Double Bass amp wattage - does it need to be higher than the cabinet's?

[drurb]

Ah, headroom...

 

[Steve Freides]

Ah, headroom...

I always go for Max Headroom.

-S-

 

[Alec Mekelburg]

Wrong again. It's not the case that any distortion will fry a tweeter. Tweeters are made to handle high-frequency content. The energy produced by hard and prolonged clipping is radically different from that produced by typical effects pedals.

Many of the seemingly "expert" articles that you'll find on the internet about this are substantially flawed. For example, one article I just looked at suggested that it's not high-frequency harmonics that fry tweeters but, rather, the energy generated by clipping. Of course, that energy is made up of high-frequency distortion products.

What is tweeters? And what is clipping?

 

[DoubleMIDI]

What is tweeters? And what is clipping?

Tweeters are high frequency speakers.

Clipping is a change of waveform due to an overdriven solid state amplifier. It's basically a limit of maximum amplitude, so if you try to amplify a signal that need to be amplified more than the maximum the amplifier can deliver, the output amplitude gets limited at the maximum output amplitude. It's like you cut the waveform horizontally at the top and bottom. This introduces a lot of high frequency content that was not present in the original signal (at least not at this higher amplitude) and might damage tweeters as they typically have a lower wattage than the lower frequency speakers.
On solid state amps this cut is really hard.
On valve amps it's more compressed than cut and called overdrive. That's the typical electric guitar sound.

 

[Alec Mekelburg]

Tweeters are high frequency speakers.

Clipping is a change of waveform due to an overdriven solid state amplifier. It's basically a limit of maximum amplitude, so if you try to amplify a signal that need to be amplified more than the maximum the amplifier can deliver, the output amplitude gets limited at the maximum output amplitude. It's like you cut the waveform horizontally at the top and bottom. This introduces a lot of high frequency content that was not present in the original signal (at least not at this higher amplitude) and might damage tweeters as they typically have a lower wattage than the lower frequency speakers.
On solid state amps this cut is really hard.
On valve amps it's more compressed than cut and called overdrive. That's the typical electric guitar sound.

So, through out everything I read, would it be wiser to get an amplifier that has more wattage than the cab?

 

[DoubleMIDI]

Better get an amp with a built-in limiter and a cab with an equal or higher wattage than the amp. You don't need a tweeter for double bass, only if you want to use it with electric bass guitar too.

With a lower wattage cab you can shoot the main speaker with impulses like connecting a cable to your instrument with a high amplification factor.

 

[Steve Freides]

Clipping is a change of waveform due to an overdriven solid state amplifier.

I don't think the term originates with solid-state amplifiers - I remember it from tube amp days, and I think the distortion that a lot of guitar players pay money for now is simply what we used to get when we overdrove tube amplifiers back in the day.

Clipping is different in the digital age, and what I wrote above constitutes most of my very limited knowledge on the subject, but I know that, in general, how analogue amplifiers clip is usually deemed more musical than how digital equipment handles the same situation.

To the OP - I don't think there's a single correct answer to your question about which ought to have a higher wattage rating. Buy your equipment with the idea that you'll use it as designed and won't be pushing the limits of either your speakers or your amp.

Most amplifier- and speaker-related gear starts to sound lousy before it starts to break - stop when it starts sounding weird and you should be OK with just about any combination. Or speaking of "combinations" just use a "combo" amp/speaker and let this be someone else's headache. I don't play rock music very often, but I've yet to encounter a situation my AI Ten2 can't handle.

-S-

 

[two fingers]

I run an Ashdown LB30 (30W amp) with a Euphonic Audio VL-210 (500W cab) all the time. That combination gets stupid loud, handles stage volume extremely well, and get over any drummer I have played with volume wise. I do put it on an amp stand. But I have even done outdoor gigs with it. And all this with NO BREAKUP by the way.

So, the "science" can be touted here for days. But I live it all the time. 30W through a 500W cab gets in done incredibly well.

 

[Alec Mekelburg]

Mark is correct that, generally speaking, it is better to pair a cab with an amplifier that has a continuous power rating that exceeds that of the cabinet.

I'd like to clear up/correct a few concepts. As I posted here a while back, "headroom" has a specific definition. It's one of those terms that's more often used incorrectly than correctly. Having extra continuous wattage available is not what headroom is, technically speaking.

What causes woofers to "fart" is not amplifier clipping. Rather, that sound is caused when the amplifier overdrives the speaker. In other words, that sound is caused when the woofer is clipped. It is a sound likely to be caused by too much amplifier power. The good news is that you get a warning and you can back off the gain.

More damage is caused by underpowered amplifiers than by overpowered amplifiers. That's true for any cab with a tweeter. When an amplifier is driven into clipping, massive amounts of energy are "splattered" to high frequencies. That'll fry a tweeter very rapidly. No warning.

So, in the end, the safest course is to have an amplifier with a continuous power-rating that exceeds that of the speaker cabinet.

Alternatively, you could have an amplifier that matches the continuous power-rating of the cab but which has a hefty amount of headroom (as properly defined). Most musical instrument amp manufacturers do not specify actual headroom. Because of this, most of us buy on the basis of continuous power ratings. That's really not a great state of affairs. It would be nice to see actual tests of headroom. If those were commonly available, some amp manufacturers might be forced to change their design philosophies when the shortcomings of their circuits were made apparent. Most of this ground was covered decades ago in the home "hi-fi/audiophile" world. It resulted in testing and specification standards. It would be nice if the musical instrument amplifier world would catch up!

Finally, keep in mind that every 3 dB corresponds to a doubling of power. Musical peaks can easily exceed 3 dB beyond the continuous or average level. 10 dB corresponds to a ten-fold increase in power. Many might be surprised to learn how little power is used on a continuous and/or average basis. It's typically only a few watts. That's why an amp with a reasonable (even modest) amount of available continuous power, but plenty of (actual) headroom is so desirable.

Okay, so, I have an Ampeg Svt810 cab, at 800 Watts, I was thinking of purchasing the Peavey Headliner 1000, at 1000 Watts, if I don't peak the amplifier, I should be fine? I do play bigger venues but even then once hooked up to the PA system I wont ever need to peak my amp.

 

[DoubleMIDI]

The opinions differ a lot. I only gave my point of view.

Tube amplifiers can be overdriven without too much bad influence on the resulting signal, so a low wattage tube amp (full, pre and power amp with tubes) can get a lot louder than the same wattage solid state amp. With tube amplifiers the upper part of the waveform gets compressed, not clipped hard. So the waveform is still smooth, but the slope is flatter than it should be in the upper (and lower?) range of the amplitudes.

Digital overdrive can be of two types, depending how the A/D-converters handle it.
The older version copied anything that exceeds the top on the bottom, so the amplitude made a huge amount of jumps from maximum to minimum and back. That was very bad and killed a lot of speakers. Maybe also ears...
The other version is a hard limit at the maximum or minimum amplitude that could be represented. This is very similar to solid state amps, but a bit more extreme, because there are very sharp corners in the digital domain. In the analog solid state domain the corners are a bit rounded, so a bit less very high frequencies, but still bad sounding in the analog and digital domain. But you don't kill speakers and ears immediately when you only have a very small clipping.

 

[DoubleMIDI]

Okay, so, I have an Ampeg Svt810 cab, at 800 Watts, I was thinking of purchasing the Peavey Headliner 1000, at 1000 Watts, if I don't peak the amplifier, I should be fine? I do play bigger venues but even then once hooked up to the PA system I wont ever need to peak my amp.

You would be fine as long as you avoid impulse noise like connecting the instrument with the amp on and gain and master in a louder playing position.

But that looks like a bass guitar rig. I won't carry a 810 to a double bass gig.

 

[Angry Bob]

I've heard this before when buying a 350 watt cabinet - that it would be ideal to pair it with an amp w/ a higher wattage (I ended up with a 450 watt amp). I'm currently looking at the pairing of an 800 watt head with an 800 watt cabinet, so wondering if I'd need a more powerful head to get the best use from the setup.

Obviously there is a limit to how much higher the amp wattage can be, but just wondering if this is a general rule. Thanks!!

 

[Ric Vice]

This thread has been dormant for nearly two years.

 

[Angry Bob]

Ok Chris, I stumbled on this rabbit hole whilst trying to explain to a fellow bassist why their logic in not choosing a particular amp head to go with their current cabinet, was total BS. Hopefully, your eyes have stopped bleeding and your headache's gone! This is WAY simpler than has been explained.
1. Size (power) of your amp is determined by the size of the venues you play. PERIOD! If you are playing outdoor festivals, an 8 inch combo ain't gonna cut it. If you tried to mic it through the FOH, you won't be playing at the festival for long. (Long enough for your manager to find a new bass player, maybe?) Conversely, if you insist on running a dimed SVT in a small practice studio, same results.
My point is, apply the rule of common sense. If you choose a cab that is rated for less wattage than you RESONABLY expect to send it while playing, then it WILL fail. The only question is when it will fail. Murphy's Law For Speaker Cabinets [squared] is; it will fail when you MOST need it and when you can least AFFORD to replace it. ( This is an immutable law...think stone tablets.)
If, on the other hand, you have a gazzilion watt cab and have to push a micro amp head with controls set for the face of the sun....well, Murphy's Law For Amps, [squared] applies!) This takes us to the rule of Daniel San......balance (tempered with a HEALTHY dose of said common sense). Can you take your 300, 500 or 800 watt, has to do all, stack to practice? Without introducing physical dimensions into the equation, sure you can. Your fellow bandmates will help you determine YOUR volume level. Your cabs WILL survive! Your amp will not be harmed in the making of this movie! As for the previous posters to your question.....OMG! REALLY......? While I have the utmost respect for ya'lls cred and knowledge, 4 pages....REALLY? He (or she) doesn't need to know how to split atoms in The Large Hadron Collider. Some of you guys were confusing each other....(A European Swallow, maybe...just not an African Swallow, that's my point!) Just my two and a half cents. YMMV.
Hope it helped. Cheers