The Big Electrical Hose Or Rolled Baloney?

[Tomorrow]

The closest I got to understanding electical matters was when my ancient high school science teacher related a garden hose to electrical processes in describing voltage, amperage, etc. So pardon my continued ignorance.

I have recently been told that with modern a/v amps it's high CURRENT that makes for the good ones...watts are relegated to secondary importance. Was I being hustled, or is this true? If it is true, why is wattage the principle mainstay of specs on receivers/amps?

 

[Sheep]

wrong forum

this thread belongs in the amp, pre/pro, receiver forum.


I'll try to answer with my limited knowledge.

They use watts as a mainstay for marketing purposes. High current amps have an easier time powering low effeiciency speakers. Watts are important, but the figures given for recivers is very, loose.

thats my 2 cents.

sheep

 

[snickelfritz]

Wattage figures are derived from current and voltage.
The number of "watts" and amp can deliver into an 8ohm resistor is secondary to the amount of current it can pass without damage or limiting.
Speakers with low impedance swings and steep phase angles within busy parts of the audio range can be difficult loads, and high-current amplifiers will drive them better at high levels.

 

[MDS]

It could just be that it has always been that way and thus manufacturers aren't about to change things now...but I think there is a logical reason for it.

We know V (voltage) = I (current) x R (resistance) and Power (watts) = V x I.

The V is known - amps are designed with a specific rail voltage. R is supposed to be constant for the equations but isn't entirely accurate for a speaker because it doesn't maintain a constant 'resistance' - it presents an impedance that varies with frequency. The amount of current that flows therefore varies depending on the value of R. They would have to present a chart that shows all the possible values of I (current) given all the possible values of R and that is way too much work.

Instead they assume a constant R (8 or 4 Ohms) and solve for the current that will flow given the maximum V the receiver can put out. That is often listed as maximum instantaneous current. Then you take that current and multiply by the voltage to get the maximum power in watts given that constant value of R. One single value that is much easier to compare than going thru all the calculations that are lost on most people anyway.

'High Current' receiver is a marketing buzz word because it means nothing without knowing the V and R (which varies).

 

[mtrycrafts]

The closest I got to understanding electical matters was when my ancient high school science teacher related a garden hose to electrical processes in describing voltage, amperage, etc. So pardon my continued ignorance.

I have recently been told that with modern a/v amps it's high CURRENT that makes for the good ones...watts are relegated to secondary importance. Was I being hustled, or is this true? If it is true, why is wattage the principle mainstay of specs on receivers/amps?

Yep, as MDS alludes to, 'high current' is a marketing buzz.

If an amp is really high current, it will be rated for RMS power into low impedance loads. If you don't see it rated RMAs into lower impedances, it ain't high current.

 

[snickelfritz]

"High current" amplifiers more closely follow the theoretical model of doubling their output with each halving of impedance.

I suppose one could loosely define any amplifier as being "high current" for marketing hype, but amps that truly provide high current output are expensive, usually have higher quality and more robust components, and will easily outperform cheaper low current models in terms of driving difficult loads at high levels.