Higher wattage amp or Cab?

[agedhorse]

That a speaker could be damaged by less power than it is designed to handle was never the intended argument.

It is not that 400W will damage a 500W cabinet. It is that a 400W rated amp can damage a 500W cabinet.

A danger is that someone might assume that they are perfectly safe driving a 500W cab with a 400W rated amp, and therefore drive the amp as hard as want.

-

This is especially important when an amp is designed to be able to be overdriven for an extended period of time, thus delivering greater than rated average power to the load. JBL had a nice discussion about this in one of their early guitar speaker application notes.

 

[seamonkey]

Here is a great article on Eminence Power rating.
Loudspeaker power handling | Eminence Speaker

"Eminence uses an industry standard method (EIA 426A) for establishing power ratings."
Imagine that, and industry standard!
Putting them into a box is gong to affect this. I don't know of a single cabinet manufacturer that rates to a standard. Nobody tests until burnout.

And there's no bass amp standards.

I believe that some are going to stick by their crazy edge case that breaks all the rules because they really don't know what they got in the first place. In Cabinet or Amp - It's a tough world out there.

 

[Korladis]

If the volume is the same, then it is the same. Power amp distortion is no more dangerous than any other distortion provided it isnt over powering the speakers.

Indeed. The reason people associate power amp distortion with damage to speakers is because typically when power amps are distorting, they're sending more power to the cab than the amp is rated as producing. It's the power, not the distortion, that's doing the speaker killing. Though the distortion might also mask the sounds of the speaker having trouble.

For the benefit of everyone else, your amp is a good example.

A Peavey Classic 400 is a 400 watt tube amp. That means it produces 400 watts clean. But if you use a 400 watt or 500 watt cab with it, you could be in trouble if you crank the amp all the way up. While it is rated for 400 watts clean, you can turn it up well past the point that it's clean, and it will be producing quite a bit more power. If your cab only handles 400 watts, this could be a major problem. If I was using this particular amp, and thought I might crank it, I would want my cab (or cabs, if I was using a modular rig) to be able to handle 800 watts or more.

 

[BadExample]

Correct, common sense helps considerably.

Sadly, that seems to be in very short supply nowadays

 

[JesseVMT]

My cab is rated at 1000 and my amp at 500. Works for me!

 

[agedhorse]

Here is a great article on Eminence Power rating.
Loudspeaker power handling | Eminence Speaker

"Eminence uses an industry standard method (EIA 426A) for establishing power ratings."
Imagine that, and industry standard!
Putting them into a box is gong to affect this. I don't know of a single cabinet manufacturer that rates to a standard. Nobody tests until burnout.

And there's no bass amp standards.

I believe that some are going to stick by their crazy edge case that breaks all the rules because they really don't know what they got in the first place. In Cabinet or Amp - It's a tough world out there.

Too bad this industry standard uses very limited dynamic range, limited bandwidth, and is in fact based on destructive tests. If you are happy with a test that only requires a speaker to survive for only 2 hours (or 8 hours depending on the standard version) and a test that in no way represents how the speaker performs within an enclosure, by golly worship those standards.

Most players prefer their speakers to be rated to survive more than 2 hours in real life, as do most manufacturers who warranty their products. The identical speaker may survive 2 hours at 600 watts, 8 hours at 450 watts and 6000 hours at 300 watts. Which number would be most representative and honest of a quality product to the average player? All 3 are accurate, but the standard is highly misleading IMO. (standards be darned).

 

[Korladis]

Sadly, that seems to be in very short supply nowadays

Read local news stories from a hundred years ago, or just look at some of the harebrained modifications made to instruments and amplifiers in the past, and it's apparent that common sense was never actually common.

 

[seamonkey]

Too bad this industry standard uses very limited dynamic range, limited bandwidth, and is in fact based on destructive tests. If you are happy with a test that only requires a speaker to survive for only 2 hours (or 8 hours depending on the standard version) and a test that in no way represents how the speaker performs within an enclosure, by golly worship those standards.

Most players prefer their speakers to be rated to survive more than 2 hours in real life, as do most manufacturers who warranty their products. The identical speaker may survive 2 hours at 600 watts, 8 hours at 450 watts and 6000 hours at 300 watts. Which number would be most representative and honest of a quality product to the average player? All 3 are accurate, but the standard is highly misleading IMO. (standards be darned).

Ah, cool so you test up to burnout, with your own amp rating. Let see the video!

 

[BadExample]

Sadly, a video of the voice coil burning silently, invisibly and buried out of sight deep within the speakers' guts will never catch up with this one in terms of views:

 

[agedhorse]

Ah, cool so you test up to burnout, with your own amp rating. Let see the video!

I often do destructive testing (amps and speakers), and I use one of several bass loops developed to test the specific limits that I am investigating. The loops used for thermal stressing are different than the ones used for mechanical stressing. There are a variety of loops for each test. This way I have high confidence that the products I design will hold up as expected for players who are playing something other than some standard (or otherwise) test signal.

 

[Rip Van Dan]

I've never gotten this "more headroom" argument. Because if your amp can put out 1000 watts and your speakers can only really handle 500, the reality is that you don't have that headroom. Sure, your amp might be clean up to 1000 watts, but you can't actually use that much. You can only use 500.

I prefer a cab that handles enough power to not care if my amp is completely cranked. Speakers can be expensive to repair.

So here's part of the answer for the OP about the amp being able to put out more power than the speakers can handle. You almost never run your amp at maximum output because you rarely need to, especially if you have an 800 watt amp. If you run an amp that is capable of delivering more watts than the speaker can handle, your amp is going to just cruise along and easily put out whatever lower amount of watts it is you need. That means the amp runs with less heat and less heat means more reliability and less wear and tear on internal components - longer life for you amp. So that's a good thing. However it does mean that you need to pay attention to what you are hearing and if you start hearing farting sounds from your speakers, either turn your bass EQ down a couple of clicks and then drop the master if needed, or just go right to the master and drop it down. Just pay attention to what you are playing and how it sounds. Having an amp with more than enough power also makes it easier to add more cabinets if you want to.

I ran a couple of cabs off a 400 watt amp for a while. One cab had power handling of 200 watts and the other only 100-watts. If I played to aggressively - got too loud - the 100-watt cab would start to distort and I would have to back off immediately. I later replaced that 100-watt cab with a 400-watt power-handling cab and no longer needed to worry much about it. However, I could still hurt the cabs even though they were capable of handling more watts than the amp could deliver if I boosted the bass EQ too much. So you still have to pay attention to what you're playing and how you're playing it.

OK...this is the part where I tell you I now play with a cabinet that can handle more power than my amp can put out. I have an 800-watt amp and the DNS410 cab can handle 1400-watts. So I really don't need to worry much about it. Good news is that the cab is so efficient that it gets unbearably loud before I can run 800-watts into it. I'm not worried about hurting the speakers in my cab. That efficiency allows my amp to use less power for more than enough volume so I run the master typically between 9 o'clock and 9:30 , and my amp gets warm but not hot. Truth be known, I don't need an 800-watt amp to drive this cab to gig levels, but you never know when you might be asked to play a stadium...always be prepared.

Another variable that perhaps hasn't been thought about is speaker efficiency. If your speakers have high efficiency to start with, it doesn't take as much power to make them loud, so you may not need a particularly powerful amp. If on the other hand you have a speaker cab that has high power handling but it isn't efficient, then your lower-watt amp might not be able to get your speaker cab up to gig volumes. My current, high-watt handling 410 has an SPL rating of 106db 1W/1M (2.83v/1M), which is huge. The 410 it replaced had an SPL of 92 db 1W/1M (2.83v/1M), which is pretty poor. So my newer cab not only handles 3 times the watts, it's also far more efficient - 14db louder with 1 watt powering it.

So this stuff really is a balance kind of thing and there are many ways to make it work satisfactorily. If you have a cab capable of handling far more watts than your amp can put out and your amp doesn't have enough watts to drive that cab to gig volumes, then you have a problem where you should either use a more powerful amp OR more efficient speaker cabs. So there are a couple of choices for that problem.

On the other hand, if you amp can put out more than the speakers can handle, then you have to be sure to pay attention to your sound so you cam recognize and compensate for any speaker stress before it creases your speaker, melts your voice coil, or just tears the cones apart. Listening to what you're playing really isn't that hard to do.

Lots of ways to skin this cat.

 

[Old Garage-Bander]

What are those circumstances?

From where I stand, running a lower powered amp into a higher capacity cab is a very safe bet, and will give you more perceived volume than the other way around.

So after reading the entire thread... Can a lower power amp ever damage a higher power speaker?

 

[agedhorse]

So after reading the entire thread... Can a lower power amp ever damage a higher power speaker?

Yes, if you drive the lower powered amp so hard that it delivers more than its rated power (such as when clipping)

 

[cchorney]

So after reading the entire thread... Can a lower power amp ever damage a higher power speaker?

I'm not an electrician, or an amp tech, or an expert (in anything), but my understanding is that an amp rated at 100 watts could, if turned up to max and played aggressively, produce spikes far in excess of 100 watts. So, if you have a 100 watt amp and a 200 watt speaker, and you dial up that bad boy and really dig in when you play, you will generate peaks in excess (maybe far in excess) of the rating of that amp and possibly of what the speaker can handle, then in that specific circumstance, a lower power amp can damage a higher power speaker - but it's do so because it's producing a signal significantly higher than it's rating. However, if the speaker is rated high than the highest possible spikes your hypothetical amp can deliver however abused, than no, in that case a lower power amp can not damage a higher power speaker.

 

[Old Garage-Bander]

Yes, if you drive the lower powered amp so hard that it delivers more than its rated power (such as when clipping)

Thank you. That was what I was trying to get at all along.
I find that I sometimes have trouble putting something into words that is floating around in my head.
Things might make sense to me but for some reason I have trouble articulating those concepts so others get what I'm trying to say.
I'd never make a good school teacher for that reason.
Maybe it's better if I don't try here, it might lend itself to doing more harm than good.
Always glad to have your reasoned and clear explanations on stuff Agedhorse.

 

[CL400Peavey]

Yes, if you drive the lower powered amp so hard that it delivers more than its rated power (such as when clipping)

Thank you. That was what I was trying to get at all along.
I find that I sometimes have trouble putting something into words that is floating around in my head.
Things might make sense to me but for some reason I have trouble articulating those concepts so others get what I'm trying to say.
I'd never make a good school teacher for that reason.
Maybe it's better if I don't try here, it might lend itself to doing more harm than good.
Always glad to have your reasoned and clear explanations on stuff Agedhorse.

But that is still over powering the speakers. It isnt that the amp is too low powered for the cab, it is still a case of too much power. Its not like a 25 watt amp is going to blow an 810 just because it is pushed in to clipping.

 

[agedhorse]

But that is still over powering the speakers. It isnt that the amp is too low powered for the cab, it is still a case of too much power. Its not like a 25 watt amp is going to blow an 810 just because it is pushed in to clipping.

Correct.

 

[CL400Peavey]

Correct.

There is too much old superstition about low powered amps sending clipped signals, and "under powering" speakers. Just trying to be clear on that.

 

[agedhorse]

I'm not an electrician, or an amp tech, or an expert (in anything), but my understanding is that an amp rated at 100 watts could, if turned up to max and played aggressively, produce spikes far in excess of 100 watts. So, if you have a 100 watt amp and a 200 watt speaker, and you dial up that bad boy and really dig in when you play, you will generate peaks in excess (maybe far in excess) of the rating of that amp and possibly of what the speaker can handle, then in that specific circumstance, a lower power amp can damage a higher power speaker - but it's do so because it's producing a signal significantly higher than it's rating. However, if the speaker is rated high than the highest possible spikes your hypothetical amp can deliver however abused, than no, in that case a lower power amp can not damage a higher power speaker.

In this case, it's not peaks but the average thermal power that exceeds the amp's rated power. This type of overpowering is purely a thermal event since the signal is bounded by the limits of rail voltage.

 

[Bob Lee (QSC)]

1. You need a loudspeaker system (i.e., a cab or cabs) that can do what you want it to do with respect to volume, frequency range, tone or voicing, etc. This is requirement number 1. If you don't have this you will not have a satisfactory setup, period.
2. You need suitable amplification for the loudspeaker(s) that will allow you to do what you want it to do. The general rule of thumb of selecting amp power that is approximately equal to loudspeaker "program" power, or about 2× the thermal or continuous power rating, will work for many applications. But if you do a lot of EQ boost in the deep low frequencies, you might be better selecting amp power that's closer to the loudspeaker's continuous (thermal) power rating.

Keep in mind that blowing loudspeakers almost always arises from trying to do too much (too much SPL, too much deep bass, etc.) with too little.