Help me work out what speaker load can be plugged into "Mono" Mixer Amps

[dunkuk]

I thought I knew quite a lot about amplifiers but I am at loss as need to get a Mixer Amp (or possibly separate mixer and amp) to upgrade a small hall that will have 4x 8ohm speakers in it. 2 front 2 rear, used for school plays.

The mixer amps that come in at the right budget are things like the Behringer PMP550M and Peavey 150M. Both of these say they are mono and will put out the most power into 4ohms which makes sense. They have 2 speaker output sockets on the back, what is not clear is whether 2 sets of 4ohm speakers can be plugged in. (2pairs of 8ohm speakers in this case wired in parallel) If the internals of the amp are paralleled that would be a load of 2ohms. The Behringer website states "Dual Mono 2 x 250w"

I have attached a photo of the Behringer PMP550M as an example, the labelling is really confusing to me as it says 2x250w at 4ohms, 4ohm min load but then above the sockets it says "Parallel Speaker Outputs" Could it be that it has a Class D amp inside capable of a 2 ohm load?

The photo of the back of the Peavy is similar, photo of the rear of a Peavey amp, not quite the same one I am looking to buy but similar labelling. The Peavey instructions state "2ohm not recommended"

I'm thinking that I may have to get a stereo amp as at least I know then that I will be able to connect a 2x 4ohm speaker load to it. Maybe these amps are designed for use with 2 speakers only. I could connect the speakers in series but I will lose a lot of power.

 

[Wayne A. Pflughaupt]

I feel your pain. Behringer couldn’t have made things more confusing.

Our best clue is the manual, which shows a pair of B212XL speakers connected to the mixer. It’s an 8-ohm speaker.

They should have just labeled the back panel “Parallel Jacks, 4-ohm load minimum.” I see no indication that it’s a stereo amp; if it were, the individual channels would have a control to pan left or right.

In addition, “dual mono” mode for pro audio amps has typically meant a stereo amp that’s sending a single input signal to both output channels. Like a “y” cable for the input, but the “y” is accomplished internally.

Basically, the PMP550 is a mono amp rated for 4 ohms. As such, it’s not suitable for your needs.

Regards,
Wayne A. Pflughaupt

 

[Miley_B]

The Behringer website and information is full of contradictions, in the marketing material on the product page it states it has 2x 250w dual mono outputs, I think we can be sure it does not have 4 amplifier channels.

This unit looks to be a mono mixer connected to independent dual outputs capable of 250w at 4 ohm each, totalling 500w.
For comparison, the discontinued PMP530M is a mono mixer amp with a single mono amplifier output capable of 300w at 4 ohm, it also has two jack outputs but makes no mention anywhere of being dual mono.

Do you have a link for the Peavey? I haven't found any information on it.