Absolute Phase... Ok, I'm OCD and An Engineer (Is That Redundant?)

[Grainger49]

Those of you who have gotten the Almost Free LPs from me may have noticed that my LPs are marked with "+ Phase" or "- Phase" which indicate if the recording is in positive or inverted absolute phase.

Since I have built everything in my LP playback from the cartridge forward I know how many phase inversions my system goes through.  I am susceptible to inverted absolute phase.  I attribute that to my having been a drummer in the 60s.

All of that to say... Why are all US masters inverted and European and Mexican (Rodrigo y Gabriella) are positive phase? ? ?  This glaring generality brought to you by my most recent labeling.  I have received several US pressings of UK artists as well as UK pressings of the same artist (Steeleye Span).  This is not to mention the 4 or 5 R y G CDs I have bought.  

Because of my preference for proper absolute phase I have dual banana plugs at my Paramours and swap the appropriately according to the indications on CDs and LPs.

I have been careful, following his request, not to subject Paully to the realities of Absolute Phase.  

Anyone else with Phase OCD? ? ?

 

[rif]

I seem to recall from undergrad years, what we call + and - on a battery is opposite to that in England?  Is that true? Is that even relevant? So maybe what we call current in engineering is flipped to other parts of the world? Just a WAG.

 

[Grainger49]

There is electron current and "standard" current.  It seems that engineers chose that current runs from plus to minus.  Sounded good.  Except when they found it was electrons that move from the minus to plus they refused to change the direction of flow. 

That might be what you have in mind. 

But absolute phase has to do with attacks, transients in music.  If absolute phase is inverted the "Tick" of a drum stick on a cymbal doesn't have a "tick."  It is dull.  A plucked or picked guitar string doesn't have the sound of the pick if it is inverted.

 

[earwaxxer]

Hey Granger - phase is an interesting topic. I know the difference between phase, as in polarity, but what does phase mean in the digital world? When I change the phase on my SRC what am I actually doing? - Thanks much.

 

[Grainger49]

Eric,

If your SRC is a D/A converter, like several that I have had with phase or polarity switches, it takes the output wave and inverts it, usually in the analog part of the circuits.  Think of a frozen single cycle of a sine wave with a little "pip" on the top of the positive going wave.  When it inverts rather than the wave going positive first then negative the wave goes negative first and then positive.  The pip is now on the first half of the negative going wave.

Or... get out a Jazz album that has some closely miked cymbals.  Listen to the strike of the drum stick on the cymbal and then swap the +/- leads on BOTH speakers, and your sub if you use a sub.  Listen again.  One will have the "Th" that begins the strike, the other will not have that.

 

[earwaxxer]

Thanks Granger - I have played a bit with the selector on the Transporter. I'll try that with cymbal sounds. I was mostly listening for bass integration with my sub. Didnt have an effect with bass.

 

[Grainger49]

When I swap my speaker leads I swap the +/- switch on my sub as well.  It is either at zero, non inverted, or 180 which is inverted.  When it is wrong there is a discontinuity around the crossover.  It kind of sucks out where the sub and main speakers are out of phase (here I mean like you swapped only one of your speaker wires).

 

[earwaxxer]

Yep, When I swap out just my sub mains, the bass will either move 'forward' into the area of the speakers, or 'backward' somewhat behind the listening area. If the sound is back there is better definition of higher bass notes from the speakers. I think I like that more.

 

[earwaxxer]

Hey Granger - Wondering if you can help with me understanding phase response in digital filters. I'm trying to get my head around it. A couple of screen pics to illustrate. Thanks - Eric

 

[Grainger49]

Eric,

What we look at and talk about is the voltage wave, or audio signal.  There is a current wave that is not often talked about.  For instance, in your air conditioner there is a capacitor that helps the compressor motor start.  The compressor has three connections on it.  When it starts the start winding in conjunction with the attached capacitor produces the torque to get the compressor running.

Aside, the capacitor causes the current wave to lag the voltage wave in the motor windings.  Current leads in an inductor and lags in a capacitor.  Conversely, voltage leads in a capacitor and lags in an inductor.  (I think I got those right PJ might correct me, please do if I got it backward!)

But the point is that the angle between the voltage and current waves produces higher torque and gives the compressor a kick to start it.  After starting with the RMP increasing the internal centrifugal switch drops the capacitor out of the circuit. 

Ok, that is a little about current and voltage waves.  The "Phase" referred to in filters is that increasing angle between the voltage and current wave.  I opine that it causes smearing of the images, blurring of the sound.

And caps and inductors can not be eliminated.  We have transformers in the amplifiers, they are inductors.  So are plate chokes.  Parafeed and coupling caps are there.  But overall there are fewer in SET amps than in amps with 50-100 transistors in the signal path.  Transistors have capacitance within them.

And maybe I have only muddied the waters.

 

[earwaxxer]

Thanks Granger - Thats interesting. Current and voltate relationships, and how they apply to the concept of phase. Similar to polarity and its relationship to phase. It makes sense. - Eric

 

[Grainger49]

Phase can be relative, whether your speakers move forward at the same time, absolute, whether your speakers move forward at a transient or relating to the voltage and current waves.  Filters are all talking about the third.