Bi-amping and power supply elco's

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Normally for an amp the rule for power supply elco's is buy as much as your wallet allows you to, right?

But i was wondering if this 'rule' also holds for the amp that drives the high section. The amount of power that needs to be delivered is substantially lower, so my guess would be that the total capacity could also be lower.

Can somebody shed some light on this matter why I should or should not lower the amount of capacity in the high section.

Emiel
 
I think you get it right. But not all amplifier PS expects high capacitance. For some circuit, the capacitance may harm the transistor or create unwanted voltage on the bridge diode. For all amplifiers though, there is a point where capacitance addition will give no benefit.

It relatively doesn’t need high voltage or current to amplify high frequencies than to amplify lows. But, are you talking about bi-amping, Emiel? I think the amp specs should have been different from the beginning.
 
Well, since we expect to drive only higher frequencies we might choose an amp design with higher slewrate, Class A vs. AB, etc.

Since the output power is lower, certainly the max current and possibly the bias is lower, which means the power supply need not be as robust.

It all depends on the design, though. A 20W Class-A design might need a better supply than a 100W A/B, especially depending upon the impedances targeted.
 
Hi,

In addition to what the others have already said, it is usual to need a fairly hefty bank of reservoir caps to give plenty of 'wallop' at the lower frequencies, but it is also important to have a good smooth supply for the HF amp, as this will otherwise be more readily noticed as a harsher and less smooth sound at HF.

Therefore, even if you try to get way with less capacitance in the HF amp, good quality low ESR (at HF) caps are a good idea here.

Regards, :)
 
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