Axiom Home Page Forums General Discussion Stereo Help me build the right system

The more I read, the more I am convinced it is worth extra effort to put together the right speaker and amp/prepro or receiver combination. EFalardeaus post on his experiences with his new A1400-8 amp with his M80s was a real eye-opener to me.

In particular, the comment about moving from a recording sounding like a really good recording to the actual instrument. I would love to be able to get this out of any system I put together.

As a side note, I don't think this is that hard to do for most rock because the source is already amplified, but with anything acousic there is another level of complexity to reproduce.

This leaves me wondering what the best choice might be to drive a pair of M60s if I want to get the most out of them.

I am planning a system for music first and possible HT down the road.

So, from what I have read so far, enough power for the dynamic range of the speaker is a must. Now, what exactly whould that be? If I remember correctly, 150w is the max for the M60. Does this mean I need a full 150w for full dynamic range performance out of these speakers? I suspect not, but how many watts do I really need?


I am guessing this is where dynamic range comes in, at
least on the attack side(??). The amp needs to be able to provide the large jump in power to drive the speakers response without running into any limits. Is this correct?

Now for that can of worms... What is at play here beyond the power to handle big shifts in range? Not being a sound engineer, it is hard for me to judge when we leave the world of fact for the realm of fiction when discussing amp. specs.

Hopefully this will help me to understand where to focus in matching the amp. to the speakers.

Fred

If you havn't already seen it here is another thread on the a-1400 you way want to read through. My motto has always been that you cannot have too much power for any speaker if you utilise common sense with the volume control. Axiom has eluded to a 2ch version of the a-1400 which may interest you if you're thinking stereo primarily.

Fred, the recommended max of 250 watts for the M60 would imply that it wouldn't go up in smoke at that input(and probably quite a bit more), but doesn't supply much helpful information as to how much power is needed for a particular use. More useful in that respect would be the sensitivity rating of 89dB. This means that at one meter anechoically(not counting room reinforcement)1 watt would be needed for a rather loud 89dB listening level. Several factors such as room size, liveness, listening distance, etc., affect what the level at the listener's ears would be, but as a rough rule of thumb at a typical distance of about 10', 3-4dB can be subtracted from the sensitivity rating to indicate the total loudness for 1 watt resulting from the combination of direct sound plus room reflections. So, with the M60s 1 watt would be used for about 85dB at the listening position.

Now, the dynamic range of the recorded material(not the speaker)is what's significant in determining how much power is needed to handle brief peaks. Some very loud pop items are mastered with a dynamic range approaching zero, while some other recordings, especially in the classical realm, have a dynamic range of as much as 60-70dB. It's often suggested that to allow for material with a wide dynamic range that 20dB above a comfortably loud(but safe for hearing)average level be provided for. For example, if 85dB(actually louder than a typical average level)was used for listening to dynamic material on the M60s, to accommodate 105dB peaks about 100 watts would be used. So, it depends on how loud of an average level the listener adopts and how much above the average that the peaks hit on the recordings in use.

Thanks for the link duckman. I should have used the search function first. Can 'o worms indeed.

John, thanks for the explanation. It seems some folks think there is even more to it than that including things like rise time etc., but there is no concensus on the effect of these other things. Don't know where that leaves me...

Given that the speakers will be located in a smaller room, ~1900 cu.ft. and my average listening distance will probably be closer to 6-8 ft unless I am in the kitchen, I don't think I will ever need and amp like the A1400.

I think I need to start a list of questions for the folks at Axiom when I go up to audition speakers. It will be interesting to a/b the A1400 against onother amp at various volumes to see what I hear.

I suppose one of the things I need to figure out when I am there is what I consider to be comfortable listening levels.

As for dynamic range, I suspect that much of the stuff I listen to (prog. rock) has a greater dynamic range than your average pop/rock.

Thanks guys. I am no closer to answering my question, but at least I know how to go about getting an answer now.

Fred

in that small of room, I would think any decent AVR from Denon, HK, etc will make you smile from ear to ear and provide as much power as you would need. In my close to 8,000 cu ft room it is a different story.

Fred, a quick comment on one parameter that you mentioned, i.e., rise time: there certainly is a "consensus" on that in the technical literature and it's unclear what you might have read someplace that indicated otherwise. Rise time and the related slew rate measure the ability to respond to voltage changes quickly enough to reproduce the highest frequencies of interest with flat response and low distortion. There are specific formulas to determine the requirements and as long as response is flat to well beyond 20,000Hz, as is typical of nearly all modern solid state units, this establishes that the rise time and slew rate are sufficient(typically anything in the double digits of slew rate)and needn't be a separate matter of concern for the listener.

Thanks jents.

sirquack. After spending more time reading about integrated amps, separates and receivers, I think that I should learn to like your answer the best and leave it at that.

The mind boggles what some folks will spend in the pursuit of better sound.

Fred

However, I do have seperate mono blocks driving my 80's.