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Why is inverting or non-inverting important?

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Posted on June 6, 2017 at 12:03:34
RayP
Audiophile

Posts: 727
Location: Maryland
Joined: June 30, 2005
 Looking at deathtubes's post below, I realized that I really don't understand why the inverting issue is important. Perhaps somebody could enlighten me.

ray

 

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RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 12:09:21
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 It's not but it's good to know if your system as a whole inverts or not.

If it does invert, and you want the sound to be in absolute phase, you will need to reverse the speakers wires.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 12:44:04
RayP
Audiophile

Posts: 727
Location: Maryland
Joined: June 30, 2005
 Yes that is my understanding too. I can remember reading about the 'wood effect' years ago but I suspect many of us have no idea if our systems are inverting or not. Or the recording we are listening to.

Which still makes me wonder why it is even an issue.

ray

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 13:01:09
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
 It's all fun until you get to the music, which as near as I understand has NO phase standards.

It is even possible for multiple cuts to be editied together from several studios and THEY aren't all in phase.

I doubt any album with the possible exception of a single, live track,is all recorded in phase. Or rather that all tracks agree as to phase.

If your stereo has an absolute phase switch, try it is the best advice. It may actually help on a few tracks but not matter on most.
Too much is never enough

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 13:11:23
FenderLover
 It's my understanding various instruments (esp multi-track, overdubbing) may not be in phase, on one song. Sometimes, done for effect.

There are no strict rules, in the studio of pop music.


8^)

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 13:31:55
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 All of what has been said above is true.

There's no way of knowing and most are mixed.

My point would be, to hear the record *as produced* one needs to know if the playback system inverts or not.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 13:35:32
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 "My point would be, to hear the record *as produced* one needs to know if the playback system inverts or not."

Bingo!

On the subject of recorded music, I have one CD of an older British group (Yardbirds, I think) where the left channel is inverted from the right. Played normally on stereo speakers, there's virtually no bass at all. Invert one speaker, and Voila!

 

boy, someone screwed up. (nt), posted on June 6, 2017 at 13:44:18
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Funny story, posted on June 6, 2017 at 14:29:07
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002

Back in the 1990's I had a client at the recording studio who was obsessed with absolute polarity.

John had a little "clicker" that he would click at the mic and a box that he would place close to the monitor speakers and "prove" that everything was in polarity.

I just looked him up. He did release the songs we worked on when he got back to Sweden in 1999.

I looked up the album and knew for sure that I had the right guy (even before finding his picture on the cover of the album) when I saw the title of the last track.

"12. Polarity Test [Correct Polarity +++ -] - 0:05"

Too funny!

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Why is inverting or non-inverting important?, posted on June 6, 2017 at 15:00:10
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 The only possible situation that I can think of is in the case of biamping with two differrent amps. If one inverted and the other didn't, there might be problems. I would expect the issue would be apparent during setup and easily remedied.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

Kinda depends on what your listening diet is., posted on June 7, 2017 at 03:41:36
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 If you listen to a lot of simply recorded real 3d stereo (a stereo mike array base) and your speakers are at time / phase coherent, then it might matter, to you.

I've been using polarity switching for over 30 years, and won't be without it.








Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

RE: Why is inverting or non-inverting important?, posted on June 7, 2017 at 08:53:54
Hornlover
Manufacturer

Posts: 2529
Joined: March 8, 2002
 There are some situations where you can indeed tell a difference. Try playing a good recording of a kick drum (which in the real world will cause an initial compression). Try it both in proper phase (woofer cones compress on initial attack), and then reverse the speaker leads, so the initial attack is a refraction. You can tell the difference. I did a lot of investigation on this years ago using the Sheffield Labs drum record. My audiophile buddies could hear it too, so its not just me. You need a scope to make sure what polarity you are sending to the loudspeakers. Because of this, I still make sure my final polarity at the loudspeakers is proper. Various recordings may be all over the place, but at least I know that if I send a positive pulse into my preamp, I get a positive pulse to my loudspeakers.

 

RE: Why is inverting or non-inverting important?, posted on June 7, 2017 at 09:35:55
Lee of Omaha
Dealer

Posts: 1800
Location: Omaha NE
Joined: September 8, 2006
 First, some people can hear absolute phase, some can't. I've never heard it, including on direct-to-disc recordings. (However, RIAA encoding and decoding causes LOTS of phase distortion due to the multiple filters used on both ends).

Second, as others have pointed out, multi-mike recordings, mixing, and electronic music have no inherent absolute phase.

Third, not all instrument have absolute phase. Strings don't, for instance, but I think most woodwinds do.

Fourth, there is no standard for absolute phase in recordings, so even those that MIGHT have absolute phase you'd have to guess (experiment) with. Almost everything in the 1960s and 1970s was multi-miked, so forget those recordings. On others, do what sounds better, if either setting does sound better.

 

RE: Why is inverting or non-inverting important?, posted on June 7, 2017 at 09:46:46
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 "(However, RIAA encoding and decoding causes LOTS of phase distortion due to the multiple filters used on both ends)."

Isn't the phase corrected, along with the amplitude, with the application of the RIAA filter* in the phono preamp?

Note* I think that filter is more correctly called a "reverse RIAA filter". The filter use when making the record is the RIAA filter.

To be clear, A "RIAA filter" (the one used to make a record) cuts the bass and boosts the highs. A "reverse RIAA filter" (the one used to play a record, ie; the one in our phono preamps) boosts the bass and cuts the highs.

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

Valid idea, if you like to listen to solo kick drum, posted on June 7, 2017 at 11:09:34
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 But (1) I doubt that the distinction between phases is as easily made with instruments that operate predominantly at higher frequencies, and (2) if more than one microphone is recording more than one instrument, then the issue of phase relationships becomes very complex. (I don't doubt that you or someone else might still prefer one phase vs the other; I think that's mostly a function of the speakers and the listening room than of the recording.) I and some other listeners have found it impossible to distinguish phase difference, using my dipolar speakers.

 

RE: Valid idea, if you like to listen to solo kick drum, posted on June 9, 2017 at 09:39:29
CaliforniaBob
Audiophile

Posts: 92
Location: SF Bay Area
Joined: June 2, 2004
 there are test LPs that test your speaker's phase
in and out of phase. on my system - you can tell
the difference.

 

I don't doubt you can hear differences between 0 and 180 degrees, posted on June 10, 2017 at 19:55:19
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 But I do doubt that the reason you can hear it is because recorded music is monolithic in phase across frequencies, regardless of microphone(s), instruments, rooms, recordings, etc. (It's not.) On my own speakers, I suspect the reason I cannot hear an iota of difference between phases has to do with the fact that they are huge dipoles from top to bottom frequencies. I double-blinded my wife and then teen-age son while I switched back and forth; they could not hear any difference, either. This was on music, not test LPs. To my mind, music is what matters. I'm kind of glad I can't hear a difference, one fewer thing to obsess over.

 

RE: I don't doubt you can hear differences between 0 and 180 degrees, posted on June 12, 2017 at 09:16:13
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 That's an excellent post Lew!

I would highly recommend you and other inmates take a look at the excerpt from an AES oral history from Edgar Villchur - the founder of Acoustic Research and driving force behind acoustic suspension loudspeaker systems. The 2nd half of the "Loudspeaker Performance" excerpt (link below) is VERY interesting! While he's talking about loudspeakers what he discusses is widely applicable to any discussion of phase.

 

Good stuff, Thank you Jim... relative phase meets reality~nT, posted on June 13, 2017 at 01:44:48
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
Joined: June 30, 2005
 ~!
The Mind has No Firewall~ U.S. Army War College.

 

RE: Why is inverting or non-inverting important?, posted on June 13, 2017 at 10:21:49
Lee of Omaha
Dealer

Posts: 1800
Location: Omaha NE
Joined: September 8, 2006
 Generally, no. There are innumerable designs for filters on both ends, each with their own phase signatures (for lack of a better term).

 

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