A Word About Power Ratings

We often get asked, “ Do I have a big enough amp to push XXXX speaker”. The following explanation is to help clarify some of the misconceptions about total output capability and power ratings.

DD Design Philosophy

Many of our speaker series, especially the 9500 class drivers, have exceptionally high power ratings. It is our continuing effort to push the material limits of the speaker parts and the assembly techniques to new performance levels. We strive to give our speakers the best chance to survive in the face of less than ideal circumstances. We attempt to overbuild the thermal and mechanical limits of the speaker to be well past the output capability. We do not compromise in our quest to build the highest quality product we can, we take pride in our efforts as we use the stuff in our cars too.

Our products are designed to extract the most potential output from a given system. Our speakers do not require the RMS rating to power them, but to the contrary they will most likely help the system produce close to its potential limits with the added benefit of future power upgrades. The design goals are to keep the moving mass as low as possible. This is the mass the voice coil and magnet system must drive to produce SPL. We keep the mass as low as possible while giving the magnet system as much drive energy as possible. The combination yields high efficiency, high power limits and good sound quality due to the fast attack capability.

We have used the method of calculating power ratings used in professional audio for long term usage. Peak power ratings differ depending on the type of install, quality of power supplied to the speaker and a host of other miniscule items that affect the performance of the speaker.

Power Required

A speaker’s total power rating should not be confused with the power required to drive the speaker. The output of a speaker is based on the sensitivity rating. Power from the amp goes into the speaker one watt at a time. This is the same for all amps and speakers. The SPL of a speaker starts at its sensitivity rating i.e., say 94 decibels at 1 watt of input power. When power is doubled, SPL goes up a theoretical 3 decibels, so 2 watts = 97dB, 4watts =100dB, etc, till roughly 1000 watts yields about a 30dB increase in SPL. The driver with a sensitivity of 94dB will yield about 124dB of output at 1000 watts. This is in an open environment and excludes boundary, box and transfer function gains inherent in vehicle interiors. Digital Designs speakers are designed for both high sensitivity and high power handling. The higher the sensitivity rating, the higher the amp/speaker combo could SPL. If a 300-watt amp is used, the speaker with a higher sensitivity will potentially yield the highest output regardless of its total power capability. There are many other factors that govern output capability, but total power handling is not a significant one and should not be the main criteria in the selection process.

Power Ratings

RMS power ratings represent the maximum continuous power input the speaker can handle. These ratings are largely dependent on the speaker’s ability to deal with heat buildup in the voice coil. When power is applied to the coil, some of it actually generates acoustic energy but most of the power generates heat. Coil temperatures can exceed 500 degrees F. The surface area of the coil is the first component of heat dissipation that lowers coil temperature. The more surface area the more thermal dissipation inherent to the coil. Again, this thermal capability is independent of its sensitivity rating. Music power represents the transient nature of the power fluctuations inherent in music. Lulls in the program material can provide cooling time for the speaker while crescendos; crashes and bass extravaganzas can send power levels through the roof. DD subs feature the FREE FLOW COOLING SYSTEM, which delivers cool air to both sides of the voice coil with each excursion cycle. This helps maintain a constant working temperature under continuous operation.

Clean Power

These ratings are based on clean, undistorted power. The signal from an amp being forced to deliver more power than its rating will begin to clip at the outputs and send a very bad kind of power to the speakers. Speakers do not like clipped power because it makes their coils get very hot. Coils that get very hot begin to get very burned. If the coils get very burned they tend to get shorted out, which can be very, very bad for the whole system. The moral of this story is that when the music starts to sound a bit fuzzy, slightly distorted, or incomprehensible, very, very bad things are about to happen. (Our amplifiers have available remotes that indicate when this bad power is being produced, right in front of you for your attention).

Built In Protection Circuit

There is a built in failsafe protection circuit controlling every audio system. Its what our parents questioned us all about repeatedly, Common Sense. Common sense says when you hook up a new system, spend some time learning its limitations, how loud can it get, how much bass EQ can I add, how hot is the speaker and amp getting, common sense stuff like that. Treat your stuff well and it will give you years of good service.
Common sense will save you lots of money. If your system isn't as loud as you really want it, don't push it over the edge. You'll just spend money getting it back working to that, "it isn't loud enough", condition. Plan your upgrades and spend money getting to the system you really want.