JJ Tesla ECC99 as a driver for 300B-2A3

[konstantin]

Hello everybody,

Has anyone tried the new JJ Tesla ECC99 as a driver for the 300B or the 2A3?
I hear great things about this tube compare to the 6SN7.

Regards

 

[dshortt9]

In case you have not seen this:

http://www.ampdesign.de/ECC99 Artikel.htm

 

[vuki]

I'm using it in my SE300b amp. Before I had 6sn7 in a "classic" arrangement with 2 capacitor coupled common cathode stages and it was already very good. Then I tried Thorsten-suggested pentode single stage drive, but didn't like it at all - it sounded agressive although it had better THD specs. Finally, last year, a friend gave me 2 ecc99's to try. I made 2 DC coupled common cathode stages and it really was singing! Great sound and excellent specs. I'm listening to it ever since.

 

[konstantin]

ECC99

Hello Vuki,

What's the input sensitivity for full output power with the ECC99?
Can you share the eschematic with the rest of us?

 

[vuki]

hi konstantin,

I can't give the exact schematic (couldn't find it anymore) but as I remember -
first triode has 22k anode resistor, 180R cathode resistor, 100k input resistor and 330R gridstopper.
Grid of the second triode is via 330R gridstopper resistor connected to the anode of the first triode and that triode has 6k8 resistors on anode and cathode. 6k8 cathode resistor is bypassed with 10uF capacitor. Second triode's anode is via 0.22uF cap and 820R gridstopper connected to 300B's grid and there is 180k input resistor connected between cap/gridstopper junction and ground. 300B's cathode resistor is 1k and is bypassed with 100uF.
B+ is 450V for 300B and ca. 350V for ECC99. Both tubes are DC heated.

 

[konstantin]

Hi Vuki,

So, you "running" the fisrt triode at about 18ma and the second about 5ma, no cap between, right?

Regards
K

 

[vuki]

No, I found it - the first one is 15k on anode and 120R on cathode (ca 16ma), the second is then also around 16ma.

regards,
Vuki