Confused about underpower/overpower amp and speakers? What gets damaged?

[canidoit]

I am a little confused as to where the line is regarding what gets damaged regarding speakers and amps.

I have a Hafler P3000 which is 200w into 4ohms(per channel) which runs a 400watt each speaker bin (18inch driver and horn tweeter) at pretty loud levels. I run the Hafler at max and use my converter to control the volume. So far, no issues.

I bought a Samson Servo 170, which is 85watts into 4ohms per channel which I plan to use on the 400watt speaker bin so I can use the bins as a sub with my NS10's because the bins do not do mid to high frequencies very well, unless I eq the bins. I do not need to have it loud, as I am more of a listening level listener. I will then use the Hafler with my NS10s, that way I have a full range monitoring setup.

This is where it confuses me? I have read, if the amp is not powerful enough to move the driver, the amp will blow. If the amp does move the driver, it must move it continuously and not be stagnant or the speakers will blow? Is this correct?

Regarding my Samson and Speaker bins setup, if I leave the amp at max high volume and feed it signal that is low, what exactly gets damaged?

How should I be running speaker bin and Samson setup in order not to damage anything? What levels should I be considering and setting up on amp and converter volume? What should I be watching out for?

Thank you.

 

[cyrano]

I have read, if the amp is not powerful enough to move the driver, the amp will blow. If the amp does move the driver, it must move it continuously and not be stagnant or the speakers will blow? Is this correct?

Nothing will blow, unless you allow the amp to distort a long time because it's clipping.

Regarding my Samson and Speaker bins setup, if I leave the amp at max high volume and feed it signal that is low, what exactly gets damaged?

That's hard to tell. An amp that's starting to fail, because of overheating, fi, might produce DC and could blow up your 400W 18" speaker.

I hope you've heard the clipping and turned down the volume long before that happens. If not, you need to get a hearing check, I reckon

How should I be running speaker bin and Samson setup in order not to damage anything? What levels should I be considering and setting up on amp and converter volume? What should I be watching out for?

Thank you.

Don't worry about it.

The only thing I'd worry about, is the occasional digital glitch at 100% output. That's why I'd put an attenuator between the DAC line out and the power amp input. Usually, the power amp's inputs are too sensitive to get the best out of your DAC anyway.

 

[JohnRoberts]

This a well explored topic in professional sound reinforcement with many old myths that refuse to die.

a) a well designed amplifier should be customer proof (at least the Peavey amps were) so cannot be harmed in normal use.

b) speakers break, think of them like tires on a car, but used properly within their design limits they will deliver a robust useful life. What you want to do is avoid premature speaker failures. This is where the most myths arise.

Too much power is commonly blamed for speaker failures, but that has two aspects. #1 is over-excursion, telling the speaker to zig or zag much further than it can will cause problems , and bad noises... #2 is overheating the voice-coil and melting a coil winding.

I sense a poor grasp of the amp/speaker cause effect relationship so will wait for better targeted questions. In general speakers do not fail from using too big of an amp, but from turning an amp up too high. Peavey offered a amplifier clip-limiter that would briefly modulate down the gain to stop amplifier clipping (DDT). That saved many Peavey loudspeakers, because the customer is always right, even when wrong.

good luck, but avoid simple answers for complex questions. I just hit on a few high points

JR

 

[PermO]

...the power amp's inputs are too sensitive to get the best out of your DAC anyway.

This is an interesting remark.
Modern DACs have very low ouput impedance 25 / 30 Ohms... I know that input impedance must be a multiple of the output impedance, it can be "too low" can it also be "too high" ?


About overpowered / underpowered, from personal experience I can tell you underpowered has a chance of faillure you will not get from a overpowered amp.
As teens we ran a drive in show, DJ ing at partys with DIY PA speakers driven from a (mine) Akai hifi amp, not one of those big old Japanese beasts from the late 70's...but a late 80's "2 x 40W" STK module.
It quit and put out DC, enough to smoke a bunch of drivers... end off the party.

It was also my hifi amp, so that sucked... So I got to borrow an amp from the place I worked, a Stage Accompany PPA500 PA amp. I hooked it up at home thinking, "oh boy now I'm going to blow these speakers also" but to my surprise it sounded amazing. My hifi setup had never sounded so good, that big old battered amp completely changed my perspective on hifi and amplifiers.

They wanted it back after some weeks

 

[cyrano]

This is an interesting remark.
Modern DACs have very low ouput impedance 25 / 30 Ohms... I know that input impedance must be a multiple of the output impedance, it can be "too low" can it also be "too high" ?

I was thinking about level, not impedance. Usually, 0 dBFS = full power. Maybe that's fine at PA level, but not at a studio monitoring level.

Obviously, your interface can lower that level, but to stay within reason, a -20 dB attenuator is needed imho.

About overpowered / underpowered, from personal experience I can tell you underpowered has a chance of faillure you will not get from a overpowered amp.
As teens we ran a drive in show, DJ ing at partys with DIY PA speakers driven from a (mine) Akai hifi amp, not one of those big old Japanese beasts from the late 70's...but a late 80's "2 x 40W" STK module.
It quit and put out DC, enough to smoke a bunch of drivers... end off the party.

These STKs fail a lot and they're certainly not made for PA duty. Some of these amps don't have the cooling needed to run long and hard, so they'll blow...

It was also my hifi amp, so that sucked... So I got to borrow an amp from the place I worked, a Stage Accompany PPA500 PA amp. I hooked it up at home thinking, "oh boy now I'm going to blow these speakers also" but to my surprise it sounded amazing. My hifi setup had never sounded so good, that big old battered amp completely changed my perspective on hifi and amplifiers.

They wanted it back after some weeks

I wouldn't mind having an SA PPA500, but these still fetch high prices...

Besides, I'm pretty satisfied with my current collection power amps (Ecler, Apart, Hypex). None of these are high-end, but when I need the power they can provide, they sound pretty decent. My main monitors (Heco and Philips) are active. A little harder to blow up, as the sensitivity is paired to the efficiency of the speakers.

 

[PermO]

Yes I agree DAC directly to amp can be a bit "dangerous" unless you have a DAC with preamp function / volume control on the outputs, but usually it's set somewhere in some software, and the day you forget to check the level setting in your software you will have a blast.

-20dB seems like a save choice, it could still get pretty loud but nothing will brake, it will just wake you up.

 

[Tubetec]

We used use an Amcron Macrotech 1200 on the NS-10's in a studio I worked . its way above the power rating of the speaker itself , but as long as the long term average power is kept within sensible limits it works just fine . In fact smaller amps are more likely to do damage if their heavily clipped . Short term clean peaks well in excess of the speakers rating arent a problem , where clipped waves from more modest amps can fuse out a voice coil very easily .

 

[Khron]

https://sound-au.com/tweeters.htm
https://sound-au.com/clipping.htm

 

[canidoit]

We used use an Amcron Macrotech 1200 on the NS-10's in a studio I worked . its way above the power rating of the speaker itself , but as long as the long term average power is kept within sensible limits it works just fine . In fact smaller amps are more likely to do damage if their heavily clipped . Short term clean peaks well in excess of the speakers rating arent a problem , where clipped waves from more modest amps can fuse out a voice coil very easily .

Hi tubetech, is the clipping problem on smaller amps caused from the input signal being too high causing distortion and the amp also has to be on full volume or will the speakers be ok if the amp is at ok/low volume(even though the sound is distorted)?

When exactly does the amp blow? If I feed the amp a signal to the point it is distorting, like on a pre-amp, the amp will blow?

Thanks everyone for the replies, I am sort of getting it.

 

[PermO]

You won't "blow an amp" by distorting it's inputs, it will just sound nasty.

You could blow an amp by demanding more than it was designed to handle, by shorting an output at full power.

In most cases you'll probably blow your ears before your amp.

 

[JohnRoberts]

at least we haven't seen that bogus old JBL consumer white paper about tweeters blowing (no do not search for it).

Hi tubetech, is the clipping problem on smaller amps caused from the input signal being too high causing distortion and the amp also has to be on full volume or will the speakers be ok if the amp is at ok/low volume(even though the sound is distorted)?

I'm no tubetech but clipping distortion receives too much blame for speaker failure. When an amplifier is driven beyond simple clipping you are also increasing the average output power in some cases significantly. Heat from higher power is what causes most speakers to fail.

When exactly does the amp blow? If I feed the amp a signal to the point it is distorting, like on a pre-amp, the amp will blow?

A well designed amp should not blow. Peavey amps would tolerate short circuits on their output and severe clipping (if DDT is switched off). With DDT switched on you can't clip them.

Thanks everyone for the replies, I am sort of getting it.

It's not rocket science but not obvious which keeps the old myths alive and in circulation.

In general I would advise against driving amplifiers into hard clipping (unless you are using a tube guitar amp for the clipping sound). Few people follow my advice tho.

JR

 

[Brian Roth]

This is slightly on topic.

In many studio installations, I've seen some pretty crazy "gain structures" in the signal path from whatever provides the control room signal (a Mackie Big knob is an example....the CR output from a desk is another).

In a poorly adjusted system, setting the CR level control to "barely on" results in thunderous SPL from the speakers. I like to set up the systems so that at "2:00" on the CR monitor pot the SPL from the speakers is "plenty loud and fun"....not at "9:00" on the CR control pot.

That will reduce the chances of blown speakers in case of an OOPS!

If there aren't level adjustments on the power amp driving the speakers, then some sort of inline pad is suggested.

Bri

 

[abbey road d enfer]

Hi tubetech, is the clipping problem on smaller amps caused from the input signal being too high causing distortion and the amp also has to be on full volume or will the speakers be ok if the amp is at ok/low volume(even though the sound is distorted)?

This is a very fundamental aspect you need to understand.
Turning the "volume" down on an amp does not mean its power is restricted. It just means the signal at the input needs to be cranked up for the same output power.
Typically an amp with the "volume" cranked up requires about 1V at the input to deliver its rated power.
Turning the volume pot at 12 o'clock will attenuate by about 20dB, which means it takes 10V at the input to deliver the same rated power.
Since many sources have the capacity to deliver 10V, it is still possible to make the amp deliver its rated power, even with the "volume" turned down.

Whether the signal produces distortion is not a matter of its intrinsic amplitude; its in relation with the actual amp's gain, which includes whatever attenuation introduced by "turning the volume down".

Now, of course, it the overall gain is low enough (read "with the volume pot turned down a lot"), the source may not have enough juice to run the amp at its max power.

 

[JohnRoberts]

One important aspect about audio hasn't been explored here yet. Music is dynamic with brief transient peaks and more continuous average power levels several dB lower. It is possible to turn up a conventional power amp higher than where peak clipping first occurs. Small amounts of clipping are generally well tolerated by listeners but if you keep turning up even louder past peaks first clipping you can deliver multiple times the average power into speaker voice coils. Fast acting clip limiters can protect speakers from excessive overpowering.

JR

 

[deedee]

a) a well designed amplifier should be customer proof (at least the Peavey amps were) so cannot be harmed in normal use.

Many years ago I was in a band that used a 400W/ch Peavey power amp for the full-range PA. During a gig, someone kicked the fan guard, preventing the fan from spinning. The first anyone knew that this had happened was at the end of the gig - the amp was too hot to handle but still working perfectly.

 

[CJ]

that was probably the infamous cs 800 rack mount designed by my ol buddy jack teagarden who was superseded by mr. dynamite.

 

[brucega]

I rented one of those for a church function in the early '80s... I almost couldn't pick it up. It coasted for what we were using it for. I know a lot of folks knock Peavey a lot, but what I've ever used was very reliable and worked well.

 

[Nick Nack]

that was probably the infamous cs 800 rack mount designed by my ol buddy jack teagarden who was superseded by mr. dynamite.

That's the one. 3u high, and a cast aluminium front panel.

I used a Peavey 2x15 bass cab for years. Again, unbreakable.

 

[Gavin Pursinger]

BE VERY VERY CAREFUL WITH BIG AMP/LOW WATTAGE SPEAKERS WHEN YOU CUE UP SOMETHING....MANY TIMES IN THE HEAT OF BATTLE, A CUE BUTTON IS PUSHED...MANY CONSOLES ELIMINATE THE FADER AND SEND AN A CUE FROM THE CHANNEL INPUT ATTENUATOR. CROWN DC 300A MANUAL HAS A CHART FOR USING FAST ACTING FUSES AS PROTECTION. LOAD IMPEDANCE TO WATTS LIMIT. EASY TO USE THIS CHART. PLAY IT SAFE !!!

 

[JohnRoberts]

that was probably the infamous cs 800 rack mount designed by my ol buddy jack teagarden who was superseded by mr. dynamite.

CS800 was designed by Jack Sondermeyer (RIP)... I used to have an office right next to his and would occasionally see flashes of light reflect off his glass door from stuff he blew up on his bench.

JR