bathroom loudspeakers

[noel]

Hello everyone,

This has to do more with sound engineering than electricals. I wish to play music from the same source through 16 water resistant ceiling mounted speakers in 16 different bathrooms in a hotel. The emphasis here is on very quiet crisp clear music with emphasis only on treble/tweeters. I have found some water resistant ceiling speakers on the internet. What is the difference between full range speakers and two way speakers? Do you think I need an amplifyer? Also am I going to jumble/merge all the speaker cables together at the back of the music set or amp?

Thanks
Freddie

 

[plugwash]

afaict a full range speaker (tries to) cover the whole range with one speaker unit whereas a two way speaker has two units with a crossover cuircuit

generally you should try and present an impedence of 4 or 8 ohms to the outputs of your amplifier

a normal hi-fi amplifier should be fine

your amplifier will probablly have two channels: left and right

if your speakers are 8 ohm i would put them in series groups of two and put four groups on each channel of the amplifier

if your speakers are 4 ohm i would put them in series groups of 4 and put 2 on each channel of the amplifier

its probablly best to bring individual cables from each speaker to some form of connection box (terminal block behind a blanking plate would be fine for this) so you can reconfigure the speaker setup if you need to then run a pair of cables from here to the amplifiers outputs

 

[breezer]

Plugwash, I am sorry but i have to dissagree about the wiring / connection of the speakers to the amp ( I agree with the 2 way and cross over)

There are 16 bathrooms To put 16 4 ohm speakers on a domestic amplifier (8 / channel, total 16) will do its output no good, and may indeed overload /destroy the amp.

Things also to be considered
Cable run from amp to furthest speaker
size of that cable
loading on amp

I would suggest that you use 100v line fed speakers and a suitable amp.

I shall expalin (plain english), 100v line, "does what it says on the tin" the special amp has an out put of 100v, each speaker has a 100v transformer to reduce the voltage.

This is "system" is used because it overcomes many problems, such as length of cable run, total speaker loading.

Alothough it is good, it is not cheap (Just seen an amp for £250) That is amp, no microphone, sound scource etc

also each speaker should have its own volume control (ideally) these are avaialble sepratley, but add more to the price.

Also as this will be on a hotel (commercial prorperty) Noel (poster) are you insured / qualified to do this job? (sorry i have to ask)

you should also bear in mind this is a diy forum, and you have posted in electrics outside UK, if the job reallly is out side the UK i suggest you check to see if you are allowed to do it.

 

[plugwash]

Plugwash, I am sorry but i have to dissagree about the wiring / connection of the speakers to the amp

wih 4 ohm speakers
4 speakers in series-16ohms
two of those series strings placed in paralell-8 ohms

the amplifier should have no problem driving an 8 ohm load

 

[breezer]

in theory yes, but it is a commercial premises (hotel) and it is always best to use the right kit for the right job. also as you said "should" it may be the amp can not work, but hey its not our decision

 

[PaulAH]

There's a lot of cr*p talked about loudspeaker impedence. The impedence (resistance to alternating current) varies greatly with the frequency of the signal applied and the natural resonant frequency of the cone.

A speaker's impedance (typically 8 ohms) is a nominal figure usually determined by its resistance at 1kHz. Higher frequencies are presented with much higher impedence, as you'd expect when fast AC is applied to a coil. But it can dip significantly below this at other points in the spectrum.

The questioner states that he only wants the high end of the sound spectrum reproduced, and that it would be for background music from the ceiling. In these conditions the power consumption would be at most a couple of watts, even with 16 speakers.

Plugwash is correct in his series/parallel calcuations but it's all rather theoretical where sound levels are low and bass is suppressed. Using his configuration, small speakers and the bass equalized out, I can't see that any harm would come to amplifier, speakers or hotel.

What it does to the guests' ears is another matter altogether. I certainly won't be staying there.

 

[TexMex]

Putting speakers in series would give no independant adjustment of individual speakers in the group. Even if you could decide what volume you wanted, not all speakers with the same impedance give the same volume output. Even identical speakers from the same manufacturer, vary in efficiency from speaker to speaker. You also have to bear in mind that some guests will want to have their volume louder (or quieter) than others.

IMHO The 100v line system would be the only way to go, as it would give the independant gain control to each room.

 

[Paul_C]

Just to add that if this really is outside the U.K., then in some countries the standard is a 70V line rather than 100V. You'll find some public address amplifiers which provide an output for both systems.