Axiom Home Page Forums General Discussion Advice from Axiom Owners It is OK to add Amps...

Now there is a good argument for extra 'unused' power. We know and understand (well, most of the time) our limits and the limits of our equipment. Teens seem not to.

Although when it comes to volume knobs, sometimes.
Adults + alcohol = teens

Allan Loft wrote what I think is the best article around describing power requirements. Easy to read for the dummies in the room (self). One watt is just fine for background noise, but for those of us who prefer things a bit louder, 100 watts becomes the minimum, not the max. http://www.axiomaudio.com/power.html

And his follow up article on head room description and power requirements. http://www.axiomaudio.com/dynamicheadroom.html

People preaching power needs should really understand these basic principles and make clarification to what they are talking about when they tell others that they “only need” a few watts of power.

Michael. It is simple physics, which is why I link to a calculator so often. There is no 'minimum' requirement per se.

It depends on room size (listening distance), listening volume, dynamic requirements and speaker sensitivity. Those are exactly the variables you enter into a calculator.

I have read and do like Alans articles on power.

No, Brian; that wouldn't be a safe assumption. The actual listening level apparently hasn't been measured, and that's necessary to know the actual power used by the speakers. If some or all of the observations are real rather than illusory(which is often the case with us)there's a strong probability that the listening volume was at least slightly higher. Amplifiers only add more voltage from their power supply section to the incoming voltage from the source material at any instant to make it drive a speaker loud enough to be heard easily(typically pre-amplifiers increase voltage 4-5 times and amplifiers 25-30 times). If they don't make it louder, they don't have any magical ability to somehow make the sound better at the same level. At a comfortably loud listening level(say mid 80s of dBs)speakers of typical sensitivity, such as the Axioms, use about 1 watt. How much more is needed for brief peaks depends on the source material. Some pop material is almost uniformly loud and has a dynamic range approachng zero. 2 or 3 watts might be the most used on such material. In contrast, some highly dynamic material, such as a few of the classical recordings I have, may have brief peaks as much as 20dB above the average and would require about 100 watts for that listening level(which I rarely actually use).

So no, there's no clear indication that any "extra" power over what your receiver could supply anyway was used.

One of the major flaws with this calculator is that room size and listening distance are not the same thing. How can listening at 4 meters (13 ft.) outdoors be the same as listening at 4 meters in a 2500 cu. ft. room?

Thanks for the clarification John. As I stated, I am not claiming to know what I'm talking about, and my post was meant for us folks who do not have the technical knowledge required to make decisions based on such. Some pre/post measurements could have been helpful, and interesting to say the least. I may break out the meter this afternoon just to "see" what I'm hearing. Let me ask this, your opinion of course, many claim there should not be SQ changes from amp to amp. But if volume and power levels are the same, meaning 100 watts from avr or ext amp, would the use of mono blocks make a difference? Just wondering why so many claim diffenrences in seperates vs. avr's. I really want to believe it's not just in one's head.
Thanks.

I love physics. I love math, and chess too. They all take discriminating opinion, perception and chance out of the situation/conversation and speak to facts, logic and numbers. Unfortunately, when it comes to subjects such as this one, and many others where “opinions” and “wives tails” play into the subject, physics then gets surrounded and lifted away within a whirlwind of bullshit. I generally avoid these topics anymore as there are hard liners who feel solid state amplifiers have their own sonic character and that they “add” all kinds of wonderful things to the electrons that make things sounds better. Then on the other side of the conversation are those who pull their calculators out of their shirt pockets, run numbers and then compare them to graphs and trends and tell you what sound looks like. I’m somewhere in the middle. I use outboard amps, but don’t really need them. I just prefer separate components over boxes crammed with crap that fight for realistate in the box. I’ve performed my own highly subjective and unscientific testing with and without outboard amps. I could not, (with a straight face), detect any notable difference in sound quality until the mean decibel level in the room reached 90 DB. At this level, the outboard amps in the mix definitely made a sonic improvement. But, as John has mentioned many times before, this is much too high for any sort of sustained listening unless that individual wants to suffer long term and irreversible hearing loss. But, for this last test, I started out with a receiver that had a robust power supply. I have also played with many other receivers “rated” at above 100 WPC and they sounded like crap above 70 DB. So when folks ask if receiver such-and-such will drive their speakers, I do more than look at their WPC rating. Some are simply better made than others and some brands are more honest than others. I’d recommend a 75 WPC NAD over a 125 WPC Yamaha any day of the week.

I agree whole heartily michael. This is why it is difficult for many to make a decision when looking for reinforcement on forums. I decided to just do it because I wanted to, not because I felt I needed to. Now the dilemma of trying to understand why I feel/hear a difference has started. The last time I had my meter out was before adding the sep amps, and I was getting readings above 90db with music and 100db+ during movies. I guess that may explain a possible improvement, but per the calculators I've been linked to my avr should be able to power to that level.

I'm just trying to help those who may be on the fence, or wondering like I was. By no means am I trying to start another argument or revitalize a topic that has been discussed over and over. This topic becomes popular due to the constant communication of possible difficulties of avr's driving Axioms, and the fact that they can handle more than what any avr can provide. I do truly appreciate everyone's help, and willingness to share information.

That is exactly why you add 4- 6 db for room gain.

I do not claim that this calculator is the be-all end-all definitive answer. It is a good guideline. If the calculator shows you are close to the limits of the receiver it may be worth while considering outboard amps. If, like me, you are only at the 60% mark of power available, outboard amps are a waste.