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Asked — Edited
Resolved Resolved by Dave Schulpius!

Sound System For My Robot

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

#1  
I used one of the round phone speakers. It can put off quite a bit of sound. I power it off of a digital pin regulated down to 5 volts. It has a volume adjustment on the board that is a part of the speaker. You can pass unamplified sound off of the bottom of the ezb. There is a thread I will dig up showing how to pass it but it involves soldering to two solder points on the bottom of the ezb.
#3  
Other than that, you would just pass audio through an amp from the computer and tie the amp power in through your on off switch. Just find an amp and that takes the correct voltage. I think Dave shows his amp on the thread.
#4  
Thanks d.Cochran, I meant to say that I followed Dave Schulpius thread on this subject. Soldering on the new leads is not my issue, finding a good amp is.
#5  
Gotcha. He will probably have recommendations. His B9 probably has the best sound out there. One of the Steve ' s probably has done this and I think tech guru has also. Mine is using the circuit board out of one of the speaker I tore up mentioned above.
http://www.jamaudio.com/jam-plus-wireless-bluetooth-speaker

It has an audio in port so bluetooth isn't used.
#6  
I used an amplifier in a robotics application recently that sounded really decent. Here's a link:

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
#7  
Wow, that sucks that you burnt up a EZB doing this mod. It would be nice to know what happened.

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.

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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


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#8  
@Dave Schulpius, Just to be clear, Would I connect the right and left channel wires from the 3.5 mm plug to the spot on the EZB (before the amp) as you show in your pictures and the ground wire to the ground on the EZB. Is that correct?
#9  
@bhouston Perhaps a sound bomb would work? Small and pretty loud. Only requires 5v to power
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#10  
The tip I showed is a stereo jack and it supports two channels (two speaker stereo). On this plug with a cable already attached you would find two wires inside the cable with a braid surrounding them inside the insolation. One wire for each channel and the braid is the ground.

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. ;)
#11  
There are plenty of mono to stereo adapters available (one of the sad things about RadioShack going bankrupt is that is just the kind of thing you could just drop in and pick up where now we will need to search the internet for the right thing).

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
#12  
One more question. If I want to use the Amplified sound out of the EZB, then I would connect one of the channel wires and the ground from the 3.5mm plug to the two points marked "SPKR" on the EZB. Correct?
#13  
Correct. It can't drive a very big speaker without distortion though.

Alan
#14  
That was the first place I attached my speakers. The sound was muffled and dull. I think that break out position option is just for really small non amplified speakers.
#15  
Thanks everyone for the information you provided me. I've got the EZB connected to a small amp now and I didn't burn anything up, Ya! Dave, I'm going to get that amp you suggested.