We should reject hard-to-drive speakers more often

Interesting...I’m considering MBL 101E speakers, but I’m hesitant due to them being hard to try.

@ricred1 MBLs are easier to drive than they might appear. That is because they are omnidirectional and when measured, the microphone is placed 1 meter away from the speaker. Most of the output of the speaker is thus not picked up. Effectively in a room you can add 6dB to their rated sensitivity. So they can be driven be amps of much less power than you might expect!

OK, thinking about this this is less about the gear and more about the awe created by hard to drive speakers. Like we somehow want to make the speakers happy because they are so demanding. Maybe we should get speakers that are happy with any amplifier instead??

@erik_squires This is a good point.

I’ve been telling people for years now that the harder the speaker is to drive, the more distortion your amplifier will make. Especially with respect to lower impedance, this is easy to see in the specs of any amplifier. Its also audible by making the amp less detailed (since distortion obscures detail) and often harsher (since more higher ordered harmonics are created).

So what I tell people is that if high quality audio reproduction is your goal, your amplifier dollar investment will be best served by a loudspeaker of higher impedance (8 Ohms or more) that is also easy to drive (no weird phase angles and higher efficiency).

Lower impedance speakers have a hidden cost of the speaker cable being far more critical to best performance. Lower efficiency speakers suffer thermal compression in their voice coils. There are some attempts to mitigate the latter problem, but whatever the technique is can also be applied to higher efficiency speakers with no downside.

If your speaker requires more than 100 Watts to really make it sing, you have an impractical speaker! This is because of the logarithmic nature of the human ear (which is why we use deciBels). If 100 Watts won’t do, how much power will you need? To make the speaker play twice as loud subjectively, you’ll need about 1000 Watts. How many amps of that power really sound like real music without being oppressive? How many can afford that? For this reason, even very expensive loudspeakers are often fairly easy to drive.

The only real advantage of 4 Ohms might be that your amp can make 3dB more power if its a solid state amp that can double power into 4 Ohm as opposed to 8. So you have a weak 3dB argument for that, if sound pressure as opposed to sound quality is your goal- good luck with it; 3dB is a slight increase in volume to the ear...

So if you want a really decent, musical system, difficult low impedance loudspeakers should be avoided. It does not matter ’how good it sounds’ to you; if that same speaker were simply higher impedance it would sound even better (speaker designers take note of this simple method of causing your speaker to sound smoother and more detailed at the same time).

"@ricred1 MBLs are easier to drive than they might appear. That is because they are omnidirectional and when measured, the microphone is placed 1 meter away from the speaker. Most of the output of the speaker is thus not picked up. Effectively in a room you can add 6dB to their rated sensitivity. So they can be driven be amps of much less power than you might expect!"

Please suggest a couple of integrated amplifiers that can drive MBL 101e speakers.

Please suggest a couple of integrated amplifiers that can drive MBL 101e speakers.

My experience is limited to the mbl 101e. It was rated at about 81 dB which you would think is crazy inefficient. Its also a 4 Ohm load, climbing to 8 Ohms in the upper midrange. But it does not have any weird phase angles so there's that.

So add 6dB and you're at 87 which still isn't great, but that's a lot better than 81!

Now you have to figure the size of the room. In a moderate sized room most of the time a 100 Watt amplifier would do the job fine. So there you have a bit of info as to what to look for. I can't say more without knowing the room size and liveliness. 

atmasphere,

My room is L-shaped...front wall is 20’ wide, length is 26’, rear wall is 26’ wide, and 9’ ceiling. My room is rather "neutral", not too lively and not dark.

As @bdp24 noted, if you can drive the bottom 2-3 octaves with a separate amplifier, it provides many more options for the rest of the range.

I have planar-magnetic dipole line arrays which are ~98db/w sensitivity, nominally 8 ohms with a minimum impedance of about 5 ohms. I'm driving these with a 300B SET amp and they sound glorious, but they only play down to about 170Hz.

The woofers for the bottom few octaves are considerably less efficient and driven with their own 370W class A/B amp and provide plenty of output to below 20Hz.

The combination can play full-range music louder than I want to listen in my 27' x 17' listening room. 

Obviously a bi-amped system is not for everyone, but by splitting out the bass, the rest of the range can be much more efficient without sacrificing sound quality.