40% tap or not

[brucetassin]

Hello All,
I am upgrading the OPT's on my 6V6SE. My new OPT's have a 40% tap, my old ones did not. On the schematic you can see a 100R resistor tied to the plate and 2nd grid. Which should sound better, as it is or use the 40% tap?
In the picture, I have to OLD OPT's sitting on top of the NEW OPT's just for
show. The new OPT's are Edcor GXSE15-8-5K.
Thanks for replys.

[DF96]

Using the tap will probably give higher output power but also higher distortion than triode mode. If you have sufficient power for your speakers and room then stay with triode mode.

[20to20]

Originally Posted by brucetassin

Hello All,
I am upgrading the OPT's on my 6V6SE. My new OPT's have a 40% tap, my old ones did not. On the schematic you can see a 100R resistor tied to the plate and 2nd grid. Which should sound better, as it is or use the 40% tap?
In the picture, I have to OLD OPT's sitting on top of the NEW OPT's just for
show. The new OPT's are Edcor GXSE15-8-5K.
Thanks for replys.

Before David Hafler left Acro, he and Keroes determined the best tap point for the 6V6 was @24% and that they used for their UL trannies for the 6V6/EL84. Edcor has a tranny with a 23% tap for those tubes. However there is still a power and distortion benefit at the 40% tap for UL. A SWAG would be about 60% of tetrode power with twice the triode distortion numbers, which are pretty low to start with, probably half of pure pentode mode distortion. (another SWAG interpolation from their UL 6L6 graph)

20

[Pano]

I tried a UL tap with my 6V6 SE and couldn't tell much, if any difference vs normal pentode mode.
May have to try again.

[20to20]

Originally Posted by Pano

I tried a UL tap with my 6V6 SE and couldn't tell much, if any difference vs normal pentode mode.
May have to try again.

I was just looking at a 6AQ5 data sheet @250v. and the power and distortion rating were the same for pentode AND triode mode.... Go figure.

20

[DualTriode]

20,
I like your style, take it apart and play with it. Are you going to adjust the bias point of the 6V6 while you are at it?
DT

[DF96]

If power and distortion are said to be the same for triode and pentode mode then either the datasheet is wrong or you are misreading it. Perhaps they accidentally duplicated a table?

[20to20]

Originally Posted by DF96

If power and distortion are said to be the same for triode and pentode mode then either the datasheet is wrong or you are misreading it. Perhaps they accidentally duplicated a table?

You are probably right about it being a mistake because it was from one of sources that just tabled the data. Also, it was the only source I found that actually posted any 6AQ5 power and distortion data for triode mode. Of the 3 true data sheets I found, all omitted SE triode mode power and distortion numbers for some reason. When I saw the table for that I said to myself, This can't be right, but couldn't find anything to the contrary.

NJ7P Tube Database Search

[TheGimp]

The numbers are overall gross numbers. They tell nothing about the distribution of harmonics which is more important than the total THD by itself.

[Tom Bavis]

This 6V6 data sheets shows 1.0W at 5% distortion for triode mode at 250V: http://www.mif.pg.gda.pl/homepages/f...84/6/6V6GT.pdf

6AQ5 should be similar.