Powering 6 speakers in office

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smac

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#242121 11-Oct-2018 19:08

I've inherited the task of sorting an office audio install. Yay.

6 x 50W 8ohm (or possibly 60W) ceiling speakers have been installed, and wired back to a central point. Keen for any ideas on the best way for piping music to them. This is for background office music, quality and volume are really not a priority (for me!).

At this stage I'm thinking the usual source will be a little Intel NUC PC (cause I found it in the cupboard).

Keen for any ideas on how to sort amplification and distribution. Am I best to go for a basic suitable amp and a speaker switch box? Or are there amps that would sort distribution to 6 speakers? Because this is background stuff stereo or speaker pairs is not really an issue.

I get that I will need to spend money, but budget has already been blown so I'll probably need to be tight....

Thanks heaps

richms

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#2106468 11-Oct-2018 19:38

You could series them up in 2 sets of 3 which will be 24 ohms so no chance of overloading an amplifier and then stick them on any amplifier that is moderatly powerfull, but they will all be at the same level.

Or do what I did for my outdoor speakers and get several cheap class D amps off aliexpress and just split the audio output across them with a headphone plug splitter. That will give each pair control from the volume knob on the amplifiers.

Richard rich.ms

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driller2000

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#2106476 11-Oct-2018 19:55

I reckon as per above given this use case ie. a cheap class D amp of the likes of Ali or Amazon eg. https://www.amazon.com/dp/B07BQC7GNL/?coliid=I8IW9D4J2XOF1&colid=1KPM0ZLCA29KW&psc=0&ref_=lv_ov_lig_dp_it

This one will also allow you to BT to it if you wanted to. (Note There are MANY of these sorts of amps to choose from...)

With the 6 speakers wired as 3 sets of stereo speakers.

PS: You could also test the proposed speaker wiring to see if it sounds OK to you with a home amp.

davidcole

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#2106486 11-Oct-2018 20:25

Why not just an old 7.1 or 6.1 amp? Then add a chromecast or something for streaming.

I run 6 speakers off a 6.1 Yamaha from about 2004.

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smac

333 posts

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#2106495 11-Oct-2018 20:47

So just so I understand the first couple of posts: you're talking about splitting the input signal from the PC just with Y connectors or similar, then a discrete amp for each pair?

For some weird reason I hadn't thought of a 6.1 or 7.1 amp. That would give volume control for each speaker, can they all output stereo as mono? Most music you wouldn't notice the difference, but now and again you get something making use of left/right....I wouldn't want any weirdness running some speakers as left and some as right.

richms

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#2106503 11-Oct-2018 20:57

Im yet to find a cheap 7.1 system that can do that, the best I have seen is using 2 of the channels as a zone 2 with its own volume control. By the time you are up the feature set to where it will have a powered zone 3 output you are way up in price and have a very large hot heavy thing that you will never use to its full potential.

I just use the amps off some 24v powerbricks I had, but people use them off old 18v laptop power bricks all the time, slight reduction in output power but probably not an issue for an office.

If you want to make it mono that would probably be best done on the PC playing audio, most media players have downmix options. Otherwise you could slightly abuse the audio outputs and just use a Y adapter backwards to combine it to mono, not ideal but the line outs on PCs are quite capable of doing that without issue.

Richard rich.ms

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#2106523 11-Oct-2018 21:44

Are you sure these celing speakers aint 100v line speakers?

Best to check one of them.... if they are you will need a 100v line amplifiyer....

edit: sorry...didnt see you actually said they were 8 Ohm. (I know some 100v line's are dual 100v and 8 ohm by way of selector switch).

Personally, 100v line speakers are best for your application. 'Even' distribution of power.

smac

333 posts

Ultimate Geek

#2106526 11-Oct-2018 22:04

Yah I realise 100v would be ideal(ish). Without seeing the physical install yet I'm pretty sure they're not. The boss just said "speakers in the ceiling" so the sparky stuck speakers in the ceiling. /thinking

When I said separate volume control from a surround amp, I wasn't thinking just twiddle the volume control. I was thinking adjusting output levels per speaker via a menu. ie. a one off set up......most would do that yeah?

davidcole

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#2106529 11-Oct-2018 22:09

Yeah a regular domestic 5/6/7.1 amp doesn’t generally have controllable volumes per zone. You can normally find a set of buttons to turn on or off sets of speakers. But it would assume you want a single volume control and you’d use the set up to set the levels initially.

It won’t be suitable if you want more fine grained control.

smac

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#2106533 11-Oct-2018 22:43

I think getting this up and running outweighs fine grain control. If somebody at a particular desk complains it's too quiet/loud I will adjust when I have time.....and they have to negotiate with their neighbour anyway...

Aredwood

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#2106539 11-Oct-2018 23:14

Since the amp that was linked above can handle 2 ohm loads, just wire the speakers in parallel (2 groups of 3). If you wire them in series, you will only get around 5W output per speaker. While in parallel, the limiting factor will be the power supply that comes with that amp. So you will get approx 15W per speaker, as well as a much higher peak level.

Those 100V line systems have their own issues. Things like transformer saturation frequencies. And the issue that the higher AC voltages means that only an electrician can work on such systems. Unless there is a special exemption for such systems.

richms

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#2106568 11-Oct-2018 23:56

2 ohms and those little class D amps seem to be hit and miss, I was briefly trying one on a small dual voicecoil sub in a box for the shed and it would shut down at moderate levels and was actually able to go louder just driving one of the coils. Really need to get a bigger one sometime.

Richard rich.ms