The two most common mistakes are bass and treble

I kind of would really like to hear @atmasphere and Fritz in a room together sometime. I think that would potentially be a phenomenal match up.

Yes it is a nice set up. Fritz and I did a show several years ago with my Atma-Sphere amps and his speakers. We also had a 300B SET amp and it was surprisingly a great match for the speaker. Fritz's speakers are typically 6 ohm and a pretty flat 6 at that, with very benign phase angle. They are not high efficiency either. Duke LeJuene has praised them as the closest thing to a free lunch and I often point out to people they are the best kept secret in audio.

While I think @atmasphere made some very good points about distortion and speaker efficiency (pay attention to his example of the 4 ohm efficiency calculation using 2.83V), there is something to be said for designs that are not high efficiency. In my collection, my best speakers are not the high efficiency Audio Note AN-e or my DIY single driver using an Audio Nirvana driver, they are my Spendor 1/2e, Quad ESL, Acoustat Model 2, and Analysis Audio Omega. None of which should be confused with high efficiency.

To Atmasphere:  I'm on my third pair of  low impedance, super-inefficient Magnepans.   I've had many other brands of speakers - Altec, Allison, Advent, AR, B&W, Definitive Technology, Elac, KLH, Klipsch, and Wharfdale.
In my opinion, Magnepans are the most neutral speakers made, as well as fantastic bargains.  

When we talk about speaker distortion and thermal compression I’m not sure it’s fair to lump systems without voice coils like Magnepans with normal to low efficiency cone speakers though I know it keeps happening. The physics of the heat and distortion are entirely different as far as I know.

Inefficient and low impedance speakers are IMO/IME a mistake.


All amps make more distortion playing into lower impedance. If you want the amp to sound smoother and more detailed, set it up to drive a higher impedance.


Inefficient speakers need really powerful amps to play properly, and they suffer thermal compression. Really powerful amps that actually sound like real music are not that common and likely pretty expensive, when the whole thing could have been solved without any loss of bandwidth or resolution by simple getting a speaker that's easier to drive.


Speaker cables get far more critical on low impedance speakers too. You can easily spend $$$$s on speaker cables, but if you have a higher impedance speaker the cables simply won't bring as much to the table.

There's truth to this, I find. Obviously efforts have been made by the industry to cover up more or less a progressing deficiency in speaker sensitivity (in tandem with lower impedance) for decades now, as pointed out by John DeVore:

https://www.youtube.com/watch?v=PEcFkSQMc8g

Speaking of difficulty of load though low impedance may be a much lesser issue than what's faced with complex passive cross-overs and their potentially high phase angles. While higher impedance as an isolated phenomenon relieves the amp in a sense, the negation of a passive cross-over, not least a complex one, will have much bigger implications here. Just like with high(er) impedance and its lessening of the importance of cables, the same is offered us going active and the importance here of amps: an important culprit of what make amps sound different lies in the passive cross-overs of speakers, and how well a particular amp is able to remain electrically indifferent to the load presented to it; remove the passive cross-over and amps start sounding somewhat more similar (though not completely similar) looking directly into the specific driver, while seeing their fuller potential much more easily realized. 

Active also means being able to direct more power and quality to where its needed. I have 30 watts pure class-A designated to the 111dB sensitive horns, some 2kw Lab.Gruppen to the 100dB sensitive bass cabs, and 500 watts Crown to the 97dB tapped horn subs. 

I'm sure many don't feel they're making any outright mistakes with their choices of lower efficiency (/low impedance) speakers, and I'm sure many of them have great sound. Coming down to it, that's all that matters. From my chair though speakers have been way too inefficient for too long, and too small and too expensive at that. I simply don't buy into the "small speakers small room, big speakers big room" mantra that's so often leveled at us. It's an excuse to make us buy generally small(er) speakers and make us feel good about it, when most of us don't have bigger spacings allocated for our audio passion. Truth is though big, pro cinema speakers can sound fantastic in a moderately sized domestic setting, even though they're build to fill auditoriums for hundreds of people. Talk about being preconditioned to a certain way of thinking. 

Boiled down the mistake is buying into it all and everything - all this "hifi." Let physics have their say with speakers, be critical of the industry, and keep an open mind - not least a pair of open ears. 

To Atmasphere: I’m on my third pair of low impedance, super-inefficient Magnepans. I’ve had many other brands of speakers - Altec, Allison, Advent, AR, B&W, Definitive Technology, Elac, KLH, Klipsch, and Wharfdale.
In my opinion, Magnepans are the most neutral speakers made, as well as fantastic bargains.

You can imagine with Manapan in my town and being on a first name basis with the owners (one of them called me last summer when my stolen bicycle turned up on Offerup, for which I am grateful) that I’ve heard them a lot . ’Some of my best friends own them’ although a trope is actually also true. They are good speakers no doubt. Imagine though what they might sound like if higher impedance: They would be less sensitive to speaker cables. The amps playing them would have less distortion. In a nutshell, you’d experience more impact in the bass (owing to the speaker cables not robbing you of impact) and smoother, more detailed sound through the mids and highs (owing to lower distortion from the amps).

I think @erik_squires is correct that planars suffer less thermal compression than lower efficiency cone drivers.

In my collection, my best speakers are not the high efficiency Audio Note AN-e or my DIY single driver using an Audio Nirvana driver, they are my Spendor 1/2e, Quad ESL, Acoustat Model 2, and Analysis Audio Omega. None of which should be confused with high efficiency.

@clio09 Its always important to be careful about conflating personal anecdote with how things are: just because you have one efficient speaker that is bested by others of lessor efficiency does not mean that what I’m saying is incorrect. I have a similar anecdote- a set of desktop Coral loudspeakers that I bought at a garage sale for $5; they are 98dB but sound pretty mediocre; the cabinets resonate and they lack definition and bandwidth, entirely because they simply weren’t built to be anything other than cheap. Obviously the Audio Notes are not that but you get my point.


The Quads and Acoustats are not as inefficient as they appear on paper; generally speaking add 6dB to any planar’s measured values to sort out where they actually sit (some amps have trouble driving ESLs which is unrelated to their efficiency). This is because when measured, the microphone is placed at 1 meter. At that distance, a good deal of the output of the speaker is not picked up by the mic. You have be back from the speaker a good 10 feet to really understand its efficiency. ESLs do not suffer thermal compression as they have no voice coils.


Efficiency and impedance are important, but like class A vs AB in amplifiers, a lot has to do with execution. As an amplifier manufacturer that makes both class A tube amps and class D amplifiers, I see how distortion plays out in systems all the time. In solid state, you lose power as the impedance is increased but you also lose distortion. Now if sound quality is your goal then your amplifier dollar will be best served be a speaker of higher impedance; if *sound pressure* is your goal then you have a weak (3dB) argument for 4 ohms.


Higher efficiency speakers require greater precision in their construction, which makes them a lot more expensive. They were the only game in town when tubes were King; speakers had to make the most of amplifiers whose power is expensive. OTOH when solid state became practical, amp manufacturers realized the benefit of no output transformer and no filament circuit- so they could make an amp of the same power that cost 10% of the cost of a tube amp and sell it for 90% of the price of that tube amp. Speaker manufacturers saw this and realized that if they went to 4 ohms and less efficiency the lower cost to build the speaker meant they could make more money too. Solid state amplifier power is cheap, so this has worked great market-wise but its been one of the barriers between sounding like real music as opposed to a really good stereo.