Regulation options for 807 g2

[jamesjung21]

Have you considered buying an ultralinear SE output tranny? It would eliminate regulators and is a nice comprimise between triode and pentode.

Like this?

http://www2u.biglobe.ne.jp/~tossie/KT44UL-E.html

Is it really OK to swap 807 with KT44?

Cheers,
JayJay

[tubetvr]

I have looked deeper into the VR tube thing and found (by reading some data) that the regulation accuracy is rather low (about 6 V for a 150 V tube). Is that critical for the g2 voltage? I assume a zener-controlled MOSFET regulator will have better precision in the voltage output, but may be overkill?

Yes, it sounds reasonably correct with 6V for something like 20-30mA change in load, if you compare withj Zeners you will see that that is worse. Either a VR tube + tube regulator or a Zener + mosfet or bipolar SS gives better performance as the current trough the reference can be made almost constant. However I believe that 6V is completely OK and is not a problem so maybe direct regulation using VR tubes is the way to go.

Regards Hans

[arnoldc]

hi, i have experimented with the 807 and never got it to have decent bass until i used tube regulators for G2. i don't know why, but zeners did not do good.

here's my amp

[illuwatar]

Thank's everyone for the help.

The design have finalized and the practical part have started. The transformer issue was solved by "Ask Jan First", who could provide a custom made power transformer for a decent price. From the same place, I was able to source the output transformers too. Tubes are soon arriving from UK (bought via eBay). The remaining hardware could be easily found here in Sweden.

The final design got these properties:

* Actual amp design not changed.
* G2 stabilization by 0C3 + 0D3 (prefer octals)
* MOSFET regulators for 300/350V to input/driver stages
* Stabilized heaters for 6SN7's
* Filter capacitors will be larger in value.

I hope this will be a decent design. Lot of stuff for just 10W, but I hope this will be nice sounding 10W...