4 4 0 wiring help needed

[johnnyreece]

I built one of these (basically) and can confirm that it's quite loud. My wife gives me dirty looks if I turn it past 3. I may try to run it to a smaller, less efficient speaker at some point, as right now it's running a 2x12 cabinet.

[pompeiisneaks]

BTW I'm moving this and the other 4 0 0 thread to the 'Technical Discussion' area as it's not a trainwreck style amp. Please stop putting these threads in the wrong place. I think this is the third time you/'ve created the 4 4 0 thread in Trainwreck Discussion. (I'm also moving the other thread but won't comment in that one)

[mehfuzhoss]

got the light sorted.

how much should the ma current read for biasing ? any input is appreciated.

thanks

[pompeiisneaks]

The datasheet for the 6SN7GTB states a max dissipation of 5W. You need to calculate the dissipation that's 70% of that at your amps B+ anode voltage.

Ex.

P = V * A

made up B+ of 400VDC,

400VDC * A = (.7 * 5)

so solving for that, A = (.7 * 5) / 400 = 0.00875A = 8.75mA

Of course you'd need to put in your voltage, and it's a bit of a balancing act. As you adjust the plate current per tube the voltage will also adjust a bit, but you should get the general idea from that.

The formula for this is in the AX84.com site's documentation on the schematic.

~Phil