High sensitivity Vs Low Sensitivity speakers

This is a question I’ve been trying to figure out for a while. What exactly, beyond ability to run on lower power, are the sonic differences between High Sensitivity and low sensitivity speakers?

I’m trying to figure out a home theatre/listening set up and I keep seeing arguments from both camps (high sensitivity/Lowpower-set-tube and Low sensitivity/HighpowerAmp) but I’m unclear as to the benefits of either and I’m not sure how “damping factor” works.

Something like A Tekton Lore/Perfect Set 15, Zu Omen/Decware HP-1 Radial allows me to run with a smaller amp, either solid state or tube. Plus I get the general benefit of being front ported which tends not to be a thing with low sensitivity speakers. Because of limitations on my space I don’t have the room to pull my speakers out more than a foot at most

Damping factor is only influenced by speaker impedance - nothing to do with sensitivity. Sensitivity is simply how much power a speaker requires to produce a certain level of loudness.

Sensitivity is is a tradeoff based on design and like most things is based on physics and therefore there’s no way around it.

Some general rules of thumb:

A lower sensitivity speaker driver is generally caused by two things: a stiffer suspension and a heavy cone material. Stiffer suspension is required for smaller box volumes. If you look back 40 years, speakers were a lot more sensitive. They also had cabinets the size of refrigerators. Cone weight is all about another set of compromises. A heavier cone will reduce the resonant frequency. This is good for reproducing low frequencies. A cone can also be made heavier by the addition of dampening materials. These are used for control of ringing. There are a bunch more reasons for cone weight but I don’t want to write a book lol.

Another factor that makes a difference is the crossover design. The more parts in a crossover, the lower the efficiency (every part has its own internal resistance). More parts are generally used when “sculpting” how a speaker sounds. Basically the more “built-in” equalization you want (for better frequency response), the more parts you’re going to use. This equalization is often required due to shortcomings of speaker drivers. Because there is no optimal transducer (physics).

Long story short, it’s all compromises. Don’t get too hung up on sensitivity. Just pay attention to it based on the amplification you want to use (lower power = you need more sensitive speakers). Or conversely, buy the speakers you want and then choose amplification based on them.

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Then that raises another question, Speaker/Amp~Preamp pairing and how to figure that whole thing out.

How do you mean exactly? Speaker <-> amp power-wise? And amp <-> preamp impedances?

Kinda both. But I hear there are factors wrt pairing an Amp and Speaker that go beyond just power. Because everything is fucked up right now and Toronto is in a second lockdown, It is impossible to audition stuff. Further complications arise with the fact that a lot of the stuff I want is factory direct (like Tekton and Decware) and it’s impossible to figure out if certain things match. I’ve tried looking around various forums for impressions but its not been great

Ok, here’s the stuff you can figure out without listening:

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Amp power required for a given speaker (rule of thumb - there are no absolutes):

If you want an average listening level of 80db at 3 feet away from the speaker, (based on how speakers are generally rated) you will need 1 watt for an 80db sensitive speaker. For every additional 3 feet you are further from the speakers, either they will need to be 3db more sensitive, or you will need 2X amp power. You need twice the amp power to make the speaker twice as loud; twice as loud is 3db.

To make things a bit more digestable, here’s an example scenario:

If we’re shooting for an optimal SPL average of 80dB (which is loud) and we want to reproduce music with 15dB swings from average-to-peak, we target 95dB as a max output.

So, at 3m (-10dB), we have:

  • 82dB speaker sensitivity = 200+wpc amplifier
  • 85dB = 100wpc
  • 88dB = 50wpc
  • 91dB = 25wpc
  • 94dB = 12wpc
  • 97dB = 6wpc
  • 100dB = 3wpc

At 2m (-6dB), we have:

  • 82dB speaker sensitivity = 100+wpc amplifier
  • 85dB = 50wpc
  • 88dB = 25wpc
  • 91dB = 12wpc
  • 94dB = 6wpc
  • 97dB = 3wpc
  • 100dB = 1.5wpc

Now there is the other thing. As in, amps are not linear. Their linear region (best sounding region) is usually the first 20% percent of output. This of course is dependent on a whole bunch of stuff but it’s as close to a usable rule of thumb as you’re going to get. So, if we want to stay in the linear region, take the power from the above numbers and multiply X 5. That’s the power you need from your amp. This is best case scenario and usually not realistic unless you have a lot of money to spend.
If you already have an amp in mind, just work the numbers backward from amp power.

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Matching amps/preamps is pretty easy and not something I pay too much attention to. Pretty much all respectable preamps these day have a high enough input impedance. But, for the sake of clarity:

As a general rule, the lower the output impedance is (of the preamp), the better it will drive difficult loads. And, the higher the input impedance is (of the amp) the less difficult it is to drive. A good example of a happy situation is a preamp with an output impedance below 1000 ohms driving an amplifier with an input impedance of 100,000 ohms. Ratio of 1 -> 100 or greater.

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Let me try to present the power math in an easier way.

We’ll assume 80db is average SPL we want at seating position with 15db swings. This is 95db. So a 95db sensitive speaker will require 1 watt of power at 3’ away. At 6’ away, it would require 2 watts. At 3’ away it would require 4 watts.

The above are constants - it’s physics so those numbers will not change. Therefore we can work off them. For each 3db less than 95 (speaker sensitivity), double the power you need.

So an 89db speaker will need 4 watts at 3’ away, 8 watts at 6’ away, 16 watts at 9’ away. This is all for 80db average with 15db swings. I, for example, usually listen closer to 73db average so I would need a 1/4 the power for the 89db speaker.

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Okay, so the average distance from my couch to the speakers is about 8-9 feet. So depending on what I get, if it ends up being about 99Db I need at least 20 watt speaker to maintain that volume and allow for headroom if need be. (though I tend to listen lower than that. Cool.)

Uhm math…let’s see. A 99db speaker would give you 99db with 1 watt at 3’ away. At 9 feet away, with 1 watt, you’re getting 93db. So a 1 watt amp will basically give you all the power you need (you’ll get 93db peaks at listening position). Let’s double that just for shits and giggles and you get 2 watts needed. If you want to be playing in the linear zone (20%) of the amp, multiply X 5, you get 10 watts. A 20 watt amp makes you golden.

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Wayyy too much going into this. What are you guys? MIT students trying to find the optimal amp/speaker combo to best study string theory at? Which, like this, is quite pointless in the scope of things. Just get an AC to DC power converter and run car audio in open air configurations. Bam! problem solved.

No

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