@lonemountain Brad, you make an interesting point. While most folk would consider your example as efficient, the other variable, which could effect how an amp interacts with this speaker is how the load the speaker presents varies across it’s frequency spectrum. For example, I know of a very good metal box speaker that has specs similar to what you post ( not quite as good, about 89db vs.90db), but this speaker drops down to less than 1 ohm in the bass regions between 35hz and 55hz. Therefore, I’m not so sure I personally would consider this speaker as an efficient speaker, or easy to drive.
How important is the efficiency of a speaker to you?
I went to an audio meeting recently and heard a couple of good sounding speakers. These speakers were not inexpensive and were well built. Problem is that they also require a very large ss amp upstream to drive them. Something that can push a lot of current, which pretty much rules out most low-mid ( maybe even high) powered tube amps. When I mentioned this to the person doing the demo, i was basically belittled, as he felt that the efficiency of a speaker is pretty much irrelevant ( well he would, as he is trying to sell these speakers). The speaker line is fairly well known to drop down to a very low impedance level in the bass regions. This requires an amp that is going to be $$$, as it has to not be bothered by the lowest impedances.
Personally, if I cannot make a speaker work with most tube amps on the market, or am forced to dig deeply into the pocketbook to own a huge ss amp upstream, this is a MAJOR negative to me with regards to the speaker in question ( whichever speaker that may be). So much so, that I will not entertain this design, regardless of SQ.
Your thoughts?
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Asking the question "What is efficient enough?" brings up mutiple challenges. the first being hardly anyone listens much over 90dB SPL! I was at AXPONA this weekend and in our room we are demong ATC. I meassuredIf the SPL when things got "loud" : it was around 92dB SPL. If the 1w/1m spec of a passive was 90dB, it would require less than 2 watts to get that speaker to play at 92dB 1M. If it was 86dB 1w/1M it would require 4 watts to get it to 92dB at 1M! 92dB SPL is very loud for many of us, most audiophiles wouldnt even want it at 90-92dB SPL in their living room or listening room. It appears in reading this thread that most would agree that above 90dB 1w/1M is efficient and 86dB 1w/1M is "not efficient". We need 2 watts to get our 86dB speaker to 89dB SPL, which is indistinguishable from 90dB to most of us. This 2W instead of 1W is really a critical issue and one that drives a purchase? My point is that very very few of us listen at 92dB SPL. The argument for an "above 90dB 1w/1M speaker" is not a relevant argument as no one even wants to listen that loud. 90% of our listening is WAY under 90dB SPL. If this is true, why is 90dB+ 1w/1M efficiency such a important spec that we all need to pay attention to it? Brad
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? Only if your listening distance is 1 meter....SPL drops by 6 db, every doubling of listening distance. If your listening distance is 13 ft, a 90db (1meter) sensitive speaker will produce 78 db avg at your listening position (13ft) with 1 Watt of power. Headroom and the variables that play into it is a debated topic and it will tend to dictate higher powered amps. Higher powered high fidelity amps could get expensive.
P.S. Take a SPL meter with you to nightclubs, concerts, discotheques, etc. When you’re really enjoying the beat (having fun), take the SPL meter out and you will often note that it is higher than 90 db and a lot more...Or just go watch an orchestra. You’d be surprised at what your db meter reads.
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@lonemountain wrote:
Brad, As you’re no doubt aware of, comparing lower efficiency speakers with true high eff. dittos isn’t an apples to apples scenario. It doesn’t only come down to how loud one enjoys playing the stereo, but rather and not least how a given volume is reproduced - i.e.: the very nature of the sound. Many aspects come into play here, like speaker principle/driver types, directivity pattern, headroom (or lack thereof), cone area and overall physical size, specific design choices, etc., and these aspects can be a product of or otherwise relate to a given sensitivity, which again has sonic implications. Choosing high eff. speakers can’t help but reflect on these interdependencies, and thus speaking of and preferring high eff. speakers doesn’t really revolve around a numeric sensitivity value in itself - certainly not as an isolated parameter and choice alone. That should be pretty obvious by now, I’d say.
That’s a very crude outline of what’s actually required power-wise. Many low eff. speakers at actual listening distance will be closer to their limits or lacking noticeable headroom at 90-95dB’s than one imagines, and moreover you have to factor in the girth of passive crossovers and their varying degrees of load-strain on the amplifiers; a 100W amp may be brought to its knees with a passively configured speaker long before those 100 watts are actually converted into an SPL that truly reflects the theoretical outcome at the listening position in relation to the rated(!) speaker sensitivity. Seems to me you’ve become a bit spoiled dealing with active speakers mostly, as well as drive units that are anything but representative of the general range of hifi speaker drivers ;)
While, all things being equal, a 85 vs. 91dB sensitivity difference isn’t trivial, the latter isn’t high efficiency by any means, period, irrespective of the general gist around here. Relative to 85dB sensitivity it’s certainly a higher number, but that’s just about as far as it goes. Keep wandering in the low to moderate efficiency spectrum however may make for a more convenient outset to discuss low vs. "high" efficiency, as it appears to keep the speaker principles within a more manageable and homogenized sameness, and thus a numeric sensitivity value varying 5-7dB’s is mostly what it comes down to here, not that it can’t be a deciding factor with regard to amplifier choice, a sense of headroom and max. SPL. Comparing low efficiency speakers with true high efficiency dittos (>97dB, or thereabouts) is another matter though. Here high eff. mostly involves horns, compression drivers and larger diameter woofers, as well as larger enclosure sizes, and this has sonic implications for a variety of reasons, as I implied above.
So, what you’re saying is that people buying high sensitivity speakers effectively and essentially has an excess of efficiency that isn’t of any use, unless very low powered amps are sought? When this speaker segment may often be referred to as having excellent dynamic capabilities, sense of power, scale, ease, etc., do you think that only pertains to SPL’s above ~90dB’s? And even if it does (in peaks), isn’t that relevant to some of us? And what about these traits (and others) specifically - are you going to tell me they aren’t partly related to higher sensitivity, with all that entails? |
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