To destroy a Valve Junior - SE octal amp using the.......

[BBQLS1]

What can/should I do with a VJ?

I'm thinking of making a board, something like a beast 5F1 with the VJ parts.

What do you think about a octal of:

KT88, EL34, 6L6, KT66??????



Any real barriers to using the stock PT and a 123ESE? I'll need a filament transformer or use SS rectification for the amp?

[zaphod_phil]

You could easily build a Beast or P1 eXtreme in there, although that would need you to drill some extra holes for the MV and tone controls with the P1eX. You might also like to try it with a pentode preamp front-end, like the one I'm discussing with kerrynet32 at the moment, using a 6U8 tube for the preamp.

The stock PT has enough juice for a single KT88, EL34, 6550, etc, including the heater current. No need to rectify the heaters. Just elevate the heaters, by connecting the heater center-tap (or virtual center-tap) to the power tube cathode. The Hammond 125ESE OT will also handle any big meat, up to a KT88 or 6550, without problem.

[BBQLS1]

You could easily build a Beast or P1 eXtreme in there, although that would need you to drill some extra holes for the MV and tone controls with the P1eX. You might also like to try it with a pentode preamp front-end, like the one I'm discussing with kerrynet32 at the moment, using a 6U8 tube for the preamp.

The stock PT has enough juice for a single KT88, EL34, 6550, etc, including the heater current. No need to rectify the heaters. Just elevate the heaters, by connecting the heater center-tap (or virtual center-tap) to the power tube cathode. The Hammond 125ESE OT will also handle any big meat, up to a KT88 or 6550, without problem.

I'm such a newb. They don't have the same heater requirements as a 12AX7? What's all this business about the heater center tap?

[tunghaichuan]

I'm such a newb. They don't have the same heater requirements as a 12AX7? What's all this business about the heater center tap?

The 6U8's heaters draw 450mA vs 300mA for a 12AX7.

Here is a handy program that I used to look up the heater requirements for the 6U8:

http://www.duncanamps.com/tdslpe/index.html

If there is a center tap on the 6.3v heater winding, connect the CT to the power tube's cathode.

If there isn't a CT, make one using two 100 ohm resistors. One leg of the resistor gets connected to one side of the 6.3v winding, the other resistor gets connected to the other side of the 6.3v winding. Then connect the unused ends and connect this to the cathode of the power tube winding.

tung

[BBQLS1]

I'm such a newb. They don't have the same heater requirements as a 12AX7? What's all this business about the heater center tap?

The 6U8's heaters draw 450mA vs 300mA for a 12AX7.

Here is a handy program that I used to look up the heater requirements for the 6U8:

http://www.duncanamps.com/tdslpe/index.html

If there is a center tap on the 6.3v heater winding, connect the CT to the power tube's cathode.

If there isn't a CT, make one using two 100 ohm resistors. One leg of the resistor gets connected to one side of the 6.3v winding, the other resistor gets connected to the other side of the 6.3v winding. Then connect the unused ends and connect this to the cathode of the power tube winding.

tung

Got it thanks!