| Author | Message | ||
| aircooled69
Junior Username: aircooled69 Post Number: 11 Registered: 1-2003 |
Hey Guys, I have a Tube Messa Boogie Strategy 500 (200w a side sterio) and Im looking into some cabs for this. Does anyone know the importance of matching the Wattage of the amp with the wattage of the speakers?? and what effect this would have on the volume/sound ect? thanks guys Mike (Message edited by aircooled69 on August 13, 2004) | ||
| davehouck
Senior Member Username: davehouck Post Number: 775 Registered: 5-2002 |
I believe the general rule is that you do not want to underpower your speakers. Thus, if your amp is rated at 200 watts per channel into 4 ohms, then the speakers should be 4 ohm cabs and not rated significantly greater that 200 watts. | ||
| son_of_magni
Member Username: son_of_magni Post Number: 91 Registered: 1-2004 |
Ok, I'll put in my 2 or maybe 3 cents. What Dave said is true, this is the general rule. But it's important to understand the reason behind it. Bear in mind though that this is IMHO only. When you drive a 400 watt speaker with a 100 watt amp, the user (knowing the respective ratings) will think it's safe to run the amp at 10 and way into distortion. The distorted, "clipped" signal is a very nasty thing and can damage the 400 watt speaker. Now if this same guy had a 400 watt amp, and knowing the rating, would he still run the amp at 10? Probably not. But if he did, the 400 watt amp would be just as capable of blowing the speaker as the 100 watt amp. So what I'm saying is a heavily clipped signal is bad for your speakers. It doesn't have to come from a big amp or a little amp to cause the damage. The real danger to the speaker is the uninformed or misinformed user. Now I'm going to really try to stir the pot. I think that this whole concept is much less important if you are using a pure tube amp. The distortion you get from a tube amp is much softer on your ears and on the speakers too. Tube clipping looks like a mountain with the top rounded off while solid state clipping looks like a mountain with the top cut off with a big hacksaw. Sharp corners on the signal are the speaker killers because when the signal changes direction suddenly, the cone can't follow it. This causes the energy to turn into heat instead of sound. Eventually the voice coil overheats and either warps or the winding burns out. Ok, maybe it was 4 cents... | ||
| gare
Junior Username: gare Post Number: 25 Registered: 11-2003 |
It seems to me the biggest issue would be matching the impedance load to the rating for the amp. Since power is additive, if you had a cabinet with 2 speakers rated at 300 watts each, the cabinet would be rated at 600 watts. Of course you wouldn't want to run a 500 watt amp into a speaker rated for 5 watts. (well,maybe you would) But isn't it the transient peaks and/or high sustained power output by the amp that causes speaker cone and voice coil damage ? A tube amp is more lenient on it's load due to the output transformer,whereas solid state amps are designed in a narrower load range. I had a solid state amp burn up on me once..burned real good. Just didn't like a 2 ohm load. You learn from your mistakes. Everyone have a swell weekend ! Gary | ||
| stoney
Advanced Member Username: stoney Post Number: 319 Registered: 7-2002 |
Another thing to consider is the sensitivity of the speaker which is rated in db. I totally forget what the ratios are but as a for instance: the ACME speakers have a sensitivity rating of around 93db whereas the Euphonic Audio speakers have a rating of around 102db. It doesn't sound like much but it is, trust me. It takes a mamouth amount of watts to get the ACME's up to speed when the EA's overall can be powered and sound great with much less watts (which equals weight and $$$) I'll stop there since I'm highly "un-technical" ,...but it is something to consider. | ||
| bigredbass
Advanced Member Username: bigredbass Post Number: 271 Registered: 9-2002 |
Aircooled: Basics on amp ratings, cabinet ratings, . . . First, be sure you do your homework on the Mesa amp: 200w into 2?4?8? ohms? Does Mesa recommend one impedance, or what is the minimum impedance they recommend? Say, 4 or 8 ohms, but never 2, for instance. Mesa maintains a pdf manual library on their website. Do yourself a favor and GO READ IT if you did not get a manual with this amp. Generally, you will not blow 200w cabinets with a 400w amp. In other words, more amp than speaker is better than the reverse. Why? A small amp pushed hard (too little bass amp fighting Marshalls, drums, keys) will distort as it overdrives. Electrically this power amp distortion (NOT the desired distortion tone that occurs in the preamp) is generating DC pulses to the speaker(s). Speakers want to see AC (+ then -) which push and pull the cone normally. When the power amp distorts into DC, you get only one-way motion at the speaker: This turns your speaker into a heat sink. Let this go on long enough and the speaker will fail. Either over a long period of time, or maybe in as little as a set or two if it's bad enough. A big amp, running at a smaller percentage of its capacity, will calmly put out clean power all night long. And this clean power is very unlikely to hurt speakers. Of course, you wouldn't bridge a big Crest through a 5" radio speaker, but you get the idea. Strategy's are one of the most delicious power amps ever made. Congratulations. Most cabinets you are likely to consider will work just fine with it. Paired with an ALEMBIC preamp you would utterly have the market cornered on tone. About power ratings, incidentally: Remember that sound pressure levels (or loudness) increases LOGARTHMICALLY: If you drive one cabinet off the A-side of your amp at 200w, adding the same cabinet on the B-side (now 400w with two cabinets) will only increase the db level by +3db. Things don't get twice as loud every time you double the power, so don't fall into that particular mental trapdoor, either. Best Wishes, J o e y | ||
| somatic
Junior Username: somatic Post Number: 15 Registered: 11-2003 |
Joey's response just saved me a heap of typing. I would like to add that doubling the power produces a +3dB change in output, which ordinarily is not very noticable; +10dB in output sounds twice as loud, and it requires 10x the power. One of the specs of a speaker that people seldom talk about is it's sensitivity. This will be listed in a (good) manufacturer's specs and will be, say, 100dB/1W/1m. What that means is if you put 1W into the speaker you'll get 100dB of sound out. If another speaker is only 90dB/W/m it will put out 10dB less sound for the same amount of power. Now if you hooked one of these speakers to each side of your 200W amp, then the first speaker will be able to put out 123dB max, and the other 113dB, and as I said above that means the second one will sound half as loud, even though it's consuming the same amount of amp power. I like efficient speakers. They almost always sound better to my ears. Personally with a 2x200W amp, I'd run a 115 and a 210 (+ horn) with one cab on each channel of the amp. |
