This is a guess. I think changing the phase is the same as turning the plug 180 degrees. If this is true a plug tester from Radio Shack would work. This is only a guess. |
Many pre maker/designers do this. I saves one step the signal doesn't have to pass thru,within the pre. You just reverse the leads going to speakers themselves. The bass will be dead center and stronger when you are in phase. |
About half of the CDs out there have the absolute phase reversed anyway. This makes a HUGE difference in the sound quality. The absolute phase MUST BE correct, so you (and everyone else) needs a component with a phase reversal switch. Some of the major labels with reversed phase are: Mercury, Capital, RCA, MCA, DG, London, EMI, Sony, Telarc, Teldec, Epic, Vanguard and Warner Brothers. For the complete list, refer to the article in FI magazine, September 1997. Food for thought: Years ago, many pieces of tube gear were raved about by high end magazines who loved to use RCA shaded dogs and Mercs as their test records. A lot of tube gear reverses phase so with these records, the absolute phase was correct. How many incorrect decisions were made because of this? |
In case this is not clear, you want to reverse the plus and minus speaker cable leads at BOTH speakers OR for both channels of speaker cables at the amplifier. Red to black and black to red. Inverted phase is not the same as AC polarity, so this is independent of your AC power. And it is not the same as out-of-phase, which is much more audible, and which happens when the plus and minus are inverted on one channel only. If your preamp inverts, as your does, I am told that it makes sense to do this procedure even though, as Elgordo says, you will still be "off" for about half of your CDs. What the audio world needs is more preamps and processors with remote control phase reversal. |
there are a number of test cd's and lp's that can be used to assure that your system (as oppposed to the source) is in phase. i use the stereophile test disc 2 or the ortophon test lp as a quick check on phase whenever i change out cables or electronics. both of my last 2 preamps have allowed remote reversal of phase, a nice feature given what elgordo rightly notes. |
The Bel Canto DAC also has an absolute phase switch that governs the analog outputs. The posts here have cleared up the confusion that I was having with this switch, specificaly on much of the classical music that we play. |
Hey Cornfed,
How do you use the stereophile test disc to check phase. I only saw a track to check if L&R were in phase. I'd love to have an easy way to check with my sytem is in or out of absolute phase. I look forward to reading any other thoughts on this topic. Very interesting post about the phase of different labels. |
There is much controversy regarding this subject which to me indicates that there is no clear right or wrong. In this context phase refers to whether your speaker cone moves outward in response to the positive half of the input signal. Some people are sensitive to this, most are not. It's easy to test your sensitivity if your preamp or D/A offers this feature. In the recording process phase integrity is rarely maintained. In fact, from track to track on most pop/rock recordings there is no consistency. It will take a serious effort on your part to accurately label a large music collection for absolute phase. I question whether it would be worth the effort. Relative phase is far more important. |
would anyone know where a test disc can be purchased,none of the local dealers have them.
and thanks for all the great info! |
onhwy61 makes several good points, that also address the query of chelillingworth directed to me. generally, you will be able to detect whether your system is in relative phase by checking the "channel phasing" of your speakers. this can be accomplished with stereophile test disc 2. if your channels are out of phase, then you've got some wire(s) crossed somewhere that affects both the relative and absolute phase. "sytstem phase" is testable with the stereophile test disc 1. i cannot attest to its accuracy, tho, i am usually able to detect by listening when a system is connected out-of-phase. absolute phase correctness requires more than a test disc or my ears can offer and i don't really worry about it, as, again, onhwy61 suggests. |
am0779@aol.com: you can buy the stereophile test discs online at: http://www.stereophile.com/
goto: "recordings."
the ortofon (i misspelled it in my earlier post) test lp is long out of print but can be found, if you're in luck, at places where used lp's are available. good hunting. -kelly |
Onhwy61's post was excellent. My recommendation that you make the change was no more than regurgitating audiophile best practices. But truth to tell, I don't hear a meaningful difference myself. I have known some who are highly sensitive to it, however. |
There might be a whole other problem that goes along with preamps that invert phase: Does it mean that your cable to the amp is sending the negative signal through the positive conductor and visa-versa?!! Think about it... most cables are designed to handle both these polarities in very different ways and if the preamp inverts them, you have just tossed out all the cable's design .I have only seen one cable that is offered specially configured for inverted phase signals, and that was the Mapleshade. |
Harv: I use the Mapleshade digital cable, however it is the standard (whatever that is) phase version. I wonder if we are all talking about the same thing as when I invert the phase on the Bel Canto it makes a very noticeable difference in the sound. With most material, inverting the phase narrows the sound stage and make the instruments more immediate and up front sounding with less air/reverb quality and very little overhang on the bass. Some of our classical CD's though sound very distant, in normal phase, almost as if I am listening from the adjacent room. Inverting the phase makes them sound much better. The term that Bel Canto uses in the manual is "absolute phase" as I recall, though the manual is buried in a closet right now. Is there something wrong with my system for the phase change to be so apparent? I have been through two different amps and sets of speakers with this DAC with the same results. |
Dekay, there is nothing wrong with your system. Quite the contrary; it no doubt has the kind of resolving ability that makes it painfully obvious when you've got the phase wrong. When the bass and "stage" are dramatically reduced, and the recording sounds "boxed in," I know I've got the absolute polarity reversed. It does seem to be a bit harder to tell on some recordings than others, though. |
As a postscript to my last post, I wanted to mention an idea that my brother and I tossed around some time ago. Before I owned a component with a polarity reversing switch (Theta thinks it's important enough that they include them on their DACs) I wondered whether it was possible to make one's own polarity inverting cable by simply reversing the conductors at one end when soldering. Is this what Mapleshade has done? It occurred to me that if you owned a source component with dual outputs, you could feed them to two different inputs on your preamp; one would have the correct polarity, and the other would be inverted. Voila! Instantly selectable polarity. One further note on whether or not absolute polarity makes a difference; let's say you're listening to a piece of classical music on a great audio system. You've paid countless thousands of dollars to have components that are "fast," that is, that have great transient response because of short rise time, colossal slew rate and all of that. But you're listening to a recording that has the absolute polarity reversed, and when the percussionist whacks that huge bass drum in the midle of The Rite of Spring, your woofers initially suck in instead of blowing air out. You've lost some impact, have you not? A good audiophile should always be able to tell the difference between "suck" and "blow." |
This is an interesting thread, so I may as well add my 2 cents. As some have said, about 50% of recordings are recorded out of absolute polarity. On some recordings, some tracks are in correct phase and some are 180 degrees out of phase. Also, on some tracks instruments can be recorded in opposite polarity to one another; for example, the piano and drums may be in correct phase and the brass instruments could be recorded in the opposite polarity. Add to this the fact that this phenomenon is normally only audible when reproduced over loudspeakers with accurate phase reproduction. Many multi-driver, multi-way speakers are NOT even close to being phase coherent, so that is why the effect is not apparent on some systems. I could be wrong, but to my ears, recordings with correct absolute polarity sound more forward and palpable in the midrange, which can be best heard on vocals and brass instruments. Incorrect polarity recesses the vocal, overemphasizes the treble and truncates the trailing edges of bass notes -- rendering the sound tight and bright, but not right. This view seems to be opposed to what some others have said. An excellent book on the subject for those interested, is Clark Johnsen's "The Wood Effect". Peace! |
I have been buying all of the classical CD's from one source (a flea market dealer who is selling them for a classical music buff friend). I wonder now if the person is editing them from his collection because of this "phase thing". I was originally purchasing them for $3 a pop which has now been reduced to $1 and I buy whatever is there each week (so far approx. 40 CD's in all, many of which I have not yet listened to). I will add that with most of our pop records it makes only a slight difference though I prefer the switch in it's out position which offers a wider soundstge and more "reverb" as I call it which is probably "air" to most. The only popular CD that really has a right and wrong is an old one with Nat King Cole that is unlistenable in the regular position. The funny thing is that when I first got the DAC I was considering asking Bel Canto to "hard wire" the switch into the position that I liked to see if eliminating the switch would improve the sound. I was also irratated at having to make the choice when it always seemed to sound best in one position. Now I will leave it as is due to it's positive effect on some recordings. It would be nice to have this feature available on a remote control as Kelly mentions. I don't consider my system with Reynaud Twins to be highly resolving though I have had some strange things happen with this setup (like very nice power cords sounding horrible) and think that it may just be the combination that I have put together that definately has shunned some items that I have tried to add. Perhaps it does this to some source material or "phase" as well. The power cord episode drove me nuts as other users of the same cords with much better systems have had good results. I finally sent them back to be checked for defects. |
Plato: That sounds like pretty much what I am hearing, especially the "truncated" (had to look it up) bass that sounds like the center of the note less it's harmonics. |
Right, DeKay -- or to put it another way -- it sounds like the fundamental note minus the natural "decay". :) |
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Dekay: Don't forget that power cords, like every other piece of wire, take a certain amount of time to break in. The last time I changed power cords it took several days for the improvement to become apparent. You can't pass judgement on a power cord or interconnect cable until it's been in your system for awhile, some say around 400 hours of actual use. BTW, I purchased my Parasound 2000 preamp largely because it had a phase reversing switch on the remote. Shortly afterward, I read that phase inverting switches add an additional circuit -- to say nothing of the switch itself -- into the signal path. More garbage between you and the music = BAD! For this reason, the Parasound has an alternative direct output that bypasses the phase inverting function for serious listening. You can't win. It's helpful, however, to be able to determine the phase setting that sounds the best on a recording-to-recording basis right from your listening chair, and then mark it right on the jewel case for the CD. Regrettably, this really only works fairly well with classical recordings, and even then, only with a good one. In a multi-mic recording, mics may be out of phase with one another. On the pop music side, I have a Joni Mitchell CD where the absolute polarity jumps around from cut to cut. Pop albums are frequently recorded in multiple studios, with the master carried around the world to have tracks added. Off to Nashville to have a rhythm guitar track added, then off to someplace else to record the horns, etc. Fleetwood Mac, for example, is notorious for this. By the time you pop that CD into your system, God only knows WHAT you’ve got. |
Thanks for the info Doug. I gave the new power cords too much of a chance (almost 3 weeks at 16+ hours/day) and they sounded so bad that we listened to the mini system in the spare room most of that time with the main rig turned down low in the living room. I can only assume that the cords were defective, otherwise we have something very odd going on with the system. I should know in the next week or so as the manufacturer is going to check them and let me know. I'm not going to get nuts about the phase thing, but it's nice to know what the switch is for and also that I am "not" nuts when I hear a differences on some of the discs. From what you tell me I would guess that the classical recordings would have a much more consistant phase as the engineers are not punching in notes and lines all over the place as is done with popular music. |
thanks for all the info.....think i,ll go back to the bryston |
