[Quetscher]

Hello Joseph and welcome to melodicaworld,

unfortunately these terms (alto, soprano, tenor, bass) are not too exact and they vary from brand to brand. When you want to buy a New model just have a look at these three charts:

https://images-na.ssl-images-amazon.com/images/I/51KmFYVmK9L._SX522_.jpg

This is for Hammond models and the next one is for the Suzukis:

http://www.suzukimusic.co.uk/products/melodion/images/melodion-range.gif

And finally, the range oft the Yamahas:

http://image.rakuten.co.jp/shimamuragakki/cabinet/100412/pianica_img4.gif

Apart from that you can find information on this site:

http://skmt.cooktone.com/text_kenhamo/catalog_e.html

I’m not sure if this is a reliable source, I’ve got the impression that he counts an octave lower than it really sounds…

Greetings, Quetscher