[modwright]

Hi guys, just got back from travelling - a wonderful visit to FL where Alan Kimmel and I had a powow about the ModWright Amplifier that we are planning to release by year end...

Okay, first of all, the SWL 9.0SE does inverts absolute phase.  Both channels are in phase with each other of course, but the absolute phase of both channels is inverted, due to the use of a single gain stage.  A single gain stage is sonically pref errable and I will not apologize for the use of a single gain stage in the unit.

When the unit is used in HT/BP mode, it is true that the absolute phase will NOT be inverted, because there is no active stage present.

I agree that absolute phase does effect the sound, but it is also perceived by some more than others.  I can't say why this is the case, but while to some it is a very significant and audible difference, to others it is not.

My logic when designing the 9.0SE was that the HT/BP feature was an added convenience for use with Home Theater, where I did not expect the phase difference to really have significant effect - i.e. the convenience outweighed the possible negative effects.  The 9.0SE is our first production unit and is reasonably priced and offers an extremely high level of performance.  We could only do so much without significantly raising the price.

The LS 36.5 - our new high-end linestage that will be available in April - does have a single set of balanced inputs and a single set of balanced outputs.  It also has a full complement of single-ended inputs and two sets of SE main outputs and a tape output.  Phase inversion will be possible for both SE and XLR outputs, both on the front control panel and via the remote control.

I am sorry to see that this has turned into a somewhat heated debate, but I wanted to clearly confirm the facts about the unit, that in HT/BP mode, the FL and FR outputs from your amplifier will be in-phase, i.e. relative phase will not be inverted.

Another interesting point that was brought up was AC absolute phase polarity.  I agree, that when using cheater plugs and physically modifying AC plugs, you are risking violating your homeowners insurance, etc. and this is simply NOT advisable.

Thanks and I hope this clears the air at least about the ModWright SWL 9.0SE.  I know that the issue of absolute phase will always remain a source of some discussion and debate.

Take care,

Dan W.

[s_cervin]

Thank you all for replying to the thread.  I plan on just switching the leads on my turntable and keeping the CD player the same.  I may eventually get a DAC that will allow phase switching.

Some good discussion in the thread.  Personally in "my" system I can't tell a significant difference in CD playback, but there is significant difference with vinyl. 

sc

[Russell Dawkins]

 

An old trick to cancel the above defined uneven polarity distortion components is "Isobarik" woofer loading, but w/ a twist.  Isobarik mounts one woofer behind the other to cut the enclosure volume in half.  A twist is to reverse the physical relationship of each driver (one's rear faces the other's front).  The cones move in reverse directions vs. their chassis (though they are wired out of phase, so the sum result is in-phase).  This entire exercise is absolutely pointless if speakers don't distort differently depending on their direction.  BTW, it works very well, at least below 100 Hz.  It's expense & mass are the only reasons it's not an audiophile standard for bass.   

Don't you mean speakers face to face, so that when they are wired in reverse polarity to each other, the cones both move in the same direction, but in opposite directions in relation to their chassis? This is intended to nullify direction-specific distortion, or at least make it the same in both cone directions. Saw this done in a pair of dual chamber reflex (like KEF) 3A loudspeakers (made in France). I presumed face to face was chosen over back to back to reduce the amount of air contained between the cones and tighten the coupling between them.

I am also in recording and take absolute polarity seriously, having twice over the years found out that a piece of equipment was inverting the polarity, without my realizing it, and each time I would puzzle how it would always sound better when the offending piece was "hard wire" bypassed. A lot of people didn't know that the Tascam DA-30, a popular DAT machine of the time, output pin 3 hot on its XLRs at a time when it was presumed that pin 2 hot was the standard. This alone resulted in a few of my CDs at the time being in reverse polarity, and quite a few of my engineer friends' masters were similarly affected, too. Not the sort of thing you tell the client, I'm afraid. A peace of mind thang, y'know.

Also, to Kevin, the only remotely convincing "technical" argument for correct polarity I've heard is that certain instruments produce particularly asymmetric waveforms, brass in particular, and if the particular brand of asymmetry is inverted, a different characteristic sound is created. Whatever, I seem to hear it, but it is really hard to be specific about what it sounds like, and I find myself basically reduced to saying it just sounds "better"! 

[James Romeyn]

Maybe I'm more sensitive to it than normal.

On "Love Can Build A Bridge" by the Judds, I am convinced one of the lead vocal mics is inverted vs. the other.  You can't seem to get both to sound similarly good simultaneously, but always one vocal sounds better than the other.  The sound indeed does sound more like it's pushing into the room instead of the other way 'round.

Look at the waveform for a burst balloon.  I know it's not music, but it's a sound.  If you invert that (the sound inverts from a compression to a rarefaction).  The chances that the difference in the static air in the room sounding the same whether the waveform goes - or + for the sound of a burst balloon seems like its between zero & none, meaning you'd certainly here the difference. 

It's this type of effect, the transient at the beginning of a note which shares some qualities w/ a burst balloon, that MAY relate to the audibility. 

No matter what though, denying the existence of the audibility of something that is so clearly audible to at least a goodly portion of audiophiles just makes no sense to me.  To say when the note starts, that the direction of the cone's first movement (+ or - ) is totally meaningless doesn't seem right to me. 

If the recording was done w/ several mics of mixed polarities, no game.  Take a superb Isomike recording & try it on ANY system w/ in-phase speakers.