I created a song on my laptop (Windows 10), converted it to .mp3 and e-mailed it to my PC (Windows 7) to play on iTunes, but it sounds faint and dull on the PC.
The mp3 version sounds great on the laptop, tho the file is identified as .WAV and not mp3 as I had specified at file conversion. What gives?
So... what every said above is correct... every time you covert a WAVE file to MP3 you are losing 80% or more of the original data depending on the bit rate of the MP3. I always convert to 320kbs MP3 files unless there is a really good reason not to use 320kbs.
But... lets back up a bit. When you finished the song and exported the wave, did you do anything else to that wave at that point or did you proceed directly to the MP3 converter?
The reason I ask is because many folks at that point will process the wave file with what is called "mastering software" to add some sparkle and thump to the music. I prefer to call it polishing or sweetening the song because "mastering" is something totally different but I am OK calling it "small "m" mastering" as well. It's simply the process of adding compression, reverb, and EQ tweeks to the finished song to make it sound a bit better and more cohesive.
Essentially, when you listen to the Wave or the MP3, there should really be very little sonic difference between the 2 files. Most people would not be able to tell you which one was which. Especially at the higher MP3 bit rates.
You also should understand that the different music players software will affect the sound quality more than the Wave to MP3 conversion. I would check that MP3 on several different players to see if that is the problem. Barring that, go back to the original Wave and do some of the polishing and sweetening I mentioned.
One other thing to check on. Be sure that the exported WAVE is normalized to just under 100%. I like to shoot for 96% on the highest peak. Run some compression first to bring the entire wave into a relatively consistent looking form. You want the finished wave to look like this.
In this photo.... the compression rate is consistent but not as high as it could be because there's quite a few spikes and "airspace" above the main body of the energy. The song is on my website and sounds good. By cranking up the compression a bit more, the song would have gained more "apparent volume" but lost some of it's dynamic range... the difference between the loudest and softest parts of the music. Once you get the compression right, and it might take a few tries if you're not worked with this before, you can then use the normalize function. Normalize brings the highest peak to a designated level that you set relative to 0dB. You don't want to go above 0dB.
As a footnote to the compression thing.... in the picture above, if I had cranked the compression up to max, that section toward the end that is obviously lower in volume would have been indistinguishable from the rest. To much compression is not a good thing.
All of that is important because you mentioned a "faint and dull sounding MP3"..... again, that should not happen if your levels are all correct before you convert to MP3, and you have done some proper sweetening.
I hope this helps you find the reasons for the weak and dull sound you ended up with in the MP3.