P.S idea

[noyan]

Hi All,

My idea is like as follow;
-In general, tube amplifier P.S. units contain a big electrolytic cap after choke trans. This electrolytic capacitor is connected in serial between OPT and tube anode. Sound flows from this cap. It is effected on the sound quality, especially on mids and highs. I thought that, if i use another small choke filter bobbine serial to this big electr. cap, then only low (Bass) freqs. can pass on these circuit. For the mids and highs, i can connect two different valued PIO caps as parallel to this circuit. Mid and high freqs. will pass easily with less distortion trough these PIO caps. Cap values on the drawing are only for example. Any comment?
Noyan

[fernando_g]

Unfortunately is not that simple.

For starters, a capacitor in series with an inductor forms a resonant circuit that will shunt the signal at the resonant frequency.
Additionally, all the other inductors and capacitors will also modify the overall frequency response.

If you have access to any sort of simulation software, please perform an AC simulation with the values you plan on using, and you'll be surprised at the oddball frequency plot.

Be sure to include equivalent series resistance of both the inductors and capacitors when you run the simulation.

[jnb]

Is the small choke and its capacitor meant to be tuned to the ripple frequency?

[noyan]

The second choke and it"s cap is not for the cancellation of ripple. Their job is to pass only lower freqs. for example below 1khz. Over 1khz, other two PIO caps will play role. Anyway, i am concern like fernando_g about the low pass filter it will work as i wish or not. I mean they will play role as band pass filter or low pass filter.
Noyan

[jnb]

I agree with fernando_g. I think your supply would improve if you remove the small choke.

You will have a low pass filter using the large choke and 680uF capacitor. The PIOs might improve the high frequencies.

[Eva]

The idea is terrible because it comes from a brain that thinks in terms of false audio metaphysics rather than true circuit physics.

If you want to play games with LCR networks and win, you have to learn the physics and the math related to these LCR systems (the real rules of the game).

[noyan]

If i remove small choke, then all spectrum of the sound will pass from these three caps. In this case, especially big elec. capacitor will try to pass trough the mids and highs then sound will be distorted.

[SY]

I think that what Eva was trying to say in his/her usual inimitable style was that you may have caused more problems than you've solved. You have a problem which is largely imaginary, and the means you have used to solve the nonexistent problem will almost certainly upset the dynamic stability of the supply. Run some simulations, and be sure to see what happens when you step the load current- I bet you'll see some astonishing ringing.

[analog_sa]

Originally posted by SY
You have a problem which is largely imaginary

You can tell this to ARC as well. They might even have a patent for this.

[SY]

Wouldn't be surprised.

There's a reason I don't copy much from ARC designs...