Most folks have probably encountered Infinity speakers in a car: Infinity speakers in vehicles are common aftermarket speakers for those who can’t afford a full system of Focal speakers. Infinity, a subdivision of Harman, also makes speakers of all sorts including the Infinity Primus 163 bookshelf speaker. A successor of the Primus 162, the 163 is a slightly better designed version of its predecessor.
These will probably be the only bookshelf speakers you can order online that come with “HEAVY” written on the side of the box. Built like a block of concrete, the Primus 163 feels like a real piece of equipment, as opposed to a flimsy particle board box with some holes for speakers. There’s even a sturdy center brace usually only seen on high end speaker cabinets. The cabinet itself is a low resonance enclosure in which internal bracing is used to reduce resonance and vibration, resulting in a smoother overall sound. The vinyl black-ash finish makes them look proud in any room (except maybe a brightly colored room).
Both the woofer and the tweeter use what Infinity calls Metal Matrix Diaphragms (MMD) that “use advanced materials to improve accuracy”. Looking at Harman’s patent of MMD, the technique uses two layers of ceramic material that are separated by a layer of light metal for the speaker core that is created after stamping the core itself and anodizing it to obtain the ceramic layers. Harman claims various advantages of this compared to “soft”, pure aluminum or titanium, and pure ceramic diaphragms including:
longer speaker life (superior immunity to UV, water, salt water, and combustibility)
more consistent performance over wider range of temperatures and humidity
higher internal damping
higher stiffness to weight ratio
tighter control dimensions
The tweeter has an unfortunate looking waveguide that makes it look a little cheap but essentially protects the tweeter from damage. The waveguide, though, disperses the high frequencies emanating from the tweeter to achieve better imaging. Checking in at 19mm in diameter, the tweeter is a bit on the small side.
The woofer is relatively large at 165mm in diameter and the MMD technology makes it rather stiff. It is mounted with a cheap feeling plastic rim; something that higher end bookshelf speakers exchange for a cast basket. The coil is very large (needed to drive the stiff speaker) and appears to have magnetic shielding, which, as noted in the review of the Cambridge SX-50 bookshelf speakers, is necessary only for those who CRT screens (there are probably more polar bears on earth than people using CRT screens). An offset, asymmetric bass reflex port sits in the front left of the face, allowing the speakers to be placed away from a wall if need be.
Overall, the sound from the Primus 163 is a bit sharp, accentuated by the removal of the cloth grill. The crossover seems to be a little low for the tweeter and this sometimes results in what sounds like distortion at high volume. Speaking of high volume, these speakers get LOUD; unfortunately, they also sound really shrill when they are loud, probably a result of the lack of bottom end on the woofer.
The stated frequency response is 49Hz-20kHz, but, as per other reviews, the response drops off very quickly after about 80Hz. This essentially means if you want thumping, round bass, you will need to pair these with a real subwoofer. I presume Infinity knows more than I do about tuning a speaker, but I would imagine that a better port design would have helped in this regard, especially given the large cabinet dimensions (only a 5cm long port for a 28cm deep cabinet?!). At least the low end is clean, even when pushed.
The midrange is very present; likely also a result of the stiff woofer. This sometimes makes vocals pop out of the mix a bit more than one would like and it seems the low resonance cabinet fails at high amplitude: there sounds to be a midrange resonance somewhere at high volume. The crossover circuitry is robust and hands off frequencies above 3kHz to the tweeter, though it sometimes sound like lower frequencies sneak through.
One can help mitigate these problems with a little bit of DSP trickery, but I personally would rather the the speakers sound great upfront, without any need (or very little need) for filtering. Out of the box, the Primus 163’s are best suited to a surround sound cinema setup with a woofer to provide some low end support. This could also be, as one Amazon US reviewer points out, that they take a very long time to break-in.
As a basic, entry level speaker, the Infinity Primus 163 is a good bet. Certainly not outstanding, with somewhat sharp and shrill highs and lackluster bottom end, but if you’re just looking for something better than conventional computer speakers or as extensions to an existing surround sound system, they’re perfectly fine on a budget. You also get an awesome 5-year warranty for manufacturer defects from Infinity, one of the longest in the business.
The lack of bottom end, though, really gets to me. I don’t have much space in my apartment and my neighbors below me already hate it when I put my sub on the floor (several visits from them to “please turn down”), so I’d rather not have to have an additional piece of equipment that transfers vibrations through the building. So if you’re looking for standalone speakers, it is probably best to look elsewhere, though if you want some extra kick to your existing setup, these are certainly a safe bet.
The Primus speakers image better than any speakers their size I’ve tested…
[T]hey are fine at normal levels, but when pushed in full range, either the cabinet’s construction or tuning comes into play as an obvious resonance in the lower midrange on deep vocals.
For a living room setup they would be okay with a subwoofer.
Frankly, these sound better, or equivalent, to other “high end” brands that cost hundreds or even thousands more.