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EPI & Epicure Speakers:
A little about power ratings
The power ratings given in the product information files usually consist of two figures. The lower is the minimum amplifier power considered by the company to be adequate for good sound with that model, the higher figure is supposed to be the approximate maximum RMS power the speaker will handle without damage or distortion.
The earliest EPI speakers were rated incredibly conservatively. Essentially, each "module" of one woofer and one tweeter seems to have been allowed about 50 watts maximum. They will certainly handle a lot more. You can easily double the figures given for the speakers built in the 1970's to come up with valid maximum ratings. By the 1980's the specifications quoted were a bit more in line with reality.
Rather than "re-rate" all the speakers this might apply to, I maintain my policy of quoting original manufacturer provided specifications (where available). I have also added comments where I feel it appropriate stating whether those original figures are:
- "very conservative" - about half of what they can really handle.
- "conservative" - 60% to 80% of reality.
- "conservative but fair" - less than full capability, but about right for what the speaker is.
I hope this is reasonably clear to the reader investigating these speakers.
An important thing to remember is that these power ratings, like most specifications, tend to become rather competitive on the sales floor. I suppose we could call this "brochuremanship." If speaker 'A' says it will "handle" 200 watts and speaker 'B' says it is rated for 150 watts, it is easy to convince the customer that speaker 'A' is better. It could not only be a poorer sounding speaker though - in reality it might handle less power in a linear fashion.
Many modern speakers compromise their sound by incorporating small overcurrent protection devices. These are mainly to reduce the manufacturer's need to ship replacement parts to their customers, and secondarily to lessen the headaches for the customer involved in broken speakers. They do affect the sound, subtly I admit, but they are right in line with the speaker parts "doing stuff". When they are doing their job they tend to compress the louder sounds a bit, eventually clamping off almost all the signal if too much current is flowing through them. I think they tend to do a little of this when they shouldn't, too.
The result of this is that a speaker that can truly reproduce cleanly and linearly a 100 watt rms signal may be able to "survive", let's say, a 200 watt rms signal (although with poor sound quality) without breaking. Now the manufacturer will be tempted to rate the speaker for 200 watts rms, giving the impression that it is much "more" speaker for the money. Without naming names, I have seen this in practice.
So, one, the early EPI models are rated far below what they can actually do, and two, please take any power ratings with a grain of salt when you are reading them.
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