Bad cat hot cat bias?

[chuckb]

Hey guys, I have a Bad cat Hot cat 30 clone finished for awhile now and was wondering the bias ma for the el34 jj's I have in there? I did a bias check and it's reading 23.45ma on one tube and 23.60 ma on the other. Is the bias for each tube a bit low? I thought the bias for a el34 was between 35-40ma? If this is the case and the bias is to low, would I increase or decrease the bias resistors to achieve a higher bias setting? I have a pair of 270 ohm/10watt cathode resistors with two 220uf/250v electrolytic caps there now as per the schematic I'm using.

Chuck.

[soundguruman]

you can basically clip on some parallel resistors until you find just the right value.
Try 220 instead of 270...

[chuckb]

So if i want to increase the bias I have to decrease the resistor value?

[soundguruman]

So if i want to increase the bias I have to decrease the resistor value?

you want to make the output draw a bit more current

[Jazz P Bass]

So if i want to increase the bias I have to decrease the resistor value?

Yes.

[Chuck H]

Eh Hem... Does "increase bias" mean increase the current? Because if you want to increase current you typically DECREASE bias. Just sayin'. There is often some confusion in the standard phrasings WRT bias. Basically, you want to make the grid more positive (or, less negative) if you wish to increase current. So, since in your amp the grids relative negativity to the cathode is dependant on the positive voltage at the cathode (while the grid is referenced to 0V), if you decrease the positive voltage at the cathode the grid is less negative WRT the cathode. So, to get smaller voltage at the cathode you need to decrease the cathode resistor value.

I thought an explaination was in order. It's always better to understand something than to simply know a rote method IMHE.

[Enzo]

You adjust the bias to control the idle current. Current is not bias.