Why do most receivers cannot handle 4 omhs speakers


I don't understand why 4 ohm speakers need powerful receivers (high current ?) when most mini systems have 4 ohms speakers and are driven by very weak amplifliers.

Since 4 ohm speakers have less resistence than 8 ohm speakers, isn't it logical that they need less power and therefore less powerful receivers (assuming both speakers are of the same sensivity)?

Why is it important to match ohms of speakers & receivers. What happen if they are imcompatible?

High quality 4 ohm speakers (Magnepans, Polk LSis, Dynaudio, etc.) require an amp that is stable at 4 ohms. Most receivers are not stable at 4 ohms because the manufacturer wanted to save money by putting in a power supply of lesser quality and to save money by putting in less protection circuitry. This is a design choice made by all of the big boys (Yamaha, Denon, Onkyo, Pioneer, etc.). By making a receiver with a narrow power envelope, they have substantial manufacturing savings.

As for the little stereos, again, they have a narrow power envelope, it is just set lower (4 ohms rather than 8 ohms). Since their included speakers have very simple cross-overs (if they have a crossover at all), they do not represent a complex load to the amp. Instead, it is a very simple 4 ohm load. Mini-stereos simply also do not face the same problems as regular amps since the power output is so low. You don't see mini systems rated at 100 wpc--for example, my daughter has a JVC Executive Stereo and it is rated at 13 wpc x 2. I have looked at several others for my other daughter and they are rated at 20 wpc x 2 or 25 wpc x 2.

If you try to run good 4 ohm speakers on an 8 ohm rated receiver, you will do one of two things. After the amp gets to operating temperature, either the receiver's protection circuitry will shut down the power or it won't. If it doesn't shut down the power because the protection circuitry is not good (typical for low priced receivers), you will damage the amp or the speakers, or both.

I trust this answers your questions.

It is true that 4 ohm speakers need less power to play at the same volume as an 8 ohm, yet ironically they usuallly draw more power. This problem arises because 4 ohm speakers may drop below 2 ohms (which many 4 ohm speakers do) and start approaching the impedance of speaker wire. This puts up a complex load for the amp section of the receiver.

Now most minisystems have short specially designed wire runs that are mated to specially designed amp sections and 4 ohm speakers that rarely, if ever get down to 2 ohms. These speakers are rarely designed to go very loud and when they are pushed, they generally sound terrible.

That is why most consumer receivers have a much easier time in playing 8 ohm speakers---they rarely go down below 3 ohms, if ever. This represents an easy load for an average power supply to drive.

The use of 4 ohm speakers generally doesn't pose a problem at normal listening levels, but may eventually cause a receiver to overheat or trip its internal overload switch when music is played very loud. Before buying 4-ohm speakers to regularly play loud music, check the manual, the manufacturer, or back panel of your receiver to confirm that the unit is compatible.

That was very informative. Thanks Hawk.

Can I run a 4 ohm bass cannon(from a car)on my home receivers subwoffer channel? On my receiver I am currently running 2 cerwin-vega 6 ohm louds,a center,
and 2 rear speakers. My Sub channel is open. I guessing I cant, but I want to know 4sure. TKS!

That would depend on the receiver, I had a receiver that had a subwoofer output(yes, the vr-6070)and it was only rated at 8 ohms minimum.

Check the back of the amp or your manual before connecting the sub. But heres a question for you, why would you do that? A powered HT subwoofer would sound alot better. That would also take a lot of stress of the amp. No one(not even Hawk)can answer your question until we know your receiver.

Thanks Dawg!!

Help! I am looking for a minisystem for my home. I want good sound for a room, but do not need a lot of extra stuff or a huge cd changer. If anyone has suggestions, I would love to hear them. I am looking at a cost of $300 - $600.


I presume you are looking for a stereo minisystem with a cd player. Consumer Reports has reviews on these types of systems.

Could someone give me an idea of how the little Denons (like the 1404) would handle a 3.6 ohm load (the minimum presented by my monitors)?

I'm trying to avoid stumping up the cash for a "real" receiver that's stable down there since my power and feature needs are actually very modest. . .



Are you looking for a stereo mini-system or a surround sound system?

For stereo, check out the Onkyo MC35TECH. It has very nice electronics, using transistor outputs rather than the cheaper and inferior IC outputs.
« Previous Thread Next Thread »

Main Forums

Today's Posts

Forum Help

Follow Us