Mixing speaker impedance

[lipinski]

My system consists of all 8 ohm speakers. Academy, Forte IIs, and KG 1.5.

If I were to replace the surrounds with 6 ohm (KG4), what would result? I realize that one shouldn't mix impedance, but has anyone ever tried it?

[WMcD]

I believe there is nothing to worry about.

For the most part no speaker exhibits its nominal impedance over its full range. The Forte may well go to 4 ohms in the bass and 50 ohms in the midrange and to 10 in the tweeter. The Heresy does this, for example.

The same is probably true of your new surrounds, also. Just about any number you assume is wrong except at a few frequency points.

OTOH, I have seen that some receivers use lower power amps for the surrounds. It makes sense because the front channels are delivering much more power just because of the volume levels.

I would not be surprised if some HT receivers' surround amps don't like low impedance surround speakers. But that has little or nothing to do with mixing nominal impedances.

Gil

[MrMcGoo]

Gil is correct as usual. The lower impedance should have little effect on good receivers or amps. When all 5 or 7 channels are playing, most receivers are challenged to some degree. If the receiver does not run hot or shut down, there is nothing to worry about typically.

Four ohm speakers can be problematic for some receivers. In many instances, the receiver's manufacturer recommends against their use. It is usually best to follow a receiver manufacturer's recommendations.

In most cases, it is important to provide plenty of ventilation for an amp or receiver. The exceptions are some digital amps that run very cool like Sunfire.

Bill

[lipinski]

thanks for the input.

[minn_male42]

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On 1/13/2005 10:33:20 PM MrMcGoo wrote:

Gil is correct as usual. The lower impedance should have little effect on good receivers or amps. When all 5 or 7 channels are playing, most receivers are challenged to some degree. If the receiver does not run hot or shut down, there is nothing to worry about typically.

Four ohm speakers can be problematic for some receivers. In many instances, the receiver's manufacturer recommends against their use. It is usually best to follow a receiver manufacturer's recommendations.

In most cases, it is important to provide plenty of ventilation for an amp or receiver.

The exceptions are some digital amps that run very cool like Sunfire.

Bill

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Actually Bill - the Sunfire is not a digital amp by definition - the Sunfire uses a switching power supply which allows it to operate in a very cool manner.

The same technology is used in the Sunfire subwoofer amps

from the Sunfire website:

"Like all of our multi-channel amplifiers, the Sunfire Cinema 200~seven uses our Tracking Downcoverter technology to run cool while tightly controlling your home cinema loudspeakers. Moreover, it looks as beautiful as it sounds."

http://www.sunfire.com/200SevenFrontPR.htm

If you take the time to read through the pdf files on Bob Carver's "tracking downconverter" technology you can see that it IS NOT the same as the "digital" amplifiers out there now such as the bel canto, spectrum, TacT, solar hi-fi, Crown, and Carver Professional ZR series (no connection to the Bob Carver in Sunfire)

Lots of pdf files here:

http://www.sunfire.com/technology.htm

BTW - almost forgot - the Sunfire amps are excellent choices for Klipsch amplification!

[MrMcGoo]

Russ,

The output devices in the Sunfires are transistors that run in the AB class. I was under the impression that the tracking down converter is digitally controled, hence the digital comment. The tracking down converter is what makes the Sunfire amps run cool. The Sunfire is nothing like the Tri-Path amps or BASH amps.

I strongly agree with the comment that Sunfire plays well with Klipsch. I have a Sunfire Cinema Grand II 5 channel amp and a Sunfire Signature Stereo amp. Both amps run cool, but the 2 channel runs near stone cold.

Sunfire amps can drive speakers with low impedances and not break a sweat. The ability of the amp to follow the impedance curve gives better frequency response, tighter bass and reproduces more of the small details.

Bill

[michael hurd]

Bill, the Sunfire amps use class H topology, where the input voltage modulates the rail voltage, keeping it slightly above what is needed, therefore keeping the voltage across the transistors low, resulting in low thermal emissions.