|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
82.46.170.49
In Reply to: RE: More about Absolute Polarity posted by HiOnFi on December 16, 2008 at 15:25:38
The only time 'polarity' comes into it during recording is when more then one mic is used to capture an instrument. Thats usually the drum kit where each drum is close mic'ed and an overhead pair is used to capture the whole kit, the cymbals and some of the room sound.
In this case one or more mics need to be inverted to avoid large cancellations.
Often the snare drum is mic'ed top and bottom in which case one mic has got to be inverted.
It has nothing to do with overall 'acoustic polarity' which once something has been recorded is impossible to reconstitute. Whos to say if a drum was mic'ed from above, in which case the soundwave starts with a rarefaction, or below in which case the wave begins with a compaction? If you stand a few yards away from a drum kit there is equally no way of telling if you hear the compaction or rarefaction first.
The engineer knows in the case of close mic'ing a drum kit but if you mic a clarinet nobody knows and nobody cares, the mic just goes where it sounds best.
The reason xovers have polarity switches is because pa speakers are hardly ever time aligned and the switch is again used to avoid the worst cancellations.
Some xovers feature 360deg adjustement of phase for the same reason, mine do anyway.
Drivers should be run the way they were designed. In case of my Tannoys they were designed to move backwards when faced with a positive going waveform, just like JBLpros. They sound better that way. The Volt drivers in my woofers were designed for either and do not sound in any way different if I flip the polarity.
Follow Ups:
Drivers should be run the way they were designed. In case of my Tannoys they were designed to move backwards when faced with a positive going waveform, just like JBLpros. They sound better that way. The Volt drivers in my woofers were designed for either and do not sound in any way different if I flip the polarity.
First off they are not designed to move backwards
The terminals are simply labled red on positive and blk on negative
The OLD JBL line speakers were labled out of phase
The new JBl stuff has been labled properly for positive and negative
for sometime now
Many people had no clue of the reverse phase on the old JBL stuff
and ran systems with out of phase JBL speakers mixed with other
pro loudspeaker gear
Which basically sucked
At least JBL has it right on the phase issue now
And that's all it is! Nothing but a means to describe which way a driver will move when a + battery post is touched to the red terminal.
Good thing though that a general agreement has been reached that "+" means an outwards-going excursion (nvver-minding the usual out-of-phase crossover wiring).
Poles Apart
Regarding JBL woofers I could almost agree, Tannoys (of a certain vintage) are somewhat different as woofer and tweeter coil share the same magnet.
Again if you have issues with Tannoys 'being designed' to move inwards take that up with their engineers. Could prove difficult though as I expect most of them to have retired a long time ago.
Until I have their word on it I stick with what they wrote in the technical manual (the one for service engineers)… and my ears.
I see you have issues with the Tannoy technical manual. You might want to take that up with the Tannoy design engineers.
If you care to research the AES recommendations for preservation of polarity, they recommend a forward motion of the driver cones as being the preferred way to mark the positive terminals. Bearing in mind that these standards were promulgated fairly late in audio history, many traditional older companies have elected to retain their older standards. I suspect Tannoy would be one of them. The fact that JBL has altered their designs reflects an acceptance of that AES recommendation (also part of the IEC recommendations, IIRC).
People like AKG, last I checked their website, openly admit that their headphones are reversed in polarity but say that is part and parcel of the AKG sound. Thus some companies retain their non standard procedures in order to satisfy their particular niche market.
The fact is, much like the dual standard for XLR pin outs, again covered by AES and IEC standards, there is absolutely no law forcing manufacturers to adhere to the standards recommended. Hence there is much confusion in the world of audio. Some can hear the differences, others can not. But with the various "standards" comes tremendous confusion, and many listeners are simply overwhelmed by trying to understand what problem is causing what anomaly in sound.
In addition, polarity inversions are used to "doctor" the sound. I have long stated that Phil Spector's "wall of Sound" was his use of inverting the polarity of the background instrumentals while keeping the vocals in correct polarity. The inverted polarity of the background instruments gives a large soundstage because it smears the sound of those players and seemingly enlarges the soundstage.
You can also hear this in the movie "The Commitments". In the newly released directors cut, the director explains how they recorded every one in the band playing their own instruments but reversed the polarity in respect to the lead singer in order that his voice project far more and sound significantly better in order to emphasize the pint in the story line.
In the Michael Crawford album, I notice that Crawford's voice is reversed in polarity to the other people in the duets he sings. I find that his voice is not the greatest, at least not in comparison to Barbara Bonney, a noted operatic singer, so to underscore that this is his album, there are polarity inversions.
In addition, the use of vocal synthesizers creates issues with polarities. The Aphex Aural Exciter, IIRC, inverts polarity and adds some EQ. Many singers use it inn order to get that husky voice which seems to be popular these days. Streisand, Ronstadt, Neil Diamond all use it. Compare their very early recordings to their latest ones and the quality of their voice has significantly changed. Then try inverting the polarity of their recordings and you will immediately hear the sound of their early recordings.
Polarity has become a tool to further emphasize certain aspects of music, when sheer volume differences are not enough. In a world where electronics are pretty much mandatory, that may not be so much of an issue. It is definitely an issue when you come to acoustical instruments and voices performing in real time and space without electronics, however.
Stu
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: