This is a review and detailed measurements of the JBL HDI-1600 two-way bookshelf speaker. They were purchased new and drop shipped to me for testing. The HDI-1600 costs US $900There is some style to the HDI-1600 but overuse of plastic degrades the image of having bought anything expensive:Back panel binding posts are OK but the bi-wire shunt is thin and flimsy (does the job though):Product is made in China.Measurements that you are about to see were 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 and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise.In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.All measurements are referenced to the tweeter axis with frequency resolution of 2.7 Hz.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:That is one flat response from about 700 Hz to 9,000 Hz. There is a peak in bass which I actually prefer in past listening tests. The dip above 10 KHz looks bad but perceptually won't be that significant due to its high frequency.The on and off-axis sounds are very similar to each other as indicated by the blue dashed line being rather smooth. This means the speaker is room friendly as reflections sound similar to direct sound of the speaker. And gives you flexibility to position the speaker angle as you like.There is strong peaking near 20 kHz but most of us don't hear that far so I don't think it is an issue.Predicted response in a simulated room shows what I just described:Due to good summation of early reflections:So don't go chasing myths on the Internet to absorb reflections.Horizontal directivity (how well the sound drops off from on-axis) resembles very good studio monitors:Vertically is chewed up as is typical of many 2-way speakers:Due to increased dip around crossover frequency (1.9 kHz) as you go below the tweeter, don't put the speaker on too high of a stand. Not a huge deal though.Impedance response shows the typical dip below 4 ohm which nearly matches the honest specification from JBL of 4 ohm:Since I started to test speakers there has been a lot of complaints about them. So I decided to spend some time on them to refine the measurements. This added a ton of time to this review so hopefully it is worth it. Two key changes are made:1. Speaker is driven at a calibrated level of 96 dB at 1 meter. This matches what soundstage uses. My measurements are actually at 1/3 of meter and then calibration compensated for 1 meter. This sharply reduces the effect of noise in the room at the potential expense of higher distortion from the microphone. Soundstage goes the other way around, measuring at 2 meters (at 90 dB which is the same as 96 dB at 1 meter).2. I use the fancy processing in Klippel NFS to dial out the room effect. This makes the display smoother but gets rid of all the room modes especially in low frequencies. For some reason it boosted the distortion level a bit in mid frequencies which I am still investigating.3. I worked on making the colors more visible (I have a very small selection of what I can choose from).For this speaker, it required 11 volts input to get to 96 dB at 1 meter so pretty close to 10 volts I used to use. Here are the results:We definitely have rising distortion at crossover frequency which could be the woofer/port at the tail end of its response, or a tweeter being asked to go too low. The range that is covered by higher distortion is middle of the road so definitely will be hit on with typical content. It is almost all second harmonic so masking will be more effective on them.I spent good bit of time on this also, using NFS filtering to dial out the room. Knowing what I was looking for, I managed to get a graph that showed the issues we already know:We see a resonance at 700 Hz which we had seen in the spinorama. And messiness around crossover frequency we saw in distortion measurements.We have seen that dip before in Kali speakers which the designer mentioned was due to waveguide diffraction. So I dug in with 3-D visualization to see if it is the same issue:Left side is with the tweeter producing 5 kHz and we generally see one large projection from it (speaker is pointed at you with "nref" being tweeter center). When we go above 10 kHz however, the highest amplitude sound source is on the two sides. They mix together and due to phase difference the middle cancels out some. So it appears to be a diffraction issue but working backward to find problems like this from the visualization can be tricky.II put the JBL HDI-1600 on my typical test stand in my listening room with a single parametric EQ to dial out a room mode as I do with all other speakers (verified in this instance to definitely make a positive contribution). The sound from the JBL HDI-1600 in a word is stunning! That extra bass and very good power handling gives full satisfaction. The flat mid-frequencies means all the detail is presented as it should making for a delightful contrast with that bass response.I put in a little filter to boost where the dip is. It made a tiny difference, providing just a hair more brightness and sparkle. I was OK with or without it.The sound was so good I sat there listening to track after track. Sans nasty room modes, this is a speaker that is designed to give you the "target room response" without having to use a room EQ to get there.With 1000 watts on tap and just a single speaker playing, I finally managed to get it to cry uncle and bottom out but that was quite loud. Funny thing, it produced so much bass that combined with its smooth plastic base, it slid back 1 inch on my metal stand!I will test it later in near-field and see how it performs there.The objective performance seems to at first blush paint a picture of very good but imperfect response. Closer look, confirmed with listening tests shows that such things as a boosted bass are likely designed in. Listening tests confirm one of the most delightful experiences I have had in small speakers. Price is high of course so you have to decide if that extra bit of performance is worth it to you.Needless to say, I am going to put the JBL HDI-1600 on my recommended list. Can't wait to test the larger ones in the line.-----------As always, questions, comments, recommendations, etc. are welcome.Have to drive 120 miles roundtrip tomorrow to return a couple of speakers. Would appreciate some gas money using