Speaker impedance, Receiver impedance matching?

[fs1]

I was thinking of getting a Yamaha RX-V430. The thing is, all 5 of my speakers (surrounds, mains, center)have a nominal impedance of 4 ohms, while the Yamaha receiver can only switch between a configuration of all > 8 ohms or to mains > 4 ohms, rear/center> 6 ohms. How will this affect this setup? How will it affect the volume, power and performace in general of my 4-ohms speaks if I use the 8 ohm Yamaha RX-V430?

[Guest BobG]

Generally speaking, an amplifier manufacturer tells you to use higher impedance speakers because the amp fails to deliver much current (amperage). Using lower impedance speakers with a current limited amplifier generally results in a bass-shy sound will reduced dynamics. Some amplifiers are rated at 6 ohms rather than at 8 ohms as that makes their rated power higher (but not the actual output power). In the case of the Yamaha, the main power transformer is likely too small to allow each of the channels to run a 4 ohm load without too much stress on the transformer. Set to the 4 ohm mode or think of choosing a more expensive model.

[LFE]

hello, i hv a similar problem. i got a Yamaha amp. and the speaker impedance options from it are 6 or 8 (i prefer to use 8 ohms). As far as my front speakers are concerend, it can handle 8 ohm (RF 82's), but if i connect a subwoofer, does this impedance matters? Moreover, though i searched the specifications of Klipsch RSW-10D the impedance is not mentioned. so my question is does speaker impedance setting from amplifiers matters for Subwoofers also? suppose the input impedance & sensistivity of Subwoofer is 5 Ohms, then the sub gets damaged by the 8 ohms setting in the amp? Thank you.

[DrWho]

The RSW-10d gets plugged into the subwoofer preout from the receiver which is a line level signal....not an amplifier level signal where the impedance matters. In other words, connecting a sub does not affect the impedance seen by the receiver.

For what it's worth, I would probably set your receiver to the 6ohm setting when running the RF-82's simply because it will better deal with low impedance dips.

[LFE]

Ok. Thank you once again (it seems that you are some kind of Engineer from Klipsch[*-)] )

[Mr. RF62]

Like "others" on this forum, when Dr.Who speaks, listen, he gives very good advice, and very knowledgeable.

[DrWho]

lol, I'm just in my last semester of college where my focus has been everything audio...

All the Klipsch employees have a little banner under their avatar.

[Kynergy]

My Onkyo receiver is rated at 8 ohms per channel. After I bought F-3 for front I connected the old front and old center in series as the center, 8 ohms each. They sound good. I am not sure if this is good idea theoretically or if that will cause any damages. Maybe I just need to connect two of them.

[Islander]

When I first got my RX-V750, I set the impedance switch at the 4-ohm position to suit my "4-8 ohm" rated speakers (not Klipsch), but I was never really happy with the sound. I did a little research and found that the switch was installed to satisfy some sort of electrical code requirement.

Switching to the lower-impedance position limits the voltage to the power supply rails so the amp will run cooler, but it really compromises the bass response.

This was posted on Audioholics:

Also, be sure to set the impedance Selector Switch to: 8 Ohm Setting

Never set the impedance switch of a receiver to 4-ohms!

Note about the 4 ohm setting on the backpanel of the RX-V3000

Selecting the 4 ohm setting significantly limits the rail voltage feed to the power amps and thus reduce dynamics, bass output and damping factor. This switch was put on the Receiver for marketing purposes, and so that it can meet UL approval for heat dissipation when presented a 4 ohm load continuously with minimal to no ventilation. With proper ventilation, this should never be a problem (at least 4 inches above and behind the Receiver). In addition, the Definitive Technology Speakers are very efficient ( > 90dB) and thus are relatively an easy load for the Receivers Amplifiers to drive in the 8 ohm setting. Thus I would have to say setting the Impedance Switch to the "8 Ohm" setting will result in better fidelity for your system.

I also found this:

(quote, taken from SoundAndVision article)

"The Yamaha RX-V2600 delivered near-benchmark performance on every test, and literal benchmarks for linearity (0 error at -90 dB) and PCM signal-to-noise, which measured -75.7, the theoretical ideal for our dithered-silence test. Power was impressive for just about any common real-world speaker load, including all-channels power. The receiver shut down when confronted with high-output/low-impedance stresses with its impedance switch set to "6 Ohms," but did fine on the same loads with the switch "mis-set" to the 8-ohm position."

One more from Audioholics, in a test of the RX-V659:

Choosing the Speaker Impedance

Yamaha still ships their receivers with the dreaded impedance selector switch. Our advice as always is to use the "Minimum 8-ohms" setting regardless of the impedance of your speakers. See our editorial note below for further elaboration.

Editorial Note about the Impedance Selector Switch

I recommend the "Minimum 8-ohms" setting even for 4-ohm speakers of moderate efficiency ( > 89dB SPL). Yamaha includes a" 6-ohm" setting to satisfy UL heat dissipation requirements when driving 4-ohm loads, as well as easing consumer concerns about driving low impedance loads. These switches step down voltage feed to the power sections which can limit dynamics and overall fidelity. My advice is to keep the switch set to "Minimum 8-ohms" regardless of the impedance of your speakers and ensure proper ventilation of the Receiver. Using the 6 ohm setting will reduce power output to your speakers about 15-20% and thus cause higher frequency of amplifier clipping if driven too hard which can damage your speakers.

After reading all this (just Google Yamaha impedance switch, without quotes), I set my switch to 8 ohms and the bass instantly improved, so I could turn the bass control back to Flat and enjoy the sound. I've used the 8-ohm setting for over two years now with no problems.

CAUTION:

Do not move the switch unless your receiver is turned off!

You

will

cause damage if you move the switch while the unit is turned on!

[LFE]

Pretty confused nw! but my amp is Yamaha RX -V1500 (120W-170W). It doESNT have any impedance switch instead the impedence change is done with remote on OSD. Did you see Dr. Who' s post? what to say bot that?

[DrWho]

Is it possible that the 8 Ohm setting is just louder and yields the perception of increased bass? The decrease in dynamics is actually there on purpose (to protect the amp), but shouldn't have any audible effect until you reach clipping...

Is the source of this information real engineers or techy DIYer types or what? It isn't exactly trivial to have a switch that changes the rail voltages. [] I was under the impression that usually these switches were related to the protection features of the amp (like affecting the current limiting and all that).

[Islander]

The sources are as quoted, Sound and Vision and Audioholics. There is a lot of stuff on this very topic on the Net.

As for the sound, the difference is obvious even at low volume. When I had the switch set at 4 ohms, I had the treble set at -1.5dB and the bass at +3.0dB to get what seemed like the right sound, to my ears at least. I even called Yamaha Canada Music to ask why my new mid-line receiver sounded quite thin compared with my bottom-of-the-line 1998 RX-V392. I was told that many owners set it to 8 ohms, but it's "the right thing" to set it to 4 ohms...

When I reset the switch to 8 ohms, I was able to get good sound with the tone controls set to Flat and they've been there ever since; actually they're set to Bypass now.