There is only a way to sort this out :
Ask Peavey !
Maybe Avenger used different studios and producers for the demos and that's why they sound a bit different from demo to demo.
Different studios can make that : Just compare Iron Maiden's 1st album to Killers.
There aren't any scans available because these demos were released in tape form without any covers.
As i said, i received this stuff from a german collector who does tape trading since early 80's.
In the 80's we used to trade dubbed tapes and that's why today it still shows up obscure old stuff as some people still rip and share their hidden treasures...As a matter of fact you can consider yourself lucky for listen these demos since the Metal Archives submitter never spreaded them.
Or you think it was Strad or Strappado who ripped and uploaded them ?
If you're trusting Metal Archives informations, i would advise you not to trust it 100% as it's full of mistakes...
Just an example - In Metal archives, it says this band was from Texas
http://www.metal-archives.com/band.php?id=114321Now, the ex-guitar player said they were from Chicago (read the profile of the user ) :
http://www.youtube.com/user/chargergsd# ... mcfnsz2eSE