Chances of overheating an amp rated for 4 ohms when running a 3 ohm Center channel speaker

[RussellS]

Need some common sense help here - I am looking to put a 3 Ohm speaker (Magnepan CC5 center channel) on a 4 Ohm amp (Outlaw Audio 2200)
I have yet to purchase both, but seriously considering it in the next couple of weeks.

The amp manufacturer tells me there is a risk of overheating the 2200 when running a 3 Ohm speaker.

What is the chance of that happening when running the CC5 crossover point at 200 hz?

I need to run the CC5 to match the 3.7 L/R fronts. Any thoughts on this or suggestions on another amp in the budget range?


EDIT: Would it be better to look at Crown XLS series amps? They seem to be rated for 2 Ohm loads.

Thanks in advance.

 

[ryanosaur]

Get a crown XLS amp. your choice of model. Stable to 2 ohms. You can run a single channel off of it... don't bridge it! 3 Ohms becomes 1.5 Ohms... baby go boom.

Don't get me wrong, I love my Outlaws... got 5 of em!

It's not the right tool for the job.

Maybe someone else has experience with Crowns and Maggies? I do not. But that's the first thing that comes to mind on a budget. Possible step up: QSC Cinema amps. Also stable at 2 Ohms.

 

[lovinthehd]

The Crown XLS are rated for 2ch, yes, and something like the 1502 would work quite well I think (one channel like Ryan said, bridging wouldn't do you any good). QSC would work, too. Some consumer amps can do 2ohm, too. Depends how much you want to spend.

ps I have four Crown XLS1500s and I use them in a couple of ways (mains and subs), altho haven't had a 2ohm load particularly...might with a sub configuration someday, tho.

 

[Sealman]

I don't think the outlaw will have any issue running the CC5. A quick search show many people running older Rotels, many Emotiva's and lots of other amps as well without any problems.

 

[RussellS]

Get a crown XLS amp. your choice of model. Stable to 2 ohms. You can run a single channel off of it... don't bridge it! 3 Ohms becomes 1.5 Ohms... baby go boom.

Don't get me wrong, I love my Outlaws... got 5 of em!

It's not the right tool for the job.

Maybe someone else has experience with Crowns and Maggies? I do not. But that's the first thing that comes to mind on a budget. Possible step up: QSC Cinema amps. Also stable at 2 Ohms.

Thanks!

When I spoke with Outlaw, they cautioned against running a 3 Ohm CC5 on their 2200. I am using an Audio Research DS450 for the L/R 3.7s and need a center channel to match their sound. Budget is an issue and I saw the Crown XLS line. It looked like they are not scared of 2 Ohm loads, so the CC5 might be perfect. Definitely will not bridge. I had not heard of Outlaw until just a few weeks ago. Good to hear you like their products. Looks the 976 will be a great preamp for my budget too.

 

[RussellS]

I don't think the outlaw will have any issue running the CC5. A quick search show many people running older Rotels, many Emotiva's and lots of other amps as well without any problems.

Outlaw seems to caution me against running the 2200 on a 3 ohm speaker, so I decided to ask you guys. thx

I understand their disclaimer, but it brought me here to learn. Here is their statement: Our amplifiers support down to a 4 ohm nominal load. If using below this, like the CC5, and the amplifier is damaged due to heat, it would not be covered.

 

[lovinthehd]

FWIW your post is indicating overheating of the center instead of the Outlaw 2200....

 

[RussellS]

FWIW your post is indicating overheating of the center instead of the Outlaw 2200....

I see what you mean. You might think English is not my first language.... hopefully the change makes it clearer.

 

[ryanosaur]

I understand their disclaimer, but it brought me here to learn. Here is their statement: Our amplifiers support down to a 4 ohm nominal load. If using below this, like the CC5, and the amplifier is damaged due to heat, it would not be covered.

FWIW your post is indicating overheating of the center instead of the Outlaw 2200....

Devil is in the details.

#Boom-Pow!

2 for 1

 

[Verdinut]

The Crown XLS are rated for 2ch, yes, and something like the 1502 would work quite well I think (one channel like Ryan said, bridging wouldn't do you any good). QSC would work, too. Some consumer amps can do 2ohm, too. Depends how much you want to spend.

Agree. Some consumer amps can drive 2 ohms too, but IMO you have to get the ones that are expensive and won't perform in most situations any better than the affordable pro audio amps.

 

[AcuDefTechGuy]

Outlaw seems to caution me against running the 2200 on a 3 ohm speaker, so I decided to ask you guys. thx

I understand their disclaimer, but it brought me here to learn. Here is their statement: Our amplifiers support down to a 4 ohm nominal load. If using below this, like the CC5, and the amplifier is damaged due to heat, it would not be covered.

A lot of companies say that to protect themselves legally. Yamaha does that too.

I've seen The Audio Critic measure the ATI 60-WPC amp into 1 ohm on the power-cube. So I'm pretty confident ATI amps can power speakers into 2 ohms. But legally, I bet ATI won't be recommending to people to use 2 ohms speakers on their amps either.

I think I've seen some 1-ohm or 2-ohm power measurements on Stereophile too.

 

[PENG]

A lot of companies say that to protect themselves legally. Yamaha does that too.

I've seen The Audio Critic measure the ATI 60-WPC amp into 1 ohm on the power-cube. So I'm pretty confident ATI amps can power speakers into 2 ohms. But legally, I bet ATI won't be recommending to people to use 2 ohms speakers on their amps either.

I think I've seen some 1-ohm or 2-ohm power measurements on Stereophile too.

I would go even further to say that in fact Ohm's law, that is, I = V/Z does not care about low impedance, so any amp can drive 2 ohms or 1 Ohm load as long as you turn the volume down enough to limit the output voltage (V). The only catch is that it no longer costs a fortune to electronically limit the current so a lot of manufacturer have done just that. Some may do it more aggressively than others.

Based on past bench test results, Yamaha appears to be on the aggressive side in their overcurrent and overload protection schemes.

 

[AcuDefTechGuy]

I would go even further to say that in fact Ohm's law, that is, I = V/Z does not care about low impedance, so any amp can drive 2 ohms or 1 Ohm load as long as you turn the volume down enough to limit the output voltage (V). The only catch is that it no longer costs a fortune to electronically limit the current so a lot of manufacturer have done just that. Some may do it more aggressively than others.

Based on past bench test results, Yamaha appears to be on the aggressive side in their overcurrent and overload protection schemes.

Now that would have been interesting to talk about in Physics class!

Very interesting to know that by actual physics fact (Ohm's Law),any amp (including amps in AVR) can power 1 ohms loads as long as the current is limited.

You think one reason Yamaha is limiting the current in their AVRs (like A880 ) is so that the AVRs can safely power a wider variety of impedances (even though they legally recommend no lower than 4 ohms) ?

That's why Yamaha has specs for dynamic power down to 2 ohms for all their AVRs -- even the cheap Yamaha V385 has dynamic power of 180W into 2 ohms.

I don't see any other AVR brands with a 2-ohm dynamic power spec.

 

[PENG]

Now that would have been interesting to talk about in Physics class!

Very interesting to know that by actual physics fact (Ohm's Law),any amp (including amps in AVR) can power 1 ohms loads as long as the current is limited.

You think one reason Yamaha is limiting the current in their AVRs (like A880 ) is so that the AVRs can safely power a wider variety of impedances (even though they legally recommend no lower than 4 ohms) ?

That's why Yamaha has specs for dynamic power down to 2 ohms for all their AVRs -- even the cheap Yamaha V385 has dynamic power of 180W into 2 ohms.

I don't see any other AVR brands with a 2-ohm dynamic power spec.

Yamaha and NAD seems to be the only two who like to mention dynamic power rating based on the now defunct IHF standard.

https://usa.yamaha.com/support/faq/audio_visual/2483.html
https://support.nadelectronics.com/hc/en-us/articles/360000158988-NAD-Full-Disclosure-Power

That does not mean other main stay AVRs such as Marantz, Denon and Onkyo's cannot output into 2 ohm for some milliseconds.

Remember, of all the AVRs Avtech bench tested, only the Denon (3805) was tested with an 1 ohm load and "passed" and it was able to output almost 170 W into 1 ohm at 1% THD. Yamaha's failed the 1 ohm test but likely because of the more aggressive approach of their protective circuit.

I am a believer of the importance of dynamic power capability, but I don't think IHF's 20 ms duration is long enough for it to be of value except for some short and damped cymbal crash kind of deals. 200 ms would seem long enough to call it almost realistic.

https://www.stereophile.com/asweseeit/489/index.html

 

[mtrycrafts]

...
That's why Yamaha has specs for dynamic power down to 2 ohms for all their AVRs -- even the cheap Yamaha V385 has dynamic power of 180W into 2 ohms....

In essence the power cube measurements are dynamic power as it uses perhaps 20 ms of signal voltage, not continuous.

 

[AcuDefTechGuy]

In essence the power cube measurements are dynamic power as it uses perhaps 20 ms of signal voltage, not continuous.

Wow.

I thought the “Power Cube” measurement was gold standard. But it only use 20 ms of power, not continuous?

 

[AcuDefTechGuy]

Remember, of all the AVRs Avtech bench tested, only the Denon (3805) was tested with an 1 ohm load and "passed" and it was able to output almost 170 W into 1 ohm at 1% THD.

I recall the 1 ohm test was Dynamic Power, not continuous power.

But I don’t know if it’s 20 ms or 200 ms dynamic power.

But in reality, though, both 20ms and 200ms are much less than 1 second of time. 1000 ms = 1 second. So does it truly matter?

 

[highfigh]

Outlaw seems to caution me against running the 2200 on a 3 ohm speaker, so I decided to ask you guys. thx

I understand their disclaimer, but it brought me here to learn. Here is their statement: Our amplifiers support down to a 4 ohm nominal load. If using below this, like the CC5, and the amplifier is damaged due to heat, it would not be covered.

So, the manufacturer didn't tell you what you wanted to read or hear and you're asking us? What do you expect us to do for you?

Simple solution- put a non-inductive 1 Ohm load resistor in series. Is it the best solution? Maybe, maybe not. Bob Carver supposedly "modified his solid state amps to sound more like a tube amp" by adding a 1 Ohm resistor.

Make it 2 Ohms and the amp shouldn't have a problem.

Why would a speaker manufacturer design something that eliminates it as a candidate for most users? That's great marketing.

 

[highfigh]

Wow.

I thought the “Power Cube” measurement was gold standard. But it only use 20 ms of power, not continuous?

20ms is a long time when excessive current is concerned.

 

[TLS Guy]

I now have time to comment on this thread.

It goes back to points that are difficult, that I have often alluded to over the years. This does relate to the fact that bench testing of power amps with resistive loads is of limited use and hides a lot of problems.

Amp and speaker manufacturers would rather not talk about, and most others, for that matter as it is complex. Viewing a speakers impedance curve alone is also of limited use. You have to consider the relationship of current and voltage as well as impedance. This is the thorny issue of power factor. This gets us to the fact that the speaker amp interface not only makes a difference as to how amps sound, but more importantly whether a given speaker is likely to blow up an amp.

The OPs question is a classic case in point. The Magnepan speakers present an almost constant resistive load with phase angles close to zero throughout the range. So there will not be retained energy in the output devices. So even though the impedance may be 3 ohms, I would say those speakers are very unlikely to blow up his amp. I would not worry about the possibility of them doing so.

Since the inception of getting to know Peter Walker of Quad and tinkering with the early 405s, I have had a huge interest in these two issues. First is designing speakers less likely to blow amps up and secondly making amps more stable under a variety of loads. This was also a great interest of Peter Cooke's, founder of KEF. He carefully designed his crossovers to avoid amp busting loads. This is also a major reason that I think that amps actually belong in speakers. I firmly believe that speaker and amp should be designed as an integral unit.

I referenced this article previously. It is an important if difficult to understand issue. All of you would do well to try and understand it, and what it that that makes different speaker designs, and different speaker combinations potentially lethal to the amp.

So if your amp or receiver blows up more likely than not the responsibility lies with both amp and speaker, whatever the speaker manufacturer says the "nominal impedance" is. I don't think there was ever a more useless and misleading spec. than a quoted speaker impedance number.

I have not been very active here of late, as I'm busy working at our new home built. I will try and post an update on the projects there this weekend if I can.