Amp with multiple stereo speaker outputs

[hazymat]

Hi

I'm here on this forum because I can't seem to find what I'm looking for in an amplifier out there on the market.

My requirement is simple but I guess it's quite rare.

End goal: to power 3+ rooms of stereo speakers simultaneously from a single line input
- reasonably cheaply
- using compact gear (I.e. boxes that could be mounted on a wall inside cupboard: not hi-fi size)
- ideally a separate volume control for each room, needn't be remote (ie 3 controls next to each other, one on each amp, is fine)
- low power- I don't listen to pumping music at high volumes, perhaps 20w at 4ohm. Haven't even chosen speakers yet.

Option 1: use 3x stereo 'T Amps' from eBay, each with its own input and volume knob. Somehow mix single line input into 3 (or more) line outputs to drive these amps from my single source.

It may be possible to buy such a distribution amp to mix the line signals but would prefer to make one.

Option 2: make my own compact amp with one line input and 3 stereo speaker outputs.

My limitations are really my own expertise, time, equipment etc. My background in electronics is reasonably strong I guess (school - A Level electronics) but I don't have any PCB making equipment myself.

My question is: what would the board recommend? Is a line level distribution amp relatively easy to make? Would I be better off taking apart an existing 't amp' or buying a kit?

Obviously option 2 is a bit nicer, because the end result is one box. But really I'm happy with anything that gives me the end result.

Any comments you can give me at the decision stage would be really helpful, thanks!

Mat

[djoffe]

If you're really just looking for background levels on 3 rooms, this might be an option.

assume 8 ohm speakers for now, and that any amp could reasonably drive 4 ohm speakers.

If you put a 4 Ohm resistor in series with each of the 8 Ohm speakers, the composite load would be 12/3=4 Ohms, and you'd be ok. You can play with the assumptions a bit.

Of course, that large an impedance would change the bass of the speaker, as the damping factor would be rather low, but in a bkgnd application, it might not matter so much.

Now, you need only the variable volume...an L-pad for each speaker should do the trick.

Of course, multiple small custom amps would be cool, but this might be an ok option.

[Bigun]

I suspect it's probably simplest to have one location for the power amp(s) and have it near the source, then run some 16 swg speaker wiring around the house from there. That way you don't have to worry about the size of the boxes in each room.

Option 2 is really Option 1 with everything in a single box, either way it's probably better to have 3 independently controllable amps if you need separate vol. control for each stereo pair.

If you build an amp, and I think you'd be quite capable by the sound of it, you will run the risk of becoming a DIY Audio addict :-) and it will take a few weeks. But if you can get some small amps off fleabay you would at least be able to set up your system and find out if what you think you want is actually the solution you really want. Then go from there.

Option 3. go buy 3 pairs of inexpensive active PC desktop speakers. The amps are built in.

e.g. http://www.currys.co.uk/gbuk/sandstr...64017-pdt.html

[hazymat]

Thanks for the responses!

I think to start with I might get one of these fleabay amps from HK / China and have a play. e.g. NEW TA-2020 T-Amp Mini Home Audio Amplifier + 5A Power | eBay UK

From a power consumption point of view, I can't help thinking it would be nice to combine the PSUs for all 3 amps. Maybe I could pull the electronics out of the 3 amps and put them into one box.

In that case, my question remains: how do I go about combining 3+ line level audio signals into one? Can this be done passively? Or do I need to make / buy something powered to do the job?

Thanks for the warning about the slippery slope to being a DIY Audio addict. I feel it coming on... :-)

[hazymat]

Wait...

Can I just use a (home made) cable splitter to split my stereo RCA into 3 (or 4), to power the amps separately?

Line level is high impedance, right? I don't need to worry about buying an audio distribution amp, right?

[crazifunguy]

Just my input...3 small chip amps would be very small and suit your needs easily. The small size and low power requirement matches perfectly. Plus they sound really good. 1 power supply for all 3 amps. Inputs could all be linked with 3 seperate outputs.

[Bigun]

Originally Posted by hazymat

Wait...

Can I just use a (home made) cable splitter to split my stereo RCA into 3 (or 4), to power the amps separately?

Yes.

[hazymat]

Originally Posted by Bigun

Yes.

And it wouldn't noticeably degrade the quality of the audio (i.e. frequency response)?

... one word answers good :-)