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Any time you are suspicious of your filter caps, you can parallel them with new caps as an easy way to test them without having to remove them.

s2 wrote:Any time you are suspicious of your filter caps, you can parallel them with new caps as an easy way to test them without having to remove them.

...but be carefull with the maximun CAPACITANCE the rectifier tube can handle...

richon wrote:

s2 wrote:Any time you are suspicious of your filter caps, you can parallel them with new caps as an easy way to test them without having to remove them.

...but be carefull with the maximun CAPACITANCE the rectifier tube can handle...

Right. Of course. I thought that part was implied :)

s2 wrote:

richon wrote:

s2 wrote:Any time you are suspicious of your filter caps, you can parallel them with new caps as an easy way to test them without having to remove them.

...but be carefull with the maximun CAPACITANCE the rectifier tube can handle...

Right. Of course. I thought that part was implied

well... i had to say this... cuase a week before i didn't know that...

and maybe there are a lot of people readind this ..an learning a lot like me

PS: i'm going to buy the new "matched" power tubes to test Phil's idea.

Richon - I hope you get the easy fix by changing the power tubes, but I think your problems are more likely ground issues.

If you think about it there are many thousands of 5E3's working fine with the standard filtering arrangement.

Have a look at the file I posted in conger's 5E3 thread (How to Castrate a 5E3.pdf) at the bottom of page five - dont take it all as gospell but pick out some of the ideas on ground scheme. Also in there is a picture of the noise floor - you'll notice a spike at 60Hz (US of course), another slightly smaller at 120Hz, another at 180Hz and so on. I think what you are hearing in your amp is just the second spike (but at 100Hz) and because its frequency is higher you hear it more irrespective of its amplitude.

so yesterday i tested another "MATCHED" pair of 6V6GT.... and ...


NOT!!

so, it wasn't this....

i will keep testing everything... and maybe RE-DO it completly...

i know i have tested and looked at everything.... but i have to keep on testing.


thanks..... and i'll post news as they come.

richon wrote:i (sadly) don't have another type of rectifier tubo here.... and even in my city (for real)

so ... now refering to the resistor

i have 5W:
-2 X 270ohms
-1 x 390ohms
-2 x 150ohms... and every combination made by theres

shoudl i use... more than 500ohms or less than 500 ohms?

would a 1K/5W be to much?

If you want to continue to attack the filtering, I would go for the 390R. I normally don't go below 500R, because I've found to to be a very reliable way of increasing the filtration while isolating the PS nodes without limiting the current too much. But 390R could work just as well. Or you could use the 270s in series.

But I tend to agree with Strat on this one. I think it's your grounding. I have 2 5E3 type amps. One uses 16uF and the other uses 20uF. They are both dead silent. I've probably built and sold a dozen or so of these and have only had noise problems with one. It was a loose ground lug.

The trick for me was using a star ground instead of the method on Fender's layout. I used a power amp star and a preamp star. The first filter cap and center taps plus the 6V6 cathodes go to the power amp star. The other filter caps and all the preamp grounds go to the preamp star.

Pictures of one of those amps are here:

http://s2amps.phanfare.com/album/55996#imageID=2646166

If you look closely, there is a star on one of the transformer bolts and another underneath the pilot lamp.

It would really help us if you could post a series of detailed photos. You'd be surprised how often members of the forum can diagnose an amp just from photos.

richon wrote:but now i can't change the cap to a higher value ('cause the 5Y3Gt wouldn't allow it) and the ripple is still too high...

i allready changed and tested another rectifier tube (of a fine working 5E3 i have builded before) and there was no difference in the ripple values

what can i do???

(i don't want to get rid of the PT and the 5Y3GT to diode rectification so i can't a quieter amp)

Regarding the value of filter cap that a 5Y3 can handle, both of the 5Y3 amps I have (A silverface Fender Champ and a multitude of Hammond AO-35 based units) use a 40uF cap in the first position. The schematic for the Champ specifies 20uF, but a 40uF unit was installed at the factory. The schematic for the AO-35 specifies 40uF and most of them that I've seen still had their 40+ year-old Hammond-labeled 5Y3GT rectifier tubes.

Cheers,

-Dana