Many Quad, Spica and others have suffered from too much power. Of course it was human error, but sans the power, their speakers might still be working. |
Bob bundus. I agree with Jsteigert - That was a concise and ealsily understood response. And also with Nalu's closing analogy. A far better visual than mine. Thanks everyone. |
Bob bundus
Nicely articulated response. |
Rogo - within reason you cannot have too much power. Amplifier-control of the speakers is one issue, headroom is another equally if not more important issue. My speakers are rated 100w/ch, but they consistently sound better with a 200w/ch amp, or more. Small amps, when overdriven, are what generally causes blown speakers. It is harder to damage a speaker by overdriving it with a big amp than with a small amp which is into clipping. If you occasionally like to crank it up then a larger amp is called for. If not then some of the issues raised above are indeed to be considered. I generally listen at only around 2w/ch, sometimes 20w/ch, sometimes more. At said 2w/ch level I have 100x that power level for an ideal 20dB of transient headroom.
Doubling or halving of power is a 3dB change, which seems like a lot but it isn't actually that much. Going from 1 to 2 watts = +3dB. 2 to 4 watts is +3dB. In the other direction, 100 to 50 watts is -3dB. 50 to 25 watts is -3dB.
for POWER:
1dB = 1.25x
3dB = 2x
6dB = 4x
10 dB = 10x
20dB = 100x
voltage (dBv) is measured differently however. |
Stne418, here you go!
Basically, it's a geometric progression. For POWER (watts) a 3dB increase requires a doubling of power, a 6 dB increase a quadrupling of power, a 9dB requires 8 times the power, 12 dB requires 16 times the power, etc. Voltage dB is the same doubling, except the measurements are expressed as 6 dB increases when voltage is doubled. Here are the formulae:
dBv (volts) = 20 x log E2/E1 (where E is voltage)
dBw (watts) = 30 x log P2/P1 (where P is watts)
by Fatparrot |
As alluded to above, I agree with matching amp power to speaker needs. After going to Vandersteen 5 speakers that have built in 400 wpc amps to drive their built in sub-woofers, I went from a huge 300 wpc (McCormack DNA 2 Rev A) to a 100 wpc of equal quality (McCormack DNA-0.5 Rev Gold), and lost nothing in music quality/character.
In fact I now prefer the 100 wpc amp for its user friendliness, and lost nothing in sound quality. The DNA .5 Gold is considerably less expensive too;>) Cheers. Craig |
I do not clearly remember the formula, old age is setting in on the brain cells, but to double your sound level output, in general terms, don't you need 10 times as much power? So...going from a 100 watter to a 250 watter really does not greatly increase your output capabilities. That said, the bigger amp will do some things the smaller one may not and sometimes vice versa. |
Nalu...great post, and thanks for the info about Plinius. I was unaware of the class A/B standby mode. Great idea...but are there any trade-off's (there usually are in audio). Things like more complicated circuit design, with a greater cost and pehaps more electrical devices (to fail), or a circuit that is not quite as stable. Again, I'm not saying any of these are true, I just don't know. But the following is truism of life, espescially in audio design, "T.A.N.S.T.A.A.F.L." or, "there aint no such thing as a free lunch!" |
Being a confirmed fan of Class A (Sumo, NEW, Classe, Atma-Sphere, Llano and now Plinius) and planar speakers (ML, Soundlab and now Apogees), power is a major issue in my audio life. I don't believe you can have too much. Having said that, there are volume control, sound quality and heat issues as pointed out above quite accurately (Fatparrot - Plinius amps have a bias switch that allows you to keep the amp warm in AB and ramp up to A in a few minutes - a very handy and unique feature, even better than the standby mode of tube amps). Could I cook my ribbons if I cranked the Plinius all the way up? Probably yes. But I couldn't stand to be in the room, so I think I'm safe from power excess. At the same time I've heard JA-200s clip on acoustic guitar through Apogees - 180W of Class A tube power was not enough! I would compare power to breast size (or horsepower if you like the auto analogy): in general, more is better, but after a point it becomes ridiculous! Let your results in your system be your guide. |
Yes, you can have too much power. |
Hmmmmmmm, I've always felt that when an amp was running too close to its limits, the sound wasn't as good as when it was just crusin' along not being pushed. I think some headroom is a good thing. |
My Cinepro 3K6II is too much power. I now have so much volume, so fast that my subs can barely be heard. Balance in your system is what you will lose. Along with power comes noise unless you have the big bucks. I will be returning to the 200wpc crowd before too long. Maybe seperate amplifiers next, I haven't decided yet. |
Subaruguru beat me to the punch and with so few words! Rats. |
Yes, I used to think that I needed a 3.5 watt 2A3 amp, but I found out that my system did all I wanted with a 2 watt 45 amp instead. |
Consider the following. Quad speakers have a protection circuit to keep them from being over driven. However, it has been pointed out more than once that less powerful amplifiers tend to trigger the protection circuit more often than high power amps. Enter current management and headroom; amplifier control is at least as important as Watts and many high power amps do it better. |
I used to go for MONDO power when running SS amps (class A/B). Now that I've switched to tubes, I like to use reasonable powered amps (say 50%-75% of rated speaker handling power). I'm using an Atma-sphere M-60 MkII.2 (60 watt mono's). Replacement power tubes 6AS7's are relatively cheap ($15-16 ea.) but even so, at this price, a set of 16 (8 per monoblock) will still cost $240-. At least Ralph doesn't run the tubes at maximum parameters, so a set should be good for 2-3 years. Other manufacturers run their circuits with the tubes maxed out (and some can be much more expensive than the 6AS7's) and are know for chewing up tubes (under a year). The MA-2 Mk. II.3 mono's at 220 watts requires a total of 40 tubes...you do the arithmatic! Not to mention the the way, WAY higher list price for an increase of slightly less than a 6 dB's of power gain over the M-60's! Why pay "mucho dinero" for something that you don't need (braggin' rights?) Especially since "tube watts" don't clip out like transistor watts will. Then there's the heat factor. Since I'm in an apartment, the air conditioning fan unit is in the hallway, and I must shut it off for any serious listening. Windows are closed (so as not to piss off the neighbors...and the management). This can be a challange on 110 degree day of an Arizona summer! At least I can keep the amp in standby (filaments on, plate voltage off) when not listening. It's a class "A" amps, so the filaments aren't the heat generators or power hogs). If you're running a class "A" transistor amp, you should leave it on all the time. Not only do they generate a ton of heat, but the idle current (power on, with no signal) can EASILY add $20 to $100 to your monthly power bill. But who ever said "braggin' rights" come cheaply! |
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Didn't you hear his speech last night? |
Too much power (especially with a very sensative amp) can get you into trouble if you have very sensative speakers and a stepped preamp.
Basically, in this situation, you could hit a very loud volume at 1 or two notches on your preamp. This gives you lousy volume control.
THe problems above actually (upon a little reflection) are primarily caused by the sensativity of the amp and not power per se.... But too much power in this case can blow real sensative speakers easily.
I think amp designers will agree that is much easier to build a 25wpc amp that sounds wonderful within it's power range than it is to build a 500wpc channel amp that sounds wonderful in it's power range. It is also a lot cheaper. My theory is that unless your speaker really require amazing power, there is little need to go overboard on power.
Then there are speakers that love power.... Maggie 3.6's.... If I could have fed the Pass X-1000's to my Maggies, I would have. 2000wpc and ungodly amps of current into the Maggies would have made em sing.
KF |
