Subwoofer test tone

A low sine meant for a sub. If you only hear it from the small speakers, the bass management or the sub cable is not doing what you think. Keep the level low. Subs move a lot of air.

A speaker test starts by standing in the middle. Left should come from the left cabinet, right from the right, both from a center image. If the spoken word and the tone come from the wrong side, one cable is swapped or the balance is. Fix one thing at a time and label the cable when it is right. Swapping both ends of a pair hides the mistake and feels like progress.

Polarity between two speakers is a center-seat problem. Out of phase, the middle goes hollow and bass drops when you sit on the line between them. Off to one side you mostly hear the nearer speaker and the problem hides. The mono sum on the polarity page makes the cancellation obvious without you having to move the couch. In phase, that same sum stays solid.

Imaging is the pan passing through a stable center. A hole in the middle is distance, toe-in, or polarity. An equilateral triangle is the starting plan: the distance between the speakers equals the distance from your head to each speaker, and the angle at your head is 60 degrees. Wider than that gets diffuse. Narrower collapses toward mono. The placement page draws this. It does not know that you have a door where the right speaker wants to be.

Tweeters belong near ear height because high frequencies are directional. Woofers are less fussy until the wavelength gets long. Bass below about 80 Hz is often handed to a subwoofer, and the sub’s position is a room problem. Play a low tone, crawl the listening seat, and put the sub where the bass was even, not where a diagram put a star. Corners raise level. They also raise boom.

Soundbars are stereo by negotiation. The drivers may be a palm’s width apart under a television. A pan that barely moves is the bar telling the truth. A bar with wireless surrounds is a different system, and those surrounds only play when the source and the bar agree on a multichannel format. A browser tone is stereo. It will not unlock rear speakers by itself.

Bluetooth delay is why dialogue looks early. The browser buffer is a few milliseconds and is labelled as such. The radio and the codec are not visible to the page. Flash the screen and the click together, film it, and count frames. Thirty frames per second means about 33 milliseconds a frame. Sixty means about 17. The count includes the camera. It is good enough to tell 40 milliseconds from 200, which is the distinction that matters for video.

Surround buttons ask the browser how many channels the device reported. Two is the usual answer, even on a machine that has a surround receiver, because the browser was handed a stereo endpoint. In that case the rear buttons are a stereo sketch and the page says so. Discrete channels are used only when the endpoint reports at least six. LFE is a low tone, not a promise that a subwoofer is wired.

Loopback delay, on the microphone side of the site, plays a click and waits for the microphone to hear it. That number includes the air between the speaker and the mic. Headphones make it fail, correctly, because the mic hears the room and not the click. Do not compare that number with a Bluetooth frame count and expect them to match. They are different paths.

After the channels are correct, sit in the chair you will actually use and play a centered tone. If the voice of the tone leans, move the nearer speaker a little farther or toe both speakers in until the center locks. Then play a low tone and walk the room once. A boom in one seat and a hole in the next is the room, not a defective woofer. Treat the triangle as the start of that listen, not as the last mark on the floor.