Basic question about power/watts
Hi everyone - I have a question that I can't seem to wrap my head around.
I purchased a pair of Magnepans a few months back. Honestly, I do not like them. They have their moments but overall, pffft.
So, related to this, I keep reading from various Maggie owners you need TONS of power to make these things sing rather than squawk. I bought a new amp that is rated at 80 wpc at 4ohms. This, I realize, is low power when I see these guys saying they are running some crazy amount like 600 watts per channel. Here is my actual question:
When you are listening to your speakers at a normal volume, the wattage you are using is not near the POSSIBLE output, correct? My 80 wpc is unbearable with the volume at the 11 o'clock position. Why does a person need or want 600 watts? I suspect I am missing something here. Maybe this has to do with why I dislike my Magnepans. Somebody take a moment to set me straight?
Thanks!
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- 50 posts total
Dear Tim in Texas, |
First, understand that speakers are not a pure resistive load, so "watts" from the amplified doesn't equate directly to "watts" at the speaker. Most amps give rated power into strictly resistive load (e.g. 8 ohms, 4 ohms, etc.) and if the speaker was a resistor, then yes "watts is watts". However, since the speaker receives an A/C signal, and there are various elements in the speaker that have capacitance or inductance, you need to think in terms of "impedance" not resistance. Meaning, the signal voltage and signal current at the speaker will not be in-phase (i.e. max or min current won't align with max or min voltage), and that difference is called the phase angle. For a real world speaker, the phase angle can reach +/- 45 degrees (for a resistor, that angle is zero). So the actual power delivered to the speaker is a function of the cosine of the phase angle, and this is basically the Power Factor, and the power supplied by the amp. So this can be as low as 0.707 for a real world speaker, meaning the amp must supply ~4 watts at the output devices for the speaker to "see" 1 watt. Worse, the phase angle will change for different frequencies, so the frequency response (not just overall volume) is also affected when the amp can't supply sufficient power. So you have to figure that a 50w @ohm amp/receiver is likely to be capable of less than 12 watts for a given "4-ohm" speaker at worse-case (relative to power factor) frequencies. Better quality amp manufacturers will take phase angle into consideration and have a sufficient number of output devices and power supply stiffness to accommodate the increase in instantaneous current load requirements (headroom available) for most real-world speakers. Can't comment on the Maggies specifically since I'm not a dipole kind of guy. Good luck! |
It ain't you amp. Don't waste your time chasing ghosts. If you can play them loud enough, and by your description too loud, without obvious clipping, then you don't have an issue, unless you are using a tube amp. Tube amps and maggies are not good bedfellows. Magnepans may dip down to 3 ohms, but they are close to being a resistor as you could ask for for a speaker. The impedance from 20-20 may not vary more than an ohm and phase is flat too.
@mlsstl gave you the answer in the first post. Wonderful speakers when dialed in and the room works for them. Awful in every other case and that is the case more often than not. |
a lot late to the party. Whenever I hit the stereo shops here, I listen to about everything, b and w, songs Fabre, with Mac amps, etc etc, I will stay there for 2 hours. I love the magnepan airy sound, guitar sounds so real, voices, then there is the kick drum, this is where boys and men separate $$$$$$$$
**as mentioned, patience and relax. If it takes an extra few months or longer to save a small bit more money, so be it. I sat on 5K as I saved it, huge wad in my hiding place, I then started gathering info, reading a lot, talking to the fine people in here,asking tons of questions. I bought used, and have a very very good pair of amplifiers, with matching pre and cd spinner. Amps were a great deal, pre was also a fair price, cd spinner was 100$ over what I wanted, but, if you want something, get it before someone else does.
maggies will take gobs of power, and sound amazing, as far as a bass driver, mentioned above, this will totally help. Get 250-300W RMS, you can thank me later. The Bryston is a great idea, also the crown, or the QSC. the crown and QSC are built better. or try the Avantones newest amp cla-400 about 1K new. Wish I knew this was being released I ,..n remind!
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- 50 posts total