First dropping resistor - value change = ?

[atmars]

I have seen several schematics for 5E3 clones, some using 5.1k for the first dropping resistor and some using 4.7k. I'm guessing this is simply because these are common values that are close to the 5k on the original schematic. My question is, what does changing this value do to the sound of the amp? What would the effect be if one went even higher or even lower?

[Bruce / Mission Amps]

Originally Posted by atmars

I have seen several schematics for 5E3 clones, some using 5.1k for the first dropping resistor and some using 4.7k. I'm guessing this is simply because these are common values that are close to the 5k on the original schematic. My question is, what does changing this value do to the sound of the amp? What would the effect be if one went even higher or even lower?

I don't know about others but I started using 5K1 because all the real ones I tested had their 5K-4K7 to 10K screen node resistors drifting up in resistance over the years.
5K1 was the closest one and at the time, and I already had 400 to 500 of them in stock at a 2 watt rating. So, bada bing.
I don't hear any difference between the two but I stock both, just in case I run into a nit picker.

[loudthud]

Has anybody ever tried anything lower in place of that 5K? It seems to me the 5E3 tends to over-compress under heavy overdrive. I only have seen one original example that may have had a 470 ohm in that position. The resistor was slightly burned and I couldn't tell if the multiplier band was brown or red. Seems like when I measured it was less than 1K and burned carbon comps go higher when they burn.

I mentioned it in this thread:
5F3 did it realy exist?

[tubeswell]

Originally Posted by loudthud

Has anybody ever tried anything lower in place of that 5K? It seems to me the 5E3 tends to over-compress under heavy overdrive. I only have seen one original example that may have had a 470 ohm in that position. The resistor was slightly burned and I couldn't tell if the multiplier band was brown or red. Seems like when I measured it was less than 1K and burned carbon comps go higher when they burn.

I mentioned it in this thread:
5F3 did it realy exist?

In the 6V6/6L6 5E3 I built last year, I ended up putting a switchable 4k7 resistor/150R choke filter, with a DPDT that switched in a 4k7 resistor to the screens when the choke was engaged.

It has more bite with the choke and more sag with the resistor, but the noise floor seems to my ear to be as quiet as a mouse either way.

I reported it here:

http://music-electronics-forum.com/s...99081#poststop

(If I may say so, the amp sounds fantastic with 6V6s and positively astounding with 6L6s.)

FYI the schematic is attached