Anybody has any idea what the hell this is? - Page 1
Forum section: electronics / general

author: Ampera
author_rank: Super Contributor
timestamp: December 15, 2016, 02:45:49 am
content: Before I start, let me stress with more intensity than words can express, DO NOT BUY AUDIO GEAR FROM LOGITECH, ESPECIALLY WIRELESS.So, now the context. I have a Logitech G930 that is a GREAT headset, when it works. Which is about 90% of the time, if it's properly charged.But on occasion I will get some strange radio interference through the headset. I recorded this, not in any measure of decent quality because I used a tablet (I have had the thing for years and still have no clue where the microphone is) but it should be fine for analyzing this.Here is the link to the recording, the bumps, whistle, and blowing are me testing the microphone. There are two tones, one is obvious and high pitched, this is when the headset has no connection to the dongle (Ruling out issues with any computer side hardware directly) and another one is quieter, deeper, but still obvious, it comes immediately before and after on some occasions the high pitched noise.https://1drv.ms/u/s!AiPBcGPqsPARghzHDWJ5AuLJU1iZMaybe it's router interference, but it's very occasional, and it doesn't co-inside with things like the microwave.

author: Buriedcode
author_rank: Super Contributor
timestamp: December 15, 2016, 04:25:40 pm
content: As far as I am aware, the recent Logitech headsets are all digital and use Avnera deviceshttps://www.avnera.com/As its digital, interference can degrade the signal, but its extremely unlikely you'll 'hear' the actual interference, but rather its effect on the error correction and channel coding of the link. So any hisses and tones you hear wont' be the actual RF interference.I suspect significantly less bandwidth is given for the mic than the stereo audio because for 'voice comms' it is still generally thought that 'telephone quality' is acceptable. Whilst the quality of the voice channel in modern wireless headsets is great, it probably means that there isn't much in the way of error correction or error masking. Given the choice between complete drop out - at the limits of its range, or from interference - or a reduction in quality, for voice comms you generally accept that it won't always be crystal clear and that its more important to 'hear the voice' than to 'hear the voice with crystal clarity - its not meant for hifi digital recording. But for the speakers/headphones, the downstream where you listen to music, games etc.. because its providing sound to you, any noise/glitches are very noticeable so this gets more attention, and much more bandwidth to prevent a horrible experience.Having been almost obsessed with wireless audio for many years (making wireless headphones, wireless guitar, bluetooth headphones etc..) it is only in the past few years that devices have come out that can carry high quality audio, with low latency, with few artifacts. Sure they can avoid fixed band interference most of the time with adaptive frequency hopping (black listing channels where packets dont' get through) but how they cope with strong interference across many bands is tricky, and there are measures taken such as forward error correction and 'error concealment' which cannot guarantee a clear signal, or no artifacts, but do a fairly good job of making them less noticeable.If that noise has only just appeared after many months of usage then it could well be a failing component. If it has always been there (on occasion) then it could be anything from crowded spectrum, multipath fading (even at a range of a few feet there will be 'dead spots' where the signal quality dives) or a consequence of the algorithm used by the link.I would send a known signal, like a 1kHz sine wave down the mic, and record the result for 10 minutes. Then look at its spectrum to see if there is simple wide band noise, or very specific tones. Sounds like it'll be an arse to track down, especially if its interference based.

author: Ampera
author_rank: Super Contributor
timestamp: December 15, 2016, 06:32:53 pm
content: This isn't through the microphone. You hear the interference THROUGH the headset. The recording is by an android tablet I had just happened to have laying around.And I am aware it's all digital, but it's gotta be something. This is my second one of these (I have to tell my relative to stop sending me them) and they both do the same thing.

author: darrellg
author_rank: Unknown
timestamp: December 15, 2016, 06:53:58 pm
content: My wife uses the G930. They have a pretty generous warranty period and they'll email you a return shipping label. When her's starts acting up we just exchange it.

author: Ampera
author_rank: Super Contributor
timestamp: December 15, 2016, 07:08:15 pm
content: Quote from: darrellg on December 15, 2016, 06:53:58 pmMine was a gift, I never bought it. It's also snapped in one place (repaired with hot glue).Nah, I'm never buying from Logitech again, maybe I can grab a Meze set.

author: Ampera
author_rank: Super Contributor
timestamp: December 15, 2016, 10:41:13 pm
content: Same thing happened again, 17:39 ESTEDIT:This has happened when the battery dies. This time it makes a BIT of sense since it was unplugged, but last time I had it plugged in for hours and while I was using it when it complained of the battery being dead after this sound started happening.Dead battery and loud noise are both happening, but there is no method to figure out which is the cause and which is the effect.I swear, I don't think I could prevent myself from throttling the idiot responsible for designing this piece of crap if I ever met him. It's a 150 dollar headset and not a SINGLE person I have EVER met has NOT had this issue. Every single Logitech G930 rolled off the assembly line broken in some way.Stupid.

author: wraper
author_rank: Unknown
timestamp: December 15, 2016, 10:50:29 pm
content: Quote from: TwoOfFive on December 15, 2016, 07:08:15 pmQuote from: TwoOfFive on December 13, 2016, 04:45:18 pmWith such logic you should run out of reasonably known brands soon. And yes, Logitech warranty is awesome, normally you should not even return anything back. They just ask you to destroy your device and ship replacement.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: December 16, 2016, 03:11:54 am
content: Perhaps they used ceramic capacitors in the op-amp circuit?

author: Ampera
author_rank: Super Contributor
timestamp: December 16, 2016, 05:04:53 pm
content: Recorded, happened again, 12:03 ESTEdit: And again it reports the battery to be dead even though it's been charging for the entire night.Somehow the charging circuit is waiting for it to completely drain, making that noise, until it recharges it, for some stupid reason. It could be a power deficiency and that the cause is a faulty charger.

author: Buriedcode
author_rank: Super Contributor
timestamp: December 16, 2016, 06:40:42 pm
content: Well, the only way would be to hook a multimeter on the battery terminals whilst charging, see if it peaks to 4.2V. Could be a failing charger, could be a failing battery, it could be that the battery management circuit (not the protection circuit) has an oscillator somewhere, and that is bleeding into the headphone amp.I would be happy to see a tear-down of itEven if its just photos of the PCB's

author: KhronX
author_rank: Frequent Contributor
timestamp: December 16, 2016, 07:22:50 pm
content: Well, that's one reason why i prefer sticking to wired devices (keyboards, mice, headphones / earphones) - less things to crap out

author: Tomorokoshi
author_rank: Super Contributor
timestamp: December 17, 2016, 01:12:19 am
content: Quote from: Buriedcode on December 16, 2016, 06:40:42 pmThis is a reasonable clue. There is likely a switcher in there, with an inductor being driven at high frequency. If there is another magnetic component, or a high-impedance line to an amplifier that has a poorly-routed track, then the switcher could couple into it.If you can probe the inductors with a scope while you can hear the noise the sound should change when the probe connects if that is what is going on.

author: Ampera
author_rank: Super Contributor
timestamp: December 17, 2016, 03:46:09 am
content: Quote from: KhronX on December 16, 2016, 07:22:50 pmMy old one is pretty bollocked, so maybe some day I will tear it down.Idk, maybe I can live with it, thanks for the help.