System Stereo Speakers

System Stereo Speakers
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How do you find the Decibels (sound pressure) of a stereo system's speakers? here are the specs....?

How do you find the Decibels (sound pressure) of a stereo system's speakers? here are the specs.... i don't know if you will need all of the specs, but here they are anyways...

Volts 120V at 60Hz
80 watts per speaker, (2 speakers) =160 watts
speaker size each- (Height x width x depth) 13 X 9 X 7.8 inches

thanks for those who help!!! have a great day

The specs you've given are only about power handling. Look up the specification for Sensitivity, which should read something like, "89dB / 1 Watt at 1 meter" or "89dB / 2.83 Volts (= 1 Watt into 8 Ohms) at 1 meter." From the Sensitivity spec, we can calculate how loud a 50 Watt amplifier will play, for example.

On each page of speaker specifications on our website, you'll see a link to "specifications definitions." I've copied and pasted it for you:

It's easy to lose sight of the basics in a world filled with a lot of technical misinformation. Here's what you need to know about the basic specifications of speakers, regardless of manufacturer:

Response (frequency response) is a measure of how uniformly loud the speaker responds from bass to treble. Perfection is plus-or-minus zero, across the widest possible frequency band. Plus-or-minus one decibel is a tight tolerance — a barely audible deviation from perfection. There are many ways to measure response, most of which, unfortunately, include the sound of the room in which the speaker was measured. We measure using short bursts of tones which end before any room imposes its own signature.

Distortion comes in two forms, harmonic and intermodulation. Harmonic distortion is the addition of unwanted harmonics to the original tone. These are measured by a specialized meter which filters out the original signal, leaving only the harmonics behind. The perfection standard is zero. Intermodulation is what happens when one tone distorts another tone, such as the bass distorting the voice. Again, a special meter filters out these two original tones to read the remaining distortions, and a perfect reading is zero.

Phase shift is time delay imposed on any frequency, measured as a portion of any frequency’s 360-degree period. Perfection is zero degrees across the widest possible frequency band.

Rise time is the ‘get up and go.’ It’s how long it takes for a speaker to go from ‘no signal’ to ‘full signal.’ Perfection is zero seconds.

Polarity is an indicator of the speaker’s motion with respect to the amplifier’s signal. Normal polarity, the ideal, means that every driver moves outward into the room for a positive voltage from the amplifier. Inverted polarity means those drivers ‘suck’ inwards for a positive voltage. Imagine a trumpeter ‘sucking in’ on his horn, instead of blowing outwards through his instrument. That’s the difference between inverted and normal polarity. Hopefully, each of your stereo components was made with normal polarity. If one component has inverted polarity, you’ll then need to re-invert it by reversing the wires on each speaker, from plus-to-minus to minus-to-plus. This won’t hurt your equipment if left uncorrected, but normal polarity results in better sound.

Dispersion describes how widely the sound is scattered across the room. Omni-directional means equal loudness in all directions, and cardioid means directional. Our speakers’ bass intentionally goes everywhere because the room works with it. The opposite is true in the ultra-highs, which, at 10kHz, are directed to the front so they don’t reflect from the side walls. The challenge is to achieve a smooth transition between these two extremes.

Power is the recommended size of amplifier to be used with our loudspeakers. Amplifiers are rated into both 4-Ohms and 8-Ohms. We benchmark our recommended power ratings using an amplifier’s 8-Ohm rating.

Impedance is a measure of the speaker’s electrical resistance at each frequency. A perfect impedance would be the same Ohms at all frequencies, over the widest possible bandwidth. An extremely low deviation in impedance allows the most power from an amplifier at all frequencies and the use of long speaker wires.

Sensitivity is a measure of how much sound is output for a certain signal input. Lower decibels means more power is required. We could send a specific amount of wattage and measure the resulting loudness in decibels, but wattage depends upon whether the speaker is either 4-Ohms or 8-Ohms, or even 6-Ohms. This would make it hard to compare ratings among different speakers. Instead, a particular voltage is sent in, as measured by a volt meter on the speaker wires, and then the sound pressure is measured. It’s a better method because that voltage remains the same no matter which speaker is connected. It’s equivalent to leaving the amplifier’s volume control at the same level while connecting speakers. Our speakers are in the average range of 88-90dB for 2.83 Volts of signal sent by the amplifier, as measured by a microphone placed one meter away, at sea level. Why 2.83 Volts? That much voltage happens to give one Watt of power into an 8-Ohm speaker. It produces two Watts of power into 4-Ohms. Why one meter away? It’s an international standard developed for convenience. The distance is far enough to measure all drivers’ outputs yet not too far away as to pick up any room echo. Why sea level? Except for Death Valley, Calif., or a few other places around the world known to be below it, sea level is the point on our globe at which the air is the heaviest with air molecules, and therefore, the one place where the speaker will have to move the most of them. For example, since air is less dense with elevation, a speaker at our Colorado Springs factory location (elev. 6,300’) requires twice as much power than it would at sea level.

Max SPL (Maximum Sound Pressure Level) is the peak loudness a sound meter would show at 10’ (3m) away from the speakers in an average room. Anything greater than 100dB is ‘shouting loud.’ Room gain means ‘how much echo from the room’ is adding to that reading. The engineering goal is to no ‘room gain.’

Pair matching involves matching the left and right speakers to each other. Why? We match speakers for balanced sound from left to right. It’s important to be able to hear voices in their correct proportions to the bass and highs. If not well-matched, instruments won’t seem to be in their right positions and voices will seem to be off to one side or the other. There’ll be more voice in one speaker than the other, or more bass, or more highs. A perfect pair match means that the speakers sound identical to each other, resulting in the clearest sound and most musicality. To make a perfectly matched pair of speakers means that their loudness (amplitude) matches at each tone. The impedance must match so the amplifier puts out equal power to each speaker. For the impedance to match, crossover circuit parts must be held to very tight tolerances. Since we want the speakers to be 100 percent matched, perfection is a zero percent difference between these crossover parts.

You may also visit one of the Internet audio forums, such as Audiogon.com, for example, and ask your question there to receive information and guidance from audiophiles worldwide.

Hope this helps!

Roy Johnson, Designer, Green Mountain Audio
Colorado Springs, Colorado
greenmountainaudio.com