g5 help needed !

sjhusting · Message non lu par **sjhusting** » 18 juin 2006, 14:04

No, no problems I didn't cause myself.
I finished my G5 in December, got the hum out in March, and it is the amp I use for recording, practicing, and occasional jamming. I'm quite happy with it.
I'm currently fixing my bad workmanship, and doing some tuning. I'm playing it through a Jensen C12Q in a badly made home built cabinet.

2 questions:

I saw in V2 the rating of R21 was reduced to 2 watts. The Babelfish translation of the explanation didn't make any sense. What is the reason?

Also, R20 has been reduced to 120R. Am I correct in thinking this will permit me to use either a 6L6 or EL34?

thanks

steven

Message non lu par **blacksnake** » 18 juin 2006, 15:23

Hi,

120R work good. You can replace this one with a variable bias (see the G5 v2). I had made this circuit and to change tube, just adjust the bias with the trimer

excuse for my little english

sjhusting · Message non lu par **sjhusting** » 18 juin 2006, 15:48

your english is better than my french, which is limited to "une cru classe, sil vous plait"

Message non lu par **bilbo_moria** » 18 juin 2006, 19:45

Hi sjhusting,

Let's have a look on EL34 typical charasteristic (e.g. at http://www.jj-electronic.com/pdf/E34L.pdf)

Ua = 250V
bla bla bla
Ig2 ~15mA

The power dissipated in R21 will be :
P = RI² = 2200 ohms x (15mA)² ~ 0,5W

OK, 2W is quite mojo-overrated, but who cares ?

Sheers ...

sjhusting · Message non lu par **sjhusting** » 19 juin 2006, 21:37

I get it. The 5-watt was just way overspec'd, which was ok, but now we have to put a huge capacitor in there, too, so space is valuable.

bit by bit I understand more

steven

Message non lu par **bilbo_moria** » 20 juin 2006, 7:09

You bet !