Under-powering cabs

[Killing Floor]

I can count the times I’ve driven my car over 130 mi/h on the highway on 2 hands. It doesn’t hurt it to go 70. Hurts my soul a little but not the car.
Your speakers are a load that an amp sends a signal to.

 

[GreyBeard]

If the 300 watt head gives you all you need, I see no reason for a bigger one.

 

[BassFalcon]

The fact that volume knobs exist should be sufficient evidence that “underpowering” is a myth.

 

[Killing Floor]

You could power that cab with thisView attachment 4543345
Speakers don't give power, they take it.

And it would be really cool, FYI

 

[mrjim123]

Search for, e.g., "under powering". This has been covered ad-nauseum.

 

[Turxile]

My set up is very similar to the example you used. I’ve been mainly using 2 500W 210s with a 300W head for the last 4 years. No issues so far.

 

[groove pump]

My set up is very similar to the example you used. I’ve been mainly using 2 500W 210s with a 300W head for the last 4 years. No issues so far.

Similar deal here: 500 watt head (into minimum 4 ohm load) running a pair of 350 watt/8 ohm 2x10 cabs and it's Godzilla loud without anything boosted and the master volume set no higher than 10 o'clock.

 

[MultiScaleMale]

Some amps' volume knob controls the wattage, some control the input gain into the power amp that is running at full rated power. The latter can be dangerous especially if you're running a bunch of pedals into the amp. Just understand if your amp and cab is rated at peak / RMS / program watts. You don't want to run a 1000W RMS rated amp into a 1000W peak rated cab. 1000 == 1000, right? Click, magic smoke leaves the speakers.

Anyways, that was a tangent and consider the speaker polarity test with a 9V battery. If you can move the cone on a woofer with a 9V battery, I'm not sure what the relative wattage of a 9V battery is, but it can't be much. There is probably a very, very low amount of wattage that will give garbage sound as it won't overcome the small amount of friction in the speaker. But that's likely far less than 1W. I've run a 50W head into a 1200W cab and it sounded great. Also remember that we're used to thinking of linear numbers. 4 is double of 2. Two packs of smokes gives you forty ciggs. But with watts you need to increase wattage tenfold to double the sound level. Most cabs can't handle 10x the wattage that we're already feeding into it. So, additional cabs is the ticket when you need more volume.

Sorry for the multiple tangents, my power coffee is just kicking in this morning. Heh.

 

[dbsfgyd1]

Just thought I'd throw this one out there, and see what the general consensus is. I've heard many differing and often conflicting ideas on this topic, over the years. Do you see any issue in under-powering a cab ?

Example: Say I have Neo 212 cab, that's rated at 1000 watts RMS @ 4ohms, not "peak", "program" or "musical" watts, as often spun by marketers. Real continuous RMS watts.
Now say I match it with a class-D head, that does 300w @ 4ohms, or even 500w @ 4ohms. What's the downside ? Is there a downside ? Is it bad for the cab in some way ? Will the cab not perform optimally, unless it's driven hard ?

I see a lot of rigs, the other way round... a 500w head (or more) into a cab that's rated @ 300w RMS. Obviously, it just takes a little common sense, with the volume knob. I rarely see rigs where the cab capacity is significantly above the output of the amp.

What say ye ?

I prefer my cabs not to be maxed out. Generally, the further you go above 80% of capacity, they tend to get harsh. So for me, more cab than watts just for the tonal value.

I’ll let the engineers explain what happens to over driven, or speakers driven hard over an extended period of time.

 

[Passinwind]

Not an issue. It was the conventional wisdom back in the 80s for some reason. I would love to know who started it.

JBL with a white paper that was greatly misunderstood then and still is to this day.

 

[JeezyMcNuggles]

And it would be really cool, FYI

Awesome even

 

[JeezyMcNuggles]

Don't know exactly where to chime in. Loudness is based on a speak cab's efficiency rating. A cab with 91 db @ one watt one meter. A cab with 101 db one watt one meter. The 101 is going to be 10 times louder than the 91.

So the 1,000 watt RMS cab's loudness depends on it rating at one watt, one meter.

Of course it doesn't hurt anything to "under power" a cab as you call it.

And by the way, a small watt amp can blow out a high rated cab. So, take a 300 watt amp, turn it up to "11", go "wham city" on your bass and you WILL BLOW OUT your cab. As an amp is over ran, it can put out full current and fry speakers.

I'm sure someone will clarify what I'm trying to say here.

For loudness, you want efficient bass cabs. Anything over 99 db, one watt one meter will be max loudness with minimal power.

(There are trade-offs with low efficient cabs vs high efficient cabs. One is louder but the other has better sound.........generalizing and not always the case.)

For example, every increase of 10 dB on the decibel scale is equal to a 10-fold increase in sound pressure level (SPL). Near silence is expressed as 0 dB but a sound measured at 10 dB is actually 10 times louder

As sensitivity goes up, bass response and handling goes down. Distortion goes up also.

 

[agedhorse]

As sensitivity goes up, bass response and handling goes down. Distortion goes up also.

This is a gross generalization that is only sometimes true.

 

[agedhorse]

JBL with a white paper that was greatly misunderstood then and still is to this day.

This may have been the start of the misunderstanding. Unfortunately, the details have been taken out of context so badly as to create such urban myths.

If folks were to really understand the paper, they would discover that JBL actually recommends DECREASING the power to speakers to 50% of rated power for musical instrument applications to account dis distortion and compression increases in signal density. Tweeters are handled differently and are responsible for some of the misunderstanding.

 

[lokikallas]

No such thing as “under powering” a cab.

 

[themickster]

Underpowering a speaker would be as harmless as running a combo on low.

 

[JW56789]

Ask @agedhorse how many warranty claims he processes for some guy running a 400w cabinet with a 100w amp.

 

[MultiScaleMale]

This may have been the start of the misunderstanding. Unfortunately, the details have been taken out of context so badly as to create such urban myths.

If folks were to really understand the paper, they would discover that JBL actually recommends DECREASING the power to speakers to 50% of rated power for musical instrument applications to account dis distortion and compression increases in signal density. Tweeters are handled differently and are responsible for some of the misunderstanding.

So, people took a 30 page paper and focused on one sentence even back then?

 

[edthebass]

Don't know exactly where to chime in. Loudness is based on a speak cab's efficiency rating. A cab with 91 db @ one watt one meter. A cab with 101 db one watt one meter. The 101 is going to be 10 times louder than the 91.

+1 this. It's really about the sensitivity rating of the drivers because in practical circumstances, under powering a cabinet may NOT work.

I have these bass cabinets built by a legit custom builder. But him being mainly a pro audio subwoofer designer, he used faitalPro high end sound reinforcement woofers which sound awesome but the sensitivity is way too low. You just can't move much air from the get go unless you slam a huge amount of wattage at it. Thus, you really CAN underpower them for the task they were designed to do.This may be an uncommon example but in the bass world, with so many different speakers/cabs types out there, there is nuance to always consider when matching amp to cab.

 

[Muttleybass]

I'm gonna go out on a limb here and just say there's lots of complicated answers to a simple question.

In general, no, you cannot under power a cab. However, distortion is not your friend. If you can hear yourself with the gain at noon and the main at a bit past 12:15, you will have no issue. It you have to run everything pegged to the max all the time you may or may not fry your amp, depending on the unit, as it will clip.

Got a clip light? Make sure it's not on all the time. Hear distortion? Back off the gain. In 40+ years of playing I have never seen a cab fry because it was under-powered. If you need more volume, keep the cab and get a more powerful amp.