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Underpowering Orange terror bass

#81
Nebadon2000 said:
Well Rick not being an engineer I was told exactly what crutchfield posted by many Engineers for over 40 years whom I then and still believe they were accurate and knowledgeable on the subject just like you seem to believe those you mention but still have not produced their post or at least a post saying what is blowing all those woofers. I am guessing you think Global Warming is a myth because 2 Scientist out of 100,000 said so.

I am going to hold on to my myth and not say it is ok to to use a 75 watt behringer amp into 2 1x15 with 89db efficiency and go ahead and crank it it will be fine you can never be underpowered.

Most of the time I was working and gigging didn't have much time for Forum; I have more time now and was first time I came across this topic.
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PS; How do you know your guy's are not 100% wrong; just a thought. You just called a lot of talented and good people I know and those at Crutchfield Idiot's or maybe just ignorant.[my guess is Idiots based on your past replies] So educate us or direct me to the education so your fellow Bass Player doesn't look the fool and reverts back to reality. Well I am not going to give up Ancient Alien Theory
 
#83
The challenge is to know what it will take to convince you that this widespread myth is myth, and how to demonstrate it. The very fact that the myth is so widespread does demonstrate that it's very plausible and that it's superficially very attractive. There's no shame in having been misled by something that has misled so many others.

One demonstration that occurs to me is square waves and crossovers. Would you agree that Crutchfield falls if the square wave never gets as far as the woofer? If so for someone with the facilities - oscilloscope and signal generator - it will be straightforward to demonstrate that while you may push a square wave into the crossover, what comes out of the tweeter and woofer terminals will be two very different wave forms. Sadly I lack that kit.
 
#84
Would one of the pros here care to critique a set of anotations of the Crutchfield piece posted above? I've written something which I think goes some way to exposing at least some of the misconceptions and misunderstandings, but I'm not an industry pro or any kind of expert and my own understanding is going to be limited. I'd hate to post something that contained errors or misconceptions of my own.
 
#88
JimChjones said:
Would one of the pros here care to critique a set of anotations of the Crutchfield piece posted above? I've written something which I think goes some way to exposing at least some of the misconceptions and misunderstandings, but I'm not an industry pro or any kind of expert and my own understanding is going to be limited. I'd hate to post something that contained errors or misconceptions of my own.
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I hear you; I understand with so many here saying I have been misled it is worth my time to investigate [which I will]
 
#90
Agedhorse is obviously very credible; read a few short post by him on subject. Comment only no explanations will keep looking.

Regardless of semantics of Square Wave/Clipping/Math technical debate/Myth and Underpowered' being a bad word choice. My point was to share my 'Real World' experience

When questioning someone who had blown their speakers [sometimes amp with them] many had IMO to small of an amp to drive speakers to level they wanted. When amp reached it's volume limit they just keep turning up volume knob hoping to get louder sound until POP.

Also many who had high power amp but not enough speaker; again when the speaker reaches its SPL max some keep turning up amp looking for more volume and eventually torch speaker. They need 'more' Speaker.

What technically is causing this I only know what I was told [see crutchfield] but it is what it is.

Yes you technically can't 'Underpower a Speaker' per se' but you can abuse it; IME failure seems easier to achieve with a low powered amp as opposed to proper sized or oversized amp.

I know through experience in the hands of Humans a low powered amp [or high powered] played into any Speaker past its limits continuously has the ability to damage itself and/or speakers; based on expectation of user.

IMO I believe it is important that when buying an amp insure that it has enough usable power to play loud enough for what you need with your EQ preferences/ drive, distortion etc. from preamp and have headroom left for dynamic's and peaks. 'What you need' is variable IE; Just need great tone for Bedroom or playing with Full Hard Rock Band.

I know in 'Home Audio world' back in the day Turntables and CD players could cause major problems with no HPF;Power being sucked up from musically unusable Ultra low frequency. I notice this has been a Topic recently in Pro Audio world.

In my experience 'Watt' spec's don't tell you how loud an amp or speaker may get in actual real world dynamic conditions cleanly.
 
#92
Most bass combos have a single 8 ohms speaker but only attain full power with the addition of another 8 ohms speaker. So, if I understand this notion of "underpowering", all combos are underpowered by design. If underpowering was a real thing, all combos would be blown.
 
#93
Nebadon2000 said:
From Crutchf
Fom Crutchfield;

Underpowering your subwoofer — Pop and Sizzle
Underpowering a subwoofer isn’t inherently bad for the sub. Not giving it enough power just means that the music will sound weak and lack detail.

The danger is when that power is coming from an amplifier that's being overworked and sending out a clipped signal. The clipped signal tries to make the sub do things it's not designed to do, which leads to it tearing itself apart or overheating and burning out.

First, what’s a clipped signal?
Clipping a signal, or squaring its waveform, occurs when the volume of a source signal exceeds the electronic capability of a circuit. Let's say our amplifier can't play a signal more powerful than what voltage V1 can produce. If we tried to increase the volume at the source, the amplifier wouldn't produce more voltage, it would distort the signal, eventually into the form of a square wave.

h12CBLCHRT-o_subwaves.jpeg
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In real practice we rarely (if ever) have to deal with things like steady sine waves.
Just to make more reliable "conclusions" you may want demonstrate the effects of clipping with more "practical" signals such as a real bass guitar signal that (natutrally) shows plenty of crest respectively rather highish Peak to RMS numbers.

For example if Lemmy (R.I.P.) would have played a 50 Watt RMS amplifier then his "distortion" was enough "suited" to get about 50 watt rms out of the ampifier.
You know that not every bass player wants to have a distorted sound like Lemmy did. You may figure that most of all players prefer a "slightly" compressed sound which equals a slightly "overdriven" sound yet not audible "distortion" to the total sound.

Lets consider the sine to square "mutation" for the distorted sound Lemmy used to do.
We have to "imagine" quite more of distortion to the (already) very distorted sound to really get 100 watt from a 50 watt amplifier.

At the one hand side we will experience (in real practice) already lots of distortion if the 50 watt amplifier would push 50 watt (bass guitar signal) to the cabinet.
At the other hand side we have to drive the amplifer even more into distortion to get twice the power (100 watt) than rated (50 watt).

If 50 watt was not enough power cause we would (theoretically) overload the power amp such as hard so the amplifier would double the power to 100 watt THEN its a good idea to predict the power that was needed for a "clean" audible signal.

In real practice you may figure non (audible) distortion to the signal for signal crest numbers in the range of 9..12dB

The 50 watt amplifier was pushed to 100 watt on the stage to get enough loudness for the task. The signal's crest was compressed down to 0dB.

If we want to reinforce the signal with at least 10dB of crest just to push 100 watt rms (loudness) we would have to provide an amplifier that was powerfull enough to push about 1000 watt rms 1% THD.


Its comprehensible that a suggestion like "have little more of amp power than the cab can take" is a very sad advice IF the advice was done with respect just to prevent from hypothetical "sine to square" scenarios.

I think "sine to square" scenario considerations are at best suitable to make "some science" comprensible to folks such as Joe Average.
So its no surprise nothing at all that even manufacturers with good reputation capture those simplifications just to make science "a little bit" comprehensible with "easy understanding" case examples.
Its not my intention nothing at all to blame manfucturers for beeing too simplistic. Without any academic approach its anyway nearly improbably to comprehent what is really going on under the hood. Any academic approach would by far exceed the capacity of "engineer Joe Average", and that's the reason why we can frequently read simplifying case examples.


However its sometimes sad to read that even "experienced" engineers frequently attempt to consider real world practice conditions with (easy understanding) simplifications which have actually only little practical relevance.
I also think that lack of understanding is (most often) a good breeding ground to let myths grow.
 
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#94
Nebadon2000 said:
When questioning someone who had blown their speakers [sometimes amp with them] many had IMO to small of an amp to drive speakers to level they wanted. When amp reached it's volume limit they just keep turning up volume knob hoping to get louder sound until POP.

Also many who had high power amp but not enough speaker; again when the speaker reaches its SPL max some keep turning up amp looking for more volume and eventually torch speaker. They need 'more' Speaker.

What technically is causing this I only know what I was told [see crutchfield] but it is what it is.
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Crutchfiled does not take into account the artifacts that come naturally along with any compression effects.
A very saturated signal can be considered as a very compressed signal that (naturally) gains transient sub noise.
The artifacts of transient (subharminic) noise can be clearly seen in this vid.
Note, transient noise is a very natural "side effect" in combination with playing any stringed instrument.
[sfx]:micro-thumpinator

Here you are with a consideration of this noise and what it means in real practice
Transient noise and what it means to woofer excursion

If there was no HPF present that prevents the woofer from overexcursion THEN it might happen that an overdriven amplifier hits too much of harmfull sub noise to the loudspeaker device and so may easily cause damage to the device.

Its also no surprise that an overloaded car amplifier may push too much of (harmfull) "random" noise to the loudspeaker which may be the real reason for damage.
Same consideration is valid for any kinds of HiFi subwoofer gear.

Academical approach for car audio.
Very likely everybody knows the "typical" synthetic "kick drum" sound which is most common with rather "modern" music genres such as hip hop.
Rather than harmonics the generated spectrum looks more close a broadband noise with a peaking at the lows yet beyond cab tuning. IF the amplifier starts to saturate then the power density below cab tuning may exceed save mechanical limits of the subwoofer.
While to the contrary an amplifier with sufficiant power may better reinforce the "peaking" of generated "transient noise" for just the same loudness demands.
 
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#96
Nebadon2000 said:
This from Barefaced Bass was clear and easy to comprehend with excellent information exceeding what is being discussed here.

Barefaced Bass - Mythbusters #1 - amplifiers
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this one is very alive and well still
Headroom is not the difference between amp power rating and cab power rating, but the difference between the maximum clean SPL your rig can produce and the normal max SPL required for your gig.
Click to expand...
when I searched for the great clipping DC square waves kills woofers beatdowns it was all 2014.
 
#98
In the application of your bass amp and a purpose built bass cabinet, I think it is extremely unlikely you would damage a speaker in this fashion. The drivers and tweeters found in your bass cabinet are extremely durable and built to handle distortion / noise.


However, as someone who builds HiFi Stereo amps and speakers and has damaged a driver with only 3 watts, please let me share my experience:


In the HiFi, audiophile world, the drivers that comprise the “speaker system” are purpose built with very a different intention than what is found in “Pro-audio” (instrument amplification and PA systems, for example). A great example of this are HiFi tweeters of various designs: ribbons, diaphragms, silk domes, metal domes thinner than a human hair – very fragile…. Basically a whole bunch of stuff you could never use to directly amplify your bass or guitar. Some of them can handle a fair bit of power (40 or 50 watts). What they can NOT handle is a distorted signal. They are designed to provide a “flat” frequency response across a given range. Most importantly, they are designed to receive a signal that is very low distortion (this is HiFi audio, after all). Distorted signals will actually damage the mechanical materials in many of these tweeters (especially ribbons), regardless of the amount of wattage thrown at them.


For an anecdote, just look at entry level integrated stereo amplifiers – their distortion specs AT MAX OUTPUT are usually around 0.01% Total harmonic distortion. THD is much lower within the normal operating range (like 0.001% THD or less – remember, generally speaking, THD increases as an amplification device is pushed to edge of its operating limits). A clipping amplifier producing 1% THD is sending a signal that is 100 times more distorted than the max THD produced by one of these stereo amplifiers.


So how do you damage a speaker by underpowering it? If you have a low powered amp and try to make it go louder than it is designed to go, you can create a relatively high amount of THD, while still only producing a few watts. Take something like a 2A3 tube based single ended triode amp. It produces up to 3 to 3.5 watts before getting close to 1% THD (within their operating range they sound amazing, BTW). If you try and push the amp and “cheat” by increasing the gain of a pre-amp you can cause the amp to clip as much as 4% or 5%. I did this and boom – metal dome tweeter damaged (it still functioned, but crackled when played). The driver was capable of handling much more wattage. It was NOT capable of handling being fed a signal with 5% THD. You do not need to hit the driver with a square wave to damage it. These tweeters will fail long before a square wave is applied.


So, YES, in some applications, damaging a speaker by underpowering is a real thing.
 
#100
Apples and Oranges. O.o You guys crack me up. HiFi speaker systems and Bass Cabs are two very different animals, just like a F1 racer and a Baja Buggy are very different cars. When the F1 pit boss tries to tell the Baja Buggy pit crew what's what is where we get our problems. You can't say that because a house cat buries it's poop, a lion has to as well, even though they're both cats.

"Underpowering" is a thing in the HiFi speaker systems world. It is not a thing in Bass Cabs.
 
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