Which Pi filter is better?

[elipsey]

I have four filter caps and a Pi filter in my SE amp layout, so I can tie the first two caps together in parallel like this:


or I can have an extra RC stage like this:


Does it just come down to a trade off between ripple and output voltage?

Which way do you think is better?

[R.G.]

The answer is - it depends on what you're using the voltages (and the current that comes out of each node) for. There's no good answer without knowing that.

It's a bit like asking whether an apple is better than a baseball. You need to know whether you intend to eat it, hit it with a bat, or play catch with it. One may be better, worse, or the same depending on the intended use.

[elipsey]

The answer is - it depends on what you're using the voltages (and the current that comes out of each node) for. There's no good answer without knowing that.

It's a bit like asking whether an apple is better than a baseball. You need to know whether you intend to eat it, hit it with a bat, or play catch with it. One may be better, worse, or the same depending on the intended use.

Sorry, I should have labeled the nodes. Images are now updated.

[R.G.]

That's better, but now the question is more focused. What is eating current from B+? Single ended? Push-pull? Class A? Class AB? It does make a difference.

Class A needs all the "clean" it can get, push-pull tends to cancel ripple to some extent, more in Class A than Class AB.

[Dave H]

If it's for the 5F2 I'd use the second circuit but have the B+ (OT connection) from the right side of the choke, the screen where B+ is and the preamp where the screen is.

[elipsey]

Thank you. It's a single ended 6V6 amp, essentially a 5F2 with a 5F2A tone stack. The power transformer is 330-0-330. In the past I have prefered the tone that results from a plate voltage of between 350V and 375V in similar circuits. The amp will be used for recording, so it is important to minimize noise.

[R.G.]

I agree with Dave. For single ended, B+ from the right side of the choke, screen from the node labeled "B+" and preamp from the right hand side.

That is, if all you have is the shown cap values. You can increase the cap value right after the choke almost without limit. Stick a 47/450 across that cap after the choke.

[elipsey]

If it's for the 5F2 I'd use the second circuit but have the B+ (OT connection) from the right side of the choke, the screen where B+ is and the preamp where the screen is.

Thanks. I just realized that the 5F2 has a 10K (!!) screen resistor, which is what I would have if I did this. That seems really big... what's up with that? Do you think that contributes to it's darker sound?

(On further inspection the second schem I posted would have a 22k screen r., which seems stupid. Didn't really think this one through. <facepalm> )