how to make a tube gyrator eq?

[Joseph R]

Hi,

Does someone know a way to do a tube based gyrator eq.
I'm trying to make two different parametric tube eq.

Please look at the attached schematic file. I need to translate those opamp based eq to tubes.

Any help will be appreciate.

Thanks

 

[SY]

Take a look here:

SYclotron Audio » The Acheron: Electronic Crossover Design

 

[Joseph R]

Thanks SY

Looks interesting I will have a closer look on it later if I can adapt my circuit to yours.
Ideally I would like it to be all tube but its a good starting point.
At first I wanted to build something around Borbely's tube opamp but its too complicated and needs to much tubes.

 

[Joseph R]

Does someone have an idea for doing it all tube?

 

[SY]

Sure. In the gyrator that I show for the Acheron, the opamp is configured as a unity gain buffer. A cathode follower circuit could be substituted using a high mu, high transconductance tube

 

[karsten21]

EQ only using tubes

Hi,
well I searched a while ago for the same thing. Look here:
"http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=equal_prj.htm"
http://www.triodeel.com/images/b9b.gif

First link is a transfer of an OP-amp schematic to tube. It look nice but need double HT and nee 6 triode sytems.
The second need 10 triode systems.

I do not found any "simpler" schematic today.

But...

There is hope: I got an EQ-1 from TL Audio for repair. Unfortunately no schematic but it´s not the first time I "reenineer" a PCB to schematic

Regards
Karsten

 

[Vix]

Hi SY,

I was reading your article about the Acheron active crossover, and I liked the idea of using a gyrator. However, I couldn't figure out how to calculate gyrator values for R and C if we need different frequency (from your stated 110 Hz high-pass). More specifically, if I'd need a frequency of 150 Hz, Hi-pass, Q=0.7, with the filter sandwiched between two buffers, with input in of 100K, what values will I need to change?
( in your article: C2=10 nF C3=10nF C4=10nF, R6=120K R7=5K1 R8=200K) but I have no clue how to recalculate these values in order to come to 150 Hz...

Thanks a lot,