I think that back in those days, there was no one manufacture who was considered a student horn maker, they were sort of all in the same category except for the biggest and most powerful "kid on the block".....Bach. I think it was around the 60's that the Bach
Stradivarious was the hotest item on the market.
Here is something interesting, a short history on Holton:
http://www.bandusa.com/Information/Holton_Co.htm
Liad