Phase as an issue in audio.

[Spectral Morn]

Hi Guys

This was meant for a thread that doesn't exist now...probably a good thing. However some of my thoughts are worth sharing.

Firstly something I want to get of my chest...

I for one dislike having other people tell me that I can't hear certain things, that I know I can hear (note I said can hear not necessarily explain )....they trot out the usual narrow world view and say if you can hear it you must be deluded or self delusional or its some sort of placebo effect. It may just be that my hearing is better or my system is more transparent. However I have always heard such things even when my past systems have not been as transparent as my current one is. It also bugs me when those nay sayers also then blame something else to account for what they themselves may be hearing but don't want to admit, either to themselves or God forbid some one else. Why can't they just say I can't hear it and leave it at that ? Answers on a postcard too..... I suppose its a lot easier to keep face if you have always been open minded, especially if you hear something improve a system which is way out there. I for one would rather say " Look I heard this...I can't explain it but check it out you may benefit ". Whats the harm in that ? It may work in that other system/application or not as the case may be. Is it not better to share and possibly help some one else get closer to their dream. Than keep silent because you might look a bit silly or crazy.

I offer this as an example...of the above.

When I recently reviewed Stans Beresford Dac 7510 I found it to be a bit fussy about what it sat on (lets say you can improve its sound with a bit of care and attention to set up and what it sits on). So when it was reported elsewhere that moving it to a stand sounded better and I would not for a moment show any surprise when moving it from a card board box top to a dedicated stand should show an improvement in sound. Its only logical to think that would be the case. Why should it not be so ? Unfortunately there are some who for what ever reason or agenda won't admit to such things and question it when they hear such things....fine let them be happy as they are, but equally they should stop trying to save us from what they perceive as our collective deluded states.....guys get a life please...do you want to be the audio Talaban and kill us next for what we believe we can hear. We don't need saving from having open minds and ears.

I have written the above because phase issues also seem to generate heated discussion and blanket statements that it does not matter or can't be heard. I think it matters and can be heard.

Any way back to the main topic of this thread PHASE.....does it exists as an issue. Yes. I firmly believe that in my experience it does and I believe that there are three main areas in which this is a potential problem.

One-Recording phase....from instruments to microphones to mixing desk to mastering to final medium (vinyl, cd etc)

Two-The design of audio kit and how it links to other item in the same brand or other brands.

Three- The design and implementation of balanced circuits and the difference between European wiring of the XLR plug/socket and the American.

The first one is really out of our control. I would have thought with so many connections (in the chain) and the possibility of many hook up errors. That these would be neutralized by the time the signal reaches the end and becomes a disc. That it may as a factor only effect a small number of recordings (either by accident. Or how many by design perhaps ?). I for one would have liked all gear (used for recording) to be set up and used properly (taking phase into account). However with issues two and three being also a potential factor, it is not a simple matter to sort out and the people as a whole involved in recordings etc would have to be pretty anal to sort it (even worry about it)....not very likely in most cases I would say. So if you want to look for phase issues in recordings or you know its an issue with a particular recording...go on flick/push the button and see what happens, or swap your speaker leads...takes but a moment to do. You never know you may hear it and like the change you have made.

The second issue. Ummm...this is more complicated in so much as should the spec of a product say it inverts phase....I for one would say Yes. This info should be present in the spec sheet (with every product and all the time) or mentioned as a last resort as part of a review. However if a designer feels his gear sounds better this way (valid design choice within the context of some one who makes items to be used together, such as a pre and power amplification system) but he/she should keep it in mind that their design may be used outside of their brand. If they make only one item, a power amp or pre then it would be vital to make known all specs so one can take these into account for proper matching (at least from a technical stand point). Phase issues aside this may not be an issue from a sonic/sound characteristic match up.

The Third issue is one I for one have plenty of direct experience with. My first cdp to have balanced outputs was my Marantz CD7, it is wired to the American system the + and - pins are wired in reverse to the European inputs and plugs...thus causing a phase issue. Wanting to have the thing wired right (maybe I am a bit anal about things like that), I spoke to a cable maker (who hadn't thought much about this either) and got him to wire a cable for me with the wires at one end (source ) wired for the swap with the + and -. It made, to my (deluded) ears a big difference in sound effecting the whole frequency and offering improvements in focus, bass and how fine detail was presented. The amplification in this case was Pathos Classic Ones. It was worth doing. Since that time I now have a pre-amplifier ( BAT VK31Se) with a phase switch button and I always set for the wiring of any set up American to European or vice a versa. Of course if your source to pre to power involves a couple of such swaps they can correct themselves by the time the music reaches the speakers. Swapping speaker + and - will not correct for a number of phase reversals upstream. So it is vital to know where these are and work accordingly.

Before I was aware of this as an issue I rarely heard/read much about it and now that I am aware of it the same is true. To my mind the ideal would be to set a world wide standard and wire accordingly with no worry. However including phase buttons on sources, pre amps and maybe power amplifiers might be a good idea accept that it adds something else into the path of the signal, and we really don't want to do that. Keep it simple....so correcting for wiring should really be kept out of things...at least in an ideal world, which this isn't.

There are also some who can't hear ( as opposed to wont hear ) phase issues...it would be nice to be like that, but I can. So blessing or curse I have to live with it.

Discuss the above. Peacefully Please.


Regards D S D L---Neil

[markf]

"One-Recording phase....from instruments to microphones to mixing desk to mastering to final medium (vinyl, cd etc)"

Goldfrapp appear to record everything inphase so you can use them as a good reference.

[Spectral Morn]

Hi MarkF


Goldfrapp....good I like them a lot, though it took me awhile to get into their last record (sound not as good as previous albums either). However I do use their music for testing as well as pleasure so I will try switching phase and see what I think. Thanks for the heads up on that Mark F

For me phase only ever became an issue when I started exploring kit with balanced XLR connections and I was mixing European and American items. In order to get the connections right I decided to have a cable wired with the + and - pins reversed, so the signal reached the amplifier right way round. After playing around with cables that were not wired to correct this problem, I found I could hear when it wasn't right. One of the reasons I bought my current pre-amplifier was its ability to switch phase. I have a mixture of European and American balanced kit and this solution was better than having to get two sets of interconnects made one set for use between matching wired items and a set to allow for differently wired kit. This would have been to dear. Strangely swapping speaker leads round did not sound right compared to using an interconnect to solve the problem.

I think my biggest issue with all this, is the lack of info that many companies fail to provide with their products and whether phase is reversed or not would be the kind of info that would be useful to have. It should be mandatory and included on their products spec sheet/list.

This is a multi faceted problem (if you view it as such of course) and recordings which are not presented with correct phase only confuse things. How many people are phase sensitive and don't know it ? How many of them are using systems that are wired/connected out of phase, and perhaps their issues with the sound of that system are related to phase, but they just don't know because of lack of info. I was shocked by how many in the trade had never thought about the wiring of XLR plugs and sockets, and how that difference could effect sound. If you run balanced products from Europe and America or vice a versa and you are using a standard XLR cable or you have never switched phase (and you can on your source or pre)...can I suggest you do so, because you are currently some times (depending on source) listening out of phase. I think you will be surprised by what you hear....go on try it.

I must admit to not having given thought to corect pahase with RCA wired kit....worth looking into, I think.


Regards D S D L----Neil

[Primalsea]

I would go as far to say that "inverted signal" (which is what you are actually referring to) doesn't make a difference when the equipment is able to treat both polarities of the signal equally.

However not all equipment is able to do this. Solid state running in class A with little headroom or valves, microphones and speakers certainly don't. So its entirely logical that a difference could be heard.

So you are not mad after all about this subject anyway. Now about your Dalek identity crisis, take that plunger out of your mouth and come here..................

[The Grand Wazoo]

From The Grave

[jandl100]

An interesting and timely resurrection!

My Krell KRC-3 pre-amp has remotely controlled polarity inversion, so I can just click the changes from my listening chair.

There is often a substantial difference, with (usually) the inverted position giving significantly more focussed imaging.

Neil describes the changes he hears as "... a big difference in sound effecting the whole frequency and offering improvements in focus, bass and how fine detail was presented." Mmm ... I don't think I hear any bass differences, but then most of my music is not bass-led so maybe that isn't high up in my listening priorities, but midrange & treble focus and fine detail for sure.

I'd be tempted to say it was due to different circuitry being employed in the pre-amp, rather than being down to polarity issues .... except that on about 10% of CDs, the non-inverted setting gives the best imaging.

It's also far more apparent on CD than LP.

I must confess that with other equipment I don't notice much difference. It's just the Krell pre that highlights it for some reason. But mayhap that's because the phase button on the Krell makes it so easy to change. Yup, that could well be it!

[StanleyB]

Phase issue is something that I studied in detail when I was doing my research for a "better DAC sound" over the last three years. I discovered that the main accepted digital filters that are designed to produce the high frequency roll off above 20KHz were a major cause of woolly bass and skinny treble. By just removing the feedback filter capacitor in the MFB filter circuit, or by adjusting the value of that cap, I could generate a wide range of phase shifts in the sound.
What Jerry noticed between digital and TT reproduction is due to the above. In the RIAA spec the phase shift is known from the RIAA correction curve. But in the case of the output circuitry of a DAC there is no accepted standard other than the recommendation that the signal is rolled off above 20KHz. So wide variations exist.

[DSJR]

Are there any phase shifts introduced in the A-D process in the first place?

[StanleyB]

I haven't seen any filtering circuit in the analogue part of any of the A to D that I have on file from the chip manufacturers. But if one is inserted you would get an even bigger phase shift since you would be adding a double entry of a brick wall filter.

[The Grand Wazoo]

Do we know whether keeping phase integrity throughout is the ideal, or do you think that by simply correcting it right at the the end of the chain you're solving the problem?

I'm struggling to get my point across a little here I hope someone can understand what I'm trying to say!