6G3 build, switchable 6V6 to 6L6

[centervolume]

just fantastic, very empowering! thank you so much for sharing your knowledge. Your generosity is very heartening, resonating with the spirit of this project - a christmas gift of sorts for a close friend who is moving out of town. Will report back with results, and photos sooner or later!

[centervolume]

I am getting intermittent results with this 4 ohm tap. I'll hook it up and it will work and then I'll turn it off and come back later and it sounds low powered again.

Resistance measurements to ground show it to be the same as the green (8 Ohm tap); they both read .5 ohms. I thought I would see .8 on the 8 ohms one and .4 on the 4 ohm tap.

then my 4 ohm celestion has only 4 holes in the frame for the speaker lugs to pass through, and the baffle has 8 speaker mounting bolts/liugs! so I am looking at drilling the frame or settling on this as an 8 ohm output amp.

I have an idea that outputs closer to ground (2 and 4 ohms) are more aggressive sounding, wanted a chance to explicitly test that out. I think the frequency response charts dont really support that hypothesis but I like to experiment.

[martin manning]

I am getting intermittent results with this 4 ohm tap. I'll hook it up and it will work and then I'll turn it off and come back later and it sounds low powered again.
Resistance measurements to ground show it to be the same as the green (8 Ohm tap); they both read .5 ohms. I thought I would see .8 on the 8 ohms one and .4 on the 4 ohm tap.

Must be some intermittent connection or short. It is very difficult to measure resistances down around one ohm with an ordinary multimeter so I wouldn't trust those measurements. To check the transformer I would put some AC (say from a 6VAC filament transformer) on the primary (at the power tube plate leads) and measure the VAC on the 8 and 4 ohm taps. The 8 ohm tap should show 1.4x the voltage on the 4 ohm tap.

then my 4 ohm celestion has only 4 holes in the frame for the speaker lugs to pass through, and the baffle has 8 speaker mounting bolts/liugs! so I am looking at drilling the frame or settling on this as an 8 ohm output amp.

Four bolts is usually enough, so no need to drill more.

[Leo_Gnardo]

then my 4 ohm celestion has only 4 holes in the frame for the speaker lugs to pass through, and the baffle has 8 speaker mounting bolts/liugs! so I am looking at drilling the frame or settling on this as an 8 ohm output amp.

Four bolts is usually enough, so no need to drill more.

What Martin says: don't drill holes in your speaker flange. If you have too many studs sticking thru the baffle, try backing-out the ones you don't need. If you manage to do this, plug the holes with a dab of silicone cement = RTV. Whan I find them impossible to remove 'the easy way', break out the Dremel and fit the mini cutting-disc, saw those bad boys off. Oh boy, sparks! Wear eye protection.