By the way, 6n8s / 6H8C is direct replacement for 6SN7, and the subminiature 6n16b / 6H16b as well.
ECC81 has too much gain.
I just ran a quick spice simulation and both the ECC82 and the ECC88 work well without any changes to the original schematic. Overall gain is a little higher for ECC88 and a little lower for ECC82 but both well behaved. About 3W out with 6v6 before major distortion sets in. The 6v6 runs at about 10W plate dissipation.
When I drop in the 6L6, plate dissipation rises to 20W and 6W output into 8ohm, again no changes whatsoever.
If you think that 20W is a bit high for the 6L6 you can make the negative bias adjustable. -28v drops dissipation to 19W, -29v down to 18W. Also cuts output to 5W or so.
ECC81 has too much gain.
I just ran a quick spice simulation and both the ECC82 and the ECC88 work well without any changes to the original schematic. Overall gain is a little higher for ECC88 and a little lower for ECC82 but both well behaved. About 3W out with 6v6 before major distortion sets in. The 6v6 runs at about 10W plate dissipation.
When I drop in the 6L6, plate dissipation rises to 20W and 6W output into 8ohm, again no changes whatsoever.
If you think that 20W is a bit high for the 6L6 you can make the negative bias adjustable. -28v drops dissipation to 19W, -29v down to 18W. Also cuts output to 5W or so.
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Oh, and although the document which came with your o.p. states "at 5 watts there is no need for grid stoppers" there is no relationship between grid stoppers and output power.
I always fit at least 1 kohm on control grids and 100 ohm on screens. If you start out without you may have trouble to distinguish between oscillation and other problems. Recommendation is to begin building with stoppers and once everything looks good you can still decide to remove them one by one if you think you want to do without them...
I always fit at least 1 kohm on control grids and 100 ohm on screens. If you start out without you may have trouble to distinguish between oscillation and other problems. Recommendation is to begin building with stoppers and once everything looks good you can still decide to remove them one by one if you think you want to do without them...
Thanks a lot,
I found this transformer and it's very cheap I think.
TSL 70/001 INDEL - Transformador: de red | 230VCA; 250V; 20V; 6,3V; 0,18A; 0,18A; 3,5A; TSL70/001 | TME - Elektroniikka komponentit
I will buy for the price.
I found this transformer and it's very cheap I think.
TSL 70/001 INDEL - Transformador: de red | 230VCA; 250V; 20V; 6,3V; 0,18A; 0,18A; 3,5A; TSL70/001 | TME - Elektroniikka komponentit
I will buy for the price.