Higher wattage amp or Cab?

[CL400Peavey]

The warning about underpowering speakers (in the sense of definitions 2 or 3 above) goes back at least as far as the 70's, and was also related to hi fi stereo equipment, not just musical instrument equipment. Low power stereo amps were quite capable of burning up tweeters when the amps were overdriven for "party" volume.

I would still consider that over powering the tweeter. More harmonic content sends more power to the range the tweeter is working in, and the tweeter or what ever is used as a filter sees more power than it can handle.

It all comes down to understanding the limitations of the set up. People need to stop trying to do too much with too little. If they dont understand why the keep killing their equipment, it is on them to rise to that challenge of understanding. Lowering the bar with "Under powering" explanations just has people doing dumb stuff like using amplifiers rated 3-4 times higher than what their speakers can handle.

 

[seamonkey]

Bass guitar signals are very asymmetrical thus they contain a lot of *DC" in theory, like most of audio program material but, that doesn't matter

+1 Link Removed
But designers can account for this - and I don't know an any amp maker who would direct couple in the MI world.

On the asymmetric, when pushed into clipping that bass compresses, and mids and highs get louder. It's easy to see if you take a bass waveform, any bass waveform, and push it into clipping. You'll see all the subtle little waves riding on the bass wave get much bigger inside the rail zones. A sine wave doesn't have any harmonics, so you don't see this.

 

[ThisBass]

Bass signals do not contain a lot of DC; in fact the pickup is not even capable of generating DC.

Overall, a bass signal is symmetrical. There are transient asymmetries that may be biased towards one polarity or the other, but these hardly constitute DC by themselves.

If there really was a lot of DC present, it would force the speaker cones away from their zero rest position and severely limit the output. This obviously doesn't happen.

-

All kinds of signals which perform the criteria of "half cycle symmetry" in the form of:
f(t + T/2) = -f(t)
are characterized by the presence of (only) odd order Harmonics for the spectrum.
Typical signals are sine, square and triangle which all fullfill this half cycle symmetry criteria.
The number 1 belongs to odd numbers thus the sine can be considered as a function that consists of only one odd Harmonic

Signals like a bass guitar signal and a sawtooth show an "unsymmetric" characteristic regarding the criteria of "half cycle symmetry".
Those signals are characterized by the existence of even AND odd order Harmonics for the spectrum.

While the sawtooth half cycles are of same amplitude number in very contrast the bass guitar signals "half cycles" are of very different amplitude level numbers. Just to "match" the bass guitar signals half cycle amplitudes would demand some DC to shift the whole signal off from it's "zero" point (base line).
That's the reason why I talked about a "theoretical" DC related with bass guitar signals.

For example, while a sawtooth half cycles may be of 1 V peak each, to the contraray a bass guitar signal of same rms may show 1 V peak as well for the first half cycle but 2 V peak for the second half cycle. Note, by same rms Volt for both signals!
Note, a poor peak number on it's own tells nothing about rms Voltage or power of the signal but, peak numbers can tell something about necessary headroom just to amplify the signal without clipping

If a bass guitar signal runs into clipping means that the half cycles are (most often) clipped something differently cause the half cycles are of different amplitude towards the zero point. That's valid as long as there is no DC involved to shift the whole signal or a distinct schematic design provides "uneven" clipping characteristic.

 

[-Asdfgh-]

There are a number of spectral analysis VSTs out there, so recording your playing into a DAW and having a look might be interesting at this point

 

[ThisBass]

Taken from the bass gear mag review of the RH450 (hope it's not forbidden)

The two different curves red/blue demonstrate nicely the "unsymmetric" half cycles in kinds of "characteristic" and difference of "half cycle" amplitude leverls.
The different curves also demonstrate different rms but nearly similar peak numbers which means the blue curve is more power efficient within a given headroom capability.

The traces also demonstrate very nicely that minipulating (clipping) the peaks top can't be directly substituded with any outcomes of a clipped sine wave.
Again, every considerations on/with steady sine waves are really nice to demonstrate/explain "something" but impact on audio program material should be stated in this case.

 

[ThisBass]

There are a number of spectral analysis VSTs out there, so recording your playing into a DAW and having a look might be interesting at this point

Never seen those spectral diagrams for transients. Would be really nice to see some sub Harmonics "transient" content which is settled down way below a distinct played note 1st Harmonic.
Although I know those transient sub Harmonics do really appear but unhappily I didn't further researches on it.

 

[Bob Lee (QSC)]

Never seen those spectral diagrams for transients. Would be really nice to see some sub Harmonics "transient" content which is settled down way below a distinct played note 1st Harmonic.
Although I know those transient sub Harmonics do really appear but unhappily I didn't further researches on it.

I would be interested to know what sort of mechanism would naturally produce subharmonics.

 

[ThisBass]

I would be interested to know what sort of mechanism would naturally produce subharmonics.

Touching a string and/or distinct string damping tenique may produce Harmonic content way below a played note.
Personally I use this "effect" to test bass cabinets regarding mechanical sub Harmonic stability
Left hand is settled down on the fretboard covering all the strings to make them all "damped", then the right hand hits all the strings like a bitchslap and, belive me sometimes a driver looks like jumping out of the frame.

It's a nice sound that can emulate a kick drum but, unfortunatelly I already damged a driver with those kinds of "nonsense"

Personally I know of at least one bass player who killed serially drivers with his very unique expressive solo part "noises".

 

[Bob Lee (QSC)]

Touching a string and/or distinct string damping tenique may produce Harmonic content way below a played note.

I'm not so sure that's true.

 

[ThisBass]

I'm not so sure that's true.

Sorry just forget,
Tracing of "distinct" schematic parts with bass guitar obviously showed every time that there is something more involved than 1st Harmonic of a played note. depending on playing technique (finger or pic) and damping technique the sub Harmonic content that appears looks different but, as already mentioned above, I never did further researches on this.

 

[BadExample]

I'm not so sure that's true.

Why not? Stringed instruments naturally produce harmonics and sub-harmonics, both desirable and not. My father tuned pianos in my 5 or 6 church small hometown. Somewhere before I reached that age where a kid won't admit having parents, much less be seen with them in public, I used to tag along and help. He described the process as "eliminating vibrations," but what he was doing was tuning out undesirable harmonics. You can see them clear as day on a strobe-o-tuner. I also remember the fella that taught him the trade. That guy was pretty amazing. A violinist for Sousa's Band, a Holocaust survivor and a man who dedicated his every waking hour to teaching music to anyone who would listen. I was there when a woman came to pick up her boy from a music lesson and said it would be his last one, because she couldn't afford the $1 per lesson. He said he wouldn't charge anymore. She politely refused, not wanting charity, as people were back then. He said he'd pay back all the lesson money she had paid if he could just keep taking a weekly lesson. Anyway, my dad was getting frustrated that it was taking him a long time to find the undesirable sub-harmonics to tune out. His mentor would just flip the strobe to the right note where the offending tone was coming from. He told my father each piano is different and you have to train your ear to know what note is being produced. That guy was tuning like that in half the time my father ever could and he was wearing hearing aides and we had to speak up for him to hear us. I think he was born during the plague.

 

[Bob Lee (QSC)]

Why not? Stringed instruments naturally produce harmonics and sub-harmonics, both desirable and not. My father tuned pianos in my 5 or 6 church small hometown. Somewhere before I reached that age where a kid won't admit having parents, much less be seen with them in public, I used to tag along and help. He described the process as "eliminating vibrations," but what he was doing was tuning out undesirable harmonics. You can see them clear as day on a strobe-o-tuner. I also remember the fella that taught him the trade. That guy was pretty amazing. A violinist for Sousa's Band, a Holocaust survivor and a man who dedicated his every waking hour to teaching music to anyone who would listen. I was there when a woman came to pick up her boy from a music lesson and said it would be his last one, because she couldn't afford the $1 per lesson. He said he wouldn't charge anymore. She politely refused, not wanting charity, as people were back then. He said he'd pay back all the lesson money she had paid if he could just keep taking a weekly lesson. Anyway, my dad was getting frustrated that it was taking him a long time to find the undesirable sub-harmonics to tune out. His mentor would just flip the strobe to the right note where the offending tone was coming from. He told my father each piano is different and you have to train your ear to know what note is being produced. That guy was tuning like that in half the time my father ever could and he was wearing hearing aides and we had to speak up for him to hear us. I think he was born during the plague.

i agree about harmonics but not about subharmonics. Please tell where they come from.

 

[ThisBass]

Only a side effect but drivers loaded into ported cabs tend to do randomly excessive large excursions which have nothing to do with the fundamental of a played note

 

[megafiddle]

I would still consider that over powering the tweeter. More harmonic content sends more power to the range the tweeter is working in, and the tweeter or what ever is used as a filter sees more power than it can handle.
...

That's correct. And as I mentioned, that's the basis for the current fallacy: that underpowering a speaker will damage it

But that amp would have been considered underpowered, not because it was underpowering the speaker, but because it was underpowered for the clean undistorted volume required.

That is the historical claim or argument, and it is often lost in modern arguments.

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[BadExample]

i agree about harmonics but not about subharmonics. Please tell where they come from.

subharmonics are a fraction of the original fundamental freq. I believe they come from a mechanical dampening of some sort resulting in a fraction of the fundamental. Like you don't get a 40 Hz subharmonic from a 50 Hz vibration (tone). The frequency is divided by and even integer. So the 50 Hz vibration can produce 25 Hz, 16.6 Hz, 12.5 Hz, and so on. That is my recollection from long ago. I believe they may also come from reflected sound waves, but not sure. I remember when my dad was doing the tuning, on the two and three stringed keys, he had to must the other wires with rubber wedges so only one string vibrated when striking the key.

 

[BadExample]

Maybe this is kind of how it works. Imagine you are God, and someone is playing a single note continuously on a bass or a harp, over and over. As God, you can do what ever you like. So you use your finger to mute part of the perfect sine wave the harps in heaven produce, but leave the other half intact. So you press you Godly finger down on just the top of the sine wave and press it down to 0, while the the other half continues at the same rate. Now you have what looks like half rectified AC:

OK, so you push at the bottom of the wave. You can't expect me to predict what God will do next, right?

The frequency of the wave for is actually the same, but once it becomes air movement, the bottom of the wave where there is no change for half a duty cycle will become a distorted, but very present bottom "peak" and it will become half the original frequency to an ear.

I guess that wave can vibrate something else and the same thing can happen for a 1/4 freq.

When 1/3 freq. comes from, I have no idea. I'm not acoustical engineer nor am I God. I am just an Ear.

It's my understanding that loudspeakers themselves produce sub harmonics.

 

[megafiddle]

Touching a string and/or distinct string damping tenique may produce Harmonic content way below a played note.
Personally I use this "effect" to test bass cabinets regarding mechanical sub Harmonic stability
Left hand is settled down on the fretboard covering all the strings to make them all "damped", then the right hand hits all the strings like a bitchslap and, belive me sometimes a driver looks like jumping out of the frame.

It's a nice sound that can emulate a kick drum but, unfortunatelly I already damged a driver with those kinds of "nonsense"

Personally I know of at least one bass player who killed serially drivers with his very unique expressive solo part "noises".

Those frequencies are simply low frequency transients. They are unrelated to the fundamental frequencies of the strings themselves and therefore are not subharmionics. They are related to how rapidly you push the string towards the pickup when you hit it. There may be some damped vibration immediately after, but that would be at the fundamental frequency of whatever portion of the string was vibrating, also not a subharmonic.

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[BadExample]

Those frequencies are simply low frequency transients. They are unrelated to the fundamental frequencies of the strings themselves and therefore are not subharmionics. They are related to how rapidly you push the string towards the pickup when you hit it. There may be some damped vibration immediately after, but that would be at the fundamental frequency of whatever portion of the string was vibrating, also not a subharmonic.

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I think it would take some pretty fast picking for that to happen. Even the lowest (slowest) frequency a 5 sting can do is about 30 Hz I believe, and that has a wave length of around 33 mSec or 1/30th of a second. Or perhaps I am just not understanding what you wrote. Not slept more than 10 hours in three days now. In fact, I think I'll go try to get into about a 12 hr coma now. Good night

 

[megafiddle]

Maybe this is kind of how it works. Imagine you are God, and someone is playing a single note continuously on a bass or a harp, over and over. As God, you can do what ever you like. So you use your finger to mute part of the perfect sine wave the harps in heaven produce, but leave the other half intact. So you press you Godly finger down on just the top of the sine wave and press it down to 0, while the the other half continues at the same rate. Now you have what looks like half rectified AC:

OK, so you push at the bottom of the wave. You can't expect me to predict what God will do next, right?

The frequency of the wave for is actually the same, but once it becomes air movement, the bottom of the wave where there is no change for half a duty cycle will become a distorted, but very present bottom "peak" and it will become half the original frequency to an ear.

I guess that wave can vibrate something else and the same thing can happen for a 1/4 freq.

When 1/3 freq. comes from, I have no idea. I'm not acoustical engineer nor am I God. I am just an Ear.

It's my understanding that loudspeakers themselves produce sub harmonics.

That doesn't work.

Instead of removing every bottom half of the sine wave, remove every other bottom half. In other words remove the 1st bottom half, leave the second bottom half, remove the 3rd bottom half, leave the 4th bottom half, etc.

That will produce a 1/2 subharmonic.

Remove every third bottom half, and it produce 1/3 subharmonic.

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[-Asdfgh-]

Never seen those spectral diagrams for transients. Would be really nice to see some sub Harmonics "transient" content which is settled down way below a distinct played note 1st Harmonic.
Although I know those transient sub Harmonics do really appear but unhappily I didn't further researches on it.

True, I haven't seen a plugin which exactly covers the requirements of this discussion and was too lazy to check last night.