4 Ohms & 8 Ohms Simultaneously ??

Diamante

I know this might be a very simple question for most folks but I'm kind of new to this. My question is , Can I run a pair of 8 Ohm speakers at the same time with a pair of 4 Ohm speakers? Thank you.

This is the amp I'll be using:

• 1000 watts RMS @ 4 Ohms bridged mono
• 500 watts per channel RMS @ 4 Ohms
• 250 watts per channel RMS @ 8 Ohms
• 1/4-inch balanced XLR and RCA inputs
• Banana binding post
• 115V/230V switchable
• Left/Right level controls
• Ground lift
• Protected LED
• Peak LED
• Fan-cooled

This pair of speakers are 8 Ohms:

Frequency response
33Hz - 22kHz
Nominal impedance (in ohms)
8
Power handling
300W
Sensitivity
92 dB


This one pair of speakers that are 4 ohms:

Frequency response
30Hz - 22kHz
Nominal impedance (in ohms)
4
Power handling
450W
Sensitivity
92 dB

Necrosis

What size drivers in the speakers?

dj_stick

i wouldn't recommend it - if both pairs were 8ohms it's possible, as connecting them via parallel (the only way that would work) would effectively drop the overall impedence to 4 ohms, the lower limit of most amps

connecting these two sets would drop the impedence to about 1.33Ohms, which would overload the amp

Matth

The interesting point is that it can also work in bridged mono into 4 ohms, and driving in push-pull like that actually presents a load equivalent to 2 ohms per channel, as each channel drives one end of the 4 ohm load in the opposite polarity.

On the basis, it ought to be able to handle paralleled 4 and 8 ohm loads per channel - actually that's 2.66 ohms overall, subject to an overall drive level not exceeding 500W per channel.

rico01

There is absolutely no risk or problems running different ohm-rated speakers in a setup. Make special note of that the rated ohm for a particular speaker is always the general rating, but the actual rating will fluctuate widely depending on frequency. For example, the B&W CM7 speakers I use are rated at 8 ohm but will dip to 3 ohm on certain frequencies.

The size of the drivers doesn't mean a thing either.

As long as you are not clipping either the amp or the speakers by playing at insane volume levels everything should be fine and dandy. Having a powerful amp is better than a low power amp since it is the clipping which damage most speakers when the amp sends out an unclean signal due to power constrains, not the power itself.

dj_stick

if you have the speakers daisy-chained in parallel, you DO NOT want to use 4ohm speakers at all

most amps will overload if the impedence drops below 4ohms

rico01

If you are going to connect more than one speaker from a speaker output on an amplifier that is a completely different beast altogether than connecting different rated speakers in a multi-channel amp and setup.

It would help to know the model of the amplifier and wether you are thinking about connecting more than one speaker in an output. Concidering the rated power levels per channel it does sounds like a 2-channel amp and in that case I agree with Stick. However, in a 5.1 or more channels setup, it isn't a problem as long as you're not connecting more than one speaker to each output.

zathrus

Hi I didn't quite get your discussion and I wonder how it would apply to what I'm doing.

We're running a Behringer EP2500 stereo 2x1200 watt amp (rated at 4ohms, minimum imp 2ohm) and we MAY be running a combination of Alto Elvis 15's - 500watt peak at 4ohm, 350watt intended operating power
in line with 450 watt 8ohm Yorkville E15's.

I'm not sure whether the speakers have parallel or series connections on the back. Still looking for that info.

We intend to run 1 8ohm and 1 4ohm speaker on each channel - at this point.
My guess is series = 12 ohm... out of the question, and parallel = approx 3ohm - which is ok.

In addition to whether or not it CAN be done.... is the sound coming out of these speakers at 3ohm any different than normal operation or is the resistance just about electrical flow 'between speakers'..... ? (if that question makes sense)

Thanks.