Speakers & Watts

Jim Peter · Post by **Jim Peter** » 26 Oct 2000 9:30 am

I am in the process of building myself a new sound system which at this point consists of a tube preamp and a tube power amp. I should have some speaker cabinets (1x12 & 1x15)soon, and I am up to the point of choosing some speakers. One of the speakers I am considering is the EVM-12L which is rated for 300 Watts. What I am wondering is, will my power amp (mesa/boogie 50/50) which is 50 watts/channel have enough power to run this speaker adequately? Can you be underpowered?

Thanks,
Jim

Donny Hinson · Post by **Donny Hinson** » 26 Oct 2000 1:27 pm

Jim, speaker design is very complicated, and how much power a speaker will handle has little to do with its efficiency. Rest assured that the EV-12L is very efficient, and will work fine with low power inputs. Sometimes, speaker manufacturers build speakers that take a lot of power to produce good sound. But usually, these are found in HI-FI equipment. A good indicator of a speaker's efficiency (watts-in vs. watts-out) is the size of the magnet. Really efficient speakers usually have huge magnets.

I find the EV speakers to be among the most efficient made. I once did a side-by-side test of an EV "SRO", and a JBL D130-F. The JBL sounded a little nicer, but the EV was twice as loud with the same input! At the time, I was playing kick@$$ Travis Tritt-type stuff, and I needed all the sound I could get, so I went with the EV.

Jon Light (deceased) · Post by **Jon Light (deceased)** » 26 Oct 2000 1:33 pm

Someone once told me that in stereo systems an underpowered amplifier (or overpowered speakers) can cause clipping which can damage the speakers. Is this apples & oranges (instrument amplification vs. home stereo) or just not correct?

Donny Hinson · Post by **Donny Hinson** » 26 Oct 2000 4:04 pm

No John, an underpowered amplifier won't damage anything! But, overpowering the speakers can cause clipping, and sometimes damage to the speakers and the amplifier.

Terry Downs · Post by **Terry Downs** » 26 Oct 2000 9:25 pm

Jim,
You probably will have no problems with what you are doing. The issue Jon brought up is a significant problem most often manifested in horn drivers. If you drive your amplifier into clipping, harsh harmonics are generated in the spectrum above our hearing. The electrical power in that output, although not audible by humans, is nevertheless dissipated in the horn. Horns in PA systems are more likely damaged by under power that over power.

Regular old speakers are affected less by this problem as impedance rises significantly at supersonic frequencies.

In sound reinforcement systems, a speaker is generally driven to 2-4x its continuous rated average power. The Electrovoice Audio Bible concurs with that as well. It is generally stated that the average audio power over a several second sample is often 10dB below its continuous equivalent. I'm not sure the head banger stuff complies with that law

.

I hope your application is not steel guitar. It sounds like your are going to crank up some good rock distortion.

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Terry Downs
http://nightshift.net
terry@nightshift.net

Donny Hinson · Post by **Donny Hinson** » 27 Oct 2000 7:59 am

What Terry said is essentially true. But, Jim's original question was on "underpowering", and not high distortion levels caused by "overpowering" a small amp. Any speaker that is forced into high energy levels with a distorted input will eventually fail. The reason is that, along with the heat dissapation problems, tremendous mechanical stresses are placed on the dynamic components of the speaker. Distorted waveforms (with their inherent low/zero rise-time "jagged edges") often cause physical cone failures, as well as voice-coil wire connection failures. Speakers last longest when they are used to produce smoother (the technical term is "more sinusoidal") waveforms. These waves allow the cone more time (wave rise-time) to flex, and to change direction, which is how they produce their sound.

Most of the speaker failures I have encountered are mechanical in nature...ruptured cones, torn suspension rings, loose wires, and detached or loose dustcaps.

gary darr · Post by **gary darr** » 27 Oct 2000 7:31 pm

I would be very carefull with a setup like that. If you find yourself cranking that 50 watt amp to the max to get the volume you think you should get out of a 300 watt speaker there is danger of sending strait voltage to the voice coil rather than the normal peaks and vallies that are found in the wave form.In a music store I used to work in we would have young kids come in a purhase JBL speakers,they would be thinking if the speakers are rated for 200 watts they should take anything a say 75 watt car sterio could throw at it.First thing you know they are cranking the radio up to the max to get the volume they want and presto, you have yourself a JBL (glowing very red) voice coil. Just hate to see a good speaker become a toaster.

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sho-bud,session 500,american standard strat,shecter tele,peavy classic 50
[This message was edited by gary darr on 02 November 2000 at 06:36 PM.]

Dan Tyack · Post by **Dan Tyack** » 28 Oct 2000 11:40 am

Guitar players have been pushing tube amps to their maximum power ratings into speakers which can handle more power for a couple of decades now, and I have never heard of any damage to any guitar speaker.

My favorite gig and recording setup now is a small 15 watt tube amp which I use with either a cabinet with an E-120 and two Celestion 10" speakers (power rating close to 500 watts) or a cabinet with a 12" Celestion, with a 70 watt power rating. Sounds great!

Jim, in answer to your original question, I think the EV-12L would be a great match for your power amp. Just don't put it in a 'too small' cabinet (like those tiny boogie cabs), otherwise it will sound boxey.

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www.tyacktunes.com

Dan Tyack · Post by **Dan Tyack** » 28 Oct 2000 11:41 am

duplicate....[This message was edited by Dan Tyack on 28 October 2000 at 12:42 PM.]

Bill Llewellyn · Post by **Bill Llewellyn** » 29 Oct 2000 9:03 am

Dan, the reason tube amps can be driven to clipping with less risk of damaging horns or tweeters is the softer clipping characteristic tube amps have with respect to transistor amps. Transistor amps usually have very abrupt, flat-topped clipping which produces more high-frequency energy than the "mushier" clipping of tube amps, all else being equal. That softened tube clipping is part of the sound of rock guitar amps like Marshall or Mesa Boogie. I don't think you'll see too many calssic rock guitar players withtransistor amps for that reason.

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Bill (steel player impersonator) | MSA Classic U12 | Email | My online music | Forum birthdays

Terry Williams · Post by **Terry Williams** » 2 Nov 2000 6:32 am

the most important thing is to have a clean signal.you could take a 300 watt speaker with a 50 watt amp and blow it, where on the other hand you could take a 50 watt speaker use a 300 watt amp and you would be surprised how much volume you could have.i have found this to be true for me, this is not wrote in cement guys, just my humble opinion.

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Bob Metzger · Post by **Bob Metzger** » 4 Nov 2000 3:21 pm

I think a EVM-12S sounds better for steel guitar application than a EVM-12L.

Bob

Donny Hinson · Post by **Donny Hinson** » 4 Nov 2000 4:48 pm

Bob...

None of the EV catalogs I have show an "EVM12S". Is that an older model? The newer catalogs show only a 12L, 12W, and a 12X, and the "FORCE" series.