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Audio: Balanced and Unbalanced

Below is what an unbalanced audio signal looks like. The Y axis is volts, the X axis is time. The red line is the + signal, the black horizontal line is the – signal. The + signal carries the music, the – signal is ground. This is sometimes called “single-ended” because only one wire carries the musical signal.

audioSignal-unbalanced

Below is what the same audio signal looks like when balanced. The red line is the + signal, the blue line is the – signal. Here, neither wire carries ground. Each wire carries the same signal, but they have reverse polarity. The difference between them is a signal having twice the amplitude. At every instant in time, the voltage sum of the + and – wires is zero, so the cable (containing both + and – wires) has a net field of zero, which makes it immune to interference.

audioSignal-balanced

This gives balanced signals 2 advantages: S/N ratio is 6 dB higher (twice the voltage = 6 dB), and immunity from interference.

Balanced audio was designed for microphones, which have low level signals carried on long wires. In this application, noise isolation is important and you need all the S/N you can get. Consumer audio analog line levels are in the range of 1-2 Volts, about 1,000 times or 60 dB stronger than microphones. And cable runs tend to be shorter.

Thus, balanced audio doesn’t make much if any difference in consumer audio applications. It’s a superior engineering design, but it doesn’t necessarily make any audible difference especially in top notch gear that already has S/N ratios well over 100 dB. It’s nice to have, but I would not pay extra, or chose one piece of equipment over another, for this feature alone.

T-Mobile and Princess Cruises

During our recent cruise to Alaska we were vigilant about not using the ship’s expensive WiFi and mobile cellular. But not vigilant enough! I learned a lesson, luckily not too expensive.

Our TMobile plan includes international roaming at no extra charge. Outside the US you simply enable roaming on your phone. The phone warns you about charges but you can ignore that, TMobile covers it.

However, this doesn’t include cruise ships. While on the ship we didn’t make any calls or use the ship Wi-Fi. But it turns out that some incoming calls arrived to our phones while we were on the ship. We didn’t pick up; the calls went straight to VM. We didn’t even know our phones “rang”. Yet just being called, even if you don’t pick up, was enough to trigger the ship to bill us for each call. The ship bills $6 per minute and the minimum is 2 minutes just to connect. So that’s $12 every time someone calls you, even if you don’t pick it up.

Fortunately we only got 3 calls so our lesson only cost $36.

The lesson: while on a cruise ship, put your phone into airplane mode all the time. If you have international roaming, as we do with TMobile, don’t take your phone out of airplane mode until you’re off the ship.

Netflix New Rating System Sucks

In April 2017, Netflix changed their rating system. Instead of rating shows from 1-5, you now have only 2 ratings: up or down. And, the ratings Netflix shows you are NOT what other users have given the show. Instead, the rating Netflix shows you is how much Netflix thinks you’ll like the show.

This sucks. To be more precise, show ratings are now meaningless and useless. This is for 2 reasons:

1. The rating you see is not how others have rated the show. The show might be rated “5” by 90% of viewers, but it shows as “1” for you if Netflix thinks you won’t like it. The reverse is also true. The show could be rated “1” by 90% of viewers but shows as “5” for you if Netflix thinks you’ll like it.

For me personally, Netflix’s algorithm is quite poor. Shows I like often rate as 1, and vice versa. And it makes it impossible to see how others have actually rated a show. This is the underlying arrogance of this rating system: Netflix prevents you from seeing how others actually rated it, instead forces their own algorithm’s ratings on you. It’s like Netflix is saying, “Who are you going to believe: us, or your own lying eyes?

Suggestion to Netflix: Never hide from customers the actual data they want to make decisions, and replace it with your own algorithmic interpretation. Especially if your algorithm sucks.

For example: most action movies have poor acting, cheesy dialog and plots with gaping holes. But there are a few good ones. You watch one good one, and Netflix floods you with abominable cheesy action movies all rated “4” or “5”. Not because they’re good – they’re not. Because Netflix’s stupid algorithm doesn’t know the difference. Humans do know the difference. If you could only see the actual ratings people have made. But Netflix won’t show you that.

2. Binary ratings have no way to differentiate between a show that was tolerable, one that was great, and the best show you’ve ever seen. All you get is up or down. This alone might be bad enough, but there’s more. This forces people to game the system, rating down shows they liked if they don’t want to see more shows like that. In the long term these fake ratings make the entire system worse. The system encourages–almost forces–people to game it with false ratings, which then spirals into a nose dive as those ratings make the recommendations even worse.

I completely understand a fast moving innovative company like Netflix must “move fast and break things”. But a rating system this arrogant and broken should never have rolled to production. However, I won’t cancel my subscription. At least not yet.

The astute reader will claim that Netflix never did show the actual ratings in the 1-5 system. The rating you saw was how Netflix thought you would rate the show. That’s true, but only partially true. The rating you saw was based on both–how others rated it, weighted mix with how they thought you would rate it. The bottom line is, however the old system worked, its ratings were more accurate and useful than the current system, which is completely broken and useless.

Call-out to Netflix: fix this broken ratings system!