Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on March 20, 2017, 05:14:57 pm
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Couple questions;
I have a 470 then 2K dropping R’s in the PS,(breadboard tweaking), since there is no tap, should they be 1K 1K, 2K then 470, makes NO difference?
I want Rg to fall somewhere between 220k – 470k per tube. Can I use a single Rg for all 4 tubes, or is it “better” for each grid to have it’s own R? Designing as Audio only.
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> a single Rg for all 4
It will BE a single resistor for all four, because the grids are all directly connected. Using four 500K is a waste of 17 cents compared to one 125K.
I would use one 100K.
2K looks like a lot of B+ drop for a power amp. The load for four 6K6 ought to be like 8K each, so 2K total. Well-biased (which it appears to be) it wants to suck around 140mA(!). That's a huge drop in 2K.
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one 125K.
1 Resistor it is
2K looks like a lot of B+ drop for a power amp
It is, here's my breadboard #'s for 1 tube, although all 7 were within +-20%
Orig B+ after bridge 336Vdc, as drawn 271 at plate
Vk 18.3 Ip .033A Pdiss 8.41 OT impedance ~~~8750. I got there with a 5K:8, took the 8 to 14 then mathed this(14 / 8 =1.75 * 5000)), not sure if that is fuzzy math or not :dontknow: