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Why do some manufacturers reverse preamp polarity in the first place?

My Rogue RP-5 reverses polarity, so I switch the pos / neg at speaker terminals. The manual does not mention this, however, I wrote the company and they the amp does reverse the polarity. 

Now my question is...why? I would say 98% of buyers of this amp do not know to reverse the cable connections. I would say most reviewers did not as well. Yes, I realize, polarity reversal is not noticable in most instances. Especially, since many recordings are all over the place when it comes to polarity (at least that is what I've read).

So the question remains...why...why not just have the amp terminals set up so the buyer can just plug in as normal?
aberyclark
bdp24's avatar
bdp24
4,908 posts
 

And in some pre-amps that contain a phono stage (or in a separate phono amp), that stage (or amp) may be of inverted polarity while the line stage is not (or visa versa). What are you gonna do, reverse your speaker leads depending on whether you are listening to an LP or CD?

And since, as atmasphere points out, most recordings are made without respect to absolute polarity, album mixes are made from recordings (done on a 16 or 24 track---or more---multi-track recorder) in which the channels may be a mix of both inverted and non-inverted signals (some microphones also invert polarity! Some effect boxes---EQ, reverb, compressors, etc.---do as well) ). Of that there is no solution.

And of course, many multi-driver loudspeakers have one or more of those drivers in polarity opposite to one or more of the other drivers. Of that you DO have control---don’t own such a loudspeaker!

viridian's avatar
viridian
4,184 posts
 
A single gain stage always inverts polarity, would you have the manufacturer add a second gain stage to change it back again?

And do you change the polarity of your speakers for each recording the you play? That would be necessary if the goal is to always be in correct polarity. In fact, many recordings that use spot mikes on different instruments will have the sax in negative polarity while the keyboard is in positive polarity, so I would suggest that you change the polarity of your tweeters, midrange and woofer as called for by the specific recording. 
aberyclark OP
594 posts
 
So at the end of the day, it really does not matter how the speakers are wired. Interesting. 
glennewdick's avatar
glennewdick
702 posts
 

what type of speaker do you have as some speakers using 2nd and 3rd order cross overs have drivers of different polarity so you will never get the right polarity as each driver in the speaker could be different.

elizabeth
6,726 posts
 
Several answers above as to why some preamp invert polarity.  
With last years big upgrades I can better than ever hear recording polarity. Lucky for me, my main preamp has a polarity switch easy at hand. Also with dipole speakers it is easy to hear a difference. Since reverse polarity the soundstage is larger and behind the speakers, with correct polarity the soundstage is more in front and between the speakers. Plus with correct polarity vocals are clearer. Bass is slightly more defined.  
There is not only correct and reverse. All sorts of angles.. Also some records multi tracked, some instruments one polarity some the other.. some 90 off due to running through gizmos.. One of the reasons plenty of Rock (in particular) recordings you cannot hear any real polarity... since in one recording it is all over the place.
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