Help with Impedance and Timbre Matching

[Schrute Farms]

I want to buy Left & Right Front Speaker towers and a Center Speaker to go with my new Onkyo 605. If I end up going with a different branded center speaker than the fronts, how do I ensure that the timbre matches?

Also, the Onkyo 605 lists Speaker Impedance as 6-16 ohms. Does that mean my speakers need to fall within than range? The speakers I am looking at have "4 ohms" written on the label.

Here is the Onkyo webpage that shows the specs for each channel: http://onkyousa.com/model.cfm?m=TX-S...s=Receiver&p=s

Thanks! Its funny how I loved my Home Theater setup until I found this forum. Then I suddenly needed to upgrade everything!

[dialog_gvf]

Originally Posted by Schrute Farms

I want to buy Left & Right Front Speaker towers and a Center Speaker to go with my new Onkyo 605. If I end up going with a different branded center speaker than the fronts, how do I ensure that the timbre matches?

That's tough. Because timbre matching means the speakers sound about the same. If they weren't, if a vocal pan (for example) were to occur from right to left as an actor walked across the scene and the three weren't matched the voice may change slightly and then back. Ugh.

This is why most people would recommend you sticking with same maker for fronts and center. Any serious speaker maker will insure their speakers are timbre matched.

If you insist on mixing, then match the mid-range frequency ranges and audition the center.

Originally Posted by Schrute Farms

Also, the Onkyo 605 lists Speaker Impedance as 6-16 ohms. Does that mean my speakers need to fall within than range? The speakers I am looking at have "4 ohms" written on the label.

Yes you should keep withing the ratings of the receiver, or you risk overheating its amplifier.

Lower impedance speakers means it will take more current to drive the speakers. And current leads to heat.

Gary

[Schrute Farms]

The Polk Audio Center channel speaker lists 4 ohms as impedence. Am I reading that correctly?

The Polk R50 floor-standing speakers should work fine with the Onkyo 605 right?

[beakergeek]

Originally Posted by Schrute Farms

The Polk Audio Center channel speaker lists 4 ohms as impedence. Am I reading that correctly?

The Polk R50 floor-standing speakers should work fine with the Onkyo 605 right?

You are reading the Polk center specs correctly, you should use speakers that have a nominal impedence that falls within the restriction of 6-16 ohms because using a 4 ohm speaker will make it likely that your center will distort when it demands current that your Onkyo 605 can't provide.

THX cinema mode on your 605 has a feature/technology built in called Timber Matching that will help compensate for using different speakers. Just make sure you listen to movies with the THX mode on. The other thing is that if you buy speakers from different makers look at what the drivers are made of and try to match based on that.

[jomari]

as mentioned already, rule of thumb is that you should match the manufacturer and try to stay within the boundaries of their reference for a HT soundstage. simply put, they know what theyre doing when they test these to all match each other.

otherwise, you'd be having an inconsistent/jumping panning scenes at times.

IMO? i prefer the one up rule, but thats just me. in the same way i run my center a little hot compared to the fronts. again, a personal preference.

[Schrute Farms]

Originally Posted by jomari

IMO? i prefer the one up rule, but thats just me. in the same way i run my center a little hot compared to the fronts. again, a personal preference.

Huh? Explain the one up rule, for an "audiot" like me!

[chasarms]

Originally Posted by dialog_gvf

. . . Lower impedance speakers means it will take more current to drive the speakers. And current leads to heat. . .

This is not completely accurate but impedance should be considered for sure.

Lower impedance means the the amp will draw more current more easily, but it will also make more output. A lower impedance speaker won't inherently cause the amp to draw more current for the same sound output level.

Most simply put, the system would sound louder at lower volume settings.

Think of it as a water supply with a lower impedance equating to a larger pipe. The larger pipe does create more demand on the supply, but it also delivers more water!

The concern is that if you are not aware, it's easier to drive the amp harder thus create heat and/or overdrive the speakers.

[richteer]

Originally Posted by chasarms

This is not completely accurate but impedance should be considered for sure.

Lower impedance means the the amp will draw more current more easily, but it will also make more output. A lower impedance speaker won't inherently cause the amp to draw more current for the same sound output level.

Most simply put, the system would sound louder at lower volume settings.

Sorry, but dialog is correct. All else being equal, a lower impedance speaker requires more current for a given output level than a higher impedance one.

Judging by your comment about volume, I think you might be confusing speaker impedance (the load it presents to an amp) and speaker sensitivity (how loud the speaker is when given a 1W @ 1KHz input). A speaker with a higher sensitivity will indeed sound louder at a given volume setting than one with low sensitivity.

A killer load for amps is very low impedance with low sensitivity. The Apogee Scintilla of years gone by--1 Ohm impedance and ~ 80dB/W sensitivity--is one of the canonical examples of amp killers.

[haste]

I'm using a Polk center channel that has a 4 ohm impedance with my 605...works fine.

I blast it all to hell a lot too.

I had 4ohm speakers across the front of my system and never had an issue with the 605. Like i said before, I blast my system a lot. =D

[welwynnick]

Originally Posted by chasarms

This is not completely accurate but impedance should be considered for sure.

Lower impedance means the the amp will draw more current more easily, but it will also make more output. A lower impedance speaker won't inherently cause the amp to draw more current for the same sound output level.

Most simply put, the system would sound louder at lower volume settings.

Think of it as a water supply with a lower impedance equating to a larger pipe. The larger pipe does create more demand on the supply, but it also delivers more water!

The concern is that if you are not aware, it's easier to drive the amp harder thus create heat and/or overdrive the speakers.

I'd also say that it was quite accurate. Ideally, the amplifier will generate the voltage and supply whatever current the speaker needs to draw. Other things being equal, a low impedance speaker will draw a higher current than a high impedance one. The current should be inversely proportional to the impedance.

All this assumes a bottomless pit of power supply and heat sinks, though. Those are often designed around the industry norm of 8 ohm speakers, and 4 ohm speakers may load the amp more than it can cope with, to the detriment of both sound quality and safety.

Nick

[Silo5]

I currently have the surround speakers from a Sony SA-VE 445H surround system and I want to keep them as surround speakers. I want to add the Sony SS-F6000 floor standing speakers and Sony SS-CN5000 center speaker, (I haven't decided on a sub yet.) I know there are better speakers out there, but my question is if I put these speakers together for a 7.1 set up, would they be voice-matched or sound too uneven? Info on speakers (minus the sub) is listed below:

SS-MS445 (surround speakers)
each handles up to 120 watts
1" Nano-Fine tweeter
dual 2-1/4" full-range drivers
8 ohm Speaker Impedance
Frequency Range: 120-50,000Hz (no dB variation given)
Sensitivity Level: 84dB

SS-F6000 (front speakers)
6 ½" Mica Reinforced Woofer
6 ½" Enhanced H.O.P. Cone - Mid Woofer
3 ¼" Enhanced H.O.P. Cone - Mid Driver
1" Nano Fine® Balanced Dome Tweeter
180W Maximum Input Power
8 ohm Speaker Impedance
Frequency Range: 40-50,000Hz (no db variation given)
Sensitivity Level: 89 dB

SS-CN5000 (center speaker)
Enhanced H.O.P. Dual 5 1/4" Drivers with 1" Tweeter
Nano Fine® Balanced Dome Tweeter Rated to 50 kHz
150W Maximum Power Handling (Center)
8 ohm Speaker Impedance
Frequency Range: 85-50,000Hz (no db variation given)
Sensitivity Level: 89dB

[Woody]

Botom line is, you should go with speakers from the same manufacturer at the very least for your front 3 channels.

Personally, I would not go with speakers rated at 4 ohms with your particular receiver.