Hello all. I am new here and somewhat new to electronics. I am learning all I can in my free time. Reading articles and trying to take in as much information as I can. I am not new to the 12 volt world as I have been a automotive tech for 20 years. But the whole semiconductor and digital and analog thing to me is very new. So I have been doing alot of reading. I have 1 project that I have been working on that has brought me here. And that is building a bluetooth boombox. I went and picked up a cheap board from amazon and I think it might be broke or it is just not what I am looking for. I also picked up a pair of JBL control one bookshelf speakers that I was planing in using in the build but I am not completely sure if they will work for what I want. I am looking for clean crisp sound with defined lows. So the Amp I got from amazon comes with a bluetooth 4.0 board installed. And it boasts 2x50 and 1x100. I hooked up the JBLs and I measured the impedance and they were 3.2 ohms a speaker . And I used a power brick @ 12volts 5 amps. ! it has a hiss when music is not playing and 2 completely not impressed with its output. So I took my labs bench supply and put 24 volts at 3 amps. No change in output. I did notice that it would not consume over .20 amps of current ? Not sure if that is correct or not. So I dont know if my amp is at fault or my speakers ? But I thought that this place would be the perfect place to find the answers to my questions.
Welcome to diyAudio 
You are probably best asking about this over in the Class D forums, this is really just for intros.
Altering the supply voltage to an amplifier will not change a given output level that it is playing at, if that makes sense.
A higher supply will allow an amp to go louder, but if its only delivering say 1 watt into the speaker then 12 volts or 24 volts, it will still be playing at 1 watt.
Are you applying enough signal level to drive it fully ?
You are probably best asking about this over in the Class D forums, this is really just for intros.
Altering the supply voltage to an amplifier will not change a given output level that it is playing at, if that makes sense.
A higher supply will allow an amp to go louder, but if its only delivering say 1 watt into the speaker then 12 volts or 24 volts, it will still be playing at 1 watt.
Are you applying enough signal level to drive it fully ?
To sort this really needs more detailed information.
If it is not loud enough then we would need to know the sensitivity of the amplifier module (how much signal it needs) and also how much signal the BT part puts out and to confirm that by measurement (looking with an oscilloscope).
Also the 'level' of the files you are playing although if they are normal MP3/WAV etc then they should be pretty standard.
If it is not loud enough then we would need to know the sensitivity of the amplifier module (how much signal it needs) and also how much signal the BT part puts out and to confirm that by measurement (looking with an oscilloscope).
Also the 'level' of the files you are playing although if they are normal MP3/WAV etc then they should be pretty standard.
Post pics of the amp you bought. Bustedparts has hit upon the likely issue you are having. There are several (many) of these amps where the dB gain setting of the amp chip is not high enough given the input (from BT or aux input on other amp modules).
Also, I presume that you turned up the volume on the BT source to max.
Lets see the module. Many here have experience with them.
Also, I presume that you turned up the volume on the BT source to max.
Lets see the module. Many here have experience with them.
Here's the board I bought. I will also provide a Amazon link to what I bought. I am waiting for the slip in the mail to send it back. I am thinking of getting something different. Maybe without a bluetooth board attached . IDK. It has left a bad first impression.
Amazon.com: Douk Audio TPA3116 2.1 50WX2+100W+ Bluetooth Class D power amplifier Completed board New: Home Audio & Theater
Amazon.com: Douk Audio TPA3116 2.1 50WX2+100W+ Bluetooth Class D power amplifier Completed board New: Home Audio & Theater
Attachments
I just tested the same board. Suffers from the ground loop hissing endemic to these all-in-one bluetooth/amplifier boards. To its credit - if you pause your bluetooth playback, it shuts off the amp a split second later to cut the hiss. The heatsinks are just glued on, so one of mine had fallen off. Otherwise the components are pretty good and the amp is very nice sounding - although there is no auxiliary input.
I was able to get it quite loud at 18v. It sounds silly - but check the volume of your bluetooth source. I was disappointed in the output until I noticed that the volume on my iPhone was at two bars. Once I turned the iPhone up, I had no problem making a lot of noise.
The controls provide good flexibility to tune to your speakers. If you don't mind the hiss, this is probably one of the best all-in-ones. There is only a mild beep with "on" and bluetooth connect - there is no loud voice about status, nor is there a super loud beep. I also didn't find any loud on/off popping, although I didn't try every combination.
I am going to ditch the all-in-one concept and go to a separate bluetooth module and amp. That way you can use an isolated power supply for the bluetooth and/or use isolating transformers for the bluetooth audio signal line to the amp and eliminate the ground loop hiss.
I was able to get it quite loud at 18v. It sounds silly - but check the volume of your bluetooth source. I was disappointed in the output until I noticed that the volume on my iPhone was at two bars. Once I turned the iPhone up, I had no problem making a lot of noise.
The controls provide good flexibility to tune to your speakers. If you don't mind the hiss, this is probably one of the best all-in-ones. There is only a mild beep with "on" and bluetooth connect - there is no loud voice about status, nor is there a super loud beep. I also didn't find any loud on/off popping, although I didn't try every combination.
I am going to ditch the all-in-one concept and go to a separate bluetooth module and amp. That way you can use an isolated power supply for the bluetooth and/or use isolating transformers for the bluetooth audio signal line to the amp and eliminate the ground loop hiss.
Ok. I did some measuring with my fluke while I am at work. In from the bluetooth module is .950 volts. Then i took a mesurment at the output with the speakers hooked up. Turned the volume to max. 2.975 is the max A/C voltage mesured. The speakers mesure 3.2 ohms from the neg to pos. I am running it on a better 19.8 volt 3 amp power supply. The speakers do not distort at all at full volume. And it isnt really that loud. So i am not sure what couks be wrong.
I presume you used a sine wave to measure RMS voltage with the fluke. If so, your only getting about 3:1 gain between the BT output and the amp chip output.
I wonder if some resistors in the op amp circuits are mis-populated reducing the BT signal level because the minimum gain the chip supports is 19 dB (9x gain) and most all TPA311X implementations are set to 26 dB gain (~20x gain). You could measure the voltage at the TPA3116 inputs to verify.
I did not use a sine wave. I didn't know that that was a standard practice . I am new at this . Is there a phone app I can get to input it to bluetooth? I will get a data sheet on the chip so I can check the voltage level at the chips. Also sending a sine wave through the bt will be somewhat annoying . What kind of resistor would be suitable to put in the speaker's place for testing.
You can create a sinewave test tone using Audacity and save it as an MP3:
Installing and using Audacity. A get you started guide.
Here is a 440Hz (less annoying than 1kHz) sine wave test tone (64kbs MP3 file) to get you started.
Installing and using Audacity. A get you started guide.
Here is a 440Hz (less annoying than 1kHz) sine wave test tone (64kbs MP3 file) to get you started.
I have a similar board, with dual TPA3116D2 chips, 3 channels, citing 2x50W and 1x100W. The issue I'm facing is that with amplifier volume set to 70-75% range, any increase in the Source (a DAC) beyond 60% of it's volume, the speakers stop momentarily during the playback like for a fraction of second. This keeps happening unless I turn down either the source volume or the amplifier volume. What could be the problem here? Source giving too much high powered signal, beyond the input sensitivity of the amplifier or the amplifier not powerful enough to handle the load?
The amplifier is connected to the source using RCA cables. It's being powered by the 90W Dell laptop PSU. I did try to swap it with a 24V 10A Switching PSU but the problem persisted.
The amplifier is connected to the source using RCA cables. It's being powered by the 90W Dell laptop PSU. I did try to swap it with a 24V 10A Switching PSU but the problem persisted.
Does this happens on all 3 output channels?
The TPA have an OC/OT protection build in (overcurrent/overtemp) which can be wired to self clear after about a second. But this involves some heat/time constant to occur.If there's a opamp based xover between BT and TPA the opamp might get overdriven into saturation which may get you in trouble if these aren't rail2rail and do some fancy amplitude folding at the output which result in something like you describe. Do the speaker cones "stay" in/out for that second?
The TPA have an OC/OT protection build in (overcurrent/overtemp) which can be wired to self clear after about a second. But this involves some heat/time constant to occur.If there's a opamp based xover between BT and TPA the opamp might get overdriven into saturation which may get you in trouble if these aren't rail2rail and do some fancy amplitude folding at the output which result in something like you describe. Do the speaker cones "stay" in/out for that second?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.