The phase switch on an amp

June 10, 2022
 by Paul McGowan

9 comments on “The phase switch on an amp”

  1. One of my Conrad-Johnson amplifiers, the preamp, inverts phase. The C-J power amplifier does not so they instruct to reverse both speaker connections to correct for this. I’ve not noticed much difference.
    That said, when I play any one of my HIFI test/setup CDs there is a track to test for correct phase set up. They play a voice in and out of phase and the difference is very distinct. The out of phase voice is indistinct and impossible to localize. The in-phase voice comes from the exact middle of the speakers. Seems to me there are different types of phase. My Wilson speakers are intentionally wired with the midrange driver out of phase at the factory. Something about the crossover. Is this the same phase you are referring to?

    1. Wilson uses second order crossovers. Because of this electrically the mids are 180 degrees out of phase with the woofer and tweeter so the mid would move in and out opposite to the other drivers. To get back into acoustic phase(which to the ears is what matters) the mid driver is hooked up physically out of phase so that now the mid moves in and out at the same time as the woofer and tweeter.

      This is not what Paul is discussing.

  2. I remember hearing way back in the 70s that in order to find the correct phase, you should try reversing the cable connections on ONE of your two speakers and whichever way yields the most bass will let you know that your speakers are in phase.

  3. I have heard many recordings sound out of absolute polarity. Geroge was correct and depending on one’s speakers, their crossover can be easily heard. One bass response is weak, imaging bloated, vowels not as clear, can one hear it? well that all depends on one’s system’s experience in hearing it when it is there and when it is not correct. I have a phase switch and mono switch on my preamp, I would never buy a preamp without them. In Mono mode, you can hear if it is correct by how much presence is in front of you, out of absolute phase you will easily hear the image withdrawn from the room, lack presence and body. Then of course you have some gear that is out of phase with each other, happens with XLR;s a lot say if your preamp is pin 2+ and the amp from a different maker has pin 2- then recordings out of phase would sound normal with that gear and the recordings in proper phase would now be out of proper phase due to the mismatch between amp and the preamp or front gear and the preamp, always read your manuals if using XLR gear and see how they have their pin configuration. Now, another curve, some tube preamps are out of phase using the RCA outputs, conrad johnson was one that can to mind and they told you that in their owners manual, then you have to flip your speaker cables to reverse that, so red and black on the amp or speaker only would be reversed. George was out their a bit, but before George their was a book called the wood effect that really got into out of phase issues in audio gear and how to learn to hear it.

  4. Hi
    So having had this conversation with a well respected designer of todays audio products the phase switch on my preamp deals with the direction the microphone diaphragm used in a recording moves and that is where the switch can be implemented. To note that you will never know that info so than it becomes a listening playback test to see if there is a sonic improvement

  5. With speakers with first order crossover and time alignment there is a distinct audible difference. And there is a right and wrong. And it does not depend on the recording. It is based on repeated observations. No hallucination.

  6. Yep whatever you do make sure the polarity of both speakers are the same or your bass will be weak and the stereo image diffuse and it will sound terrible. A phase switch is nice to see which one sounds better. A lot of subwoofers have those. AC wall polarity is important too which is why I don’t understand why all audio power cords are not polarized.

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