
Now that my InMoov is mobile, I need a good sound system for it. I did at one point have it over WiFi to the robot thru the EZB as per d.Cochrans "Breaking out the sound" thread, however, I was not happy with the amount of volume, so I tried a little larger amp and promptly blew the sound board in the EZB. Since then I have had it hardwired from my computer to a small amp to the two 1" speakers in the robots head.
So instead of blowing the sound board out of another EZB - experimenting - I thought I would get some advice from the community, I am looking for some guidance to the great sound I have thru my computer on board the robot. Hardware and wiring advice would be appreciated.
Thanks
http://www.jamaudio.com/jam-plus-wireless-bluetooth-speaker
It has an audio in port so bluetooth isn't used.
Stereo 20W Class D Audio Amplifier - MAX9744
I used two of these speakers with it.
20W 4 Ohm Full Range Speaker - XS-GTF1027
The Amp can be powered from 4.5V-14V DC voltage. I used 12VDC.
I used the Trim pot the comes with the AMP to control volume, but you can control it with an I2C interface.
Amp has Digital pins for Mute to silence inputs and Shutdown to save power.
You do need to do a little soldering as not all the connectors are installed.
Adafruit has a nice tutorial on the amplifier.
I didn't have the Amp connected to the EZ-B, but an EZ-B was controlling the robot.
Amp Tutorial
If you are brave enough to try it again follow my thread and make sure you solder the cord leads of a male 3.5 mm plug or female 3.5 mm audio jack to the proper locations shown. It's also very important you make sure you have the right wire wired to the right spot. If you have the ground and one of the channels swapped you could burn up your sound board. Use a continuity tester to make sure you have the proper wires selected before you solder anything down.
Then just plug in the cord you choose into the 3.5 "line in" port of an amp that has this size port. This can also be done with other audio plugs like RCA if your amp doesn't have a 3.5 mm line in. Lastly your speaker wires into the amp.
Here's the amp I'm using but it requires 12 vdc power in. You'd need to regulate the power to match your power supply.
Lepai LP-2020A+ Tripath TA2020 Class-T Hi-Fi Audio Amplifier with Power Supply
The EZB supports only one speaker (mono). You could use either channel wire on the cable and cut off the other one. And attach the braid as your ground.
On the "speaker out" ports on the amp you would then have to find which one is active as you only have one channel active coming into the amp. You would attach your single speaker to that port.
I'm not sure you would want to attach both channel wires to the sound breakout point in the EZB. In theory it should work and give you mono sound on both speaker out ports on the amp. However the double draw by the amp may be too much for the EZB to handle. Without knowing all the variables I'd play it safe and only attach one channel wire to the breakout point on the ezb and just find the speaker port that's working. Feel brave? Go ahead and wire both wires to the EZB point and see if it will push it. Ask yourself; What's the worst that could happen and what losses are you willing to take.
With that all said the little amps with built in speakers like the Boom Ball shown above may work OK. However you may only get sound out of one speaker here also if you follow my suggestions.
anyway, they basically do the same as just wiring the ring and tip together, and the amount of power they pull is certainly not enough to burn an EZ-B. More likely is that Bob hooked ground to EZ-B ground and one of the channels to the speaker - solder point and the other channel to the speaker + solder point.
It should be sleeve to speaker - , and then both ring and tip to the speaker + (can be backwards, won't make a difference since you aren't trying to balance stereo speakers). Then you will get mono sound but it will be on both channels. If you get humming, and your amp is DC powered, you can share the ground between the amp and the EZ-B power supply. Or, you can put a ground loop isolator inline with the cable going from the EZ-B to the amp. (basically, it is a magnet that the wires wrap around many times. I don't fully understand the electronics of it, but it quiets down the hum when connecting audio equipment. I have one between my iPod and my car stereo and it works wonders on the sound quality).
Alternately, just get a mono plug, connect sleeve to speaker - and + to speaker tip. Then you can get a mono amp, or use a stereo amp, but you will only have sound on the left channel.
Alan
Alan