speaker hiss

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PacketLoss
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speaker hiss

Post by PacketLoss » Fri Oct 23, 2015 10:41 pm

The 9Xtreme appears to be working well in all other circumstances but I've got an annoying hiss coming from the speaker.

Previously had the 9x solder-less programmer board installed and no other mods have been made.

I did read someone else had mentioned something about a buzz on the main thread here but this appears to be more pronounced and audible when the TX as at a normal distance from my head.

I've used an old iphone to record the sound so the pickup wasnt great but it's audible here: https://vimeo.com/143430585


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Re: 9Xtreme speaker hiss

Post by s_mack » Sat Oct 24, 2015 2:27 am

I couldn't hear it in your video... but I believe you that you're hearing something.

So far I've read two "complaints" (for lack of a better word) about this, including you. I would suspect if it were a problem with the design overall that we'd be getting more. With that said, however, hearing is a funny thing especially when it comes to droning noises like I think you're describing. What one person can't even perceive drives the next person up the wall. So maybe the two of you are just more sensitive? Or maybe it isn't happening with others and it is with you? That is to be determined, I guess.

I'm not going to lie and say the speaker is some specially made high quality component. I know virtually nothing about speakers. The 9X Voice community seemed to be just using whatever random 8ohm speakers were available to them, so when it came to sourcing I didn't even know what specs to look for besides "40mm diameter" "max 5.5mm thick" and "8 ohm" and "at least half a watt". There are a slew of other specifications when it comes to speaker selection, none of which I had even a modicum of understanding about.

Anyway, my point is we don't know what it is... if it is a few defects or a design issue or if these are just low quality speakers.

Its also quite possible that its none of the above, and its something vibrating in your case so perhaps a first test could be to remove the speaker and hole it in your hand away from the radio (as much as possible) and see if you still hear it?

Just throwing ideas out.

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Re: 9Xtreme speaker hiss

Post by jhsa » Sat Oct 24, 2015 7:39 am

I have an idea. Remove yout RF module if you have an external one, or if you have an internal one, create a new model with the protocol set to OFF. This will turn the module OFF. See if it still does the same noise. It is known that RF introduce noise on the speaker. All my radios have that problem, and I don't expect the 9xtreme to be different when it arrives :) ;)


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Re: 9Xtreme speaker hiss

Post by siwoz » Sat Oct 24, 2015 9:34 am

I have the same thing happening. Definitely not the RF module as I noticed it while using a sim. Slightly annoying but no big deal :)

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Re: 9Xtreme speaker hiss

Post by PacketLoss » Sat Oct 24, 2015 11:42 am

S_mack, appreciate the brutal honesty but don't do yourself an injustice. It's a great priece of kit and you've done a superb job, I've got more prototypes than I care to admit to, that never quite achieved half of what they were meant to or got anywhere near production for that matter. I'm also actually quiet flattered, clearly signs of age, that there is (arguably) a piece of my body that works better than the average ;)

I'll try isolating any sources of interference and let you know how I get on.


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Re: 9Xtreme speaker hiss

Post by PacketLoss » Sat Oct 24, 2015 1:11 pm

jhsa wrote:I have an idea. Remove yout RF module if you have an external one, or if you have an internal one, create a new model with the protocol set to OFF. This will turn the module OFF. See if it still does the same noise. It is known that RF introduce noise on the speaker. All my radios have that problem, and I don't expect the 9xtreme to be different when it arrives :) ;)


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I have an external DJT but this doesn't appear to remove the hissing, when removed. Will keep hunting ...

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Re: 9Xtreme speaker hiss

Post by jhsa » Sat Oct 24, 2015 2:40 pm

Please do a little test. Go to Radio Setup/Hardware menu. Check if there is an option called "Software Vol." If so turn it OFF and see if the noise is still there. Don't make your radio speak after changing because it might be at full volume if you change that option..
This is just to try to find the cause of the problem.

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Re: 9Xtreme speaker hiss

Post by PacketLoss » Sat Oct 24, 2015 5:41 pm

jhsa wrote:Please do a little test. Go to Radio Setup/Hardware menu. Check if there is an option called "Software Vol." If so turn it OFF and see if the noise is still there. Don't make your radio speak after changing because it might be at full volume if you change that option..
This is just to try to find the cause of the problem.

João
Thanks for the tip but I don't have a "Software Vol" option under Hardware menu.

There is a Software Volume option via eePskye but this is current disabled.

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Re: 9Xtreme speaker hiss

Post by Nate » Sat Oct 24, 2015 6:06 pm

I'm definitely hearing a buzzing from my speaker also, it's not the end of the world but a tad annoying.
I don't have a 'software vol' option under hardware in setup, setting the volume to zero under 'audio/haptic' settings doesn't make a difference.

Nate

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Re: 9Xtreme speaker hiss

Post by IanF9X » Sun Oct 25, 2015 6:13 am

I have modded two 9xs now and do get a very light hum from my speakers but nothing that I would call annoying.Speakers do like good connections however.

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9Xtreme speaker hiss

Post by ShowMaster » Sun Oct 25, 2015 6:30 am

This is a common complaint also with the Taranis. It's usually heard in quiet places. Try it under flying conditions outside.
RF, data and audio don't play well together in close proximity. Adding a UHF or dragon link rf setup and it really gets messy.
As a ham radio operator, my neighbors can vouch for that.

I removed my XJT module and it's still there. That means data noise. It may be the on the audio power buss or coupling into the audio circuit.
If you live in the city, stand outside and hold it as you would when flying, and listen.
After the 9Xtreme is in use for awhile, I'm sure minor tweaks will be done. What I do hear seems high in frequency. To be honest, I've been flying this setup for 2 days at my busy RC field and never noticed it.
I'm not concerned enough to worry about it. It's less than my Taranis.
SM

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Re: 9Xtreme speaker hiss

Post by s_mack » Sun Oct 25, 2015 6:54 am

If multiple people are already annoyed by it though... I'm issuing a bounty.

Someone figure out a fix: clearly describe said fix: have 5 people confirm it eliminates the hiss; Boom... $50 by PayPal or a free next-gen board.

Parameters: The fix must be something that can be translated into an on-board electronic solution for future revisions. In other words... I need to be able to add a couple of components to the board. Not silly things like "stick the unit in an insulated box" or impractical things like "using this gold-plated jewel encrusted speaker" and nothing that will require the end user DO anything. Bonus points (that aren't worth anything) if it can be done entirely with discrete components (resistors, capacitors).

If it turns out that we can't do anything about it, so be it, but I'd like this to sound better if possible and (as I said before) audio is really out of my wheelhouse.

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Re: 9Xtreme speaker hiss

Post by PacketLoss » Sun Oct 25, 2015 7:29 am

I'll add $25 to that bounty if I may.

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Re: 9Xtreme speaker hiss

Post by ShowMaster » Sun Oct 25, 2015 8:05 am

Fly it and make sure it's not like a scratch on your car. You can see it from a mile away but it's really little
Brent of Skyboard and the 9XR pro fought it, and Frsky took maybe 4 generations of board designs and lead chokes to reduce it. Then you add a uhf or dragon link with its rf and data, and it starts all over. The spectrums I've listened to are quiet, but the audio freq range to me it restricted a lot.
I'm just saying, in due time things could be improved, but it'll take a donor board to mess with due to the small traces and parts layout. Not easy to tack on stuff and not trash the board, at least not my board. I'll make it talk more while I'm flying and really listen for excessive noise. I honestly didn't think about it flying as I said. While flying, unless it's on a quiet glider hill, the pocket rocket planes, cell phons, BTooth speaker "tunes" playing at my busy field, drowns out everything. Add turbines and 1/4 scale 3D 100 ft away, and I honestly don't think I'll do anything with the audio. Sitting in my quiet computer room programming it I do hear noise. I don't fly there.
Again, please fly it at your site and see how it goes first.
SM

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Re: 9Xtreme speaker hiss

Post by andrewju » Sun Oct 25, 2015 8:40 am

s_mack wrote:Someone figure out a fix: clearly describe said fix: have 5 people confirm it eliminates the hiss; Boom... $50 by PayPal or a free next-gen board.
Mike?

:)

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Re: 9Xtreme speaker hiss

Post by jhsa » Sun Oct 25, 2015 8:54 am

andrewju wrote:
Mike?

:)
Ha ha ha. I knew someone would say this if I didn't.. ;) :mrgreen:

Anyway, in music equipment there is something called "Noise Gate". Specially guitars can be very noisy even at low gain (or if I'm playing them) due to many factors, bad cables, bad amplifiers, pick up radio frequencies, etc.
The noise gate can be adjusted to cut all sound under a certain level, so there will be no sound at all when we are not touching the strings. Some computer audio outputs can also be noisy.
So, the noise gate eliminates all noise without changing the quality of the sound by cutting frequencies like normal R C filters do and therefore destroying the sound quality. Maybe it's worth it looking into this option.

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Re: 9Xtreme speaker hiss

Post by PacketLoss » Sun Oct 25, 2015 9:35 am

ShowMaster,

I do get your point and don't want to be one of those people but it doesn't hurt to put a bounty on it and see if it can be fixed.

It sounds like you have a professional flying field and I'm leaping that you're not an FPV pilot. In the UK (well for me at least) I'm often sitting in the corner of a random farmers field in the middle of nowhere, goggles on and with near silence (except the birds) and at the moment that hum is niggling. It's not the end of the world, doesn't ruin what is a great mod for the 9x but again no harm in trying to resolve it.

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Re: 9Xtreme speaker hiss

Post by don9f » Sun Oct 25, 2015 11:09 am

Sorry to add in this way, but yes mine "hisses" as well....but it's not something that bothers me personally. As said by others, the Taranis does it as well and that's never bothered me either. I think outside, it's no problem at all.

Cheers Don

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Re: 9Xtreme speaker hiss

Post by Bill » Sun Oct 25, 2015 3:10 pm

Perhaps a signal diode in the pre-amplifier stage (as used in the original Dolby systems to give a noise gate for hiss) would work, is there a published circuit diagram?
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Re: 9Xtreme speaker hiss

Post by jhsa » Sun Oct 25, 2015 3:39 pm

This of course if the noise source is before the amp. If it is the amp itself maybe there's nothing it can be done?
Does the board have a hardware volume control? If so, could the input be pulled to ground by software if there is no audio signal?

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Re: 9Xtreme speaker hiss

Post by MikeB » Sun Oct 25, 2015 5:10 pm

I can hear some noise on mine, but I need my ear within 2 or 3 inches to hear it (may be hearing of course).

I'll put a scope on to see if I can locate the source.
Note: We are using a class D amplifier chip, so this may be switching noise that is not being filtered by the speaker.

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Re: 9Xtreme speaker hiss

Post by jhsa » Sun Oct 25, 2015 5:15 pm

On my 9XR-PRO I also have some humming noise similar to the one you sometimes hear on guitar amplifiers.. But the volume is very low. I also need to put my ear near the speaker to be able to hear it..

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Re: 9Xtreme speaker hiss

Post by s_mack » Sun Oct 25, 2015 5:19 pm

I don't hear it at all on mine, but enough of you are reporting it that I think I better get my hearing checked :(

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9Xtreme speaker hiss

Post by ShowMaster » Sun Oct 25, 2015 5:42 pm

PacketLoss wrote:ShowMaster,

I do get your point and don't want to be one of those people but it doesn't hurt to put a bounty on it and see if it can be fixed.

It sounds like you have a professional flying field and I'm leaping that you're not an FPV pilot. In the UK (well for me at least) I'm often sitting in the corner of a random farmers field in the middle of nowhere, goggles on and with near silence (except the birds) and at the moment that hum is niggling. It's not the end of the world, doesn't ruin what is a great mod for the 9x but again no harm in trying to resolve it.
Of course it should be on the list of things to look into. I don't think it's going to be a bubblegum fix? Maybe a redesign of the board trace layout to eliminate inductive or capacitive coupling of the data into the audio. That or better DC filtering or some logic controlled audio gating? I hope I'm wrong but it's a common problem mixing audio and data. Many times a multi layer board is used to add shielding in some layers and separate the audio from the data. I'm concerned that this if required will push the price too high if most aren't bothered. Let's see where this goes as more users come on line. Especially those with a good technical background.

I thought that living in the quiet countryside was the case. To be fair, if that's a important requirement, why are you adding a $60 board into a $60 tx? They're are much higher end systems that won't have this and other issues.
I'm concerned that all this preliminary audio hiss discussion will discourage readers from trying a super upgrade to their normally dumb, but quiet 9x.
I paid $1000 for a 2000kw Honda generator for earthquake backup power, because in can barely be heard if run at night. I could have bought a 4K for $600 but it sounds like a rock crusher when running. Something my neighbors wouldn't stand for.
Pick the right tool for the right job and pay the price, is my motto.

Ok, now the important question! ️
So how's it flying that fpv in the quiet countryside already? It's flying my planes in the noisy city great so far, going flying again today. ️

Let's get more actual flying updates posted, and deal with the audio once we're all enjoying the many other upgraded features. We're all beta testers at this introductory price. I'm grateful Steven didn't spend 6 mo in beta testing before he released it. Pretty great job for a 3 month idea to flying project.
SM
I hope you get the humor in my post and understand that I agree with your concern. It will be looked into.
SM

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Re: 9Xtreme speaker hiss

Post by s_mack » Sun Oct 25, 2015 7:07 pm

I'd like to say that I *did* put care into keeping digital signals away from analogue to reduce noise, but that focus was on the sticks more than the audio. Looking at the layout just now, I don't see any obvious issues. I read through the datasheet again and there is a suggestion of putting a large value cap "near" the inputs to reduce noise but also goes on to saying it shouldn't be necessary (we didn't).

I'm wondering still if its just a crappy speaker? Does anyone have a higher quality 8 ohm that they can try? It would be good to know if its the speaker or the circuit, because that would be an easy fix.


As far as discouraging readers from buying a product due to a perceived "flaw"... I think it is more benefit to having a discussion like this than a detriment. People should see that a) it is a minor issue and b) its being actively looked at! I mean, if this is the biggest issue we can come up with to obsess about... the mod must be pretty good ;) :lol:

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Re: 9Xtreme speaker hiss

Post by ShowMaster » Mon Oct 26, 2015 3:00 am

Let's see what the mod squad can find out once everyone's got theirs installed and working. I'm pleased that you didn't keep it off the market for 6 mo to a year in beta testing while making it perfect for $60-70. No reason to not try this product if your flying a dumb terminal 9x, or want to step up from a non talking er9x modified system. Even if you never use the audio, the 60 model memories and super processor features are worth the price. Add D and X receiver support, Sbus, smart port, multicolor backlight, and can all done with a screwdriver!
Pretty impressive!

I'm a paying customer if anyone is wondering.

I did many 9x solder er9x upgrades for club members over the years. I've spent many hours at the bench. With this setup I can do it at the field between flights, or better yet, they can! We install and fly it in a short time while their.
Sweet!

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Re: 9Xtreme speaker hiss

Post by Bill » Mon Oct 26, 2015 9:43 am

Try decoupling the power supply with a 10mf and a 10nf at the amplifier, that will probably work.
The low impedance output of the amplifier probably excludes pick-up between the amplifier and the speaker.
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Re: 9Xtreme speaker hiss

Post by jhsa » Mon Oct 26, 2015 10:15 am

I think it is very important to know what kind of noise we are trying to fix. There are even different types of humming. It could be power supply related, it could be due to a ground loop. Then there is even another type which could be caused by a too long connection between the DAC and the amp, or perhaps it needs some kind of ground shielding. This is the reason why audio appliances are normally built in metal cases.

I have another radio that has yet another type of noise (sshhhhhh) generated by the amplifier itself. And I don't think we can do anything here except using another amp IC.

And of course, RF also introduces noise in the audio circutry..
Not easy, as the right type of noise must be determined before attempting to fix it..
Just my 2c anyway.

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9Xtreme speaker hiss

Post by ShowMaster » Mon Oct 26, 2015 4:53 pm

Jsha, did you get your board yet? I unplugged my XJT module and no difference in the hiss were discussing, I don't think RF is the cause.
We keep beating this up and because we tech types like to solve issues, I'll also look into it. I honestly think it's in the same noise range of the all the the other systems we've used here over the last 3-4 years. I can't hear it outside at the 3 club fields I fly at. They are near a freeway, or in the city. Even the country field has a busy freeway at one end of the field.
This doesn't solve it, but I don't fly on my quiet hillside, there isn't one, or hobby room.
That's why I ask it be used at the flying site before judging it. It also sends the wrong message to those reading about the upgrade. If you have a simple can't do much 9x, and want a TX with super features, and can't solder, this is the answer!

Ok back to tech talk.
Yes, it could be a D to A converter, inherent audio IC noise, power rail/regulator noise, data noise coupling inductively or capacitively, ground loop? A scope picture should show a tell all trace picture of what it is I'm thinking. I'd scope mine but I want to fly it before risking a probe slip since it doesn't bother me. It's more about what it is!

It may also be that the speaker has too good a response at the frequency.
I'm enjoying the flying right now.

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Re: 9Xtreme speaker hiss

Post by PacketLoss » Mon Oct 26, 2015 5:47 pm

ShowMaster wrote:We keep beating this up and because we tech types like to solve issues, I'll also look into it. I honestly think it's in the same noise range of the all the the other systems we've used here over the last 3-4 years. I can't hear it outside at the 3 club fields I fly at. They are near a freeway, or in the city. Even the country field has a busy freeway at one end of the field.
This doesn't solve it, but I don't fly on my quiet hillside, there isn't one, or hobby room.
That's why I ask it be used at the flying site before judging it. It also sends the wrong message to those reading about the upgrade. If you have a simple can't do much 9x, and want a TX with super features, and can't solder, this is the answer!
I really didn't want to prolong a discussion that wasn't productive but I'm failing :)
Nobody is beating it up, all the conversation has otherwise been rather collaborative and productive.
$60 mod to give me the functionality of a $400 dollar TX, even us country bumpkins can do math :)
All I've seen so far is an incredibly supportive community and a developer who's response has been exceptional (I owe you a testimonial for your site s_mack).

That's the last hiss/hum you'll hear from this speaker ;)


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