I have read all the physical differences, but what does the octal do better or different from the classic?
Thanks
Thanks
3 posters
Octal driver vs "Classic" board
NuttyLemur- Posts : 18
Join date : 2013-06-29
quadaptor- Posts : 60
Join date : 2009-05-04
Good question, been wondering the same thing myself.
Bob Latino- Admin
- Posts : 3263
Join date : 2008-11-26
Location : Massachusetts
I have never found octal driver tubes to be "superior" from an audio quality point of view. If octal drivers offered anything in the way of "better sound quality" over noval (9 pin driver tubes) then I am sure that Conrad Johnson, McIntosh, Rogue and all the other USA companies would be using octal drivers to gain an edge in better sound reproduction. Octals do have a drawback too .. They use more filament current and your power transformer with 3 octal driver tubes in place of three noval tubes will run warmer. I know that Roy does offer an octal driver for the Dynaco ST-70 and Dynaco Mark III if you do want to try the octal driver circuit. I do not offer any of the VTA amp kits with an octal driver. A 6SN7 is pretty much the same electrically as a 12AU7 - BUT - a 12AU7 draws .3 amps and a 6SN7 draws DOUBLE this at .6 amps. THREE X 6SN7's will use almost 1 amp (.9 amp to be exact) more current than three 12AU7's. In a stock ST-70 the extra .9 amp (IMHO) will stress out the already undersized PA-060 power transformer even more. If your stock ST-70 runs hot now, it will run even hotter with three octal driver tubes.
There was a post on our forum here about the octal driver circuit from May of 2011 at the link below ...
Octal driver circuit post on the Dynaco Tube Audio Forum
Bob
There was a post on our forum here about the octal driver circuit from May of 2011 at the link below ...
Octal driver circuit post on the Dynaco Tube Audio Forum
Bob
Last edited by Bob Latino on Fri Jul 05, 2013 4:20 pm; edited 1 time in total
quadaptor- Posts : 60
Join date : 2009-05-04
Thanks for the explanation
NuttyLemur- Posts : 18
Join date : 2013-06-29
Thanks, now I know what upgraded driver board I will be buying.
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