This is a review and detailed measurements of the Dayton Audio B652-AIR budget bookshelf speaker. I purchased a pair of these for US $67.70 from Amazon with Prime shipping. A kind member also bought a pair and sent them to me. The measured speaker is his.I have to tell you, someone in China has managed to nail the look of these speakers as to make them seem more expensive than they are:I took the grill off for my testing. The back panel shows the cheap construction all around:The whole package is quite light and those spring connectors don't inspire confidence but are workable.Still, the whole package has my admiration as far as visual execution at this price point. You start wanting this thing to measure and sound good.Researching this speaker, seems like the star of the show is the "AMT" tweeter which was added to this model variation. There seems to be this love for AMT tweeters out there which I don't understand.This review is super popular so has been reviewed to death. I thought I quote a few starting with Steve Guttenberg's CNET review Clear and clean, Steve? We shall see. Sound and Vision magazine had this to say after giving it 5 stars for performance: Stereophile dunk its beak into the water and had this to say:Always enjoyable? We shall see about that as we get into measurements and listening tests.Measurements are performed using the Klippel Near-field Scanner (NFS) . This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics) to subtract room reflections. It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room. All measurements are reference to tweeter axis with the grill removed.740 points were measured (from 20 to 20 kHz) around the speaker resulting in less than 1% error across the full frequency spectrum.Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:Well, this is a bad way to start things. There are so many problems here. We have a suck out at 340 Hz. Then various peaks and dips due to resonances. By the way, a resonance is some part of the system singing at that range of frequencies when activated. To the extent it is from the mechanic construction of the speaker, it makes for a horrible little speaker creating its own sound. Depending on its phase, it may combine, subtract or something in between with the main sound playing by the drivers. The moment they show up in this graph, it means they are loud enough to make an audible impact so are worrisome.Stepping back, instead of a flat on-axis/listening window response, we have all kinds of peaks and valleys. Depending on what music you play, the accentuation may be a good thing (if a ton of distortion doesn't come for the ride) or more likely, not.Looking at predicted in-room response, we see that these sins are written all over the graph when you include the room reflections:None of these rough edges were apparently audible to our reviewers.Here is our impedance and phase:Kinks in the phase/amplitude response as noted usually indicated resonances. We saw the same problems in the spinorama though so there is no need to look for them here.Rated impedance of 6 ohm doesn't hold at 40 Hz where in my analysis has the peak response in music. It is more like 4.5 ohms.Some of you love to see these CSD/waterfall measurements. Here is one of countless views I can make up with this graph:Distortion data for a change shows useful information:What did Steve say? Clear and clean with this much distortion in upper frequencies?Here is the "in-room" (in-garage) response:Note that the above is highly compressed graph so the frequency response looks much flatter than it is.Above are some of the ugliest measurements I have seen so far.Our Klippel NFS system reconstructs the full soundfield around the speaker down to whopping 1 degree of resolution. Using that, we can get a 3-D picture of what is going on. Let's look at the problem at 3.7 kHz:We see that both the tweeter and woofer singing strongly together so no wonder there are cancellations all around.We had a severe notch at 340 Hz. Let's look at the response below, at and above 340 Hz:Dark color indicates loudest signal. We can readily see that some kind of cancellation has sucked out the energy from the woofer at 340 Hz (middle image).I set up the measured speaker to the left of my monitor, elevated about 5 inches from the desk and tilted up and pointed toward my ear. On the right side I had the Pioneer SP-B22-LR for comparison. The Dayton Audio B652-AIR sounded good for about 2 seconds until the piercing and distorted highs started to bother me. They stood out because there is no upper bass. There is lower bass that was vibrating my desk a bit but lack of upper base made them almost absent. Female vocals were deadly with distorted lisping galore. In sharp contrast, the Pioneer was warm, and far, far more balanced in response.Having been biased with the measurements, I thought I drag my poor wife up for a listen without telling here anything. She immediately commented on the female vocals being annoying in the Dayton. I forget her exact words but they were right on the money as far as what I observe with respect to shrill and distorted sound. However, she liked the sound of some of the instruments that were brought out more by the Dayton. Since she plays musical instruments, she focuses on them a lot more than I do. I listen for overall balance but she seems to search for the individual strings and if she hears them, she likes that.The Dayton Audio B652-AIR does everything wrong that you want to avoid in modern speaker design. The woofer is run full bandwidth with no crossover meaning it sings along with the tweeter way above its linear frequency response. The thin cabinet sings (easily audible in measurements) and combines with the woofer to create problems even in its target range. The AMT tweeter has only a capacitor (single order filter) and resistor to tame it and clearly that is not enough. All of this is due to the fact that a good crossover would cost far more than the individual components or even price of a full speaker!Does it sound better than a truly garbage speaker? Yes. But I am here to keep you from bad sound and this is bad sound folks. Spend a few more dollars and get the Pioneer SP-BS22-LR.Needless to say, I cannot recommend the Dayton Audio B652-AIR. I have no idea how those reviewers have written what they have written. Five star performance? Are you kidding me? Clear and clean with no obvious flaws? Mr. Guttenberg, please get your ears trained and perform some comparative AB tests using single speakers. This is embarrassing.------------As always, questions, comments, recommendations, etc. are welcome.Hungry for some Chinese food. Going to go out to get some. When I get back, I hope you all have collected enough money for that using