Audio

[Ohm1]

I'm sure Mr. T will be all over this one. Ok seeing that I'm no audio guru, what do you think about a set of speakers with each supplying these specs. also, what does all this mean:

speaker type:2-way coaxial-- in-ceiling
tweeter: Pivoting 1" silk dome
woofer: 6.5 Polypropylene Cone with rubber surround
Impedance: 8 ohms
Sensitivity 91dB 1W/1m
Frequency response: 36hz-20khz
Power: 100W

[jeffo]

Originally Posted by Ohm1

speaker type:2-way coaxial-- in-ceiling

The x-way designation means there are x drivers in each speaker. It doesn't mean that the sound goes 'x ways'. So a two-way speaker means there are two drivers, one woofer and one tweeter. Coaxial speakers have the two drivers so that the centre of the drivers are on the same axis. Think of it as having one driver, and then stacking another on top of it centred. Most floor or bookshelf speakers are not coaxial, but the nice thing for ceiling speakers is that it makes the exposed area smaller.

Originally Posted by Ohm1

tweeter: Pivoting 1" silk dome
woofer: 6.5 Polypropylene Cone with rubber surround

The tweeter is responsible for the high frequencies; woofer for low. High frequencies are more directional than low frequencies (the reason why subwoofers work), so by having pivoting tweeters, you can aim them to create a sweet spot in the listening area. A 6.5" driver will give decent low frequency response.

Originally Posted by Ohm1

Impedance: 8 ohms

The impedance of the combination of the two drivers. 8 ohms is pretty much the standard for most amplifiers, but some allow 4 ohm speakers. You can go higher but not lower, so you should be ok unless you plan to parallel speakers.

Originally Posted by Ohm1

Sensitivity 91dB 1W/1m
Frequency response: 36hz-20khz
Power: 100W

The sensitivity is a measure of how loud sound you get from the speaker with a unit of power input from the amplifier. To keep it simple, the higher the better.

Frequency response is the range of frequencies the speaker can reproduce. Most people can't hear much above ~19kHz, CDs have a top frequency of 22 kHz. Most subwoofers are 20-150Hz.

The power is tricky. Manufactures have been 'cheating' with the power rating of amplifiers and speakers for a while. A 100W speaker today, may be quieter than a 40W speaker from 20 years ago. Theoretically, you can supply 100W of power to a 100W speaker as long as the signal is not distorted. If clipping occurs, you can destroy 100W speakers by delivering 10W. Make sure the amplifier is capable of delivering at least 100W, if not, just don't turn it up into the distortion region.

All-in-all, I think these are pretty decent specs. Something to double check though is if back-boxes are available. Typically they make the low frequencies sound better, and keep the top side of the cone clean (from drywall dust, chips of wood, etc).

[suemarkp]

speaker type:2-way coaxial -- In-ceiling means a ceiling mount speaker (it has no enclosure) with two separate "speakers" or "drivers". One speaker can't do both low and high frequencies well, so you can split it across two (coaxial) or three (triaxial or coax+subwoofer) or four (triaxial + subwoofer). In this case it is 2.

tweeter: Pivoting 1" silk dome -- This is the second speaker. Tweeters are for the high frequencies and are rather small. Don't know what silk means.

woofer: 6.5 Polypropylene Cone with rubber surround -- this is the larger of the two speaker drivers and does the lower and mid freqencies. Cone material is polypropylene with the outer edge made of rubber. The larger this speaker is, the lower frequencies it can produce. A 6.5 isn't very large, but is common for a co-ax speaker. If you have a subwoofer (does real low frequencies), then this is about an ideal size for bass and midrange.

Impedance: 8 ohms -- This is the load presented to the amplifier. Most amplifiers will take a 4 ohm load. GO too low, and you'll burn up the amp. Too high, and you won't put out as much power as you could with a lower impedance.

Sensitivity 91dB 1W/1m -- This is how loud they are. Apply 1 watt of power, and the speaker will make a sound pressure of 91 dB at 1 meter. The bigger the number, the louder or more efficient the speaker is.

Frequency response: 36hz-20khz -- This is the range of frequencies the speaker can reproduce within a certain similar sound level. Usually, it is + or - 3 dB, but if the don't say it is easy to mislead. You can advertise a much wider frequency response if you allow + or - 10 dB of output to be the range you measure. I wouldn't expect a 6.5" driver to be too loud under 80 Hz.

Power: 100W -- This is the most amount of power you can apply to the speakers without burning them up. If it doesn't say, this may be a peak value. Usually it is an RMS level. Generally, look for an amplifier that makes 100W or less per channel and the speaker won't burn up.

[jeffo]

Originally Posted by suemarkp

Power: 100W -- This is the most amount of power you can apply to the speakers without burning them up. If it doesn't say, this may be a peak value. Usually it is an RMS level. Generally, look for an amplifier that makes 100W or less per channel and the speaker won't burn up.

I generally have to disagree with this. Infact, using an amplifier that has an output less than the speaker handling may damage a speaker!

If you have a 20W amp and a 100W speaker, and drive the 20W amp to its max, you'll clip the output signal. Amplifiers that are operating in the clipping range actually output DC (as opposed to AC) for the duration of the waveform that is clipped - Speakers are destroyed by DC!

[scuba_dave]

Some good info here
With adding the sunroom & enclosing front porch I'm now looking into wiring for speakers and other electrocnics while the walls are open
I'm just going with a "standard" stereo setup
The new great room will have the full entertainment center setup

[AllanJ]

When a speaker system is rated for so many watts, that should mean so many watts worth of reproducing sounds normally heard in nature or reproducing acoustically produced music. The high frequency content is a very small fraction of that and the tweeter is intended to handle just that small fraction. If an amplifier is driven to clipping, the overall high frequency content becomes a much larger fraction (even with the treble control all the way down) and will blow the tweeter when total power well under the speaker system's rating is applied.

If the speakers came loose and you have to build your own cabinet or in-wall baffle, hopefully the speakers came with instructions specifying dimensions. It's very tricky building a cabinet from scratch and getting a flat frequency response. The 6-1/2 inch woofers can give good response down to 50 Hz for background music, but for volume or extra bass you will need to add a subwoofer system.

[Mr T]

I agree, not too bad. As mentioned, if you are just running a standard 2 speaker stereo receiver you should be fine. If you are hooking these to a 70V system you may have some issues unless you use transformers.

Are they designed to be free air suspension (no enclosure. Otherwise I'd find out what size enclosure they need. If at anything make sure theres nothing above them in the ceiling that can fall into the cone and cause buzz sounds...

What is the purpose of this setup? Pa, background music, main music?

[Ohm1]

Outstanding info.! I plan to install them in my home just for basic sound, and understanding. I will be adding an automated system to run them--while incorporating RIM's, and VSC's. This is all geared towards getting a better understanding of what we plan to install in the field. starting with my home is idea!

Thanks for the schooling!

I will have more questions in time.

[Mr T]

Some more info...

paper is considered to be the best material for speaker cones, however it can be weak at times and does not hold up well against water, UV light (in cars), and whatever else is thrown at it....It is also lighweight.. Less weight means more efficient and less strain making sounds. Polypro is about the next best thing found. Plastic can "color" your sound a bit but at low frequencies its more or less undetectable.

The rubber surround is a good thing. Most surrounds are foam (and sometimes paper). The foam will dry rot over time and your speaker is trash or it needs the surround replaced. A rubber surround ina home enviroment probably wont go bad in the speaker's lifetime.

As for tweet's there are several types.. The cone tweeter (not really seen anymore, just looks like a normal speaker. There are horns which are used in PA"s.. They are very loud and VERY harsh sounding. There are film tweets which can be anything from piezo to some ultra expensive stuff. Then you get your domes.. THey are popular and dont create the harsh or tinny sounds that other types can... Silk is popular material due to it's weight. There is also different types of plastic tweet's out there too.

Being a 2 way system, the crossover (blocks low's from your tweeters) is already built in so theres nothing to worry about there..

Just curious, where are you gettin them from?

[CR500]

Unless you're just looking for something to make some noise and be louder than normal room conversation, LISTEN!!! to any audio component BEFORE you buy it. You will be unhappy purchasing based solely on specs.

Power, sensitivity, freq resp are all bunk unless you are supplied the complete information (peak, rms, peak to peak, +/- dB, Harmonic distortion, ....). Will you get 111 dB @100w at 1m re 20 microPascals as the spec's lead you to believe, with low distortion, without burning up the speaker, probably not. Would that be loud enough? The pressure will decrease at 20 Log (r) [2m = 6dB Loss]. Max required sound pressure level needs to be considered when looking at the total system.

If these are of an infinite baffle type design (open behind the woofer), low frequency response is hard to predict since the enclosure (wall cavity) will be a factor. Your room will also greatly affect the low frequency response due to standing waves.

My adivce on amplifiers is to always choose one that produces more power than required for the desired peak SPL. If its a cheap amplifier, get significantly more power since they typically have over-rated specs and low to no headroom. If the amp is underpowered and you are playing it loud it may "clip" (producing a DC output) which will burn out the tweeters in short order (many times instantaneously and faster than a fuse will react). If you have the bass turned up, it will clip even easier.

I have never damaged a speaker due to an amplifier having too much power. Well, ok, I've done it once when I was young and stupid and wanted to smoke the speaker for the fun of it.