4 ohm speakers? can I use them? (1 Viewer)

[Brian Bowles]

I have an onkyo 595 and was thinking about building some 281's. They are 4 ohm speakers. Will my onkyo be able to play them? If not what would I need? I was all pumped about building some speakers and now I worried that I will not be able to do it. Thanks!!!

 

[Colin Dunn]

Check the spec sheet for the "official" answer. If the receiver is only rated for 8 ohms or more, the manufacturer does not recommend using lower-impedance speakers.

The reason has to do with current delivery. By Ohm's Law, if you halve the resistance (ohms), you have to double the current output (amps) to maintain the equation. This can cause problems with receivers that cannot adequately deliver the additional current required. It can especially be a problem if you drive 5-6 channels of low-impedance speakers with a power supply that can't dish out the current.

You can often get away with driving 4-ohm speakers on a receiver, but don't hold me responsible if you experience amplifier or speaker damage. You may find that your maximum clean volume level is limited. If you hear your amplifier distort, back off immediately to avoid damaging your amp (from overdriving it) and/or speakers (some tweeters can't tolerate a highly distorted signal and may blow). Some receivers may have internal protection mechanisms that shut off the amps if the current demands are too much. If you're in the habit of watching movies at/near reference level, you should get a receiver or amp that is rated for 4-ohm speakers, or investigate other speaker designs that have an 8-ohm nominal impedance.

I don't know why manufacturers continue to make receivers that can't drive 4-ohm speakers. Must be some sort of skimping to cut costs. Most of the quality speakers I've encountered have a 4-ohm impedance, so I recommend that anyone shopping for a receiver or amp get one that can adequately handle a 4-ohm load.

 

[Frank Frandsen]

Colin,

Good advise on the 4 ohm rating. I purchase a Marantz MM-9000 THX certified amp which had no 4 ohm rating. It kept shutting down when I tried to drive my 4 ohm subwoofer. It never dawned on me that a alledgedly quality seperate would skimp in this way, pretty cheap.

Frank

 

[RichardH]

The 595 has the 4/8 Ohm switch on the back. Just set it to 4 Ohm and you'll be fine!

 

[Colin Dunn]

Frank:

I'm surprised that a separate amp from Marantz wouldn't do a 4-ohm load. I'm also surprised that THX would certify an amp that won't do 4 ohms. (Is Lucasfilm determined to destroy the credibility of the THX brand? Between this and approving the 'Highlander' DVD, I have to wonder...)

 

[LarrySkelly]

I have a Marantz SR8000 receiver driving B&W rears (4 ohm) and Martin-Logan mains. The Martin-Logans are notoriously difficult to drive and drop down to 1 ohm. The receiver handles it with no problems. I've been driving them at full levels for about a year with no problems so far.

That's not to say I won't have a problem in the future. But so far I have to say the SR8000 has been superb for what it is.

 

[Ted Todorov]

I see I have come to the right place -- I have a Denon AVR-2800 and was considering Swan Diva 4.1s, which are rated at 6 Ohms. Will it work? I haven't a clue as to whether the Denon has an impedence switch.

Thanks!

Ted

 

[ChrisAG]

Here's a related question. My dad has a Yamaha RX-V490 DPL receiver, rated at 70Wx3 across the front and 15Wx2 for the rears. He's thinking about using his old (like, 39 years old!) Harmon Kardon HK-40 floorstanders as the rears. The speakers are easy to drive, but the impedance is rated at 4 Ohms. Since DPL doesn't send a full-range signal to the rears anyway, will there be a problem?

Incidentally, when these same speakers were employed as fronts, there was never any problem with the Yamaha.

 

[MichaelG]

I have a Denon AVR3300 with the M&K 750THX speaker system, which has each speaker is rated 4 Ohms. I have never had any problems what so ever, and I have cranked up the sound plenty of times. So, I would feel safe using Denon to drive lower than 8 Ohms speakers. I am sure that other good quality receivers are equally capable, but I don't have any first hand experience.