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Forum Index : Microcontroller and PC projects : MicroMite controlled 4-CH stereo...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
Not married, no current girlfriend. Any single female members here?   Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
UPDATE Houston, we have sound!!! 
I have another very short video demo. In this video, the source selector is working, but the hard-mute is not. There is a mute pin on the 7419 chip, but pulling it high or low has no effect other then to produce a click in the audio. Soft-mute via I2C works. Quick video of stereo working WARNING! - There is a loud thump noise at the very end of the video. This was me pressing the record button on the camera to stop it. If not aware of this, it might make you jump, as it is much louder then the sound picked up during the video. The preamp sounds OK audio quality wise, but the output is drenched in white noise, and unless there is some way to filter that out via the settings, it makes the device practically useless, as you can hear as much noise as actual signal, and this gets worse the lower the volume setting. With an unconnected source selected, the noise is very, very noticeable and prominent. This may be something that can be dealt to in the commands, but if not, then it is new audio processor time. Datasheet specifies a 100dB SNR, which is quite acceptable I would have thought, so it is probably my having set the input gain wrong or something. If I unplug the preamp output with the amps and speakers running, and no audio selected, ALL the white noise vanishes, so it is being generated by the preamp, not the power amps. 
UPDATE Progress. I had the attenuators set to maximum, and the input gain set to maximum!
Setting the speaker attenuators to +15dB does not set them loud, it sets them very quiet. The tinkering continues. I will upload yet another video once I make a few changes to the code. I also found a bit of a byte I need to set to make the hard-mute pin have any effect. If you can soft-mute via I2C, I guess it is not worth worrying about. Anyhoo, having set the attenuators and input gain to 0dB, most of the white noise has now vanished - progress. Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Hi G, Yep, the thump at the end of the video certainly came as a 'shock' (and probably blew my headphones!) I was about to say have a look to see if you need to set a bit in a register somewhere for hardware Mute, but just seen that you found it. Very unusual that by default the hardware mute pin is 'disabled'. Anyway, great progress there (don't annoy the neighbours too much at this time of night with your 'DiscoMite' ) 
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
UPDATE I have the tone controls working now. When I set the loudness and AC coupling bits correctly, I just about shattered the windows - it goes loud if you program it right! 
The coupling was set to bypass by accident - input signal was passed through the input gain stage, then right to the output stage. Once you put the actual processing in-line with the AC coupling byte, boy it fecking works then!!!! 
Trying it out on a bit of Pink Floyd at the moment. Will have to get back to work on the GUI tomorrow. Smoke makes things work. When the smoke gets out, it stops! |
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CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1427 |
"Trying it out on a bit of Pink Floyd at the moment. " Yeeeessss! Micromites and Maximites! - Beginning Maximite |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6269 |
Brick in the wall, My phone ring tone.... Jim VK7JH MMedit |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
Who's Pink Floyd (showing my age) Paul "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4036 |
And by the way which one's Pink? John |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
The band is just fantastic, that is really what I think. I assume you are joking Paul, but if not, follow this link. Tried some Lily Allen on it this morning, but now I have to go out to a job. I hope to get back to the GUI tonight. One thing I need to add, is confirmation when you select one of the inputs, before it goes back to the main screen. The system IS selecting the inputs right, but you get no confirmation at the moment. Smoke makes things work. When the smoke gets out, it stops! |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Great job Grogster. I am glad you found your noise problem. That would have freaked me out after all that work. Can't wait to see video of final product! |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1982 |
Yes I agree, great job. And I wasn't joking about Pink Floyd I have heard the name but wouldn't know them if I fell over them,my music is 60's. Paul. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| VK2MCT Senior Member  Joined: 30/03/2012 Location: AustraliaPosts: 120 |
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| CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1427 |
Micromites and Maximites! - Beginning Maximite |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
UPDATE Getting REAL results now!
Have a look at this video link. It's 168MB in size, and 7 minutes. The camera's AGC on the mic prevents the video from showing just how loud this thing is going at one point, and it was not even full throttle. There is a slight bug in the volume control, that's why I did not go right up to 0dB. Sorry for the wobbly camera work, but it is still a work in progress....
Lots more to do yet, but we are getting there, folks! 
Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Hey - great progress . . . Couple of questions: 1: On mute, is there any noticeable 'hiss' from this set-up? (The hiss on the video I assume is down to the camera? 2: Do the amps run warm/hot with current usage? I am curious as to how much current the amp pulls at peak; also the 'standby' current. So am I correct in assuming it is mainly GUI work left to do? I am sure lots of people are following this thread with great interest 
WW |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
2AM so i'm off to bed now, but a quick answer to your questions: 1) No noticeable hiss. You can hear it, if you put your ear right to the speaker on mute, but more then about half a meter away, and you can't hear it. I also had a projector running in this room, so the camera may have been picking that up(the cooling fan whirr). 2) The sub amp module gets warm, but only warm, and I was only using one of the two speaker outputs. This amp can actually drive a double-sub, or even a quad in a 2x series arrangement. Anyone have any spare PA quads they could loan me?
As to current, I have not measured it yet. Amp modules can pull about 6A @32v full output and they are about 93% efficient. PSU is 32v @ 11A. I have a 5A fuse in-line for the moment, just to protect against something nasty happening during testing. 11A could do quite a lot of damage... I will measure the current when running over the weekend. EDIT: Yes, mainly, but there is also the loudness, bass/middle/treble controls, sub filter controls - still a few things to do. Smoke makes things work. When the smoke gets out, it stops! |
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| mpep Newbie  Joined: 09/11/2014 Location: New ZealandPosts: 29 |
Sounding great. Looking great. I'm guessing that sleep is overrated!
Just my 5c worth, in the volume display, it would be more intuitive to have "-" in front of the numbers seeing as you are dealing with levels of attenuation. 0 being none. You can select different inputs? |
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| HankR Senior Member Joined: 02/01/2015 Location: United StatesPosts: 209 |
G, Very nice. For the volume, why don't you reverse the numbering so higher numbers equals higher volumes? Maybe you'd be getting around to that and just taking care of the big picture right now. H |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
@ mpep and HankR - Yeah, still not decided on the final volume control looks, but you are both right. I have added a minus sign and put back the "dB" on the display for now, but Hank has a point in that most people think higher numbers mean more volume. I have found that the subwoofer channel is still drenched in white noise. You canhear it when in mute, so I think there are still some tweaks I need to do with the input and output gain settings. With a 100dB SNR as in the datasheet, I would have thought it to be pretty clean most of the time, so I guess it is something in my settings - again.
EDIT: Oh, and mpep - yes, you can select from four analog stereo inputs using the remote. Smoke makes things work. When the smoke gets out, it stops! |
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| CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1427 |
Please number your amplifier volume from 1 to 11. :-) Micromites and Maximites! - Beginning Maximite |
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