Flip the absolute phase of a CD/Album

I can’t see what absolute phase shifting would bring. If it does I would look at room acoustics or your system first. Swap the polarity of your speaker cables if you must. What’s the point?
You would notice if one speaker was out of phase as this may have a noise cancel effect on your music.
The only poor CD’s are the over compressed ones and phase shifting won’t change those either.

Nope, I don’t get it at all.

On my Meridian set up, with 5.1 speakers you set up the levels, distances and check phases between speaker pairs at set up. This I have done very carefully and am pleased with the results. Out of phase pairs are easy to spot.
Just my take, what do I know? Not much lol

Go back a few messages and read the difference between absolute phase and relative phase. Your post reads like you are referring to the latter, not the former. And, as others have said, when you do notice a difference it tends to be very subtle.

Expectation bias is a bitch when comparing SQ, but if there actually is a difference in sound when you switch phase 180 degree, its because you enable/disable some DSP or passive phase change which means a change in signal path and/or DSP, not because the phase itself changes. In fact, to even speak of absolute phase you also need to speak about a specific frequency and a distance from speaker to listener. And of course, both ears has to be equally far from all elements that produce sound (which gets complicated when you have 2 speakers).

Inverting a digital stream does not involve use of DSP or change signal path in any way as far as I know. @brian ?

I don’t see what ‘expectation bias’ has to do with it either (the correct term is ‘confirmation bias’ by the way :wink: )

At least not when I activate the ‘inverse phase’ setting in my NAD M51. I did several blind listening tests with it, to rule out any confirmation bias, and found the effect audible, but it was very hard to determine which AP was best.

Of course, in a way, the NAD M51 DAC could be considered a DSP because it uses NAD’s proprietary Direct Digital amplification technology (first featured in their now legendary M2 amplifier) which - for the M51 - was ‘turned down’ to a line level output. You could call the M51 a DDC instead of a DAC because it converts PCM to PWM rather than converting it to analog. But I digress…

I agree with ogs that absolute phase inversion can be applied completely transparent, so every audible effect can be attributed to the inverting of the AP itself.

Yeah, I can’t see confirmation bias being an issue here as there’s no real expectation that the switch on the Yggy will sound better in one position or the other. Probably one of the psychologically cleanest A/B tests I’ve ever done.

There’s really only two ways to do it: flip the polarity in the analog domain or use DSP to negate the bits in the digital domain. Since Roon doesn’t have any analog parts, …

When you flip it on, we insert that inverter into the signal path, that’s why it hiccups, as @Magnus said.

It is very low-touch as DSP goes. It does change the data, but it does not require bit-depth conversion or dithering since it can be done in place for all formats, even DSD.

Thanks @brian. The invert function in my amp is completely seamless and silent. I do not know how it is implemented, but I have always thought of it as maths. DSP is probably what it is then.

Sorry @Max_Delissen I see that I replied to you and quoted @Magnus. I simply clicked the wrong reply button. The reply was meant for Magnus’ post, but I guess you saw that!

Yes I noticed, and no problem.

As a matter of fact, I was reacting to him myself in my last post, but somehow I forgot to use the Quote button :wink:

@Geoffrey_Binder : Sorry, forgot to answer your question :

Of course I have, many many times :). I would never comment like this, with no actual experience.
I have never been able to detect meaningful differences, by just flipping polarities. (Let’s agree to use the word ‘polarity’ here, shall we ? It hasn’t got much to do with phase…)

But no, I can also not rule out the possibility, that other people CAN detect polarity flips.
I know there have been studies in the eighties (Lipshitz, others) that seem to prove this. At least, for specially created test files; not with real music per se.
These studies claimed that our ears/brains work kind of like a half-wave rectifier below a certain frequency; your ears would only process the positive or negative portion of a wave.

Who am I to judge others’s experiences…? All I can say is : there is no solid scientific background to this claim, and my own trained hearing cannot detect this difference at all (not even with specially created ‘worst case signals’.

I guess all I wanted to say, was : you can never have any way of knowing, which polarity better represents ‘the truth’, and which one is ‘wrong’.
The only thing you could do, is state your preference. That’s something entirely different.

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Ok, folks no more traffic here for 2 years now!

Did a „INVERT“ or „INVERT PHASE“ tag find a way into roon 1.5 right now ?

Unfortunately this is not yet done AFAIK. It is maybe not a “worthy” feature?
I’d certainly love to have this, especially after I sold my Devialet amp which had invert as a main feature on it’s remote.

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Don’t get me wrong, I really don’t intend to say ‘Don’t implement that feature’, here :slight_smile: . It wouldn’t me hurt if we had this feature tomorrow. Just wondering out loud.

If you or anyone is really that confident, that a track or album is universally wrong in polarity.
Why wouldn’t you just edit the audio files themselves ? It’s a simple and quick operation. I guess it’s not more work than tagging them, and hoping for Roon to support that new tag.
Plus : you have now solved your problem for any playback chain. Not exclusively for Roon, or other players that support that tag.

Another way of putting that : why must that track be re-processed in the exact same way, every single time that you are playing it ?
I just seems… inefficient to me.

We don’t place tags for ‘this one needs more bass’, ‘this one could use a little compression’, ‘perhaps a bit of BBC dip here’… The list of required DSP presets would be virtually infinite.

(BTW. If you only need a switch, and not an automated system based on a phase-tag : I think this may be possible already. Haven’t tested though. Phase is switchable in DPS->speaker setup. Just make two DSP presets; one for each setting ?)

If you don’t need it, stay away :slightly_smiling_face: This is a thread for us who want the feature. There is another thread for the other DSP needs: By-track or by-album DSP settings
If it is very easy to change file polarity on an album with, say, 15 tracks, show us how. We might do it… if it takes only a few seconds. Making a DSP preset with invert is also a good option, but there is no easy way to access those. At least I haven’t found it.

Well, thanks a lot for that warm welcome. I know my place now :wink: .
I guess you are reading something in my message, that I certainly didn´t mean to say…

My stance is not ´I don´t want phase reversals !!1!´.

My stance was : using a tag for that, is not an efficient or elegant solution.
If you need a tag for every possible DSP action, then the amount of required tags will very quickly grow out of control.
Read : it will hurt your usability in the end.

Very similar case is : left and right are switched in a recording. Would you switch them back yourself, or would you set a tag, and (hope to) rely on the playback software of various vendors to do that for you upon play ?
I know what I would do. Fix it, so it plays well on anything.

As you say : for instance, this could indeed be implemented as part of DPS-per-track. Much more elegant, integrated, and avoids the need for a gazillion different tags.
Not that I need DSP-per-track myself. But at least it is elegant-ish. Much more so, than a phase tag, an L/R tag, a bass boost tag and who-knows-what-more.

Phase inversions can be done in any audio editor you like. It´s one of the most basic edits. Audacity (freeware) will certainly work. Perhaps there are more user friendy or purpose-specific tools, I haven´t searched.The calculation itself is extremely fast, should take much less than a second per track.

Don´t be offended, okay ? I´m having a friendly discussion. Not a strange thing to do on a forum…

Well @ogs, @Marco_de_Jonge lets talk about a realy crasy new Tag-Feature called
„Tag with User Defind DSP Settings“ like a Userdefined Tag „DSP:change Phase“ or
„DSP:Equ_Dip_on_150Hz“ - where, I think you got it - „change Phase“ or „Equ_Dip_on_150Hz“ are Settings made in Volume -> DSP -> User Settiings by Name.

Now you could use those Tags per Album or per Track if you like and got an immense bag
of possibilities!

Ok, I‘m a programmer myself, so that are my early ideers to do an easy automated workflow
on special Settings without using the UI and do it by hand - Album for Album or Track by Track

  • puuuh!
    Well what u say, and what will the roonies say ?

so long Bassmann from Germany

Don’t worry Marco! Did not mean to be unfriendly and I know what you stated about phase reversal. I think a tag for this is a good idea. Also Brian from Roon liked the thought, but he warned that it was not straightforward to program in a good way.
A tag is easy to use. Can be a Roon tag that lives in Roon DB or a file tag. The argument for a Roon tag is strong when we include Tidal and Qobuz. How else would one flip phase on a file streamed from internet?
I get your argument on using files in a different player, but I have so much time invested in Roon that I doubt I’d easily switch to something else.

Nice :). Have to admit that I didn’t think of ROON tags, I assumed that we were speaking of file tags. Yes, this makes a bit more sense now (I can’t see other vendors supporting those tags in the exact same way). Also, didn’t include streaming in my brainfart. Makes sense.

Still, I don’t want it :slight_smile: , but others may have it. As long as an elegant and unobtrusive implementation can be found.

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While waiting for Roon to respond/follow up, I thought it’d be nice to try and find a better answer to this question.

It turns out, that there doesn’t seem to be a free application, specific for this purpose, or at least user-friendly.
It’s sad that I’m so bad with writing software…because the mathematical operations are really not hard.

Anyway. The easiest way to to this, by quite far, is with JRiver. Sorry to mention that name here… I happen to have an old license, and use it solely for audio conversions.
Took an album 44.1khz/16bit FLAC. One hour length. It took a little less than one minute, to flip its phase.
This was very simple to do (first trial took, I guess, about 10 clicks. After which it is fully setup for all following conversions, requiring maybe 3 or 4 clicks).
This time included all unpacking to wav, and recompressing to FLAC (all happening under-the-hood, without user interaction).

You can queue up a few hundreds of albums. Meaning : a few seconds of work. Then go to sleep, wake up, and find your albums all new-and-improved.

Alternatively, it is indeed possible to batch-process them in Audacity. This application is quite a bit slower with the processing.
I think you will run into problems with the more ‘exotic’ formats like DSD though.
And I certainly wouldn’t call it a user-friendly process. (Can explain if appreciated, but wouldn’t really recommend for people that need a how-to…).