I have fixed this problem pls see this thread
Tweaking Audiopara.csv louder earpeice and spkphone! - PPCGeeks

fixes earpiece, bluetooth, and speaker phone!!!

Awesome work!! The volume has been terrible on this thing AFAIC.. So the only file that gets replaced is the AudioPara3.csv file, and not the others?

I switched from Verizon and the i760 to Sprint and the Mogul. I noticed the low volume of the Mogul immediately. Now I am about to switch to the Diamond. Is the volume issue with the Diamond worst or same as the Mogul?

it's about the same, but this hack blows your ears off, so have no fear.

yeah the hack works! back to how it was on the mogul...

I have never messed with a registry editor and I'm a little afraid. Is there a better way. Or am I making it look harder than it really is. I really would like to increase my volume

I didn't notice a real difference with bluetooth. But Speaker phone sounds great though.

There is no registry editing involved. You need to overwrite the existing .csv file in the \windows directory on your Diamond with the one in the .zip posted on PPC Geeks. There are several ways you can accomplish this, but one way would be to:

1.) Download & uncompress the zip to your desktop

Inside the .zip is a .csv file

2.) Copy this file over to the internal storage folder on your device

3.) Remove the read only & hidden attributes of the original .csv in the Diamond's \windows. The built in file explorer does not provide this functionality. You will need a 3rd party program, such as Total Commander or Resco File Explorer (recommended) to edit these attributes.

4.) Replace the original .csv (in \windows) with the one you installed to internal storage.

5.) Soft reset.

hmm, i didn't do step 3, is it necessary?? I checked the files after in the directory and they both say modified today.

I just assumed step 3 was necessary because of the instructions on PPC Geeks, but if it worked without doing that, then all the better

resco will overwrite the file regardless of the setting. i didnt do step#3 and it replaced it just fine.

the stock file explorer will not do this

I cannot find the windows directory and I did a search for .csv files on my diamond and it did not find any. What am I doing wrong

If you are using Resco file explorer, you will need to go to Menu>Options>General>Browser and uncheck the hide checkboxes in order for \windows to show up.