Warszawa

DAC "reconstruction" filters

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2 minutes ago, Metatron said:

Roll-off always comes across like a negative thing if it's before 20khz.

Thing is, most of us can no longer hear that high. So just in case anybody rules out a filter because it rolls-off early before 20kHz... check to see what frequency you can still hear up to, and the filter rolls off at or after that frequency, give it a whirl.

Very true. I can understand how roll off before 20KHz effects the sound, it's the roll off beyond that that had me confused.

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The ear works in the time domain as well and 44.1kHz and reconstruction filters make a mess of that.

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Super Dealer

Perhaps read Archimago’s post that Martin linked to earlier or any digital ‘primer’ Monty Montgomery’s are very informative.

Keith

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26 minutes ago, Warszawa said:

Very true. I can understand how roll off before 20KHz effects the sound, it's the roll off beyond that that had me confused.

A slower roll-off reduces ringing but is not as effective at filtering out the aliases:

714Lux6fig01.jpgP-1 (normal FIR filter)714Lux6fig03.jpgP-3 (high attenuation FIR filter)

.

714Lux6fig04.jpgP-1 (normal FIR filter)

714Lux6fig06.jpgP-3 (high attenuation FIR filter)

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Posted (edited)
53 minutes ago, Warszawa said:

Very true. I can understand how roll off before 20KHz effects the sound, it's the roll off beyond that that had me confused.

You need to do some reading if you want to understand why, but if you don't have filters that remove frequencies above 20 kHz (ish) then, as unlikely as I know this sounds, it will cause distortion below 20 kHz (which you can therefore potentially hear).

However, if you read the first link I posted I think you'll find that actual filter selection isn't something to get too hung up on, and personally I'd be tempted to just say pick a linear fast roll-off filter and forget about it. If want to go a stage further then you're not going to do any better than listening to them and seeing if you can tell a difference / have a preference, but note that what is 'best' may vary with how good the recording is.

Edited by MartinC
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Posted (edited)

Here you can see the aliasing produced below 20kHz:

518HoloSpringfig03.jpgNoOverSampling

518HoloSpringfig04.jpgOverSampling

.

P.S.: These images are signal correlated and this means that some people are bound to like them...

Edited by tuga

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NOS  DACs produce copious amounts of intermodulation distortion. This, the aliasing and the jitter may contribute to their success amongst vinyl lovers.

518HoloSpringfig13.jpgNOS

518HoloSpringfig14.jpg

OS

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Posted (edited)

I find the differences between some of HQ Player's filters easily noticeable but it is possible that this is caused by the fact that I am running my DAC NOS and digital-filterless...

I spent some time comparing linear- and minimum-phase versions of the "poly-sync-short" and also tried the "asymmetric FIR", preferring the first (lp). I am currently using the "ext2" filter, which has recently ousted the Chord-like "xtr".

Edited by tuga
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Posted (edited)

I wouldn't loose any sleep over non oversampling distortion figures. I measured one on an old school distortion analyser. Now granted this is no longer total harmonic distortion as indicated, but distortion it is. Anyway, it rises steadily to 33% (or more, I can't quite remember) at 20kHz. I took that to Scalford in 2017, I am sure some people would keel over and die rather than say they enjoyed 33% distortion,  😀 if only they knew.

I do worry about putting those fast edges into a transistor feedback amp though.

Edited by dave

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34 minutes ago, dave said:

I wouldn't loose any sleep over non oversampling distortion figures. I measured one on an old school distortion analyser. Now granted this is no longer total harmonic distortion as indicated, but distortion it is. Anyway, it rises steadily to 33 Percent (or more, I can't quite remember) at 20kHz. I took that to Scalford in 2017, I am sure some people would keel over and die rather than say they enjoyed 33 distortion,  😀 if only they knew.

I do worry about putting those fast edges into a transistor feedback amp though.

There's an RMAF video on YouTube in which some chap from AP plays the same track to an audiophile audience with different types of distortion which he gradually increases until a significant number of people raises their hand in protest.

I guess people have different goals and expectations but it's still alarming to see how much distortion some people can take, people from whom you'd expect some discernment.

And perhaps music genres also play a significant part. After all the sonic complexity of an orchestral piece is far more challenging to reproduce than a string quartet, a jazz trio or a girl with an acoustic guitar.

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16 hours ago, tuga said:

There's an RMAF video on YouTube in which some chap from AP plays the same track to an audiophile audience with different types of distortion which he gradually increases until a significant number of people raises their hand in protest.

Do you have a link? I do hope they are blindfolded, so that it's not a case of as one person puts their hand up, the others follow suit because nobody wants to be last.

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57 minutes ago, Metatron said:

Do you have a link? I do hope they are blindfolded, so that it's not a case of as one person puts their hand up, the others follow suit because nobody wants to be last.

Here you go:

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@tuga

Thanks for the video link.

It's much the same as my view.

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FWIW, I tried the P-3 filter this afternoon for the first time. Maybe I imagined it, but it seemed like it made the "timing" a bit more like my Chord DAC. Injected a bit of adrenaline without losing the Luxman's rich tonal balance. Thoroughly enjoyed the music anyway.

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Super Wammer

That was a fascinating video, thanks for that.

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