I picked up this little Sure Electronics AA-AB32231 board a while back and got to playing with it this weekend. I tried driving 8 ohm and 4 ohm speakers and it sounds pretty good. I used a variety of different phones to drive the board's 3.5mm jack and when I got up to 80%+ volume output on the phones, the louder parts of the song just sort of disappeared almost like stuttering. It's almost as if the amp is muting the output on strong hits in the music.
If this is expected behavior to protect the amp, this doesn't seem to be covered in any detail in the manual. Is there a way around this? I would like whatever I do with it be easy enough for the wife to use, i.e. plug it in and turn the phone all the way up.
If this is expected behavior to protect the amp, this doesn't seem to be covered in any detail in the manual. Is there a way around this? I would like whatever I do with it be easy enough for the wife to use, i.e. plug it in and turn the phone all the way up.
The TPA3110 chip is what I believe the Americans call "dirt cheap". It is specified to be able to operate until 26V supply voltage like the TPA3118 and TPA3116. It even sounds surprisingly good.
BUT, it is not a TPA3118/TPA3116 chip inside and it is not intended for as high output power as the TPA3118/TPA3116.
If you read the datasheet for TPA3110, the maximum output power is specified for a supply voltage of 16V! 15W in 8 Ohm and 30W in 4 Ohm. Not at 26V supply voltage as you could expect.
Why? The TPA3110 has 240mOhm output switches (TPA3118/TPA3116 have 120mOhm output switches) and TPA3110 can simply not supply the current that appears theoretically possible with a 26V supply. Probably an internal current limiter or at least strong heating with a very simple cooling layout.
Why is then a 26V input voltage specified? - probably because the TPA 3110 may be used with 16 or 32 Ohm speakers.
What do you do to make life easier for your wife (apart from cleaning her car)? Use a voltage divider (damping element) between the phone output and the amplifier input such that at 100% volume on the phone the amplifier does not show any signs of surrender.
BUT, it is not a TPA3118/TPA3116 chip inside and it is not intended for as high output power as the TPA3118/TPA3116.
If you read the datasheet for TPA3110, the maximum output power is specified for a supply voltage of 16V! 15W in 8 Ohm and 30W in 4 Ohm. Not at 26V supply voltage as you could expect.
Why? The TPA3110 has 240mOhm output switches (TPA3118/TPA3116 have 120mOhm output switches) and TPA3110 can simply not supply the current that appears theoretically possible with a 26V supply. Probably an internal current limiter or at least strong heating with a very simple cooling layout.
Why is then a 26V input voltage specified? - probably because the TPA 3110 may be used with 16 or 32 Ohm speakers.
What do you do to make life easier for your wife (apart from cleaning her car)? Use a voltage divider (damping element) between the phone output and the amplifier input such that at 100% volume on the phone the amplifier does not show any signs of surrender.
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Well, I figured putting some device between the phone and amp would be the only thing that could be done. For reference, I am using a 12v 5 amp power supply to feed the amp. I haven't measured the heat, but maybe I can give that a shot. I am mostly curious about what exactly is causing the limitation. Is the chip being limited by current? Thermal? Is there a test I can do to figure it out for sure?
You can, for short moments, switch-in a load that will overload the TPA3110 and see if the output voltage drops considerably. The overloading must be invoked for so short moments only that the temperature cannot raise significantly in that short time. Some 1-2 seconds. Use a storage oscilloscope, if you have.
The datasheet is explicit about short circuit protection being implemented. Fig. 17 mentions "thermally limited regions". I have found no current limiting value.
My guess is still that a current limiter is being invoked.
The datasheet is explicit about short circuit protection being implemented. Fig. 17 mentions "thermally limited regions". I have found no current limiting value.
My guess is still that a current limiter is being invoked.
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