Receiver on 4 or 8 ohms with 6ohms speakers?? (1 Viewer)

i just received some yamaha speakers for my birthday, last night i was hooking them up to my sony ns-de1075 receiver and i couldn't figure out if i should set it at 4ohms or 8ohms. the speakers claim an impedence of 6ohms. unfortunately sony's manual for the receiver appears to be written in a dialect similar to swahilli. who writes their manuels??

but i digress, what would you do in this situation?? from what i could deduce from the manuel setting the receiver to 4ohms seemed correct but i want to make sure before i forget about it and melt my receiver. any suggestions for a newbie?

Listed in the "Basics" area:

What’s an Ohm?

The ohm is the unit of measure for impedance, or electrical resistance. What does this have to do with your home theater? It affects how much power your amplifier produces. Power = voltage^2/resistance. Anything that is fed an electrical signal provides resistance. The higher the number in ohms the higher the resistance. Many loudspeakers are rated at 8 ohms. This rating is usually listed as “nominal” because resistance changes over the frequency range. It is usually not too high resistance that we have to worry about, but too low resistance. Say you have an amp that will produce 25 watts (power) into 8 ohms. If you show the amplifier a 4 ohm load, you decrease resistance and increase power because any given number will be larger when divided by a smaller number (80/8 < 80/4). As the resistance decreases and power will increase (a theoretically perfect amplifier would double in output) the current will also increase because Ohm’s law states that current = voltage/resistance (power = voltage^2/resistance). If the amp has the capability to produce this much current and dissipate the heat, you will be fine, but if not, you will over heat the amp and may ruin it or at the least trip the protection circuitry. You should always know the limits of your speakers and amplifier to avoid damage.

-by Charles JP

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Since the speaker is rated at 6 ohms, and we know that that rating is an average, we can conclude that the speaker will dip below 6 ohms on certain frequencies. The safer setting would be the 4 ohm setting. You may be able to get by on the 8 ohm setting, but I would be vigilant in noticing any increases in temp..

The short answer is try the 8 ohm setting. Just check the top to the receiver to see if it is getting too hot. A lot will depend on your listening preferences. If you don't go for Rolling Stones Live levels then you may not have the slightest problem even with some 4 ohm speakers. However, if you really like it loud and are driving surrounds also the current transformers of your receiver probably won't keep up as well. A 6 ohm load is probably in the range for most receivers. But again, keep an eye on the heat at first. It is OK if it gets warm but not hot.

My current Sony receiver (SRT-DE 845) manual states that if the speakers are lower than 8 ohm' then the ohm switch should be set to 4 ohms.

I liked the way "HAN" at AVS accurately answered this question so instead of rewording it, I'll just paste it here. This is the second time I've borrowed it, I hope he doesn't start charging me for it!

"The issue is heat buildup. The switch is there to help the receiver pass UL or CSA heat safety tests when driving lower impedence loads. When in the 8 ohm position, the receiver outputs it's highest potential wattage. The 4 ohm position lowers the output section's power supply voltage, thus lowering the overall possible heat buildup/wattage. (Measurements I've seen range from around 20 to 40 percent less power at the 4 ohm setting than what's available at the 8 ohm setting.)

You want to consider heat related problems (when using lower impedence speakers in the 8 ohm position) versus the higher risk of amplifier clipping (when running the receiver at high volumes when in the 4 ohm position.) Too much heat can mess up your receiver and clipping can eat tweeters.

Bottom line...

It kinda comes down to ventilation. If your receiver gets a good, constant breath of fresh air, then you're probably fine with the 8 ohm setting. (BTW, don't stack ANY components on top of your receiver. Even slightly blocking the top can cause heat buildup.) But if your receiver gets very warm and you can't really improve the ventilation, then you might want to consider the 4 ohm setting."

Or put another way, here's another fine treatment from "GDS" of Audioholics.

"Impedance Selector Switches

This so called feature, used by some manufacturers, is designed to prevent overheating of the receiver or damage to its output transistors because of excessive current flow. The manufacturer accomplishes this in one of 2 ways: 1) Stepping down rail voltage supplied to the power amp or 2) feeding half the signal strength to a voltage divider of power resistors. Both of these methods severely limit dynamics and current capability of the power amp. This results in an audible decrease in bass capability and dynamics transient sound because the 4 ohm setting effectively increases the receiver's output impedance. Unfortunately many manufacturers put these features on their products to ease customer concerns with driving low impedance loads and for safety reasons when getting UL approvals. Note: In order to meet UL requirements, a receiver cannot be rated down to 4 ohms without having this switch onboard. Receivers without this switch are usually rated down to 6 ohms. In most cases, well designed receivers can easily handle 4 ohm loads safely and efficiently. It is highly recommend to keep the impedance switch set to 8 ohms regardless of your speakers impedance and make sure your receiver has plenty of ventilation."

The ohm switch is for UL certification. Keep it at 8ohms setting like I do with my Yamaha reciever. If the heat bothers you put a fan from Rat Shack on top of your amp.

The information on this thread is not necessarily accurate. I connected some very expensive Wharfedale speakers (6 ohms) to a Sony 4 ohm receiver. The sound was wonderful for a couple of days -- speakers were never played loud, as the wife will not permit. Then the Sony fried, nothing but crackling and high sounds. I threw it in the trash. Thankfully, the Wharfedale speakers were not similarly fried. If your speakers state 6 ohm, hook them up to a receiver that can be adjusted to 6 ohm, as Yamaha. Otherwise, you're looking for trouble. In short, if you have 6 ohm speakers, don't purchase a Sony. Only trouble can be in store.

Originally Posted by goforit
The information on this thread is not necessarily accurate.

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Your situation is not typical and a thousand other issues may have been in play. That does not make this thread any less accurate.

Your situation is not typical...

Interestingly, I used the information on this forum to see if it was safe to hook up 6 ohm speakers to a Sony with an output of 4 ohms. From what I had read, it appeared safe. However, I met with disaster when I followed the advice. The Sony fried in less than 2 days. I had had this receiver for some time with 4 ohm speakers with no problem whatever. However, when I hooked up the high-end Wharfedale speakers, the Sony gave out. As before, I threw it in the trash. A Wharfedale surround system costs around $2000.00. I can't afford to put these on anything that is not designated as 6 ohm compliant. I would recommend that you purchase speakers and match them with a compliant receiver. Otherwise, you are asking for trouble, especially if you turn up the volume. One reply said to put your hand over the receiver to see if it is heating up. The proper terminology is "FRYING."

Clarence,

If you say your Sony was fried, I believe you of course, but if the outputs are designated 4 Ohms, it's certainly not caused by connecting a set of 6 Ohms speakers. Connecting speakers with a higher impedance will result in a lower current, so it will help protecting your amps.

The end amps could be fried if they are "asked" to output more power than they are able to. So the point is: what was the power rating of that receiver? In this case, Ohms have nothing to do with it.


Cees

I have a Onyko TX-SR 607 receiver. I also have all 8 oms speakers with it. I recently purchased two Pioneer 3-way CS G403 speakers, which are rated at 6 oms. I would like to use the pioneer 6 oms speakers as front channel speakers, and the rest of my speaker system speakers would be 8 oms. Would this be OK??? I would not like to possibly damage or "fry" my receiver. Guess this would be a mix and match thing. Would appreciate an answer from you more knowledgeable people.
Mick

According to the Onkyo web site, the 607 supports speakers from 6 to 16 ohms. It should have no problem driving the Pioneer speakers.

The Sony was rated at 100 watts per channel and was of sufficient power to run the speakers. The first thing that went was the bass, then the mids; it was left with only shattered highs. My point is that the Sony was fine until I hooked up 6 ohm speakers; 2 days later it was fried.

You want to consider heat related problems (when using lower impedence speakers in the 8 ohm position) versus the higher risk of amplifier clipping (when running the receiver at high volumes when in the 4 ohm position.) Too much heat can mess up your receiver and cheap wholesale Christian-Louboutinclipping can eat tweeters.

Goforit, what your are saying doesn't make any sense. The cause was obviously something else.

I am trying to find speakers for my jolida FX10 which has a 4 and 8 ohm switch. Can I use the Wharfedale 10.2 which are rated at 6 ohms?