speakers and power consumption

whgarrett1394

Hi, I was hoping someone could educate me. I have a pair of M5jr+ speakers and an Adcom 535. If I am running a full range signal to the Polks which have a frequency response of 30hz-25khz is the amp still using power to produce inaudible low end frequencies? If I only send the speakers(lets say 80hz and above) via a crossover, will I have alot more head room in the 60wpc adcom? The latter question is more applicable to my situation, and the first is just for increasing my knowledge of sound. I hope that wasn't too confusing. Appreciate all feedback. Thanks.:)

mhardy6647

Yes, the amp is amplifying whatever is being fed into it, based on the limitations of its own bandwidth. Most of the power being produced is in the low frequencies; that is why it is perfectly possible, in bi- or multi-amped systems, to use extremely low power amplifiers (e.g., single-ended vaccum tube amplifiers of just a couple of watts output) with the midrange and/or HF sections of even quite inefficient (insensitive) loudspeakers.

This is why, in the old days, amplifiers often had infrasonic "rumble" filter slopes built into their phonograph preamp sections. The very-low (sub 20 Hz) noise in a typical phono system would suck up massive amounts of amp power in their reproduction - with no audible benefit, and the real risk of damage to loudspeakers.

HTH, as they say.

Joe08867

What he said^^^^^^Nicely put mhardy6647.

munk

The RTi A's go down to 18hz- that's not a significan't impact on power requirement, is it- since the human range is down to 20 hz?
What I'm trying to ask is if the power requirement is much different between 20 and 18hz?

The miminum power requirement is 50 watts, so these speakers do eat up juice.

sda2mike

I have a pair of M5jr+ speakers and an Adcom 535. If I am running a full range signal to the Polks which have a frequency response of 30hz-25khz is the amp still using power to produce inaudible low end frequencies?


i think you're theoretically stretching the sack on those 5jr's..60hz on a good day...IMHO, YMMV, :cool:

heiney9

You guys are funny, Monitor 5's won't come close to hitting 30Hz nor with the RTi A's come close to 18Hz. The op's questions is a non issue unless you are using a cheap TT and need to worry about subsonic notes from turntable "rumble".

5 jR's on a good system in the proper room might hit as low as 50Hz.

H9

munk

damn. I guess that answers that. So specs are not actual in-home?

tonyb

munk wrote: »

damn. I guess that answers that. So specs are not actual in-home?

Not really, every home is different,so how can it be?

sda2mike

munk wrote: »

damn. I guess that answers that. So specs are not actual in-home?

they're in-labratory...highly optimistic and marketing wiz-bang NUMBERS...just like horsepower, amps, gallons and anything else you can StReTcH the truth with

heiney9

munk wrote: »

damn. I guess that answers that. So specs are not actual in-home?

You need to refer to the specs that give a +/- 3dB rating when looking at freq. response, it still doesn't really tell you much about how the speaker sounds. Even then that frequency response is under test conditions, in a perfect environment using test tones or a freq sweep of tones, not real music content. Those specs are a very rough guide.

H9

whgarrett1394

Thanks for the responses. When I gave the specs I wasn't sure which to regurgitate. I guess the -3db @ 48hz is the more tangible measurement to performance. So just to repeat what I think the answers are. Amps are using energy to produce all frequencies within their range no matter the speaker capabilities, and using an active crossover such as the rane 22b @80hz should free up more power to the mids and highs of 5mjr+. Thanks again.

tonyb

Hmmm...adding an external crossover and removing the one in the speaker seems like alot of trouble to go through for speakers worth 50 bucks. But hey,if thats your project,go for it. To me,everything has it's limits and you can only get so much out of those 5's.

whgarrett1394

I suppose my intentions are somewhat misleading since I posted in the 2 channel stereo section. I'm actually running a 2.1 system. I'm not doing anything to the internal passive crossovers in the mjr5+ polks unless at a later time I do an upgrade/mod. Thanks again.:) They are, however, a damn good speaker for a mere 50 bucks.:D