A difference of 10 dB is perceived by the human ear as roughly twice as "loud" - not ten times as loud. A 10 dB increase will result in 10 times the intensity, but not perceived loudness.. Great article on it here.
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Under-powering cabs
- Thread starter aus_bass
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A difference of 10 dB is perceived by the human ear as roughly twice as "loud" - not ten times as loud. A 10 dB increase will result in 10 times the intensity, but not perceived loudness.. Great article on it here.
JeezyMcNuggles
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- Feb 23, 2018
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Well yeah, like with everything that is not a direct comparison between specific products.
Generally speaking, the more sensitive speaker will be louder with less power, and sacrifice low end.
The less sensitive speaker will produce more low end, but you need to keep throwing power at it to compensate for its inefficiency.
Or, throw it in a more efficient box.
That may be one of today's standards, but when it was first introduced, that was not the standard - the drivers in the original 810 cabinets weren't robust enough, so you used 2 cabinets to share the power among 16 drivers.
There are two reasons to be wary of "underpowering":
1) "I have a 300 watt, amp going into a 1000 watt speaker - I'm bulletproof". There is a temptation to think that, if your speaker has a higher rating than your amp, that your amp can't ever damage your speaker. Speaker power ratings are generally thermal ratings - at mid and high frequencies, they apply pretty much straight up (for the woofer - the tweeter is another thing altogether). At low frequencies, however, your "1000 watt" speaker probably can't handle that much power - it's excursion limited, and if you go past that, things physically break.
2) Your tweeter isn't as tough as your woofer. The "underpowering" legend came out of time when there were (there may still be, but let's hope not) a lot of amps that didn't clip gracefully - when an amplifier "gracefully clips", it means it reaches a voltage (or current) level where it can't produce anymore, and the voltage hangs out there until less voltage is called, for, and then it goes back down with the waveform. If an amplifier clips gracefully, it generates high frequency information, but in most cases, not more than would be there with an unclipped musical signal. There were a few technical papers many years ago discussing all this - there were debates about whether clipping produced more tweeter killing high frequencies than a bigger amp that didn't clip (one source of the underpowering thing), but in the end after much discussion the consensus seemed to be that clipping (done gracefully) wasn't an evil unto itself. A side note to all of this is, if you play an instrument like some synthesizers, that can produce blazingly hot treble frequencies, and you play them loudly, there are a lot of tweeters that will go south before they hit their power ratings. Speaker ratings assume a certain distribution of spectral energy, and if your spectrum is particularly treble heavy, your tweeter can easily pay the price.
All that being said.....
Some amplifiers, when they hit clipping, will do ugly things, like resonate (often at ultrasonic frequencies), or throw a spike to the opposite voltage rail. In that case, the amplifier can generate a LOT of high frequency information/power, and your tweeter can very easily be in peril. In theory, a more powerful amplifier avoids the issue (as it doesn't clip), but in practice, the point should be that we shouldn't be using amplifiers with this bizzare behavior. It's not an underpowering issue, it's a bad amplifier design. The hope is that this behavior is a thing of the past - not entirely sure if that's the case or not.
The short answer is it won't hurt your cabs at all. There's no difference in using a 300-watt or 500-watt rms amp to drive that cab than using your 1,000-watt cab with the master on a 1,000-watt amp turned down to a comparable level. Doesn't so much matter how much the amp puts out as it does how many watts your cab needs to drive it to gig levels.
TL/DR answer:
I personally use an 800-watt Eden head to drive my DNS-410 cab by DNA for outdoor venues and Music Festivals. It is rated at 1400-watts rms handling power and has a max SPL of 137db. Theoretically, my 800-watt amp can drive it to 134db (well above the threshold of pain). I've never had it up that high. Obviously my cab could handle another 600-watts over the power than my Eden WT500/800 can provide but I certainly don't need it. if I turn the master on my Eden amp up to 10:30 at outdoor music festivals, I get told to turn down. So at music festivals with wide open spaces, I'll typically run that master up to 10:15. A normal outdoor venue I'll run it around 9:30.
Actually I'll run my DNA-800 amp at most other venues with it because it has the same clear, clean sound that my Eden amp does (both were designed by David Nordschow who founded both Eden and DNA); it sounds great;, weighs all of 4.7-lbs; and the 400-watts it will put out into an 8 Ω load is more than enough for most venues. My Eden amp bridges at 800-watts into 8Ω, which is what my DNS-410 cab is and why I bought the cab in 8Ω back in 2015. My DNA-800 amp that puts out 800-watts rms into 4Ω (or 2Ω) only puts 400-watts into 8Ω. That is still louder than needed indoors. In fact I use my DNS-210 (handles 700-watts and has max SPL of 134db) for all my indoor venues with my DNA-800 amp.
A huge thing about using lower rated amps into higher rated cabs is how sensitive, and thus loud, the cab is. There are multiple ways to rate the sensitivity of cabs with Mesa being the only one I'm aware of that actually checks sensitivity at multiple frequencies. Most just throw a 1Khz signal at it and use results from that. Because we play lots of frequencies and not just 1KHz, some cabs can claim a higher sensitivity because of their testing methods than Mesa cabs does and yet, in real world use, the Mesa cab with its averaged sensitivity will still be louder than the other cab. DNA does publish sensitivity levels but also includes the Maximum SPL that the cab can produce, which I think is a better measurement of how loud a cab actually can get. Mesa also includes max SPL in their ratings too.
So if you have a cab that can handle lots of watts and it is actually a sensitive cab, running a comparatively low powered amp into it is no big deal. I had my Eden 800-watt amp in for repair a number of years ago after if fell from the top of my cab while rolling the cab along (don't do that!!) and had to use my Eden Nemesis RS400 amp for gigs for about 2-months waiting form my big amp to be repaired. That RS400 puts out 400-watts into 4Ω and 275-watts rms into 8Ω. So I was using 275-watts into my DNS-410 that could handle 1400 watts rms, and had no trouble at all playing at gig levels at indoor venues. I was actually pretty surprised at how loud it got with only about 20% of the power that the cab can handle.
So as long as your cab has good sensitivity, you should be fine with it. I had a 410 cab from another manufacturer that only had a 92db sensitivity, which is low. Most major brands are well above that. Specs can give you a general idea of what to expect, bu the only real answer of course is to take your cab to the music store and try out these class D heads to see how they work with your cab.
Actually though, with your cab's rating, I'd bypass the small stuff and go right up to the 800-watt Class D amps. The DNA-800 street price is $799 and it also includes a built-in compressor with adjustable threshold and ratio controls. If you need more power than that there's always the DNA-1350 which produces 1350-watts into either 4Ω or 2Ω, but it's right around $1500 for that one and if your cab has decent sensitivity, you won't even be able to stand anywhere near it with 1,000 of those watts driving it.
Many of the major manufacturers have class-D amps at 800-watts in that same price range. And they are not that much more than a 500-watt rms class D amp. My DNA-800 amp ($799) is only about $150 more than the Eden TN501 ($649), which is a 500-watt class D amp and a very nice one. That's 300-watts more for 50¢ a watt and I also get a really versatile adjustable compressor included inside it. Plus my DNA-800 is absolutely dead-quite (no fan, so no fan-noise).
Here's my DNA rig with my big Eden WT500/800 class A/B amp that I bought from David back in 2010 after he sold and left Eden. This is the only time I've had both cabs stacked and I only ended up using the 210 cab on top. Even with that I had to rearrange my slice of the stage to get it as far away from me as I could because that 210 was killing my ears. Sounded great out in this "almost large" venue but I was standing way too close to it and the 210 was too close to ear level.
My typical indoors rig now is my DNS-210 in an amp stand with a 45° tilt using my DNA-800 on top of it . I'll use my DNS-800 outdoors and pull out my big Eden amp for the Festivals. Lugging around and using an amp that weighs only 4.7-lbs sure beats the 36-lbs my big Eden amp weighs in its rack. Here's that DNA-800 amp:
there isn't really conflicting information if you go to the most knowledgeable sources.
For example agedhorse, who is not only working in the industry but is a designer of some of the top popular bass cabs and heads over the years.
For example agedhorse, who is not only working in the industry but is a designer of some of the top popular bass cabs and heads over the years.
Let me put it simply.
If your amp says 200 watts and your cab is rated for >200w you can theoretically use your full power and it will never overload your cab.
If your amp says 200 watts and your cab says <200w, you can theoretically only use half of the power of your amp, if you go higher than that you risk damage to the cab.
Resistance only has to do w/ how the power flows to the cab from the amp.
Edit to say this: No, it's no problem to under power, only to over power. Your speakers don't want to work hard and neither does your amp, so find a good balance.
If your amp says 200 watts and your cab is rated for >200w you can theoretically use your full power and it will never overload your cab.
If your amp says 200 watts and your cab says <200w, you can theoretically only use half of the power of your amp, if you go higher than that you risk damage to the cab.
Resistance only has to do w/ how the power flows to the cab from the amp.
Edit to say this: No, it's no problem to under power, only to over power. Your speakers don't want to work hard and neither does your amp, so find a good balance.
JBL knew the science and physics behind speakers as well as the best - well, they were the best in the industry. This is a company who's speakers were used in horn systems driven by relatively low power amplifiers (by today's standards) to deafening leavels with low distortion.JBL with a white paper that was greatly misunderstood then and still is to this day.
As you suggested, the whitepaper was wildly misunderstood, probably by sales folk in stores who didn't know what anything in the details actually meant.
This isn't a factual statement. A 200 watt cab isn't rated to handle 200 watts from 20hz up. The maximum excursion of the driver (Xmax) will be a limiting factor for power handling in lower frequencies. There are few boxes out there, if any production bass cabs, that will handle their rated power in lower frequencies. Feed a cab rated at 200 watts a signal that is 200 watts of low bass (lets say below 40hz) and see what happens. The drivers will likely hit their excursion max, be physically damaged and ultimately fail.
Hence why I said theoretically and then added the part about amps and cabs not wanting to work hard.
I promise you that if you even touch that knob and it moves past zero, you will blow your cab through underpowering it.
(Random figures for illustration)
I suppose you might have an amp rated for 300W RMS at 1% THD that might put out 450W at stupid% distortion and could blow a 400W cab. I doubt that 'not underpowering' it with a 600W RMS amp at cranking that up to stupid% distortion will help, but I suppose it might manage 400W clean. Ideally you don't use stupid% distortion unless you like to (ab)use vintage amps like Jack Bruce et al did. In my early days I did run a 60W solid state amp into Jack Bruce territory, but it survived every time. But then I don't know if the farting noise was the amp, speaker, or what the speaker was rated to. That was stuff still in my future in terms of discovery. Fun times, although the shared PAs in dive bars seem to have had some combination of under or over powering as often something was blown in them.
I suppose you might have an amp rated for 300W RMS at 1% THD that might put out 450W at stupid% distortion and could blow a 400W cab. I doubt that 'not underpowering' it with a 600W RMS amp at cranking that up to stupid% distortion will help, but I suppose it might manage 400W clean. Ideally you don't use stupid% distortion unless you like to (ab)use vintage amps like Jack Bruce et al did. In my early days I did run a 60W solid state amp into Jack Bruce territory, but it survived every time. But then I don't know if the farting noise was the amp, speaker, or what the speaker was rated to. That was stuff still in my future in terms of discovery. Fun times, although the shared PAs in dive bars seem to have had some combination of under or over powering as often something was blown in them.
- Feb 12, 2006
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- 5
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- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
There are other variables at work as well, for example changing the gap clearance, motor strength, moving mass, compliance, winding density will all change sensitivity, LF extension.
Better get rid of these Blues Jr. amps before one of 'em explodes! 15 watts of death!
For sure. I like to remind myself that a 500w amp is 10db louder than a 50w amp. (Double the volume).
Last edited:
- Feb 12, 2006
- 61,024
- 5
- 220,889
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
JeezyMcNuggles
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- Feb 23, 2018
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- 20,970
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- I suck, but nobody really notices
No jimmy, the cab is rated far higher than the amp. Therefore, you'll blow the amp because the amp cant handle the power of the cab. DuhI promise you that if you even touch that knob and it moves past zero, you will blow your cab through underpowering it.
