speaker hiss

gb21914 · Post by **gb21914** » Fri Oct 30, 2015 6:33 pm

I have the DJT module. When I remove it...the same thing.

Module Removed
https://www.youtube.com/watch?v=kvKfXJIGcto

gb21914 · Post by **gb21914** » Fri Oct 30, 2015 6:36 pm

I'm thinking I might open the case up later (or tomorrow) to mod the back for the telemetry cable, I'll take a look at the wire path...it's not a show stopper, but it's perhaps a better highlight of the hiss some of us are getting.

Post by **jhsa** » Fri Oct 30, 2015 6:36 pm

Hmmm, weird.. Also the other noise when the voice is playing

I really need to install mine.. Must finish some stuff first.
João

Post by **ShowMaster** » Fri Oct 30, 2015 6:59 pm

The hiss I'm hearing is more like data noise. We're there any prior mods the the 9x board?
Is your 9X board stock?

Try disconnecting the LED bl cable.
Disconnect the cable labeled Frsky on the 9Xtreme board. The idea is to eliminate and cables that can act like an antenna to radiate data. The ic under the speaker connector is the speaker amp. Reroute anything running over it.
Maybe revive the 9xtreme board and polish the pads on the 9x board. If a bad ground, a ground loop, or other connection issues.
The popping hits in the announce audio is not normal for sure. About the hiss as you're calling it, how close was the recording mic? Right against the speaker or normal holding while flying distance?

Reformat your SD card and reload the audio files?

Post by **s_mack** » Fri Oct 30, 2015 7:21 pm

I definitely don't have that noise!

I agree with SM that sounds like data. It sounds like its picking up a ringing cell phone. Weird.

Post by **jhsa** » Fri Oct 30, 2015 7:33 pm

I know this sounds weird but can you go outside the house with the radio and see if the noise is still there?

João

gb21914 · Post by **gb21914** » Fri Oct 30, 2015 7:34 pm

So...the board is stock, and the frsky cable is not currently installed.

I will take it apart again this evening.

Previously I was running er9x with the 2.4 board with zero issues.

To me it seems like the speaker gain is somehow too high.

I'll re-route and see what happens.

Sent from my iPhone using Tapatalk

gb21914 · Post by **gb21914** » Fri Oct 30, 2015 9:45 pm

So I took it all apart, and reseated the board.

- took out the speaker and checked the wiring etc [result:same crackle]
- ran the speaker outside the case [result: same crackle]
- put it all back together [result: same crackle]
- took it outside [result: same crackle]

I'm inclined to think that it's an issue with the speaker, or perhaps a setting somewhere that controls gain?

kiwihornplayer · Post by **kiwihornplayer** » Fri Oct 30, 2015 10:16 pm

I don't know if my experience is relevant but here is what happened to me. While rewiring DHT module into COMM 2 using pads 7,8,9, I suddenly encountered the dreaded crackle. I got rid of it when I discovered that the Grnd wire in pad 8 was a bad/dry joint and re-soldered it. Perhaps you are chasing another bad ground connection somewhere?

Post by **ShowMaster** » Fri Oct 30, 2015 10:23 pm

Just to be sure. Maybe another sd card with sounds loaded? That a reformatting of the one your using with sounds put back on.
Finally a loading of the latest fw Mikes posted? I need to usage the fw myself. I don't have the links I used in front of me. Many forums and links going on. I'm sure that will get posted when this is read. I'll dig them up. Not easy multi reading posts on my iPhone. In any case, it's important we all have the same sounds files and fw when helping troubleshoot. The hiss is not new and not everyone is bothered if it's low. The choppy audio playback isn't normal however, and needs to be checked out first.
It's either a SD card, audio file issue, or you actually have a faulty 9Xtreme board. A faulty board could also make the hiss and gain structure more pronounced.
Now to find the audio link I used on day one. I'm sure it's in the install forums first posts. Mikes also set up a dedicated fw topic that has the latest and isn't for posting by the users.
Sorry for your install issues.
As for a bad speaker, got any test options? Old talking greeting card?

Post by **ShowMaster** » Fri Oct 30, 2015 10:41 pm

These are the links I referred to. I'll be doing the latest fw upgrade myself.

9Xtreme install
Fw
viewtopic.php?t=7751

Voice packs
viewtopic.php?t=7715

gb21914 · Post by **gb21914** » Fri Oct 30, 2015 11:27 pm

Ok...

The firmware is up to date as per the latest on the site
I formatted / re-applied the voice directory

same thing, still crackles.

Post by **MikeB** » Sat Oct 31, 2015 9:50 am

That does sound rather like the noise I'm getting on my speaker, but mine is at a much lower level.

I'll try to find time today or tomorrow to see where it might be coming from.

Mike.

PacketLoss · Post by **PacketLoss** » Sat Oct 31, 2015 11:38 am

gb21914 wrote:I have installed the audio files and get a 'warble' when speaking as well as a hiss (when the voice portion is not in action). The attached video demonstrates the hiss pretty clearly I think.

https://www.youtube.com/watch?v=yIknaq6MFnI

That's exactly what I'm getting although your video pickup is clearly better than mine

I've had a chance to install the SD card today and put the voice files on, I noticed that when copying files via USB I get the crackle (almost like it's correlating to the individual reads/writes to the card). Similarly when the voice files play it's the same sound as gb21914 is getting, so possibly something to do with the IO circuit for the SD?

Post by **jhsa** » Sat Oct 31, 2015 11:47 am

Did you try another card yet?

PacketLoss · Post by **PacketLoss** » Sat Oct 31, 2015 11:49 am

jhsa wrote:Did you try another card yet?

Yes but they're the same brand/model but different sizes (Samsung EVO 32gb/64gb).

The additional noise you can hear in gb's video as the voice file is playing is identical.

Post by **jhsa** » Sat Oct 31, 2015 11:52 am

Still worth to try another brand card if you have one.
I'm hoping to install my board sometime next week after I finish some stuff I'm doing.. Normally when there are problems I get them too

João

Post by **ShowMaster** » Sat Oct 31, 2015 4:47 pm

MikeB wrote:That does sound rather like the noise I'm getting on my speaker, but mine is at a much lower level.

I'll try to find time today or tomorrow to see where it might be coming from.

Mike.

I honestly have to be in a quiet room to hear the residual noise. I don't hear any choppy audio and when outside I'm ok with it all. I haven't loaded the latest fw due to other projects and no issues. I always see shutting down at power off, it's quick, but there.
I've done nothing to avoid these issues, I just can't complain about them.
There may be some faint choppiness to the greeting audio if put my thumb over the speaker holes, and my ear to my thumb, but it's faint!
I had my wife listen, really good hearing, and she doesn't hear any choppy audio, but does hear the data noise (hiss). Stepping outside our back door, we both were ok with it.
I'll be glad to iPhone video record what I hear if we set a level and announce file and distance standard distance from the speaker.
I haven't uploaded videos so a quick how to post them is needed.

gb21914 · Post by **gb21914** » Sun Nov 01, 2015 1:02 am

It's reassuring to see someone else having a similiar issue...it's not a show-stopper by any means.

I am running the Lexar 16gb micro SDHC card (class 10).

*updated NOV 1st*

I don't have another card to test handy at the moment...but will try later this week.

Is everyone using a LIPO to power their tx? Maybe I'm getting some sort of bleed through there? Gonna try with batteries later and see if there is any change.

LTMNO · Post by **LTMNO** » Tue Nov 03, 2015 5:04 pm

Wow. That is loud.

Sent from my iPhone using Tapatalk

PacketLoss · Post by **PacketLoss** » Tue Nov 03, 2015 5:11 pm

gb21914 wrote:
Is everyone using a LIPO to power their tx? Maybe I'm getting some sort of bleed through there? Gonna try with batteries later and see if there is any change.

I wondered the same and am using a Life battery but then dusted off the original AA battery pack and that didn't make any difference.

Post by **MikeB** » Tue Nov 03, 2015 7:00 pm

Those with a loud noise from the speaker, please check the value of two resistors on the board if possible.

Just below the speaker connector is the audio amp chip (very small 8-pin device). Just below that are two resistors. One should be 120K and the other 130K. There is a 10K resistor in series with the 120K one, so that both resistances total 130K. These need to be the same or there is an imbalance in input to the amplifier.

Mike.

Post by **ShowMaster** » Tue Nov 03, 2015 7:30 pm

MikeB wrote:Those with a loud noise from the speaker, please check the value of two resistors on the board if possible.

Just below the speaker connector is the audio amp chip (very small 8-pin device). Just below that are two resistors. One should be 120K and the other 130K. There is a 10K resistor in series with the 120K one, so that both resistances total 130K. These need to be the same or there is an imbalance in input to the amplifier.

Mike.

Thanks for this info Mike. I'll check mine just to know since I'm ok with my audio. If any show up locally that I can hear the difference, I'll check theirs out.

Not hearing what others are complaining about its easy to misunderstand.

I do know when on the bench, if I place my finger on those parts, I was able to introduce louder noise into the speaker. That may be a troublesome area if high powered rf modules are used?

PacketLoss · Post by **PacketLoss** » Wed Nov 04, 2015 6:35 pm

MikeB wrote:Those with a loud noise from the speaker, please check the value of two resistors on the board if possible.

Just below the speaker connector is the audio amp chip (very small 8-pin device). Just below that are two resistors. One should be 120K and the other 130K. There is a 10K resistor in series with the 120K one, so that both resistances total 130K. These need to be the same or there is an imbalance in input to the amplifier.

Mike.

Apologies Mike, been working up north so only just had a chance to test this. I measured the two resistors directly below the amp chip and am getting 130k on the left one and 120k on the right one (pictured).

Post by **MikeB** » Wed Nov 04, 2015 11:28 pm

Those are correct, I just wondered if there was a problem there that could cause the noise.

Mike.

Post by **jhsa** » Thu Nov 05, 2015 12:41 am

Mike, what about scoping the 5V rail? it is a switched regulator, right? maybe noise? That high pitch sound is very similar to some power related audio noises I heard before..

João

Post by **MikeB** » Thu Nov 05, 2015 1:04 am

I hope to get my 'scope on this tomorrow, too many other things so I haven't got round to it.

Mike.

drkavnger99 · Post by **drkavnger99** » Thu Nov 05, 2015 4:44 pm

Excuse my ignorance on the subject but what powers the backlight as I've seen the power supplies (power innverters) cause audio noise before in car stereos. Has anyone with this issue tried unplugging the backlight to see if it's still producing the issue? Mine has a ever so slight hiss but not distracting or problematic in my case and no where near as bad as the video portrays.

Post by **s_mack** » Thu Nov 05, 2015 5:03 pm

The backlight is LED, which runs on DC. So no inverter.

It most likely comes down to either a) I didn't use a high enough quality speaker; b) the switching regulators are producing too much noise; c) I didn't get the ground path right (since i have zero experience with audio, I wouldn't be surprised); or d) we're using single-sided input instead of differential, which is recommended in the datasheet to reduce noise. Or some combination of the above.

The variance in how much it bothers me suggests it could be 'a'. Or it just comes down to peoples' ears and their differences. That video... mine doesn't sound like that at all, but is that a difference between his and mine? Or is the camera picking up the audio differently than if I heard it in person?

This is tricky.

drkavnger99 · Post by **drkavnger99** » Thu Nov 05, 2015 5:27 pm

Understood

Great first run of the product though. If speaker hiss is the only major snag I think this went off much better than could have been hoped for. Love my 9xtreme now I just need to get someone to port over the "Amber" sounds from OpenTX to confuse my buddy when flying together

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