amplifier needs

Almarg,
What do you think then would be a good amp for this application so that there would not be a question?

Hi Markus,

Let us know the make and model of the speakers (and any technical parameters that you can readily provide, e.g., rated impedance, efficiency, power handling, etc.) and we could make better informed recommendations.

I did find these specs on the G-9000DB (don't know what the "DB" means, but I would suspect that it doesn't mean anything significant as far as power output and load impedance are concerned). They indicate 160W into either 4 or 8 ohms. But of course many "8 ohm" speakers are really less than that at many frequencies, which would mean that two of them in parallel would drop below 4 ohms, as Rodman pointed out. I would feel comfortable if the combined impedance dropped SLIGHTLY below 4 ohms at some frequencies, given that the receiver is rated for 4 ohm operation. But I would not feel comfortable, for example, if the speakers were nominally rated at 6 ohms, meaning that their parallel combination would be nominally 3 ohms, and would drop down lower than that at some frequencies.

http://www.sansui.us/SM-G9000DB.htm

Regards,
-- Al

The oudoor speakers I am using are Presidian and they are rated at nominal 8 ohms. I'm really concerned that I don't harm this old classic amp. 2 speakers in the screened room area and 2 in the pool area. At an impass as to how to wire them. In series might be good but sound quality may suffer. I really appreciate your time and trouble here guys, thanks a bunch.

Markus -- I couldn't find an impedance vs. frequency curve on those speakers. I did find this descriptive information, which might be of interest:

http://www.audiokarma.org/forums/showthread.php?t=70808

The fact that the low frequency driver has no crossover elements in series with it lessens my confidence that its impedance does not drop below significantly below 8 ohms over a significant part of the spectrum. So I would not hook them up in parallel to the G-9000.

If all four speakers are the same Presidian model you could try wiring them in series, and see how you like the sound. The main sonic consequence of the series connection, given that the speakers are identical, would be to bass damping, but they probably don't have much bass response anyway. Also, the maximum power available to each speaker would be reduced substantially, perhaps to 25% of the amplifier's capability (the nominal 160 watts reduced to 40 watts), because each speaker would see only half of the voltage being put out by the amplifier at any given instant.

Alternatively you could add a second amp as Bob has suggested, or else purchase an amp known to be able to drive low impedance loads. The older Adcom models (GFA-535, GFA-545, GFA-555, GFA-565 etc.) would do fine, and are not expensive. Also, probably any amp that can be strapped for use as a monoblock would do well, because a bridged mono amp sees a load equal to one-half of the speaker's impedance, and therefore presumably is designed to drive low impedances. Bridgeable amplifiers usually specify that nominally 8 ohm speakers should be used in bridged mode, as opposed to nominally 4 ohm speakers, btw.

Hope that helps,
-- Al