Impact of phase inversion by preamp

@ieales I believe the passive concept you are defending so vehemently has nothing to do with the passive comment from atmasphere. Different application. 

I'm sure you want to say something relevant I just couldn't understand your last posting if you could please elaborate more? 

Nothing is completely passive. The more revealing the circuitry, the more it exposes component 'flaws'.

Experience with phase flip switches in active and passive balanced hardware often left something to be desired in terms of routing and hence inaudibility.

Making both halves of a balanced circuit identical is EXPENSIVE. Add in tube vagaries and the probability of a sonic delta is fairly certain.

These statements are by no means universal truths :)


'Passive' refers to a component that does not involve a semiconductor or vacuum tube. Switches, sockets, capacitors, resistors, volume controls, transformers, wire and the like are considered *completely* passive.


Our MP-1 preamp was the world's first balanced line preamp for home use. The phase switch has been on it since its inception 30 years ago. Quite simply, operating the phase inversion switch is subtle- on multi-channel recordings you can't hear any effect at all. IMO whatever your experience was, it would seem to have been done with equipment that wasn't thought out all that well.

We use differential circuits for our balanced operation. This is not particularly expensive to do- our preamps are pretty affordable compared to the competition in the same class! It is true that each half of the differential amp is slightly different, but you might be amazed at how well they work- the key is a good constant current source, with which we get Common Mode Rejection Ratios (CMRR) in the neighborhood of 100dB, which is pretty good. In a nutshell, no 'sonic delta' when the inversion switch is used (unless playing a true stereo recording); but even if the differential amp is poorly balanced, its a simple fact that there is no 'sonic delta' anyway; you might want to think about why; hint: it has something to do with differential amplifiers :)

These statements are by no means universal truths :)

EXACTLY!

My point is to get people to consider what's behind the faceplate. Far too much HiFi is buzzword-bingo.

Quite simply, operating the phase inversion switch is subtle- on multi-channel recordings you can't hear any effect at all.

Then I would say that the speakers may not be well aligned. The point of the mentioned test was to determine the audibility of polarity. We used polarity correct recordings of acoustic instruments, 80's pop with all live players recorded with polarity correct mics, analogue reverb [plate and chamber] and 80's pop with drum machines, synths, digital reverb and effects. The polarity correct channel inversion was a side show to demonstrate that identical seldom exists.

100db CMMR is excellent. I've endured 'differential' circuits that barely made 60 at some frequency and drifted all over the map with temperature. No offense, but I note that neither CMRR nor the bandwidth over which 100db is attained is listed on the MP3 web page. The only mention of CMRR on the Atma-Sphere site is an explanation here http://www.atma-sphere.com/Resources/balanced.php

25 or 30 years ago Clark Johnson wrote about polarity in a book titled THE WOOD EFFECT.
If I recall it had listed many LPs and what polarity they were recorded in. This came out before CDs.

OK, you made me do it. The whole story according to the Polarity Pundit. Metaphors be with you!

http://www.audiogeorge.com/the-polarity-list/