SDS100/SDS200: SDS100 - Headphone Jack is Wired Out Of Phase - Uniden Support Notified and Temp Fix Made

[KevinC]

One is new firmware, one is not. Two threads in seven years is still not indicative of a problem.

Whether it affects you or not I think the big news is Uniden is actually responding.

 

[Ubbe]

My SDS100E are from 2018 and one audio channel from the earphone jack have full frequency range but the other channel lacks low frequencies, maybe below 250Hz. If I listen to its audio difference between left and right channel, instead of either left or right in relation to ground, there's about half of the audio level but the lowest frequencies are gone. I connected tip of my earphone to the scanners left channel and ground from my earphone to the scanners right channel. If it was a true mono signal I would have heard no sound at all.

The earphone audio are not taken from a mono amplifier and then split up thru two resistors to left and right channels, they are two individual signals that are amplified and have different phase anomalies.

To me it is like one channel are full range audio, like when listening to the audio from a digital system, and the other are run thru a high pass filter to get rid of low frequencies where subtones can be found, like in an analog system, and at the same time the filter processing change the phase of the whole audio signal.

/Ubbe

 

[crippledchicken]

There are plenty of online descriptions (by speaker manufacturers etc.) regarding what it sounds like when stereo speakers are wired out phase. There's also a thread on diyaudio.com called "If headphones are out of phase, can you hear it?"
But these assume a wideband high fidelity stereo audio signal with plenty of bass and treble. There is loss of bass, a "hollow" sound and poor stereo localization.

With the scanner, we are dealing instead with a narrowband mono voice audio signal so it is harder to describe the effect. It sounded hollow and poorly focused to me as soon as I put the headphones on for the first time. But YMMV. Plus I found that the signal is not 100% out of phase in that the line on the scope was (dynamically) not a straight line. I can see where some folks may not be bothered by this.

In any case, Uniden have acknowledged the problem.
They may or may not provde a fix. I suspect there is more likelyhood of a fix if the problem is fixable in the software.
Even if they don't, I'm OK using the adapter cable I made.
If it doesn't bother you, thats OK. If it does, you can make the adapter cable like I did.

diyaudio.com is a very informative forum which I have been a member of for years.