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FAQs - AC Current vs. Peak

One of the common questions and/or misconceptions many Home Theater and audiophile retailer-installers have relates to the matter of current draw. Here are answers to the most frequently asked questions.

If you do not see your question asked here, or would like to clarification, please contact us and we will do our best to answer your question.

 

Can a 15 amp rated power conditioner be used with a 20 amp dedicated AC line?

Absolutely!

The advantage of the 20 amp line is not just its capacity to withstand up to 20 amps RMS before its circuit breaker trips (typically in your electrical panel), but by necessity it has LOWER resistance thanks to wiring with more surface area. This is an advantage to power amplifiers, as they will always prefer a low impedance (low resistance) source.

However, very few audiophile systems and most small to moderate home theaters will never exceed 15 amps RMS. RMS stands for root mean squared, and it refers to a constant current load (not a fast current transient or peak). When an AC line or an AC power conditioner is rated for a given current input or output, the number refers to the maximum R.M.S. current draw that can be handled before the circuits breaker of fuse engages and disconnects the power source or shuts down the power conditioner.

If a 5amp, 10 amp, or 15amp power conditioner is used with a 20 amp dedicated AC line, all that will occur is that the power conditioners circuit breaker will trip when it’s maximum RMS current rating has been reached. This will in no way effect the AC line supplying the power conditioner.

Can a 20 amp rated power conditioner be used with a typical 15 amp AC line?

Yes!

Often a discriminating audiophile, videophile, or home theater enthusiast will wish to take advantage of superior filtering or other features that might be exclusive to a 20 amp rated AC power conditioner. In this instance there is a possibility of the homes AC panel circuit breaker tripping long before that of the power conditioner if the 15 amp rating is exceeded, but this is merely an inconvenience, and an unlikely occurrence unless the system draws in excess of 15 amps RMS.

I understand each of my power amplifiers require a 20 amp circuit, and that my power amplifiers can draw as much as 50 amps! Won't I have a problem with a 15 or 20 amp AC power conditioner shutting down?

It’s VERY unlikely

What the amplifier manufacture has failed to explain is that they are concerned with peak current draw, not RMS current draw. There are very few power amplifiers manufactured regardless of price or topology that will exceed 5 amps RMS at FULL VOLUME! Typically, it’s half that amount. An amplifier manufacture is concerned about very fast current peaks that rarely last more than 20 mS! As they are concerned with the effects of current compression, they will typically as for an over sized, over rated AC supply, because they know that a 20 amp circuit will have less resistance than a 15 amp circuit of the same length. This lowers the AC impedance, and allows the power amplifiers to perform better when high volume transients are reproduced by the amplifier. An even better way to reduce the AC source impedance and improve the performance of any power amplifier is Transient Power Factor technology.

Current compression occurs when a power amplifier attempts to draw power for fast transient signals that exceed the short term capabilities of the unit’s power supply. Because of the relative inefficiency of today’s loudspeaker designs, and an ever increasing quest for greater fidelity and frequency extension, many power amplifiers routinely drain the AC power tap from your service. The percentage of voltage drop is typically small and rarely sustained for more than fractions of a second. However, this distortion is quite audible, particularly in a premium system.

Often a discriminating audiophile, videophile, or home theater enthusiast will wish to take advantage of superior filtering or other features that might be exclusive to a 20 amp rated AC power conditioner. In this instance there is a possibility of the homes AC panel circuit breaker tripping long before that of the power conditioner if the 15 amp rating is exceeded, but this is merely an inconvenience, and an unlikely occurrence unless the system draws in excess of 15 amps RMS.

One of the reasons for the proliferation of after-market AC cords for Home Theater and Audiophiles is that any attempt to lower the resistance or impedance from Your AC service to the Power Amplifier will aid in reducing this unwanted compression. Unfortunately, many AC conditioners have filtering circuitry that can actually raise the incoming AC line impedance, and compromise system performance.

Not so with Furman’s Power Factor Technology. By creating a reactive shunt network of sufficient size and proper tuning, the capacitors and inductors utilized will not only provide the level of linear noise suppression required for transverse mode filtering, but the circuit can actually lower the line impedance. This provides a significant increase in fidelity because the amplifiers power supply can recover more efficiently.

 
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