Will preamp manufacturers tell you if the model is phase inverse?

good point. I recognize phase in the recording process A/B ing back and forth (I have a studio), not certain if I would recognize if nothing to compare to.

According to the Polarity Pundit, who has probably looked into the whole polarity issue for not only CDs but also LPs, much more than anyone else, Clark Johnsen's book on the subject notwithstanding, the actual percentage of CDs that are in reverse polarity is 92%, less for LPs. Therefore you would obviously be much better off in the long run if your system was in reverse polarity. One of the most disturbing things that the Polarity Pundit’s list of audiophile CDs and labels is just HOW MANY are in reverse polarity. 😩

For the record, multi-way speakers often invert one or more drivers relative to the others to achieve correct phase matching through the crossover regions. You can see this in the Stereophile step response measurements.

In general (but not legally enforced) the woofer’s are positively aligned, and other drivers are chosen to invert or not based on phase matching to the driver below. Of course, some designer may think that mid-range phase is most important, so this is a general rule.

To test the polarity of your woofer, take a 1.5 - 9V battery and attach positive to positive. If your woofer moved outwards, then it is in positive polarity. You may even be able to tell the midrange as well.

1.5V cells are safe to use on tweets too.

Best,

E

So much for plug and play. Lots to consider when purchasing a preamp

I think the idea of having a phase inverter makes the most sense, given the possibility of a recording being inverted or not, however...

I should also point out that the simplest designs invert phase, since they use a single tube stage per channel. That's the simplest possible design. To get phase accurate, you have to add at least one more stage.

Best,

E