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I'm replacing the old filter capacitors on Marshall guitar amp and I was wondering if I should use low/non-low ESR caps for this.

As my understanding is (which is neither deep nor correct probably) that with higher frequency you should use lower ESR. So if I operate on 230V/50Hz system, that means low frequency thus high ESR capacitor would be preferable?

Here's the schematics: https://www.thetubestore.com/lib/thetubestore/schematics/Marshall/Marshall-Valvestate80-80W-8080-8100-8412-Schematic.pdf

More specifically two 2200uF 50V and two 1000uf 16V capacitors.

Thanks for any advice.

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  • \$\begingroup\$ It depends. Why can't you use the correct caps as specified by the manufacturer? \$\endgroup\$
    – Lundin
    Commented Nov 2, 2023 at 11:29
  • \$\begingroup\$ I'm guessing they're just general-purpose types. Replace with comparable ratings. There's a chance you can identify the type/family and find a datasheet or direct sub / cross-reference. \$\endgroup\$
    – Tim Williams
    Commented Nov 2, 2023 at 11:32
  • \$\begingroup\$ You must think the load is “high” frequency also. \$\endgroup\$
    – Michal Podmanický
    Commented Nov 2, 2023 at 12:35

1 Answer 1

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Those electrolytic capacitors are part of the AC power supply rather than the amp itself. Lower ESR is better, although it likely will not matter much. I would pick high quality, name brand capacitors regardless. Better than needed will not hurt if you are unsure.

In general lower ESR makes the capacitor better at filtering ripple in a low impedance circuit. It's not directly related to frequency.

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