IMHO I would still revert back to the original values. The 2k2 will keep the PI voltages at a good level (ie around the 290V mark) and then by increasing the 22k to 27K, that will stabilise the V1 and V2 plate voltages to the level I have suggested. I must give credit to Talbany for these suggestions. They definitely worked for me....and we share the same iron!Raoul Duke wrote: ↑Wed Mar 13, 2024 12:22 pmThanks for the info Doc!Dr d wrote: ↑Wed Mar 13, 2024 8:02 am Great results, well done. Having just build a 2nd gen amp, it was interesting to follow your experiences. If I could make a comment on voltages, you may find this helpful. I found that the V1 and V2 plate voltages were particularly sensitive to the performance of the amp. With Hammond iron also, I found 2k2 > 27K > 2k2 (Tonys dropping string values) gave me 175-180v V1 and about 185 - 190v on V2. These voltages really opened up the amp and made it sing. Ge 12AX7As and balanced GE 12at7 sound really nice and yes, the EVM 12L is perfect for this amp. I am really impressed with the Hammond iron and the amp improves significantly as it burns in. Lovely amp. I hope this helps. Enjoy.
Ps. I much prefer the 3rd gen setting!
I’m still thinking of increasing the 3k3 I replaced the first dropping resistor with just because the line voltage seems to vary up to 8vAC. My V1 is sometimes 185, sometimes 192; and V2 can vary from 193 to 201. I’m leaning toward that resistor vs the B+5 because the voltage swing on the plates doesn’t really affect the tone - but the “feel” between 445vdc and 455 vdc is noticeable in the amp’s response. Very subtle, but certainly there.
I’m also starting to prefer the “bass knob pulled/3rd gen” sound as well.
Cool that you like the 3rd gen setting!