HF85 gain reduction?

[ferninando]

could I swap 12AT7s for 12AX7s
to reduce gain in the Eico HF85?

 

[gadget73]

Try a 5751. Its a 12AX7 with a gain of 70 vs a gain of 100. All the rest of the parameters are the same, so it won't need any circuit tweaks to run right. Possible that the 12AT7 might need some resistors changed in order to make it optimal in that circuit, though plugging one in won't hurt anything.

 

[ferninando]

thanks gadget. just what I want to know.
How about a 12AU7?

 

[gadget73]

Those also have different characteristics, so it might not sound ideal. It will plug in and function though. Worst it'll do is not sound good.

 

[ferninando]

thanks again gadget. you know the tubes.
the info I need.

I just sprung for a new matched pair of 5751 by sovtek.
they'll be ok for my needs.
this is great.