doesn’t? How can they sound different? Same tablet, same usb c hub, same original file, different detail levels

short of sending amir my dsp and a topping D10 I’m not sure how I can find an answer to my question...

My suggestion would be to learn more about it... The whole 'measurements' thing isn't as bad as some make it. Maybe read through a half dozen random DAC reviews to see how Amir tests them, learn what the graphs mean, and you'd be in a much better position to understand what's happening, or could be happening. It isn't necessarily intuitive, but it also isn't that bad...

Please don't take that as being a pushback in any way, but an hour or three of reading might go a long way.
 
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Dumdum

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My suggestion would be to learn more about it... The whole 'measurements' thing isn't as bad as some make it. Maybe read through a half dozen random DAC reviews to see how Amir tests them, learn what the graphs mean, and you'd be in a much better position to understand what's happening, or could be happening. It isn't necessarily intuitive, but it also isn't that bad...

Please don't take that as being a pushback in any way, but an hour or three of reading might go a long way.
But measurements of a topping or any device as a dac doesn’t help me, and the one item linked to for a topping as a digital transport i understand, but the one doesn’t let me compare others with it if you see what I mean

I understand the freq response, the jitter, dual tone tests etc to a certain level and there relevance as a dac

it seems I’m not the first to ask for comparisons as I am... someone did just that in the topping D10 review, but I guess time isn’t on Amir’s side, but that’s exactly what I’m speaking of

A4AF2F3D-9C8A-4B9C-B619-5FD5B413E835.png
 

Blumlein 88

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It would help me follow the OP's discussion if he were careful about naming. Digital to analog converter (DAC), Analog to digital converter (ADC), as to clearly separate those from digital converter which might be USB to SPDIF or toslink vs coax. I'm a bit unclear exactly what is being compared to what here.

If the OP is just saying his Topping DAC sounds different than another DAC that might not be surprising. And if that is the comparison being done here, did you match analog output levels at the speaker input posts?
 
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Dumdum

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It would help me follow the OP's discussion if he were careful about naming. Digital to analog converter (DAC), Analog to digital converter (ADC), as to clearly separate those from digital converter which might be USB to SPDIF or toslink vs coax. I'm a bit unclear exactly what is being compared to what here.

If the OP is just saying his Topping DAC sounds different than another DAC that might not be surprising. And if that is the comparison being done here, did you match analog output levels?
I have used dac as the topping is both a usb to digital device and a competent dac

I have also expanded on my original post as it somewhat went off tangent, partly due to me writing my thoughts

I am not using the topping as a dac, however it is a dac, but to most people if I refer to it as a topping D10 usb to digital converter they may think I’m talking about a different piece of kit

in any comparison level matching is a given, if you care to read I even stated specifically that I made sure levels were matched to ensure it wasn’t this I was hearing in an above post
 

Blumlein 88

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So can you lay out a simple line diagram of the signal path you have for the two conditions that sound different to you.

Like I am listening to:

Lenovo computer feeding USB >March Audio DAC RCA analog out >Wyred 4 Sound ST500 power amp over speaker wire>Soundlab speakers.

Macbook Pro feeding Thunderbolt>Antelope Audio Zen Tour interface analog XLR out>Wyred4Sound ST500 over speaker wire>Soundlab speakers.

I sometimes listen to:

Macbook Pro feeding thunderbolt>Zen Tour recording interface analog XLR out>JBL LSR305 speakers.
 
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Dumdum

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So are you using the digital output of the D10 to feed a pair of DACs which sound different?

Or are you listening to the D10 as a DAC, versus another DAC fed from the digital output of the D10?
No, I don’t use the d10 as a dac, I use it to feed digital signal into a 6 to 8 dsp which then contains a dac (as listed above) to give 8 outputs of analogue to my amplifiers running 3 way plus sub fully active

I have compared the d10 as a dac to the d10 as digital into my dsp and digital sounds way better!

I am enquiring as to why amir doesn’t test the digital outputs of devices which have digital output (like the D10 for example) as digital usb to digital coax or optical outputs when he tests the unit as a dac, and if so how and what can set different digital converters of this kind apart... as I have had markedly different results from two devices which are both digital converters for usb digital in... the topping being superior (this is not what I was referring to earlier when comparing digital vs analogue which was purely the topping via two different outputs)
 
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