Understanding amps and amps.

[braminator]

So Gene,
Based off what you are saying about electrical amps in your house can only handle 15amps at the wall.

How can Amplifier manufacturers say there amps can push x amount of amps if the wall sockert can not handle more then 15amps?

Such as the Music Fidelity A5cr.
Power 255 Watts per channel into 8 Ohms (24dBW),
416 Watts per channel into 4 Ohms
Voltage, RMS 45.2 Volts 20Hz to 20kHz
Voltage, Peak-to-peak 118.8 Volts
Current peak-to-peak 200 Amps
Damping factor 170
Output devices per channel 8

So does it come down to the power supplies and caps storing the amps as needed?

I am just looking to understand, not to cause me to be abused

 

[ehurnie]

Maybe I can help. The wall socket runs off 120V AC and the circuit can handle 15A. Power is equal to Volts*Current, so the Power=120V*15A=1800Watts for a wall circuit. Your amplifier takes the 120V AC and steps it down using the transformers. In the specs you gave it says max current is 200A. Lets say it draws max power of 1800watts. To do this it would be running off of Volts=Power/Current=9V at the time its running max current. When its running the max voltage of 45.2V it would be using Current=Power/Volt=40A. I believe that amp would require a 20A circuit though, you would need to know how much max power it draws. Hopefully this is clear enough, and a good enough explaination.

 

[PENG]

How can Amplifier manufacturers say there amps can push x amount of amps if the wall sockert can not handle more then 15amps?

Such as the Music Fidelity A5cr.
Power 255 Watts per channel into 8 Ohms (24dBW),
416 Watts per channel into 4 Ohms
Voltage, RMS 45.2 Volts 20Hz to 20kHz
Voltage, Peak-to-peak 118.8 Volts
Current peak-to-peak 200 Amps
Damping factor 170
Output devices per channel 8

So does it come down to the power supplies and caps storing the amps as needed?

I am just looking to understand, not to cause me to be abused

The problem is, Musical Fidelity specifies peak-to-peak numbers instead of just RMS numbers like most other manufacturers do.

FYI, Voltage, Peak-to-peak 118.8 Volts = 42 volts RMS
Current peak-to-peak 200 amps = 70.71 amps RMS or 35.35 amps RMS per channel. So you see, once you convert those numbers back to RMS, they suddenly shrink to numbers that look more familiar. Even then, I am sure that kind of current rating is specified on "instantaneous" basis, i.e. for very short duration, rather than continuous. That amps consume only 750 watts maximum into 8 ohms so it is not possible for it to deliver a total of 70.71 amps RMS on continuous basis.

A 120V 15A outlet can deliver 15A RMS at 120V (or 42.43 amp, 339.46 Volts peak-to-peak), so at 42V, it can deliver 42.85A. Now, current = Voltage/Impedance so at 42V RMS, if you speaker load drop to 2 ohms, current = 42/2=21 amps.

So, it seems to me a 120V 15A outlet is adequate for your Musical Fidelity amp, albeit a little marginal under those occasional peak demand conditions.

 

[braminator]

Thanks to all for the help in understanding.

 

[mtrycrafts]

Now, current = Voltage/Impedance so at 42V RMS, if you speaker load drop to 2 ohms, current = 42/2=21 amps.
.

If that amp can maintain that 42V at 2 ohm loads. I seriously doubt it I haven't seen an amp do this when David Rich measures the V at various loads and phase shifts to inductive or cap side.

 

[badabing]

If that amp can maintain that 42V at 2 ohm loads. I seriously doubt it I haven't seen an amp do this when David Rich measures the V at various loads and phase shifts to inductive or cap side.

Do you have data on this amp? How do you know it wont do this? Have you measured it? Didn't think so.

 

[Audioholics]

Do you have data on this amp? How do you know it wont do this? Have you measured it? Didn't think so.

Are you going to contribute anything to the forum? Do you have any real experience or measurements to your name? Do you have a purpose in being here? Didn't think so.

 

[PENG]

If that amp can maintain that 42V at 2 ohm loads. I seriously doubt it I haven't seen an amp do this when David Rich measures the V at various loads and phase shifts to inductive or cap side.

I agree with you. I was only trying to use an example to show him that even into a 2 ohm load, the amp would only deliver 21A per channel at its maximum output voltage. If we refer that 21A back to the 120V level, the current would be 7.35A. A 120V 15A outlet can still handle it.