Amp for 2 pairs of speakers with different impedance

[swraife]

I have come into possession of 2 celestion DL8 series speakers (8 ohms) and 2 Bose 151 outdoor speakers (4 ohms). The Bose are 40 watt and say they are compatible with amps 10-80 wpc. The Bose will be outdoor right outside of the room where the Celestions will be. I would like the option to listen to one pair, the other, or both simultaneously, preferably with differential volume control. I'd like to not spend a fortune on a receiver (<$200).

What receiver do you recommend to accomplish this? Looking at specs, I find it pretty confusing to determine how they handle multiple zones.

How do I need to wire it to ensure that I don't destroy my amp, but also have adequate power?

Thanks!

 

[DocG]

Hi, and welcome!

I think you want something that's hard to find. There's many receivers/integrated amps with A and B speaker outputs, also within your budget. The problem will be the impedance. To put it simplistically, the lower the impedance, the harder to drive (that is: the more current you need, so the bigger the transformer in the amp). And driving two pairs of speakers in parallel will further lower the impedance your amp sees...

In short: you'll need a very capable (relatively expensive) amplifier to drive these speakers together properly. For playing A or B separately, you won't run into trouble.

Alternative suggestion: look for a AV amp that has a 'zone 2' output (as often found on 7.1 or 7.2 amps). That way your speakers will have their own dedicated amps, which avoids the impedance issue.

As for dedicated volume control in both rooms, that's a whole different matter again...

 

[Thompsonuxb]

find an amp that has A and B speaker sets that you can switch and an impedance selector usually 4 or 8ohm.

Set the impedances to 4ohm you should be ok.

 

[andyjm]

You will struggle to find an amp in your price range that will allow different volume levels over two sets of speakers. To do that, the amp will need to have two separate stereo amplifiers inside, one for each set of speakers. Typically, amps with an A/B switch just switch one internal amp to either the A or B or both A and B connections on the back. Nothing wrong with that, but electrically no different to wiring both sets of speakers to the same speaker output - it won't allow you to adjust the volume separately.

As for impedance, if you put both speakers in parallel you will be presenting amp with a 2.7ohm load - which is a bit low (this would be the result of using the A/B connections on a cheap amp). You can connect the speakers in series, then the load will be 12ohms which will be fine (you can't do this using the A/B connections - you would have to do it yourself).

All other things being equal (and the rarely are) the speakers will be different volumes. In the case of the parallel arrangement, the 4ohm speakers wil be louder, in the case of the series arrangement, the 8 ohm speakers will be louder.