I have a SE point to point wired tube amp and want to experiment with upgrading the stock caps in power supply. I'm clear on the UF specs and minimum voltage specs but a bit lost on what constitutes "beefier caps in power supply". There's tolerance (lower is better), UF, working voltage etc. but what specs should I be looking at to determine whether cap would be an improvement? I need 160uf 300v so realistically only looking at electrolytic?
There are several specs worth considering for a capacitor in a power supply, but ripple removal is the most important, IMHO. ESR can be important in the circuit itself, especially in digital circuits. UF is also important. However, high ripple ratings are the most desirable in power supplies. It's an indication of how well the capacitor can "absorb" the ripple current coming from the AC-to-DC conversion that takes place in the power supply. If the capacitor cannot handle as much ripple current as the power supply is producing, then some of that ripple will reach the load. In other words, the power supply will not be quiet and in the worst case, you will start hearing 120 Hz hum over the headphones.
There are other factors that cause this, to be sure. Also, ESR and ripple current ratings are closely related. Bottom line, choose a range of capacitor UF ratings (as high as will fit), make sure the voltage rating is adequate to survive the voltage present. NOTE: many transformers will produce quite a bit of over-voltage, depending on the load and transformer power rating. Be sure you have an adequate safety factor when establishing a voltage rating for a cap. For instance, a 24VAC power supply may easily produce 35VDC when rectified. I often use 50V rated caps in that case. Once the cap is positioned in an actual DC circuit farther down the line, it's OK to get a little closer with the voltage rating, but not in the power supply.
Anyway, after choosing the biggest uf's that will reasonable bit and have adequate voltage ratings, then look at the specific mfrs and model caps to determine the best ripple rating, etc.
Yes, only electrolytics are going to be available in the hundreds of uf ratings. You will also find your selections quite limited at 300V, so most of the discussion above will probably be moot. Better to just increase the uf's if they will fit and if you can afford them.
