Power increase on receivers using an 80hz crossover point.

[anamorphic96]

Is there any information available on much of a power increase a receiver might have when running a receiver with an 80hz crossover ? Considering it doesn't have to output any real bass I would think it might be a decent increase.

 

[corey]

I think you're spot on about the direction of your question, but not the detail. It's not about a power increase in the receiver/amp, but less demand from the speakers. It can't be measured on the amp side, because it is more a question of the speaker's power requirements.

 

[mike c]

but i think anamorphic is asking: since receivers are spec'ed at 20hz-20khz

80hz-20khz would yield some more power ...

kinda like a 1khz spec from an amp has more power than one from 20hz.

 

[highfigh]

If the amp distorts a lot between 20Hz and 80Hz, it might be 10% but that probably won't be noticeable. What should be more obvious is that the sound is a little cleaner when it's pushed hard, but if the room is acoustically live, it'll be masked by all of the reverberation.

Removing 20Hz-80Hz from the amp's input generally allows pushing it to the maximum output without sounding like crap and keeps the speakers from receiving frequencies they can't reproduce well, if at all.

 

[krzywica]

I did notice that my mains sound a LOT better after installing my sub and being able to cross them over at 80Hz. I think I was pushing my amp near its limits before.

 

[AVRat]

If I'm not mistaken, frequencies below 80 Hz consume about 20% of the energy across the spectrum. If you give back the 20% to the other 80%, that is 25% or a little less than 1 db back to the frequencies above 80 Hz.

 

[Nextlevelaudio]

I agree with Cory. Hard to measure any instance of increased output power in relation to limitation of frequency. True it may improve the effeciency, but I don't know if you can put a number on the increase in ratio to efficiency. Impedance would have an affect on output power that of course is measurable.

 

[anamorphic96]

but i think anamorphic is asking: since receivers are spec'ed at 20hz-20khz

80hz-20khz would yield some more power ...

kinda like a 1khz spec from an amp has more power than one from 20hz.

This is pretty much what I was getting at. Receivers rated at 1khz tend to have 10 to 15% less power when rated full bandwidth.

Its an odd question I know, but figured I would throw it out their.

Thanks for the input everyone.

 

[aarons915]

I know this is an old thread but I was wondering the same thing. Taking it 1 step further I would say with most people using bass management these days there isn't much need for a ton of power anymore, I bet most of us are very rarely even using 1 Watt of power when watching movies or listening to music.

 

[mercary48]

Before that was a bottle of Rickards Red beer.

 

[ImcLoud]

This is why i cross to a sub in almost all of my systems, even music... It seems when you ask the amplifier to reproduce the freq's under 80hz there isnt much left for the voice and highs, which in the music I listen to is most important...
So as long as you do it correctly, placement, power gains, crossover points, ect a [air of bookshelfs and pair of fast sealed subs can sound much better than a pair of towers... You end up with more power on tap since the subs are active and normally 300w each. but for example we are finishing a system today.

2-csb1 bookshelfs with a pair of 200w mono blocks and 2 svs sb12 nsd's, that is 1200 watts rms total and after a little work with the fmods and placement Im sure it will sound much better than any set of towers in the same price range... $1600 Some people will say "a good set of towers sounds better" and "adding subs adds problems" but most of these people haven't listened both ways, I have tested this 20 different ways and adding a sub, relieving the speakers and primary amp of the lows, adds range, adds volume, and adds to sound quality... getting them integrated takes a little doing but its worth it..

Its even better in low end systems, a topping tp 60 amp, a pair of fmods, with a pair of pioneer AJ bookshelfs and the andrew jones sub sounds really good for music and can be had for under $500... I cant think of a pair of $300 bookshelfs that will sound as good from the bottom up...

 

[j_garcia]

I'd say you aren't getting "more power" out of the setup when crossing, it is just that you are making use of more of the available power. Crossing the mains higher does not mean the amp can deliver more power than it is rated for, it just means it isn't working as hard.