Axiom Home Page Forums General Discussion Stereo speaker efficiency in relation to power amp watt.

Hi,
I'm not sure if i state the subject correctly or not, but i have question. Here it is:

Is the power amp wattage has anything to do with speaker sensitivity in db, especially M60ti? I read somewhere that if your speaker has high sensity, then you won't need very high power amp. So, let take an example of Rotel RB-1070 (130wpc) and RB-1080(200Wpc). Is RB-1070 is good enough to drive M60 or RB-1080 needed? I'm talking about the dynamic and soundstage of these amp.


thanks.

hey audiofan

The soundstage will not be affected by the amp as long as proper stereo seperation is maintained in the amp - and relatively any amp company still in business maintains stereo seperation in the amp.

Go with the RB-1070. Everytime you double the watts, you gain 3 dB, a slight change in volume. The minimum volume you would probably get with 130 watts would be 107 dB - your ears would give out before the amp did.

Check this spl calculator, you'd be surprised how little difference between the two amps there really is when driving such an efficient speaker. It'll probably tell you that you could get over 111 dB.

The Rb-1080 watt amp retails for $300 more than the RB-1070. Take that money and get a HSU subwoofer with it - it'll make a _lot_ more of a difference in your system than an extra 70 watts would. Or you could just pocket the $300 and spend it on other stuff.

great. Thanks for the information.

I actually has STF-2, and I just want to get a 2-channel power amp for music and release power load from Denon 3805. With $300, i can do lots of things....:) i'll check it out.

Either amp will do nicely for what you are contemplating.

IMO, the Rotel amplifiers you are looking at are better than the Denon you have. Assuming you used preouts, drive the front speakers with the Rotel - but I am sure you figured that much out!!! LOL

AF, what you're considering is unnecessary. Your 3805 is very powerful and your use of the sub already has taken a significant load off the 3805's amps(incidentally, as was said, the soundstage isn't affected by any competently designed amp). It's highly likely that you're using only a small part of the capability of your 3805 now and there's no good reason to consider a duplicate amp which isn't significantly better. Don't waste your money.

bigwill made a post about this recently - it won't make any discernable difference in sound, yet the extra power will be nice for when you really want to crank it. He added an Onkyo amp to his denon 2803, and was able to get it a bit louder(when playing five channels, not two - only the most horrible receivers are power shy when it comes to two channel music). Receiver amps work nicer powering three channels than they do powering five. Only the worst receivers, when barely pumping out anything under 80 Hz, sound bad without an external amp.

If it were me, well.. you already have an amp - I'd get another STF-2. It'd make a hell of a difference, and it'd be $300-$600 less than the amps you're considering getting. I thought you didn't have an amp yet.

So when using the SPL Calculator, do you use the "SPL in room" efficiency, or the "Anechoic SPL?"

You probably want to use the in-room efficiency data. Give both a try, though. The difference in total SPL at different wattages will be similar regarless of what you choose.