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user454569 , 01-05-2026, 06:22 PM

Hi, I want to use a 8 Ohm speaker by sourcing it with 0.5W, I calculated that the voltage and current through the speaker would require 0.25A RMS, and 0.35A Peak, and thus 0.7A Peak-Peak (see screenshot for calculation). So do I need to use a power supplycapable of delivering 0.7A? I am sure I am misunderstanding please help me, thank you!!

QDrives , 01-05-2026, 08:28 PM

How do you get the negative?
Positive peak is 0.35A and negative peak -0.35A.
RMS for the power supply. Peak for the capacitors? Or are the peaks to long for that?

user454569 , 01-05-2026, 08:38 PM

"How do you get the negative?" => I am planning on using a BLT Amplifier

So you say that when sizing the power supply I should only care about RMS current since th epeak current will be handled by the bypass capacitors of the amplifiler power pins right? Not sure to understand "Or are the peaks to long for that?"

QDrives , 01-05-2026, 10:52 PM

"*So you say that when sizing the power supply I should only care about RMS current since th epeak current will be handled by the bypass capacitors of the amplifiler power pins right? Not sure to understand "Or are the peaks to long for that?"*" -- I am asking you. If the peaks are long or the capacitance to low, your power supply should be able to provide the higher power.
For a 'bridged' amplifier, there is no need for the peak-peak power (current).

Sniper2 , 01-06-2026, 08:49 AM

just to be safe consider a 0.5A source

Sniper2 , 01-06-2026, 08:50 AM

since there are powere requirements all over the circuit + loses in circuits so 0.5A is like a safe amout

user454569 , 01-06-2026, 07:43 PM

I am new to audio electronics (and analog in general), I think I have to see it just like in a digital PDN design, the VRM will supply only the lowest frequency range of the spectrum, so I size the VRM for the RMS voltage and current that my amplifier/speaker will require.

Then the Peak Currents will be supplied by the nearby capacitors, and they may be big since I often see very bulky electrolytics capacitor on audio board

user454569 , 01-06-2026, 07:44 PM

Yes I was only looking at the audio part of the design right now, I am new to audio electronics and it seems that not so many people really know what they are doing in this field (talking about the "audiophiles")

Sniper2 , 01-07-2026, 07:39 AM

often those are the vibes ones