18Watt.com

I'm making an amp out of an old radio trying to use the radio's own loctal tubes instead of "usual" ones. I'm sorry it's not going to be 18W - although I planned it to become the one but the PT seem not to have enough current for this.

I've got a 7C7 sharp cut-off pentode which seem to be pretty similar to 6SJ7 and might become my preamp tube. Both tubes are cheap but 7C7 is more "weird" so I'm trying to see if it will work as a 6SJ7 preamp substitute.

Here's a link to 7C7's datasheet:
http://frank.pocnet.net/sheets/127/7/7C7.pdf

And this is 6SJ7:
http://frank.pocnet.net/sheets/127/6/6SJ7.pdf

I'm not an experienced tube dude so I'd be very gratefull if someone will explain me what are the differencies between those two and how using 7C7 instead of 6SJ7 might affect the sound or anything else.

They look fairly similar, but the 7C7 has a bit more transconductance. They're both a lot lower then the familiar EF86. I think they'll work fine, you might need to tweak the resistor values.

--mark h

Your tube is on this chart. Depending on your supply voltage, pick an intermediate set of values for your components.


Edit: Whoops, I thought I posted an attachment.

should be fine. go for it.

germ