Cabinet under powering?

[Ric5]

I have a 700 watt 2x10 8 ohm. cab and a 900 watt Bass head (4 ohms) If I add another exact same cab (1400 watts total); Will I be "Under Powering" my cabs. or is that ridiculous? Is there any risk involved at all to the cabs. or the head? Thanks. btw, it's a Genz Benz Streamliner 900 and a (? soon to be two) Avatar Delta pro 2x10 cab(s) ceramic not neo if it matters at all ...?

I cannot imagine a 900 watt head underpowering a cab ... unless you set the volume to zero.

Also 2 700 watt cabs does not equal 1400watts. 700 watts is the max power that the cab can take. 700 watts will mean hearing loss for those in proximity. Don't try this at home.

 

[Downunderwonder]

Well, the CONCEPT is valid.
If you have an underpowered SYSTEM you risk damage to the speakers by running it to the point of BAD distortion when attempting to achieve the volume you need. OR if you have a LARGE inefficient cab that needs a wad of power to really work you can "underpower it" and it will SOUND terrible (though zero risk).
I suspect this are where the myth of underpowering amps comes from.
Also - in sound reinforcement and hifi applications under-powering really is a thing - again, because if your power amp is distorting all night at truly full frequency reproduction you can easily damage speakers rated for considerably higher than what the amp is rated at - because the spikes in frequency are unsmooth (moving the speakers in a way they don't like) and potentially 2 to 3 times the rated RMS power. (so a 100 watt amp could be putting 250-300 watts into a 200 watt speaker - see?).
Again - really does NOT apply to bass reproduction - but probably a source of the mythology.

This is the underpowering myth complete with pseudo explanations. Square waves are not square in any other way than on a graph. A full clip is double RMS power.

What speakers don't like is either of too much voltage at too low a frequency sending the cone system past physical limit, aka over exursion, OR too much voltage at ''whatever'' frequency that results in too much heat transfered to the voice coil, aka overpowering.

 

[madjazzbass]

Not to drag this thing out any longer BUT, (2 weeks ago) when I asked someone else at Avatar about the Kappa Pro 10 LF speaker(s) (which is a 600 watt EACH speaker) and it IS listed on the Eminence site btw; Anyway, Avatar says they used to use those in their 2x10's but found they were too Heavy (like a 100+ Lb. magnet I believe) so they had the Delta pro 10 LF's designed specifically for them/Avatar and THAT'S why you wouldn't find them on the Eminence website.

 

[Ric5]

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[tonemachine]

I have a 700 watt 2x10 8 ohm. cab and a 900 watt Bass head (4 ohms) If I add another exact same cab (1400 watts total); Will I be "Under Powering" my cabs. or is that ridiculous? Is there any risk involved at all to the cabs. or the head? Thanks. btw, it's a Genz Benz Streamliner 900 and a (? soon to be two) Avatar Delta pro 2x10 cab(s) ceramic not neo if it matters at all ...?

Time for non-scientific, layman observations that have yielded no ruined equipment for 25 years.

Regarding OVERpowering: For a long time, I operated under the information that your amp should be more powerful than your cabinet rating. Like 2x powerful. This was assuming I wouldnt turn the amp up near 10. Someone smart suggested it and there was no Internet to bash it. I was told "just use your ears" for potential damage. I never had any ill effects but I rarely had to turn up over 5 or 6 for ear bleeding loudness so the speakers never strained.

My recent GK cabinet manual says:

DO NOT connect speakers with a total power handling capacity below the power output rating of your amplifier. If your amplifier is rated at 400 watts at 4 ohms, then the combined power handling of your
speaker enclosures should be 400 watts RMS or higher at 4 ohms.

So, this suggests that you can damage cabs by overpowering but it's silent on underpowering, which implies to me that underpowering isn't a threat to damage stuff.

I defer to just keep things roughly matched up so that 1) the speakers are highly rated enough that you can turn amp up loud enough to get the volume and sound you want and 2) the amp is powerful enough to not have to turn amp so loud that you over-stress the amp (I know nothing of this other than what God- knows- who wrote here). These are layman's observations but I've never ruined an amp or cab, no has my friend who seems to operate the same way.

I use a 500w 8 ohm amp into a 350 rated 210, or a 300 rated 112 or a 600w rated 212. My volume is between 2-6 on any amp and I turn the pre up to just under clipping.

I use the same amp at 800w at 4 ohms into a 300w rated cab paired with a 600w cab (so with 400w going into each, one is overpowered and one is underpowered- this is a potentially dangerous thing to do as the 300 is at risk but I don't turn up past 5 and the speakers still have much room for more).

I also have a 350w/500w amp that I run into the same cab configurations...so as little as 250w going to the 600w. No problems.

So there you have it....a range from 350w underpowered (less than 50% of potential) and 100w overpowered (33% over but never turned up past 6 so not really).

Nobody can seem to agree on this subject (science has been cited to back up opinions on both sides) so experience tells me to just stay in the ball park and use your ears. If you need to turn up to 8-10 to make your 250w amp loud enough to make your 600w speaker sound good, get a bigger amp. If at 6, your 800w amp is pushing your 350 w speakers too hard, get a bigger cabinet or add a cabinet (ideally a matching cab to assure a good sound with no clashing of any sort, according to those who study this).

Thanks.

 

[madjazzbass]

I'm curious. What did Trevor have to say about underpowering their cabs?

He told me with my amp (Genz Benz Streamliner 900), that I had nothing at all to worry about, that I'd be just fine with that setup /combination and that's the way it should be done. (in my case two 2x10 8 ohm cabs)

 

[moody]

Well, the CONCEPT is valid.
If you have an underpowered SYSTEM you risk damage to the speakers by running it to the point of BAD distortion when attempting to achieve the volume you need. OR if you have a LARGE inefficient cab that needs a wad of power to really work you can "underpower it" and it will SOUND terrible (though zero risk).
I suspect this are where the myth of underpowering amps comes from.
Also - in sound reinforcement and hifi applications under-powering really is a thing - again, because if your power amp is distorting all night at truly full frequency reproduction you can easily damage speakers rated for considerably higher than what the amp is rated at - because the spikes in frequency are unsmooth (moving the speakers in a way they don't like) and potentially 2 to 3 times the rated RMS power. (so a 100 watt amp could be putting 250-300 watts into a 200 watt speaker - see?).
Again - really does NOT apply to bass reproduction - but probably a source of the mythology.

Hi Fi and bass reproduction have no fundamental differences. Under the pseudo-gabble all this is talking about is clipping an amp (producing more watts than it is rated at) and overpowering the speaker.

If you got a low powered amp (e.g. 10 watts) and a high power handling speaker (e.g. 100 watts), and drove the snot out of the amp so that it was clipping and producing 30 or 35 watts of actual power then that speaker would be absolutely fine (and sound absolutely awful).

For the past 2 years I have been running for rehearsal an amp rated at 45ish watts clean into a speaker rated at 150 watts. I do drive the amp a heap in order to play with two guitarists and a drummer in a decently loud band and that speaker is still absolutely fine.

 

[Ric5]

Time for non-scientific, layman observations that have yielded no ruined equipment for 25 years.

Regarding OVERpowering: For a long time, I operated under the information that your amp should be more powerful than your cabinet rating. Like 2x powerful. This was assuming I wouldnt turn the amp up near 10. Someone smart suggested it and there was no Internet to bash it. I was told "just use your ears" for potential damage. I never had any ill effects but I rarely had to turn up over 5 or 6 for ear bleeding loudness so the speakers never strained.

My recent GK cabinet manual says:

DO NOT connect speakers with a total power handling capacity below the power output rating of your amplifier. If your amplifier is rated at 400 watts at 4 ohms, then the combined power handling of your
speaker enclosures should be 400 watts RMS or higher at 4 ohms.

So, this suggests that you can damage cabs by overpowering but it's silent on underpowering, which implies to me that underpowering isn't a threat to damage stuff.

I defer to just keep things roughly matched up so that 1) the speakers are highly rated enough that you can turn amp up loud enough to get the volume and sound you want and 2) the amp is powerful enough to not have to turn amp so loud that you over-stress the amp (I know nothing of this other than what God- knows- who wrote here). These are layman's observations but I've never ruined an amp or cab, no has my friend who seems to operate the same way.

I use a 500w 8 ohm amp into a 350 rated 210, or a 300 rated 112 or a 600w rated 212. My volume is between 2-6 on any amp and I turn the pre up to just under clipping.

I use the same amp at 800w at 4 ohms into a 300w rated cab paired with a 600w cab (so with 400w going into each, one is overpowered and one is underpowered- this is a potentially dangerous thing to do as the 300 is at risk but I don't turn up past 5 and the speakers still have much room for more).

I also have a 350w/500w amp that I run into the same cab configurations...so as little as 250w going to the 600w. No problems.

So there you have it....a range from 350w underpowered (less than 50% of potential) and 100w overpowered (33% over but never turned up past 6 so not really).

Nobody can seem to agree on this subject (science has been cited to back up opinions on both sides) so experience tells me to just stay in the ball park and use your ears. If you need to turn up to 8-10 to make your 250w amp loud enough to make your 600w speaker sound good, get a bigger amp. If at 6, your 800w amp is pushing your 350 w speakers too hard, get a bigger cabinet or add a cabinet (ideally a matching cab to assure a good sound with no clashing of any sort, according to those who study this).

Thanks.

Yes ... is there any single instance of speakers ruined by too little power? Of course not.

What will happen if you get a severe mismatch between head and cabinet then you will get bad tone.

 

[iualum]

Not to drag this thing out any longer BUT, (2 weeks ago) when I asked someone else at Avatar about the Kappa Pro 10 LF speaker(s) (which is a 600 watt EACH speaker) and it IS listed on the Eminence site btw; Anyway, Avatar says they used to use those in their 2x10's but found they were too Heavy (like a 100+ Lb. magnet I believe) so they had the Delta pro 10 LF's designed specifically for them/Avatar and THAT'S why you wouldn't find them on the Eminence website.

And yet the 10" Delta Pro LFs aren't shown as an option for either of Avatar's 210s. The 3 that are shown, for both, are the Delta Pros, DeltaLite II 2510s, & Faitals.

If they do have the LFs, why do they hide the LF's light under a bushel? How do they expect to sell LFs if no one knows they're even available? Having dead inventory isn't a particular hallmark of a for-profit business the last time I checked, anyway.

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[Downunderwonder]

Not to drag this thing out any longer BUT, (2 weeks ago) when I asked someone else at Avatar about the Kappa Pro 10 LF speaker(s) (which is a 600 watt EACH speaker) and it IS listed on the Eminence site btw; Anyway, Avatar says they used to use those in their 2x10's but found they were too Heavy (like a 100+ Lb. magnet I believe) so they had the Delta pro 10 LF's designed specifically for them/Avatar and THAT'S why you wouldn't find them on the Eminence website.

It must be something like Acme's oem specials.
They have crap tonne of power handling with piss poor sensitivity enables extended low range production.

The physics dictates that two tens need a certain amount of xmax for a given amount of lows from a reasonably sized box. The typical bass ten can't use 350w of bass.

The typical amount of available power has always dictated speaker cab solutions. Perhaps Avatar is going down same road as Acme.

 

[wcriley]

Interesting that the Xmax and sensitivity of the Kappa Pro 10LF are only slightly lower than the 3010LF, the power handling is a lot higher, and the VC diameter is identical.

 

[iualum]

Interesting that the Xmax and sensitivity of the Kappa Pro 10LF are only slightly lower than the 3010LF, the power handling is a lot higher, and the VC diameter is identical.

The really major spec difference is the weight. The 3010LFs coming in at nearly 10 lbs. less, lightening a 210 load by nearly 20 lbs.

 

[will33]

Interesting that the Xmax and sensitivity of the Kappa Pro 10LF are only slightly lower than the 3010LF, the power handling is a lot higher, and the VC diameter is identical.

Size/type of wire, windings, former, cooling design?

Suspension stiffness, flexibility of the cone, moving mass, motor efficiency & strength could all be added as well as far as X power being needed to move it X amount?

 

[agedhorse]

One factual correction... an amp can not produce more than 2x it's rated RMS power under the most extreme clipping possible (ie. a perfect square wave).

This whole speaker rating numbers race has gotten to the point of absurdity IMO.

The Kappa-pro 10LF is a generally poor choice for a bass cabinet just based on it's raw efficiency. At ~91.5dB/1W/1M, a big tradeoff has been made in sensitivity in order to support 7mm of linear excursion, but this loss of sensitivity might have been better handled (for overall performance) by a driver that is 1/2 the power handling but >3dB more sensitive which is what most engineering analysis would lead to. Without running the numbers, I would expect that Xmax would be exceeded in any reasonable sized cabinet at low frequencies somewhere between 300 & 600 watts RMS. Just because it may be able to handle the thermal energy for a short while (the duration of the test) doesn't mean that it will do so for a long time.

The Kappa-pro 10A is a better example of this, while rated at 500 watts RMS, it does not have sufficient Xmax to handle low bass frequencies anywhere near this power level. Now looking at the sensitivity of ~97dB/1W/1M, it's obvious to anybody involved in transducer engineering that a completely different set of tradeoffs have been made and that this driver would not be a good choice for a bass guitar cabinet but might be a good choice for a mid-bass driver in pro audio where high passed above 80Hz. With the HPF in place, there will not be the energy available at low frequencies to exceed the driver's mechanical limits.

One possible explanation for why cabinet power ratings are ever increasing is that the marketing departments are taking the ball and running with alternate methods of ratings, like program power (2x the RMS rating), or peak power (4x the RMS rating). This is no different than amp manufacturers publishing the peak power but not the RMS power. If we were to publish the peak power of, say, the Streamliner 900, it would be an 1800 watt amp when compared with other amps rated the same way. You can (maybe) see now why the folks who understand the science behind this topic are so frustrated by the perpetuation of these myths.

 

[will33]

The really major spec difference is the weight. The 3010LFs coming in at nearly 10 lbs. less, lightening a 210 load by nearly 20 lbs.

The 10-pounder prolly better for heavy metal.

 

[will33]

One factual correction... an amp can not produce more than 2x it's rated RMS power under the most extreme clipping possible (ie. a perfect square wave).

This whole speaker rating numbers race has gotten to the point of absurdity IMO.

The Kappa-pro 10LF is a generally poor choice for a bass cabinet just based on it's raw efficiency. At ~91.5dB/1W/1M, a big tradeoff has been made in sensitivity in order to support 7mm of linear excursion, but this loss of sensitivity might have been better handled (for overall performance) by a driver that is 1/2 the power handling but >3dB more sensitive which is what most engineering analysis would lead to. Without running the numbers, I would expect that Xmax would be exceeded in any reasonable sized cabinet at low frequencies somewhere between 300 & 600 watts RMS. Just because it may be able to handle the thermal energy for a short while (the duration of the test) doesn't mean that it will do so for a long time.

The Kappa-pro 10A is a better example of this, while rated at 500 watts RMS, it does not have sufficient Xmax to handle low bass frequencies anywhere near this power level. Now looking at the sensitivity of ~97dB/1W/1M, it's obvious to anybody involved in transducer engineering that a completely different set of tradeoffs have been made and that this driver would not be a good choice for a bass guitar cabinet but might be a good choice for a mid-bass driver in pro audio where high passed above 80Hz. With the HPF in place, there will not be the energy available at low frequencies to exceed the driver's mechanical limits.

One possible explanation for why cabinet power ratings are ever increasing is that the marketing departments are taking the ball and running with alternate methods of ratings, like program power (2x the RMS rating), or peak power (4x the RMS rating). This is no different than amp manufacturers publishing the peak power but not the RMS power. If we were to publish the peak power of, say, the Streamliner 900, it would be an 1800 watt amp when compared with other amps rated the same way. You can (maybe) see now why the folks who understand the science behind this topic are so frustrated by the perpetuation of these myths.

Some reasons I think people can "get away with" these type of ratings. Feel free to correct any or all....



When people come on here and say stuff like "no way that 210 handles 700 watts", they (rightly) point to mechanical excursion...BUT...they often quote the xmax figure. We'll call that "clean bass" just for purposes of discussion.

These manf. say nothing about a clean tone resulting from all that power. It's just a one-number rating. A lot of speakers, including most from Eminence "Pro" series can move a long way between clean tone and physical/mechanical damage.

Ok...combine that with the dynamics of a bass signal. Player with 700 watt amp, playing loud but keeping things in check enough to not sound like ass, won't be sending it all 700 watts except for the occasional, milliseconds of transient peak. The average signal is far less.

You think those two combine to make this thing keep from self-destructing?

In order to send it a constant 700 watts, or say even something less than that allowing for the speakers true mechanical limits in its particular cab design...the user would have to be hitting it with something like a 2000 watt amp, due to the dynamics of the signal.


User won't do that because now they cranked a "2000 watt" amp on their "700 watt" speaker, and now it's their fault for blowing it.

 

[iualum]

The 10-pounder prolly better for heavy metal.

Definitely .

 

[agedhorse]

Driving speakers that hard would result in cumulative damage... Xmech does not reflect cumulative damage but "instantaneous" mechanical limits that result in "smack-kaboom"

There are displacement versus time curves that reflect estimated lifespan of the mechanical suspension components. The more power over time you use, the greater the cumulative damage and the shorter the lifespan. How long you expect a speaker to last determines where on this curve you will want to operate.

 

[madjazzbass]

I cannot imagine a 900 watt head underpowering a cab ... unless you set the volume to zero.

Also 2 700 watt cabs does not equal 1400watts. 700 watts is the max power that the cab can take. 700 watts will mean hearing loss for those in proximity. Don't try this at home.

One factual correction... an amp can not produce more than 2x it's rated RMS power under the most extreme clipping possible (ie. a perfect square wave).

This whole speaker rating numbers race has gotten to the point of absurdity IMO.

The Kappa-pro 10LF is a generally poor choice for a bass cabinet just based on it's raw efficiency. At ~91.5dB/1W/1M, a big tradeoff has been made in sensitivity in order to support 7mm of linear excursion, but this loss of sensitivity might have been better handled (for overall performance) by a driver that is 1/2 the power handling but >3dB more sensitive which is what most engineering analysis would lead to. Without running the numbers, I would expect that Xmax would be exceeded in any reasonable sized cabinet at low frequencies somewhere between 300 & 600 watts RMS. Just because it may be able to handle the thermal energy for a short while (the duration of the test) doesn't mean that it will do so for a long time.

The Kappa-pro 10A is a better example of this, while rated at 500 watts RMS, it does not have sufficient Xmax to handle low bass frequencies anywhere near this power level. Now looking at the sensitivity of ~97dB/1W/1M, it's obvious to anybody involved in transducer engineering that a completely different set of tradeoffs have been made and that this driver would not be a good choice for a bass guitar cabinet but might be a good choice for a mid-bass driver in pro audio where high passed above 80Hz. With the HPF in place, there will not be the energy available at low frequencies to exceed the driver's mechanical limits.

One possible explanation for why cabinet power ratings are ever increasing is that the marketing departments are taking the ball and running with alternate methods of ratings, like program power (2x the RMS rating), or peak power (4x the RMS rating). This is no different than amp manufacturers publishing the peak power but not the RMS power. If we were to publish the peak power of, say, the Streamliner 900, it would be an 1800 watt amp when compared with other amps rated the same way. You can (maybe) see now why the folks who understand the science behind this topic are so frustrated by the perpetuation of these myths.

Thanks for explaining that to me in a civilized manner.

 

[hsp-sandiego]

A Genz Benz 900 powering (2) Avatar 2x10 8 ohm cabs? sounds like a nice rig.