Home Theater Forum and Systems banner

1 - 15 of 15 Posts

·
Registered
Joined
·
212 Posts
Discussion Starter #1
A pair of 8 ohm speakers, and a pair of 4 ohm speakers are wired in series.
What is the ohm load felt by the amplifier?

I know that two 8 ohm speakers in series would be 4 ohm.
 

·
Registered
Joined
·
1,849 Posts
A pair of 8 ohm speakers, and a pair of 4 ohm speakers are wired in series.
What is the ohm load felt by the amplifier?

I know that two 8 ohm speakers in series would be 4 ohm.
Two 8ohm speakers in series would be 16ohms but two 8ohm speakers in parallel would be 4ohms.
Two 4ohm speakers in series would be 8ohms but two 4ohm speakers in parallel would be 2ohms.
An 8ohm and a 4ohm speaker in series would be 12ohms but, in parallel, they would be 2.67ohms.
 

·
Registered
Joined
·
212 Posts
Discussion Starter #3
Two 8ohm speakers in series would be 16ohms but two 8ohm speakers in parallel would be 4ohms.
Two 4ohm speakers in series would be 8ohms but two 4ohm speakers in parallel would be 2ohms.
An 8ohm and a 4ohm speaker in series would be 12ohms but, in parallel, they would be 2.67ohms.
Thanks.
 

·
Registered
Joined
·
212 Posts
Discussion Starter #5
I have a spare set of very nice tower speakers, 8 ohms. My main L&R speakers in the theater are 4 ohms. I was just wondering if they could be connected so all 4 could be used. My amp is only rated for 4 ohm loads.
 

·
Registered
Joined
·
212 Posts
Discussion Starter #7
Okay, that’s not four wired in series, only two.

Question: Do you know the difference between series and parallel wiring? Because, if you connect the second speaker to the amplifier the same way the first one is, that’s parallel, and you’ll have a load lower than 4 ohms.

Wayne A. Pflughaupt
Yes, I was just trying to find a way to use these extra towers. The ohm load may not work. Don’t want to drop much below 4 ohms.
 

·
Super Moderator
Joined
·
9,186 Posts
Well, you have to wonder, if dual speaker pairs was a great idea, everyone would do it and it would be a pretty common thing.

There are a few potential problems.

For one, a series connection pretty much cuts amplifier power in half, which is then divided between the two speakers. So, an amp with 100 watts (per channel) at 8-ohms becomes a 50-watt amp at 16-ohms. That is divided between the two speakers, so they’re each only getting 25 watts. Power calculation is bit trickier in your case – you’d probably end up with 12 ohms per channel with both speakers in series, which would theoretically get you something like 75 watts per channel, again divided between the two speakers.

The other issue is that the sound from respective drivers will be arriving at your ear at different times. IOW, with the speakers side by side, the sound from the “outboard” speaker will reach your ears later than the inside speaker. The result is a phenomenon called comb-filtering. You can probably hear it as a difference in the soundstage, or even a strange timbre-shift as you move your head slightly left or right.

Still, experimenting never hurts. You aren’t going to blow anything up – the worst that can happen is that you don’t like it. But hey, maybe you will!

Regards,
Wayne A. Pflughaupt
 

·
Registered
Joined
·
212 Posts
Discussion Starter #11
Well, you have to wonder, if dual speaker pairs was a great idea, everyone would do it and it would be a pretty common thing.

There are a few potential problems.

For one, a series connection pretty much cuts amplifier power in half, which is then divided between the two speakers. So, an amp with 100 watts (per channel) at 8-ohms becomes a 50-watt amp at 16-ohms. That is divided between the two speakers, so they’re each only getting 25 watts. Power calculation is bit trickier in your case – you’d probably end up with 12 ohms per channel with both speakers in series, which would theoretically get you something like 75 watts per channel, again divided between the two speakers.

The other issue is that the sound from respective drivers will be arriving at your ear at different times. IOW, with the speakers side by side, the sound from the “outboard” speaker will reach your ears later than the inside speaker. The result is a phenomenon called comb-filtering. You can probably hear it as a difference in the soundstage, or even a strange timbre-shift as you move your head slightly left or right.

Still, experimenting never hurts. You aren’t going to blow anything up – the worst that can happen is that you don’t like it. But hey, maybe you will!

Regards,
Wayne A. Pflughaupt
Thanks for your input. I do have an amp that is stable into 2 ohm loads, so that is not an issue. My only goal in this "experiment" is to utilize another set of very nice tower speakers (VMPS), that I built from a kit (8 ohm). These would go next to my factory built VMPS towers (4 ohm).

The hope is to increase the soundstage a bit, and perhaps get audio out that may have a bit more overall impact. And...to be able to put the spare towers to good use.

On a side note, these are currently running paired up with a pair of BIC DV-84 towers in another room, creating a 4 ohm load. The DV-84's are much more sensitive, so the volume is a bit more pronounced. But the VMPS has greater bass extension, and this fills out the lower octave nicely.

The comb filter effect is not noticeable, but this is in a smaller sized room.
 

·
Registered
Joined
·
1,849 Posts
It'll work if you wire them in series, but not in parallel.
The problem with wiring different speaker systems in series is probably not a matter of impedance load but that each speaker with its particular complex impedance curve will act as a series filter for the other. The resulting sound quality is completely unpredictable.
 

·
Registered
Joined
·
819 Posts
The problem with wiring different speaker systems in series is probably not a matter of impedance load but that each speaker with its particular complex impedance curve will act as a series filter for the other. The resulting sound quality is completely unpredictable.
And the phase angle will be so grossly exagerated. Never wire speaker systems in series for two reasons.
 
1 - 15 of 15 Posts
Top