Upsampling with no interpolation

I would like to have an upsampling feature which ONLY increases the sample frequency and clock speed by 2x 4x 8x and/or 16x without doing ANY change to the samples - just repeat them

Sounds stupid, but for some applications in NOS DACs this could be VERY useful…

Yes, quite stupid! :slight_smile:

You can do this with a custom upsample table (I have). Here is an example:

But, yes, a toggle would be nice.

LOL, Savero, you tried to kick in the ball I put in front of the goal. You obviously has no clue on Delta Sigma Modulators and the effect of FS frequency on noise :upside_down_face:

Roon, players like Audirvana offer this option in the resample function. Please consider it

iPe that is not what I mean. This up sampling is using interpolation filters and I need the option of no interpolation

Can HQ Player do this for you, perhaps?

I’m not sure I understand what you’re asking for. Do you want to up-sample a signal by just repeating the last sample? If I’m not mistaken, that’s a zero-order hold interpolation, which is basically the worst interpolation algorithm there is.

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Is this still supported in Audirvana? I thought this got removed when they removed iZotope.

Didn’t think you could turn off interpolation in SoX.

IPe, you are correct, only the older versions with Izotope can do this

Marian, exact, in a DSM NOS DAC it has the advantage that the modulation speed goes up, but the Signal is not altered by a FIR or IIR filter. I know this can become a discussion between digital filtering and NOS, that is not the intention of my post. I just want this option in Roon, next to the already 4 options of digital filtering

Mikael, not sure, need to look into that, thanks for the reply and hint

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Shame, I really liked iZotope.

I assume Roon uses SoX so similar limitation would be in Roon. Honestly, when I get my NOS DAC I plan to deploy HQPlayer at the same time. Seems like a killer combo. Looking forward to Roon’s response to this and if they plan to do any enhancement within the upsampling areas.

100% agree Ipe! as said, can try and compare the two players :slight_smile:

let see what Roon has in its sleeve…

As far as I know, NOS DACs don’t do any sample rate conversion, they just convert samples at their own rate and bit depth to analog. That’s what they’re called non-oversampling. Using a zero-order hold to up-sample will introduce tons of aliasing.

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Yeah. I agree. No DAC that I’m aware of would benefit from this style of upsampling, particularly NOS DACs. But, perhaps I’m wrong. I’d like to better understand the intended application.

My Gustard X16 DAC has a NOS mode, and it sounds amazing when fed a properly upsampled signal (with interpolation).

@David_Snyder I fail to see any benefit whatsoever, other than to practically demonstrate aliasing.

@Doede_Douma As long as the signal is band-limited (which it should be, since it’s been digitized already), using a proper interpolation filter should not change already existing samples. This kind of up-sampling has nothing to do with delta-sigma, since it is not accompanied by any bit depth reduction. You can use Roon to up-sample your signal and feed it to your NOS DAC just fine, as @David_Snyder says.

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Thanks everyone for your inputs. I have tested this already and all is fine. I know what I am doing and how it sounds. Noise gets less. So let stop this discussion on NOS versus OS and FIR filtering good or bad and I like to repeat my request to

@ Roon, a function where “No interpolation” is being a option would be great.

Just curious, what NOS DAC are you planning to use with this?

DDDAC1794 - as BCK is used as SCK this feature is useful…

Oh, another boutique DAC that reinvents the wheel… I’m a little confused though. How is this a NOS DAC if it uses PCM1794A? That chip has an internal delta-sigma modulator.