4 ohm speaker set and a Yamaha RX-1800

[dewey]

Hi everyone I have a new 5.1 speaker set, all 4 ohms and an RX 1800 . I am hoping someone can help me out because I don't know if this reciever will support the load. I really don't understand the impedence of the speakers vs the watts per channel of the amp. I was told when I bought the speakers that the amp would drive them no problem because it is a high current amp.

Thanks for any insight.

 

[TLS Guy]

Hi everyone I have a new 5.1 speaker set, all 4 ohms and an RX 1800 . I am hoping someone can help me out because I don't know if this reciever will support the load. I really don't understand the impedence of the speakers vs the watts per channel of the amp. I was told when I bought the speakers that the amp would drive them no problem because it is a high current amp.

Thanks for any insight.

I looked up the specs and they are silent as to what impedance that device is stable into and will drive. I refuse to download Yamaha manuals as that gives them permission to spam me, and there is nothing I'm interested in from Yamaha. What does your manual say about speaker impedance?

 

[3db]

Hi everyone I have a new 5.1 speaker set, all 4 ohms and an RX 1800 . I am hoping someone can help me out because I don't know if this reciever will support the load. I really don't understand the impedence of the speakers vs the watts per channel of the amp. I was told when I bought the speakers that the amp would drive them no problem because it is a high current amp.

Thanks for any insight.

How big is your room and how loud do you want to go?

 

[fmw]

The answer is that, under normal conditions, you will be fine. The problem is that low impedance loads draw more current. If you reach the amplifier's limit in terms of current delivery then that is bad. The unit can overheat and distort the sound.

The truth is most receivers are way overpowered for filling a typical room in a home with sound. Most people only use a fraction of the power available. So, in most cases, the receiver would not reach its current delivery limit. If you play very loudly in a room this is significantly larger than you find in most homes, then you would want to have an amplifier that can deliver all the current necessary.

That isn't as definitive an answer as you wanted but just go back to the first sentence. The rest of it was simply to satisfy the sea lawyers that would add all this information after the fact anyway.

 

[Midcow2]

From your Manual 4 ohm support ..

Hi everyone I have a new 5.1 speaker set, all 4 ohms and an RX 1800 . I am hoping someone can help me out because I don't know if this reciever will support the load. I really don't understand the impedence of the speakers vs the watts per channel of the amp. I was told when I bought the speakers that the amp would drive them no problem because it is a high current amp.

Thanks for any insight.

I just downloaded and checked you manual. By the way anyone can download Yamaha manuals after a free registration with you name and email address.

Page 10 of quickstart says you can use 4 ohm speakers see page 117.

Page 117 says to set at 6 Ohm and front speakers can be 4 ohm and other speakers can be 6 ohm.

However, in reality you have a very substantial AVR in the Yamaha RX-V1800 rated at 130 RMS iinto 8 ohms.
And most AVR manuals are very conservative. When you switch to a setting other than 8 ohms , such as 6 ohms, basically you areputting na internal 2 ohm resistance in series with your circuit and you are reducing your effective power output. The purpose of the 6 ohm setting is not to enhance your HT system but more of a protection to your AVR.

Running at the 6 ohm setting should work, but your power will be reduced by 25% ( you probably won't notice it). Or you could run at 8 ohms and everything will work unless you turn up your AVR to max or very high volume settings.

Remember power = voltage * current = voltage ^2/ resistance

You need twice as much power (RMS) to run into a 4 ohm speaker as opposed to an 8 ohm speaker.

Using the max of 130 RMS = voltage^2 /resistance=8 ohms => voltage= 32 volts , current= 4 amps

Assuming current limitation ,running 4 ohms = max=22.8 volts then amps = 91 RMS still very good! So you could go up to 91/130 = 70% of maximum volume. At full -volume into 4 ohms you would get acurrent of 8 amperes and a total power requirement of 260RMS; trying to run this would trip the AVR protective circuitry.

 

[TLS Guy]

I just downloaded and checked you manual. By the way anyone can download Yamaha manuals after a free registration with you name and email address.

Page 10 of quickstart says you can use 4 ohm speakers see page 117.

Page 117 says to set at 6 Ohm and front speakers can be 4 ohm and other speakers can be 6 ohm.

However, in reality you have a very substantial AVR in the Yamaha RX-V1800 rated at 130 RMS iinto 8 ohms.
And most AVR manuals are very conservative. When you switch to a setting other than 8 ohms , such as 6 ohms, basically you areputting na internal 2 ohm resistance in series with your circuit and you are reducing your effective power output. The purpose of the 6 ohm setting is not to enhance your HT system but more of a protection to your AVR.

Running at the 6 ohm setting should work, but your power will be reduced by 25% ( you probably won't notice it). Or you could run at 8 ohms and everything will work unless you turn up your AVR to max or very high volume settings.

Remember power = voltage * current = voltage ^2/ resistance

You need twice as much power (RMS) to run into a 4 ohm speaker as opposed to an 8 ohm speaker.

Using the max of 130 RMS = voltage^2 /resistance=8 ohms => voltage= 32 volts , current= 4 amps

Assuming current limitation ,running 4 ohms = max=22.8 volts then amps = 91 RMS still very good! So you could go up to 91/130 = 70% of maximum volume. At full -volume into 4 ohms you would get acurrent of 8 amperes and a total power requirement of 260RMS; trying to run this would trip the AVR protective circuitry.

I know you can register free, however then I expect them to spam me like Pioneer do after registering on their site to help someone out.

Now I know that it needs reduction in voltage to even supply a six ohm load, then I know the amps in this receiver are current limited, as are most receiver amps.

A decent amp should be able to drive a four ohm load with twice the power of an 8 ohm load. A four ohm load by the way does not take twice the power, it needs more current. Power is the square of the current X the impedance.

However if an amp is current limited it can not provide the required current. So your amps into a four ohm load are in fact 67.5 watt amps and not 130 watts.

The next issue is that in almost all speakers the impedance varies greatly with frequency. Speaker impedance specs usually mean almost nothing. What you really want to know is the minimum impedance and the frequency at which that occurs. Better still speaker manufacturers should publish the impedance curve.

So if you push you receiver hard into those speakers, if they are truly 4 ohm or lower, then your receiver will get hotter than it should and have a shortened life.

This whole issue causes endless problems. If the receiver manufacturers would spend a little more on power supplies and output devices, instead of bells and whistles, we would all be better off.

 

[Audioholics]

DON'T set the switch to 6-ohms...

http://www.audioholics.com/buying-guides/how-to-shop/av-receivers-buying-guide (see bottom)
http://www.audioholics.com/education/frequently-asked-questions/connecting-4-ohm-speakers-to-an-8-ohm-receiver-or-amplifier

 

[Midcow2]

I agree completely !

DON'T set the switch to 6-ohms...

http://www.audioholics.com/buying-guides/how-to-shop/av-receivers-buying-guide (see bottom)
http://www.audioholics.com/education/frequently-asked-questions/connecting-4-ohm-speakers-to-an-8-ohm-receiver-or-amplifier

I agree completley Clint. Thats what I was trying to say when I said "And most AVR manuals are very conservative. When you switch to a setting other than 8 ohms , such as 6 ohms, basically you are putting an internal 2 ohm resistance in series with your circuit and you are reducing your effective power output. The purpose of the 6 ohm setting is not to enhance your HT system but more of a protection to your AVR."

 

[jcPanny]

Yamaha power

Dewey,
I have a lower end Yamaha and it was driving my 4 ohm Onix Ref speakers for a while without any problems. Your 1800 should not have any problems at reasonable volumes and with adequate ventelation.

If you find that your receiver gets really hot or goes into shutdown, then turn down the volume or add an amp.

 

[wire]

Dewey,
If you find that your receiver gets really hot or goes into shutdown, then turn down the volume or add an amp.

I like this , to add .
Take out the worry and just add the 2 channel amp now . Im sure you can find a Adcom , Carver , B&K or NAD power envelope ( Used ) cheap on E-bay or Audiogone .
That way the" What if " is gone and you don't hurt your reciever by over heating it .

 

[santeini]

Don,t worry

Your Yamaha should have no problem to drive the 4 ohms speaker.

 

[GlocksRock]

I agree, while I have a 1800, I use an separate amplifier to drive my speakers, and the unit still puts out a decent amount of heat. Just keep the unit well ventilated and you should have no issues. Yamaha receivers tend to run on the warm side regardless, so if you are running a low impedance speaker, it may not be a bad idea to use some sort of cooling method, such as adding a couple fans, just to help prolong the life of your gear.