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What is the point of upsampling?

Krunok

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The point of upsampling is to move the reconstruction/anti-aliasing filter well above audible frequencies, where it can be more gentle and not affect the audible spectrum. A high-quality filter at 22khz is hard to make in hardware without distorting phase and without cutting into frequencies below 20khz. A gentle filter at 88khz is much easier, and it can distort there all it wants without affecting the audible range. It's a simple engineering solution to a problem that could otherwise become audible... at least to some of us (not to me, not for a while :()

Ok, I agree with that, but is that really an issue with modern DACs? I didn't notice it in measurements presented on this site..
 

pkane

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Ok, I agree with that, but is that really an issue with modern DACs? I didn't notice it in measurements presented on this site..

If you mean do they need additional/external upsampling, then most don’t. Internally, I suspect you’ll find that most modern DACs and DAC chips already upsample.
 

DonH56

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Ok, I agree with that, but is that really an issue with modern DACs? I didn't notice it in measurements presented on this site..

Most are oversampling DACs (delta-sigma designs of some sort) and so the initial filtering inside the chips is already at a much higher rate.
 

patient_ot

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If you mean do they need additional/external upsampling, then most don’t. Internally, I suspect you’ll find that most modern DACs and DAC chips already upsample.

I had a CD player from 1987 that upsampled to 18 bit/176khz.

Upsampling is a big marketing thing now, like DACs and disc players that upsample to 32bit or even DSD. I see no benefit to the consumer based on what I've read here and other places. Look in the latest catalogs from Music Direct, Audio Advisor, etc. and you'll see plenty of marketing talk about upsampling though.
 

March Audio

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Thank you very much March, I'm going to watch right now!

Btw, how're you and your projects going, last I seen you were conjuring an amp for us :}
Things are going very well, the initial production run of everything has sold out :). After a few delays getting the next batch of enclosures manufactured (Chinese public holidays) everything will be back in stock next week.

There is never enough time though. Need to do a few finishing touches to the HPA1 headphone amp and the P701 monoblocks power amp and they will be ready in a few weeks.
 

bwinlr

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Converting a digital (sampled) signal to a continuous analogue waveform requires interpolation to produce the values between sample points. Doing part of this interpolation digitally (upsampling) simplifies the analogue circuitry and gives better results. That's all there is to it. Whether software upsampling is audibly superior to that built into DAC chips is debatable.

Thanks for that explanation. I've recently gotten back into pure analog with LPs, and have enjoyed the difference. The analog has a presence and vividness that digital lacked, and I attribute that to the sampling process that omitted important and audible information. I think we jumped (I jumped) into CDs a little too quickly because of the convenience of the format.

I also had an interesting thing happen today that goes to this issue of upsampling. I replaced a NuForce upsampling UBS-to- S/PDIF connector that was between my computer (and outboard digital music storeage device) that had gone bad suddenly and inexplicably. The new converter has no upsampling capability. At first, I was disappointed that my Moon Simaudio DAC didn't indicate a higher sampling rate than 44.1. The NuForce upsampled to 192.

I assumed that I would hear an audible, negative difference. But, I didn't, surprisingly. In fact, my digital files sounded slightly better. I think I erroneously assumed that the higher the sampling rate, the better the sound quality. That's not the case. I think now that upsampling can actually degrade the digital file by adding superfluous information.

As I said, I've been a little surprised by all this.
 

DonH56

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The biggest problem with CDs is that many have been remastered poorly. A good CD sounds every bit as good as an LP; better, in fact, with greater dynamic range and cleaner sound (also deeper bass).
 

bwinlr

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The biggest problem with CDs is that many have been remastered poorly. A good CD sounds every bit as good as an LP; better, in fact, with greater dynamic range and cleaner sound (also deeper bass).
The biggest problem with CDs is that many have been remastered poorly. A good CD sounds every bit as good as an LP; better, in fact, with greater dynamic range and cleaner sound (also deeper bass).
The biggest problem with CDs is that many have been remastered poorly. A good CD sounds every bit as good as an LP; better, in fact, with greater dynamic range and cleaner sound (also deeper bass).


I don't agree with you, but hearing is a very subjective thing. In my case, I have been surprised by the audible difference between CDs and LPs. To me, at least, there is a distinct, noticeable improvement in sound of analog versus digital. I don't hear a greater dynamic range or deeper bass with digital, in fact, it's just the opposite.

My guess is that the digital sampling process, of necessity, leaves some music UNsampled. This may be relatively small, but I'm beginning to think that it is very important to imparting realism and presence to the music. Again, my opinion only.
 

DonH56

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Three times? :)

Didn't really expect you too but that's OK. I can hear a difference and have many times; yes, it is quite audible. But a good CD sounds much better to me than the LP version. Many CDs have been subjected to compression (see "loudness wars") that sucked the life out of them. Nothing to do with the technology, just music execs etc. who decided "louder is better". Sheffield Lab makes some good ones (among other companies).

The "unsampled" and "digital leaves music behind" arguments are myths espoused by those who do not understand the technologies. Objective measurements, which I realize you may dismiss, clearly show the superiority of digital systems over LPs. CDs can capture much greater dynamic range than LPs and resolve to levels well beyond audibility. And extend bass response essentially to DC. The limitation of most (perhaps all) stereo systems is the speakers. What you hear is very likely real (and I and many others here agree), but it is not due to digital's inferiority, but rather what the music industry has done to the mixes on the CDs.

IME/IMO - Don
 

Wombat

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Or personal and mind biases. Preference does not necessarily mean better in a profound sense.
 

patient_ot

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I also "got back into" records about 6-7 years ago. I have a good deal of records (around 1400 LPs) and a good deal of CDs (around 4000+). IME when people jump back into vinyl they are in the honeymoon period and the downsides haven't really set in yet. It's also easy to knock CDs if you just bought whatever was in front of you with without researching what to buy first. With CDs, as with LPs, everything needs to be taken on a case by case basis. There are many well mastered CDs out there, and many poorly mastered ones, and yes newer remasters are often horrible (though not always). Same deal with records - lots of crappy vinyl out there new and old mastered poorly or pressed poorly or that used an inferior source. Now, I enjoy both formats (and lossless digital files as well) but have a realistic view of the technical shortcomings of vinyl.
 

samshaver

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If I may ask, is there any website or source I can visit to hear what imaging artifacts even are? Perhaps even an artifically induced test just to demonstrate what such a thing even sounds like?

Yeah, I’ve always been curious as to what exactly interpolation and quantization errors actually sound like.

And I’ve been curious about the whole idea of upsampling recently, since it appears that Amazon Music HD upsamples everything to 192kHz if you are using a DAC that can support it.
 
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BDWoody

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I attribute that to the sampling process that omitted important and audible information.

It sounds like you may have misunderstood the explanation. The waveform is recreated per Nyquist-Shannon with no loss of information. It isn't like a connect the dots situation where more samples mean a 'smoother' sound. More samples of the original source simply allows you to sample higher frequencies, not sample the rest any 'better.'

Edit: If you record your vinyl through a decent A/D converter, and play it back through your DAC, it will sound 'like vinyl.' Maybe do a test and see if you can tell the difference?
 
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solderdude

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My guess is that the digital sampling process, of necessity, leaves some music UNsampled. This may be relatively small, but I'm beginning to think that it is very important to imparting realism and presence to the music. Again, my opinion only.

So all digitally recorded music (which is the vast majority) has lost vital information yet when such recordings are released on vinyl it magically returns ?
 

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bwinlr

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Three times? :)

Didn't really expect you too but that's OK. I can hear a difference and have many times; yes, it is quite audible. But a good CD sounds much better to me than the LP version. Many CDs have been subjected to compression (see "loudness wars") that sucked the life out of them. Nothing to do with the technology, just music execs etc. who decided "louder is better". Sheffield Lab makes some good ones (among other companies).

The "unsampled" and "digital leaves music behind" arguments are myths espoused by those who do not understand the technologies. Objective measurements, which I realize you may dismiss, clearly show the superiority of digital systems over LPs. CDs can capture much greater dynamic range than LPs and resolve to levels well beyond audibility. And extend bass response essentially to DC. The limitation of most (perhaps all) stereo systems is the speakers. What you hear is very likely real (and I and many others here agree), but it is not due to digital's inferiority, but rather what the music industry has done to the mixes on the CDs.

IME/IMO - Don
Yeah, my first time to comment, and didn't realize it was repeating. ; -)
 

maty

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