Ceiling speakers

[David WE Roberts]

Looking for some ceiling speakers for the new kitchen area. I plan to use a T amp something like

suits 4 ohm speakers with which it has a max power output of 20W RMS (so 10W RMS with 8 ohm speakers?).

After going to HiFi stores and seeing speakers at £100 each (not a pair) and looking at car speakers which are much more affordable but are generally marked with 'max power 200W minimum power 35W' or such like I went to TLC where the prices are much more reasonable.

However I am now looking at this speaker and don't understand a lot of the features

"All metal, flush fit grilles fitted with quality speaker and 100V line transformer.

Size - 6.5" Woofer - 160mmØ (6.5"Ø) Frequency response - 165Hz - 20kHz Power rms: 8 ohms - 40W Power rms: 100V line - 8W Cutout - 166mmØ Mounting depth - 60mm SPL @1W/1m - 85dB Tappings - 2, 4, 8W & 8 ohms Dimensions - 68 x 200mmØ Weight - 760g"

The bits I don't understand are the 'tappings' and the '100V line transformer'.

The attraction of this speaker is that it will fit in a ceiling box

may help with issues such as crap falling on the back of the speaker and the noise reflecting upwards.

These seem to be specialist speakers to fit in industrial areas where fire protection is needed, so you may lose some sound quality. However I can't even tell if they are suitable.

Any help much appreciated.

Oh, and I've checked out some mini systems in the £60-£100 range and they generally seem to have 4 ohm speakers and a maximum output of around 10W RMS so I think that the system I am proposing will have enough grunt for the location.

Cheers

Dave R

[Andy Burns]

100v line is a system used by public address systems where all speakers are wired in parallel to a speaker bus and have built-in step down transformers, in short it's not suitable for use with a "normal" amp.

[Dave Liquorice]

Well what you say is true but the spec quoted also has:

Power rms: 8 ohms - 40W

So I, as I would expect, the 100v line transformer is not "built in" but wired seperately. So Mr Roberts could connect his normal amp direct to the speaker. Yep looking at the images the transformer is seperate.

Though also in the spec:

Frequency response - 165Hz - 20kHz

Will be a lacking in bass, OK in a kitchen maybe you don't want thumping bass but male voices will sound a bit emasculated. Some of the other speakers on the TLC site look a better sounding choice but note the word "look" when refering to something you listen to. B-)

They are also more effcient (more dB at 1W/1m) than the one specified. 10 to 20W per channel should be ample for "Radio 4 at breakfast" listening.

Also the comment about the fire dome keeping crap off the back of the speaker is a good one and as this is a kitchen a fire dome is probably a good idea. I'm sort of surprised that the others don't have that option as well.

[Dave Plowman (News)]

On the different ones I bought from TLC, the 100 volt line transformer could easily be removed (or just disconnected) and the speaker treated as normal.

100 volt line is used with a special amplifier and very long cable runs with multiple speakers - like say in a railway station. But generally, the speakers them selves are just the same as direct drive - but with a transformer added.

[Percy]

On Mon, 19 Nov 2012, "Dave Plowman (News)" writ:

If you look closely at the picture on the OP's link, it shows the speaker terminals wired to a separate line transformer as you suggest.

[Owain]

You would just ignore/disconnect the transformer and connect directly to the 8 ohm speaker terminals.

However the 100V line would be very useful if you want to extend to multiple speakers around the house, garden, or neighbourhood.

Owain

[Dave Plowman (News)]

A decent quality 100v line amp isn't cheap.

[meow2222]

approx, yes

ceiling speakers shouldnt cost anything like that

not a problem

=20

You wont use the 100v line transformer for domestic use. But that and the l= ousy frequency response are a clear indicators that this is going to be a P= A speaker, don't kid yourself it'll be any sort of 'fi.'

r=20

A pillowcase over the top does the same job, preferably one from a feather = pillow.

some, ha

if you like the sound of pocket radios with 2" speakers, sure

Ceiling speakers are pretty much always no-fi. If you want something that a= t least tries to be ok, I'd get a pair of used bookshelf hifi speakers and = fit them into the ceiling.

An easier option is a 3 speaker system where the 2 on show are very small, = and dont need building in anywhere. You can get these as active computer sp= eaker setups.

NT

[Owain]

Still better for listening to Magic in the garden than DAB, though.

Owain

[Dave Plowman (News)]

A ceiling gives you a (near) infinite baffle, and assuming the drivers are optimised for that won't sound at all bad. No cabinet resonances to cope with. And much easier to fit than using a bookshelf speaker. Car speakers are designed to be mounted like this - a decent pair might be the best solution, assuming your amp can drive them.

[meow2222]

In the real world you get a weak plasterboard baffle that moves all over the place. If you're going to take that approach, stiffen the PB up all you can.

NT

[Dave Plowman (News)]

I have got them in the real world. 8" speakers in a normal plasterboard ceiling (bathroom and separate toilet). They sound just fine - especially considering the cost.

[Grimly Curmudgeon]

I've never tried this, but I suppose simply connecting the transformer in reverse to the output of an amp would likely blow the shit out of the amp. Like a diy amp/trans/wire/trans/spkr

[meow2222]

neighbourhood yes, house no unless you've got a mansion, in which case its better to use active speakers run off an ordinary amp.

1m of 1mm^2 cable gets you 44 milliohms, so 180m of 1mm^2 loses 50% efficiency, or 360m of 2mm^2. A pretty big house.

Its how they all work.

NT

[Owain]

Not necessarily. It's not uncommon for separate transformers to be used to convert 8 ohm amps into 100V ones if needed, or to provide transformer isolated 100V outputs where the amp drives the 100V output directly.

think the main caveat is if the amp has a significant DC output on its speaker terminals it can saturate the transformer.

Owain

[Dave Plowman (News)]

I'd have thought the design considerations of an output stage quite different for 100v line versus low impedance? Even where an output transformer is used?

[Owain]

Depends on the amp power - once you get towards the kilowatt 100V *is* low impedance :-)

Owain

[The Natural Philosopher]

not necessarily.

Used to do that in PA work on some installations. The amps were normal ones with a special output transformer added.

biggest danger was DC offset on the amp output.

[The Natural Philosopher]

Not really. Yes you COULD make it look like a valve amp circuit wise but its easier to take a stock amp and stick the transformer on it,.

Remember you cant get PNP valves, as it were..or valve amps would be deigned different.

[meow2222]

Some valve 100v line amps had spark gaps, so I don't know if its worth adding a couple of protection diodes to each supply rail.

NT