Hi, new here. Let me begin by saying I have very little knowledge when it comes to amps and speakers and looking for some help. I'm making a Bluetooth speaker with this amplifier board:
Amazon.com: 50W + 50W TDA7492P 2x50 Watt Dual Channel Amplifier Wireless Digital Bluetooth 4.0 Audio Receiver Amplifier Board (Blue): Home Improvement
(TDA7492P 2x50W)
I know it's not anything amazing, but I want to try getting the best possible sound quality/volume I can out of it. It has 50W per channel, but I'm using 8 ohm speakers so I assume it is 25W (correct me if I'm wrong). I'm putting 12v into it, which is on the lower end of what it is allowed to take. I bought some sets of bookshelf speakers from goodwill and have been switching trying to find which give the better results. I don't know the proper speakers for it, which is why I'm probably having some issues. One set is the Sanyo st-95 (8 ohms, can't find specs) , another is JVC SP-D402 (3-way, 6 ohms, capacity 80W, 87dB/W), and finally soundesign 0657blk (2-way, nominal 3W, 8 ohm, 90dB/W). I probably don't have all of the info needed to figure out the problem, but ask and I'll see if I can find it.
No matter which speakers I use, I can't get above about half volume without distortion. I tried putting them into my lepai-2020A+ and all speakers sound good at high volume.
My question is what causes clipping (or distortion)? Not sure if those 2 terms are similar. I've read it can be from a lack of power, but both have the same input voltage but the TDA7492P has 50W and the lepai has 25W, so I have no idea why the sound quality goes with the higher volume. As you can see I really have no idea what I'm doing, but I love tinkering with this stuff and want to learn. Any help is greatly appreciated.
Amazon.com: 50W + 50W TDA7492P 2x50 Watt Dual Channel Amplifier Wireless Digital Bluetooth 4.0 Audio Receiver Amplifier Board (Blue): Home Improvement
(TDA7492P 2x50W)
I know it's not anything amazing, but I want to try getting the best possible sound quality/volume I can out of it. It has 50W per channel, but I'm using 8 ohm speakers so I assume it is 25W (correct me if I'm wrong). I'm putting 12v into it, which is on the lower end of what it is allowed to take. I bought some sets of bookshelf speakers from goodwill and have been switching trying to find which give the better results. I don't know the proper speakers for it, which is why I'm probably having some issues. One set is the Sanyo st-95 (8 ohms, can't find specs) , another is JVC SP-D402 (3-way, 6 ohms, capacity 80W, 87dB/W), and finally soundesign 0657blk (2-way, nominal 3W, 8 ohm, 90dB/W). I probably don't have all of the info needed to figure out the problem, but ask and I'll see if I can find it.
No matter which speakers I use, I can't get above about half volume without distortion. I tried putting them into my lepai-2020A+ and all speakers sound good at high volume.
My question is what causes clipping (or distortion)? Not sure if those 2 terms are similar. I've read it can be from a lack of power, but both have the same input voltage but the TDA7492P has 50W and the lepai has 25W, so I have no idea why the sound quality goes with the higher volume. As you can see I really have no idea what I'm doing, but I love tinkering with this stuff and want to learn. Any help is greatly appreciated.
You have to understand a "50W" specification such that it can deliver 50W maximum IF you have the right supply voltage (normally close to the maximum supply voltage the amplifier can handle) and you use the right speaker impedance such that the current limiter in the amplifier will not limit output.
Many who are new to electronics believe the output power to be something you get disregarding the operational situation of the amplifier - absolutely wrong. It is a bit like if you have an electrical motor that can deliver 0.1hp with a 60V input and you feed it only 40V and put a light load (mechanical) on the rotor. It will not deliver 0.1hp. The motor hasn't got the potential because the voltage is below what is needed and further, you don't even give it the possibility by only applying a light (mechanical) load.
Many who are new to electronics believe the output power to be something you get disregarding the operational situation of the amplifier - absolutely wrong. It is a bit like if you have an electrical motor that can deliver 0.1hp with a 60V input and you feed it only 40V and put a light load (mechanical) on the rotor. It will not deliver 0.1hp. The motor hasn't got the potential because the voltage is below what is needed and further, you don't even give it the possibility by only applying a light (mechanical) load.
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Thanks for taking the time! I bought a step up module in case the 12v weren't enough and experimented with voltage a couple days ago.
Amazon.com: JacobsParts FP5139 60W DC-DC Buck Boost Voltage Converter SEPIC Module Step-up Step-Down Constant Current Adjustable Power Regulator Board: Home Audio & Theater
For my tests, I used 12v 2A DC and a green indicator light turns on. I put it to 15V, 18V and 20V, but each time either the amp board or the step up module would just cut out and the green indicator light would turn off. Any thoughts on this?
And getting off topic, I bet some of you are pretty familiar with lithium ion batteries. Just as an example, if I have 12.6v going into the amp, when the battery starts to discharge, would the voltage drop and underpower the amp? What would happen if I put it into a step up module and raised to to around 20V?
Amazon.com: JacobsParts FP5139 60W DC-DC Buck Boost Voltage Converter SEPIC Module Step-up Step-Down Constant Current Adjustable Power Regulator Board: Home Audio & Theater
For my tests, I used 12v 2A DC and a green indicator light turns on. I put it to 15V, 18V and 20V, but each time either the amp board or the step up module would just cut out and the green indicator light would turn off. Any thoughts on this?
And getting off topic, I bet some of you are pretty familiar with lithium ion batteries. Just as an example, if I have 12.6v going into the amp, when the battery starts to discharge, would the voltage drop and underpower the amp? What would happen if I put it into a step up module and raised to to around 20V?
I fully agree with Mr Fahey, it is bound to go wrong. Your input source is 12V/2A=24W. You believed you would get 2x50W=100W. Mr Fahey estimates you can in reality expect 2x35W=70W.
An SMPS is no miracle with more power coming out than going in. When you try to step the voltage up to 20V, you would have around 1A at your disposal if you succeeded. For two channels, thus, 0.5A for each channel. Not much power to be expected (around 8 W).
When a 60W SMPS looks into discharged power decoupling capacitors for a start, it will use its 60W capacity to charge the decoupling capacitors. But, your source can only handle 24W and will enter current limit. Then the SMPS gets too little input voltage and stops working. No good.
As suggested, find a good 25V (standard 24V) power supply with at least 100W. Or for a start, if you have, use a 19V/96W laptop charger with an extra decoupling capacitor as supply.
SMPS DC voltage boosters are attractive for power amplifiers in theory. When it comes to reality, there is often a catch.
An SMPS is no miracle with more power coming out than going in. When you try to step the voltage up to 20V, you would have around 1A at your disposal if you succeeded. For two channels, thus, 0.5A for each channel. Not much power to be expected (around 8 W).
When a 60W SMPS looks into discharged power decoupling capacitors for a start, it will use its 60W capacity to charge the decoupling capacitors. But, your source can only handle 24W and will enter current limit. Then the SMPS gets too little input voltage and stops working. No good.
As suggested, find a good 25V (standard 24V) power supply with at least 100W. Or for a start, if you have, use a 19V/96W laptop charger with an extra decoupling capacitor as supply.
SMPS DC voltage boosters are attractive for power amplifiers in theory. When it comes to reality, there is often a catch.
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correct !
if you have troubles with pop noise....i found this by doctormord...expert...:
How to prevent popping sound on power on on TDA7492P Amp?
chris
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