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[Tom Roche]

It seems this was discussed some time ago, but I couldn't find it on a search.  It's claimed by some that putting a load (think typical MI 12" speaker) on only one side of a solid state stereo powered mixer (for example, Yamaha EMX5) is bad for the amplifier.  This presumes the system is running within normal operating parameters.

I maintain it has no negative effect.  Can anyone explain the technical reason why this is a potential issue or a non-issue? 

Similarly, it's claimed that running one side using a nominal 4-ohm speaker and the other side with a nominal 8-ohm speaker is equally bad for a solid state amplifier.  Again, I see no issue as long as the system is running within its limits.  Thoughts?

[Bob Faulkner]

Seems this type of usage with an amp was a problem many, many years ago.  I can't speak for powered consoles, but with "stand-alone" amplifiers, I have on many occasions run the amps (2-chnl amps) with various loads on each channel (for monitor duty).  Never any issues... I've moved to 4-chnl amps since then and same setup with various loads on each channel... no issues.

[Riley Casey]

Your amp is happier running on only one channel than on two. Well as happy as a metal box full of semiconductors is likely to get. The only thing common to both channels in almost all modern power amps is the power cord and the on/off switch. Running one channel with no load or a lighter ( read higher impedance and/ or lower duty cycle ) load simply means less current flows thru those common elements.  This was even more true back in the days of 'heavy iron' Class AB amps where a common power supply feed both channels and less current on one channel meant more current available for the other.

[Paul G. OBrien]

I suspect you are misremembering. A solid state multi channel amplifier has no problem powering a speaker from one output or powering different inpedance loads on each channel... withing rated specs. None. In fact it's safer for the amplifier than powering very low impedance loads.

[John Roberts {JR}]

no problemo...

JR

[Chris Grimshaw]

Some valve amps would be very unhappy if left to drive an open circuit, but pretty much anything solid-state will be fine.

Chris

[Jeff Bankston]

My amps have no idea what each channel are running or not running.

[Ivan Beaver]

A basic "rule of thumb".

Solid state like opens (higher impedance loads) and tube amps like shorts.

Running a solid state amp with no load does not cause an problem.  But tube amps can kill themselves.  This is why Fender used a shorting 1/4" jack on the speaker jack of tube amps.  If you didn't have a loudspeaker hooked up, the jack would provide a short to the amplifier, to keep it from dying.

This is also why it is important to properly match the load setting of the amp to the loudspeakers being used.

Solid state doesn't care, but they can sound bad, shut down, reduce power, or die if the load impedance is to far below rated impedance

[Corey Scogin]

I maintain it has no negative effect.  Can anyone explain the technical reason why this is a potential issue or a non-issue? 

Playing devil's advocate here...
Say you run one side of an amp hard for years. That side of the amp regularly gets hotter than the unused side, potentially causing some uneven "wear" of the electrical components. This uneven wear just might cause one side to have a different response than the other. This may be undesirable versus having both sides "wear out" evenly. Obviously, more desirable would be to operate it well within its limits to extend its life as much as possible.

[Scott Helmke]

This uneven wear just might cause one side to have a different response than the other.

By response, you mean frequency response?  It would sound different?

That seems very unlikely to me. 

[John Roberts {JR}]

typical internet discussion.... now people are just making up sh_.

no problem...

JR

[Brian Jojade]

Playing devil's advocate here...
Say you run one side of an amp hard for years. That side of the amp regularly gets hotter than the unused side, potentially causing some uneven "wear" of the electrical components. This uneven wear just might cause one side to have a different response than the other. This may be undesirable versus having both sides "wear out" evenly. Obviously, more desirable would be to operate it well within its limits to extend its life as much as possible.

The differences would be SO minimal as to be not noticeable under any normal situation.  If that actually DID happen, buying a new amplifier of the same model as one that's been abused would sound different than the original. It's just not going to happen.

[Corey Scogin]

typical internet discussion.... now people are just making up sh_.

no problem...

JR

Do electrical components not degrade, changing their performance due to age, stress, or other factors? Is it exclusively work/fail for everything in the signal chain?
Serious question.

[Chris Grimshaw]

Electrolytic capacitors can and do degrade. They lose their value over time, and one in the signal path will eventually result in reduced bass response. IIRC, I replaced the caps on some speaker crossover boards and the harmonic distortion of the finished speaker dropped quite dramatically. I'd need to double-check my files to confirm that, though.

Resistors, inductors, semiconductors etc work until they don't in my experience.

Valves (tubes) also degrade during use and with heating/cooling cycles. The HiFi community puts great value in NOS valves for that reason.

Chris

[Chris Hindle]

Playing devil's advocate here...
Say you run one side of an amp hard for years. That side of the amp regularly gets hotter than the unused side, potentially causing some uneven "wear" of the electrical components. This uneven wear just might cause one side to have a different response than the other. This may be undesirable versus having both sides "wear out" evenly. Obviously, more desirable would be to operate it well within its limits to extend its life as much as possible.

I'd just bridge it to the one load, and keep "the wear" even.......
Chris.

[Scott Helmke]

Do electrical components not degrade, changing their performance due to age, stress, or other factors? Is it exclusively work/fail for everything in the signal chain?
Serious question.

Generally components degrade at their extremes of performance - more likely to burn out, more likely to behave differently at extremely high or low frequencies, etc.

Part of a designer's job is to not run components at extremes, so that variations in component tolerances don't cause variations in product specs.

[John Roberts {JR}]

Do electrical components not degrade, changing their performance due to age, stress, or other factors? Is it exclusively work/fail for everything in the signal chain?
Serious question.

I actually wrote a column about this back in the 1980s for my "Audio Mythology" magazine series. The specific question I addressed back then was it better to turn gear off over night or leave it always powered on.

Electronic components do not suffer linear wear patterns like brake pads or auto tires, some components do degrade from exposure to elevated temperature over time. One popular rule of thumb for reliability engineering is that MTBF (mean time between failure) drops in half for every 10'C nominal temperature increase. So elevated heat is bad for product reliability, but I can't imagine heating up one channel enough to make an audible difference between two channels inside the same chassis. The most obvious components degraded by temp/time would be electrolytic capacitors from losing electrolyte (while forced air cooling would reduce capacitor temperature differences inside a common chassis). Without repeating my entire column, there is one subtle use over time mechanism in solid state devices (related to metal migration), but on human timeframes solid state devices appear to work pretty much the same, until they stop working completely (fail). 

So to answer the OP's question a third time... No problem....

JR

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