Inverted Amplifiers

In the following thread you'll find several suggested methods for setting the phasing of subs relative to mains, which is what it sounds like you are trying to do:

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1258010309

Keep in mind that both possible settings are probably compromises to some degree, and are influenced by the physical positioning of the subs relative to the mains.

Regards,
-- Al

My RELs instructions indicate that this is best set by ear, in my case out of phase sounded better. The Sumiko site has their set up guide for subs which is simple and helpful.

You can tell that an amplifier is inverted if the feet are on top and the lettering on the front is upside down.

Thanks for the information on setting up subs. In my case the actual setting up is easier. The main modules (tweeters and mid-subs) bolt on to the subwoofer modules, so the problem of positioning subs is taken care of. And the manufacturer recommends values for most of the various subwoofer settings. The end user (me) only has to choose two settings: the volume of the subs, set by ear to complement the volume of the main modules (no problem for me), and the matter of deciding whether the main amplifier is inverting or non-inverting. The phase settings on the subwoofers have only two values: 180 (for non-inverting amps) and 0 (for inverting amps). So my question is most immediately about amplifiers rather than about subwoofers.

Any of the methods indicated in the thread I linked to, or that Stan referred to, will allow you to determine the correct setting of the 0/180 switch, without first determining if the amplifier inverts.

Alternatively, you could contact the amplifier manufacturer and ask them. And sometimes their literature or website pages will indicate inverting or non-inverting. If nothing is indicated, as Elizabeth said the chances are it is non-inverting.

If you have the wrong setting, the symptom will be very weak reproduction of bass frequencies that are in the region of the crossover frequency. Nothing will be harmed, though, if that is not clear.

However, unless the sub's literature indicates it is ok to do so, it might be best to avoid changing the setting of the 0/180 switch while power is on, to prevent the possibility of transient thumps that may occur as the switch is being changed.

Regards,
-- Al