Receiver and 4 ohm speakers?

A lot depends on the speakers efficiency and listening levels.

It's not designed for that.

It may work just fine.

You may want to manually set all speakers to small. It can only be worse if your speakers are large, and the receiver has problems driving all those 4 ohm speakers.

You may want to listen at reasonable volumes as well. Seems prudent to me to not push the limits.

If you push the thing hard, bad things could happen. Receiver could shut down. In the worst case scenario, it could fail (not saying that's likely, but I maintain that the receiver is not designed for 4 ohm loads.)

Are these regular Sony speakers, or from a HTIB set?

For full disclosure, I should note that some people are less paranoid than I am about using 4 ohm speakers in spite of the receiver not being designed for it (maybe it's designed for it, but they have failed to explain that in the manual...up to you to decide that one.)

Here's what one site says on the topic-

http://www.audioholics.com/education...r-or-amplifier

It's possible the HITB speakers are designed for optimal use with the HITB electronics. They may not be the best choice for use with a receiver. You can try it out though.

You may want to keep it at moderate levels at first. Maybe increase it a bit if all seems well.

... and ensure (as you mentioned earlier) that even though the speakers are "big", that they are set to "small" with a xover of (at least) 80hz on the the avr..


as they should be, anyway...

Yeah, good point

I've used many 4 ohm speakers with a variety of receivers and have never experienced anything different than when using 8 ohm speakers. I can play both just as loud and the receiver heats up the same amount.

... and I've successfully ran with scissors. Looks like we can throw caution to the wind.

Totally depends upon the loudspeaker's brand/model..
If it is a high sensitivity product such as the Klipsch models not an issue, but try connecting one of the less sensitive brand/models..
Then stand back...
As the lower cost AVRs lack enough voltage/current to drive adequately..

Just my $0.02..

What db is considered to be high sensitive speaker?

Just off the top of my head, I consider 92db/watt/meter and up high sensitivity.

89dB @1 meter, 1 Watt...

Just my $0.02..

I figured 90 dB was about average, and high sensitivity is at least 93. Klipsch used to make some pretty high (> 100 dB) speakers.

In my experience most mass market speakers hover around 90 dB. There's some less efficient speakers out there though, like my B&W center speakers which is only 85 dB.

Old theater speakers used to be really efficient by using MASSIVE horns. I saw one at the museum of broadcasting in St Louis Park MN. This driver was connected to this massive horn. Was pretty cool.

I wonder how many people who say you need to be cautious with 4 ohm speakers even understand what impedance is or how impedance is measured or even know what's actually different between an 8 ohm and 4 ohm speaker. I doubt many of them have actually ever owned a 4 ohm speaker out of fear it will explode if played too loudly. My hunch is they were told to be careful with 4 ohm speakers and just echo what they heard.

For example...
Why would sensitivity matter more for a 4 ohm speaker than a 8 ohm speaker?

My opinion is closer that of Michael's. I'd say 93-94db w/ 1 watt(8ohm nominal load) is the bottom of what's considered high sensitivity.

92db is just an arbitrary number. To me that's high as compared with my fronts that are 89db and the center 86db. There are big trade offs for sensitivity.

A higher sensitivity speaker need less power. As such it needs less power to reach the same SPL as a lower sens. speaker. Therefore it's less likely to result in a receiver shutting down due to going into protection mode.

Clearly using 4 ohm speakers increases the chances of going into protection as the higher current needed to drive 4 ohm speakers will cause more heat.

Does that mean something will fail? No. Does it increase the chance? Maybe.

To drive a 4 Ohm loudspeaker typically takes more voltage/current..
How much power really depends upon the enclosure type as a sealed box is less efficient compared to a port/bass reflex. Also the loudspeaker reactance which is the load presented back to the amplifier's output stage is crucial here.
Thats why certain low sensitivity 4 Ohms loudspeakers need a lot of current to drive adequately. While keeping in mind that for an amplifier to produce high current requires more expensive components within the power supply & output stage. That is why in today's price compression for lower cost AVRs (SRP <$999) very few if any can drive a 4 Ohm low sensitivity loudspeaker satisfactorily..
Additionally an AVR brand will frequently include an impedance sensing circuit that if the impedance falls below 4 Ohms the AVR will simply shut down to protect itself. Thus saving a significant warranty expense to replace blown amplifier components...

Just my $0.02...

Basically, speakers track the voltage. But the amp has to be able to source enough current, or it will not be able to swing the voltage into the speaker. Why? because Ohm's law says so. At the same voltage, a 4 ohm load requires twice the current as an 8 ohm load. It's frankly not unusual in the consumer electronics arena to see speakers' sensitivities stated in terms of dB at a specific voltage input (usually the voltage to achieve 1 watt with an 8 ohm resistance). That means that a 4 ohm speaker that we think of as 89 dB at 1 watt may really be 89 dB at 2 watts which starts to be meaningful if you double the perceived level twice - - at 8 ohms that's 100 watts, but at 4 it's 200 watts.

No speaker has a perfectly steady impedance, they vary up and down. An 8 ohm speaker may very well have dips to 4 ohms or even lower, and a 4 ohm speaker may dip below 2 ohms. An amp that can't source enough current to service a lower impedance transducer at the desired level is going to distort, potentially overheat and hopefully go into self protect mode rather than dying.

Ultimately the issue is how much power your maximum listening levels require with your speakers. I listen pretty quietly so if I had 4 ohm speakers that were moderately sensitive, I probably could "abuse" a receiver not rated for 4 ohm operation without problem. But each "notch" louder is about 3 dB, meaning about twice the power, so the line between "no problem" and "where's tha smoke coming from?" can be, audibly, rather fine.

I am always surprised that some people totally discount the potential for issues. Maybe that's an indication that it's not common for people to run into problems.

But I don't see how you can dispute the assertion that many receivers are not designed for 4 ohm operation. Why would a manufacturer spend the extra money to test and certify 4 ohm operation on cheaper models?

The manual for the Yamaha RX-v750 indicates that with a 4 ohm load it can deliver 200 watts Dynamic Power. Dynamic Power is essentially music power which means it can deliver this in short bursts. If there is a lot of bass in the music then it is not going to be able to supply the necessary current. However, it does look like you can use the 4 ohm speakers without too much problem as long as you are not trying to run things at their max. It is interesting to note that the manual does not give continuous power ratings for a 4 ohm load but it does for 8 ohms. If you assumed the limiting factor was current then with a 4 ohm load, your amplifier should be able to continuously deliver 50 watts into the 4 ohm load as opposed to 100 watts into an 8 ohm load. Probably not a problem.

If the v750 has a 4ohm-8ohm switch. Leave it at 8. Setting it at 4 is like putting a governor on the throttle. It simply lowers the available power.

For parties that receiver @100W per channel should be fine. I'd sell the speakers and buy Klipsch or some other efficient loudspeaker. HTIB speakers aren't designed for raising the roof. HTIB speakers are designed for the AVR that usually comes with it.

My personal experience is 4 ohm speakers slowly destroy receivers even if it appears as if it's working fine initially. Receivers start doing strange things after a while.

I've read many accounts of people with 4 ohm speakers who have the same amp, trouble free, for decades. Magnepan speakers are one example. I've used 4 ohm speakers (not Magnepan but DIY) for decades and never had an amp fail. Don't buy amps that deliver less than 50% more output than their 8 ohm rating.

so you isolated a failure, and did a cause analysis, and found it was the 4 ohm load that caused it?