speaker hiss

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ShowMaster
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Re: speaker hiss

Post by ShowMaster » Sun Feb 21, 2016 7:15 pm

I received a care package from Steven with some practice boards and several with what should be good replacement audio ICs.
Thank you Steven.
Now to learn to use hot air to safely remove and install a new audio IC. It's the fact that the IC underside is also soldered to a larg pad that's the challenge. I'm reading that usually the board is pre heated to be close to the solder melting point so that the hot air can do a fast job of heating. That or you just have to be really foot at it. I guess I'll find out very soon.
This back and a scheduled MRI has been very distracting to my hobbies. I'm counting on it being a temporary distraction!
Again thanks to Steven, I can practice as time permits, on learning to hot air solder, and still have a 9xt to fly as conditions permit.
As for technique, with the snd parts so close, I'm thinking of covering the ones I don't want to dialogue with aluminum tape as a heat deflector? Just leaving the IC exposed to the hot air tube tip.
Maybe several layers of tape with one as a defector?
I don't have any solder bearing flux past I'm reading one should out in the replacement part leads before hot air heating.
Any recommendations on what I should buy? I'm all in as far as learning to hot air solder. Good project to learn on, especially if I'm successful.


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ShowMaster
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Re: speaker hiss

Post by ShowMaster » Mon Feb 22, 2016 2:28 am

Well... I actuality went for it. I actually think I did an ok job of removing and replacing parts using hot air. I did remove and move a audio IC from a board to my 9xt board. I apparently from past work, damaged the pad ( gone) on pin 5, one of the speaker outs. I actually improvised a flattened wire wrap wire as a new pad ( more details on that if required. The IC actually soldered fast with the hot air and all connections ohmed out as connected. No audio to the speaker. At this pin I'm thinking of calling it!
I used an external maybe 30 year old radio shack small 9v external test amp, and good audio is still at the IC input pin 4.
What I'm thinking of doing since I don't want to retire this board, is add a small eBay amp.
The board is still in good working condition except for the amp.
I could use some links to some very small amps I can just tack into this board.
One that's equal to Stevens amp power.
Then I can proceed in trying to filter out any hiss, but maybe another amp may not have it?
I lost this battle but gained some good experience. I'd keep trying but at this point, with a pad missing, I can only risk damaging the board trying to replace the original IC.
I plan to resurrect this board and use it for flying or other mod we may want to try.

Amp ideas please.

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Re: speaker hiss

Post by LTMNO » Mon Feb 22, 2016 1:09 pm

Hello ShowMaster,
I have a few AMP's lying around from when we built the original MegaSound years ago.
LM386M-1 (.325W)
LM386N-3 (.7W)
They are both IC's but you can solder directly to them if that is what you are looking for.
You can have them...

Anything for the Hissing Cause. ;-)
Last edited by LTMNO on Mon Feb 22, 2016 4:06 pm, edited 1 time in total.
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s_mack
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Re: speaker hiss

Post by s_mack » Mon Feb 22, 2016 3:58 pm

The LM386 is the most common (and cheapest) amp in use... it is also relatively old. I wanted something "better", but maybe I should have stuck with the old tried and true. It will be interesting to see if that works out better.

I kind of doubt it though, because it seems we determined the noise was pre-amp, right?

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Re: speaker hiss

Post by LTMNO » Mon Feb 22, 2016 4:10 pm

Personally, this is all over my head... I just have them from when we built the original sound boards... they work flawlessly... sound fantastic.
That being said... if you need them, want them, I am happy to put them in an envelope and send them regular mail to anywhere with a $3 stamp ;-)
I am sure that Stamp costs more than the AMP...
I have the IC Header to if you want them as well, that way you can switch them out or perhaps buy a few more to test with. IC format that is.
Custom 9x with M64/Telemetry Mod


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Re: speaker hiss

Post by ShowMaster » Mon Feb 22, 2016 5:46 pm

Thanks everyone for your offers.
I had a eBay credit and was ordering other parts so I just bought these to try. Ultra small .8" and a spare. I will however if they don't work out, contact you all.
I would like to get back to the hiss that while searching for, I killed my amp IC.
This board is also a class D so it'll be interesting to hear what the normal hiss level will be on it with the input open or terminated with a resistor. I'll have to see if it's has a cap input to protect it from a aborted input to ground. That's how I killed the original IC. I was on the input pin after the input cap. Wow those electrons are fast when you screw up!
This is a little Apple vs oranges as far as substituting audio amps, but it will eliminate the audio circuit and IC Steven used for his design.
If it's way better, it would be a $1-2 fix?
Hot glue it to the board and go fly!
I'll also try a DC battery source to power it to isolate it from the 9xt power buss noise if any.
Thanks to Steven I have a new 9xt board to carefully, compare hisses to.

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Re: speaker hiss

Post by LTMNO » Mon Feb 22, 2016 6:08 pm

very interesting... best of luck.... look forward to the findings...
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Re: speaker hiss

Post by ShowMaster » Mon Mar 14, 2016 3:11 pm

I received the class D stereo eBay boards and plan to tack one into the 9xt board to bring the audio back to life. It should nestle ok on the board with a dab of hot glue or 2 sided tape.
I plan to use one side of the amp and plan to terminate the unused input with some resistor value tbd?

This will be interesting to listen to its idle hiss level. I have no plans of deserting this board yet! Maybe it'll be an improvement?


I've been fighting a few enlarged back disks that will be treated later today with injections! Damn birthdays! Hopefully I'll get some pain relief to let me focus on bench time. It's a first attempt at relief. If this doesn't work I may switch hobbies and learn how to bake brownies.

Good timing as the parts I ordered are finally arriving from China.

To catch up.
I damaged the audio IC trying to diminish the hiss many were questioning. In removing the bad IC and attempting a install of a wrong pin config replacement, I lifted some pads. Steven sent me a few damaged boards for parts. With all the rework going on and several critical pads lifting, I decided to try a daughter amp board thats just arrived.
Sort of a house of cards effect.
None of this was a failure issue to start, just some R&D work looking into the low level hiss some questioned that went sideways. It never bothered me.

I'm not ready to retire this board even though I have a new spare!
More when I get to it.

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Re: speaker hiss

Post by LTMNO » Mon Mar 14, 2016 3:26 pm

All the best.. I am still very much monitoring your progress as i am interested in finding out the cause of the hiss as well. ;-)

hope the back feels better.
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Re: speaker hiss

Post by jhsa » Mon Mar 14, 2016 3:51 pm

I hope you get better really soon Showmaster..

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Re: speaker hiss

Post by ShowMaster » Tue Mar 15, 2016 3:55 pm

Thanks everyone. I survived the epidermal shots and now it's wait and see if it's effective, or if I'll need more. It's those birthdays I'm told to blame.
It's a bother, but shouldn't me from my hobbies now that I'm getting help.

Off topic but a blast to the past while I've been waiting for the audio board.

I did stray from our project while waiting for parts and seeing dr's.
I bought a vintage circus hobbies JR Century VII single stick system from a guy at our field.
It's on 72Mhz FM gold sticker so it's narrow banded.
I only flew JR in the 80's and only on 53 and later 50 MHz, until 2.4G came online. I have 50mHz modules and receivers so it's now on 50.840 MHz ch02.
It's a heli tx but I've set it up for fixed wing setting wise ( lots of switches and hidden pots to set.
Sadly in the late 70's early 80's, JR didn't recess the module bay connector male pin block. Instead the JR modules had their female connector recessed into the module.
This make it such that a modern JR DJT module can't fully seat and lock into place. It mates with the connector and functions ok, it just can't lock into the tx's case.
JR now recesses the longer male pins block so any JR type module will seat and lock.
I hope to mod this tx like that. I have a old unlimited 8 to practice on. I'd don't want to use a Dht DIY if posable. I'm d also like to use a XJT module if I can later.
For now I'll fly it on 6 meters and let the new kids wonder what this box is, and how the frequency with a long antenna works!
Maybe I'll add a 9x and 9XT board or SKY board in it later on?
I'm also thinking of buddy boxing it to my 9XT setup to let anyone try single stick.
Especially the thumb flying video game converts. No thumb flying with this setup!
I see SS is making a comeback, as is retro looking systems. Price the new JR Heathkit looking system just released.

Ok, I'll get back to the hiss and new audio board project this week.
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Re: speaker hiss

Post by Rochester » Tue Mar 29, 2016 9:18 pm

I have the exact same issue. Humming/static. Maybe the equivalent of having a fan running or something. Very disconcerting to this kid.

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Re: speaker hiss

Post by ShowMaster » Thu Mar 31, 2016 3:24 pm

Have you used your tx outside at your flying site yet? The background noise usually gets overtaken by other ambient noises.
At my field the giant scale, turbines, and high speed electric motor planes overcome everything. Then the cellphones and boom box crowds next.

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Re: speaker hiss

Post by griff83 » Sun Apr 24, 2016 1:04 pm

hi dose anyone know what i can do about my speaker as yesterday it started to sound really tinny and just now i gave up totally ( the radio works fine )

not sure what to replace it with really and its the main reason i got the 9xtreme

cheers

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Re: speaker hiss

Post by jhsa » Sun Apr 24, 2016 1:21 pm

It looks like you have a monday speaker ;)

Contact Steven at Smartieparts. He can tell you what the specs are.. maybe he even send one to you.. I don't recall him ever letting a costumer down :)

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Re: speaker hiss

Post by ShowMaster » Mon May 02, 2016 11:04 pm

Well, I finally got back to trying to add a after market eBay class D amp to my damaged board today. Steven provided me with a new working one so in the end, I'll not suffer from blowing up my test one. Trying to eliminate what some call hiss, I did kill the audio amp ic off. I did try and replace it from some parts boards I got from Steven. It did not go well for me and the very tiny pads lifted off the board from all the other fix attempts prior.
I have one parts board left I may try and cut around the ic and leave it on the piece of board I cut out. Easier to tack wires on then removing the parts.
So now to my latest attempt by adding a class D stereo amp board from EBay.
It actually powers up and has audio out. Very hot and distorted. If I use the input resistor network still on the damaged board, the input level is very very low. I'll be trying to pad the input down and see/listen if I can tame it.
What I do hear with the hot input, is what I think is the same data noise/hiss as before, only of course way amplified. It tells me this is coming in this way and the original amp and circuit isn't the source of the hiss.
I'll know more when I pad it down, but I heard that early on before the amp input.
I have the same amp board but it has an input pot. I may sub that to save trying input resistor values for now.
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Re: speaker hiss

Post by ShowMaster » Tue May 03, 2016 2:43 am

Solved the distortion issue. I used a 4 ohm larger speaker bought in error for my Taranis upgrade and it's clear and loud.
Too much gain for the original 9XT speaker it seems. I tried padding down the input but probably need to do that on the output instead. If I was keeping this setup I could just use this speaker.
What didn't change was the data noise/hiss we keep discussing. I've said this in the past, the 9XT as delivered and using the supplied speaker, hasn't bothered me when actually at the field flying. This is just an attempt to find the source and see if it can be reduced more. I'm not sure I have an answer to offer yet?

I tried some filtering up stream where I heard it originally.

I'm putting this on hold and installing the working board do I can spend some time flying it. I haven't kept up in the latest features or FW versions.


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