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4.7mf/270 ohm instead of 22mf/250ohm?

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12/7/2003 9:34 PM

4.7mf/270 ohm instead of 22mf/250ohm?

I'm building my first 5E3 and thought of using a 270 ohm/10W power tube cathode resistor instead of 250 ohm.As I always try different tubes,I think it's better to have a lower voltage,in case I put weaker tubes in. A 10W resistor is supposed to handle the heat better and I could even use 6L6??
I also heared that the 22mf bypass cap is much to high and you get less bass and gain by using a smaller value. unfortunately I could only find a 4.7mf cap .Is it too small,do you think the resistor+cap mod makes any sense or should I stick to the fender values?I don't want to change much after I finished my amp and it's probably easier to do it now before I wire everything up.Can I just change the cap and resistor and leave the rest?
sergio

12/7/2003 10:35 PM
Joel	You can find 22mf caps at Antique Electronics Supply. That is where I got mine and just finished my 5E3 build and let me tell you it is sweet. Check out www.tubesandmore.com Good luck!

12/7/2003 10:43 PM
Joel	It appears I don't know what I'm talking about. Others will post. Stay tuned.

12/8/2003 2:14 AM
bnwitt	Sergio, check out the "6L6's and new OT" post below and you will see the suggestion of replacing the 22uf cathode bypass caps on the three preamp triodes to change the sound of the 5E3. Your 10 watt resistor is mentioned as well. Scott reveals some good info on his amp which was modded by "Bruce Almighty" and I use that title with all respect as Bruce knows his tone!

12/8/2003 2:17 AM
bnwitt	Sergio, my mistake, the 4.7uf caps are mentioned in the thread "Anyone ever build a 5E3 plus" below which is also information from Bruce. Be sure to read both threads.

12/8/2003 3:04 PM

i switched out the 22mf to a 4.7mf bypass cap. the change is not terribly noticable, but it does this:

1. makes bass a little less farty
2. clears up that odd problem of high e string being very low in volume - so the balance of b and e strings is better.

it doesnt really change the character of the amp. i don't think you could even tell the mod was done unless you knew specifically what to look for. you can even experiment by using everything in between 4.7 and 22mf. there's a big range in there. i just stuck with the 4.7 since it didnt subtract at all from the tonal characteristics.

i don't know about changing 270 to 250. i would stick with the 270 though because you want to stick on the safe side for *hotter* tubes normally (instead of, like you say, the case where you'd put weaker tubes in).

the 10W instead of 5W is good. it's halfway towards the 6L6 adaptation if that'w where you want to go.

hope this helps

Aaron

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