Need help with speaker setup (ohms)

[AnestisManiaaa]

Soooooo hello random stranger that you see this post ill get right into the point

 

Sooo i have an receiver that is capable of driving speakers with 6-16 ohms... soo ok... all good all fine 

 

next .. i have 2 huge speakers now that are rated 4-8 ohms

and im going to add 4 more bookshelf speakers that all of them are rated 6 ohms...

there is a chance that my receiver will suffer with this setup???

 

Thank you  (for your time) 

[Steinway]

If a single amp channel is rated at 6-16 ohms, one of your speakers rated at 4-8 will probably be OK.

But, if you add speakers to that amp channel, the impedance will drop, and when that happens it will increase the current draw and it may get to a point where the amp gets too hot and dies.

 

If the speakers you are adding will have their own channel, that's fine. If not, see above.

[AnestisManiaaa]

One more question then if the front speakers where 6 ohms and the other 4 speakers that i will add will also be 6 ohms we are fine right?>

[anothertom]

40 minutes ago, AnestisManiaaa said:

One more question then if the front speakers where 6 ohms and the other 4 speakers that i will add will also be 6 ohms we are fine right?>

No, _{well almost}. This all depends on 1) what amplifier you are using, and how many/what outputs it has and 2) how you intend to add them to your system. All due to the way impedance is calculated.

 

Assuming a single output from the amplifier:

 

If you are meaning speakers, then each cabinet will be rated so that it presents an 6 ohm load to the amp, using a single positive and negative terminal. If you intend to add a second speaker by running cable from the amp terminals to both speakers (or from the terminals of the first speaker) you have added a second 6 ohm load in parallel with the first load. For parallel circuits I_t=1/((1/I₁)+(1/I₂)...) which comes out at a 3 ohm load being presented to the amplifier, which is outside it's specification and will make it more prone to be damaged through use. To do this you will need to find an amplifier able to drive low impedances at a suitable power rating.

 

If you were, however to run from the positive of the amplfier to the first speaker, the negative of the first speaker to the positive of the second, and from the second negative back to the amp, then you have a series circuit of two 6 ohm loads, meaning a load of 12 ohms presented to the amp, which is within it's spec but will produce a lower volume at the same level compared to a single speaker. I'm unsure how going through the first crossover will affect the signal to the second speaker, i don't think it should have any effect a it is summed at the negative, but there will likely be some frequency colouring.

 

If you were to add two speakers to each side in series you get an 18 ohm load, which will not be driven properly by the amp; in parallel then you get a 2 ohm load, which will damage the amp quickly. Don't do this.

 

With Multiple Amplifier outputs:

 

If you have two outputs per channel from the amplifier, and they are driven separately (this is important, read the manual for details) then you can add a single speaker to each channel with no adverse affects. You won't be able to change the volume of the two outputs separately so you'll likely end up with one pair louder than the other (which will be more evident if they aren't identical models).

 

 

 

The ideal option is when you have multiple outputs per channel. If you've already bought four new speakers then replace the original speakers and add two, if you've not bought them yet, then only get two. if you've not got multiple outputs then you'll also want to look at upgrading the amplifier you're running them from.

 

 

Depending on what speakers these are (if they're a single full range driver or not), then you may be able to use them in series without any frequency colouring. Details, as ever, will provide the best advice

[AnestisManiaaa]

Thank you for your help Mr.anothertom and soo here is what you asked for... The speakers are 2 from a philips system (fb mz7 ph)

and 2 for a sony system (sony mhc-ec55)

All of them 6 ohms..

 

to an receiver (denon avc-a11sr)

 

What else do you need :D... thank you again

[anothertom]

36 minutes ago, AnestisManiaaa said:

to an receiver (denon avc-a11sr)

Do you intend to use the new speakers as surround speakers or just for a stereo signal?

What sources do you have connected and use?

[AnestisManiaaa]

14 hours ago, anothertom said:

Do you intend to use the new speakers as surround speakers or just for a stereo signal?

What sources do you have connected and use?

Probably surround.. i only use the front channel now

Edited March 9, 2017 by AnestisManiaaa

[AnestisManiaaa]

Or i might stop the sound bars and use 6 bookshelf speakers that are rated 6 ohms for surround and front channel

 

[anothertom]

On 09/03/2017 at 3:40 PM, AnestisManiaaa said:

Probably surround.. i only use the front channel now

For surround, simply connect them to the correct terminals. When you feed it from a surround source it should just work, you may be able to set it to duplicate the L & R signals when not in surround as your receiver is quite clever.