Infinity Primus P363 Floorstanding Loudspeaker Review

Infinity P363 Introduction

Infinity has been making speakers since 1968 and is probably one of the most recognized names in the industry, especially since Harman acquired the brand. While their core business these days is car audio, they were once an esoteric high end home audio loudspeaker manufacturer. These days, Harman has refocused the brand more mainstream for big box stores and internet sales channels leaving Revel to fill in the gap for those discriminating audiophiles wanting more upscale products. The Primus series is currently the top of the line offering from Infinity. In fact, this line of product is a favorite among our forum community, as many have claimed them to be a superb value. You can check out Tom Andry's review of the Primus P162 bookshelf speaker for his thoughts.  I was curious to see how their flagship P363 tower speaker would perform so I requested a review set.  The Infinity Primus P363 is a 3-way floorstanding speaker featuring dual 6.5” MMD woofers, a dedicated 4” MMD midrange and a ¾” MMD dome tweeter.

Let’s take a tour of these speakers to see if they live up to the hype and benefit from the vast R&D Harman resources to make them a solid product offering from a brand that has built a reputation of quality for over 40 years.

Infinity Primus P363 Floorstanding Loudspeaker Design Overview

The Infinity Primus P363s were double boxed with plenty of foam padding to ensure a safe arrival to our sound lab to conduct this review. There were no fancy socks or white gloves included with these speakers. Apparently Harman didn’t get the memo on how consumers often associate these accessories with “high end.” The P363’s were encased in plastic wrap to protect the finish. The P363’s came with plastic feet installed that physically raise the cabinet about an inch off the floor. They also provided the option of using rubber feet, but I stuck with the plastic ones. I’d probably recommend people with hardwood flooring to use the rubber feet since they would make for more solid footing to the floor while also better protecting the finish.

Infinity P363 drivers

The Infinity Primus P363 is a rather compact 3-way tower design, standing about 3 ½ feet tall and sporting 4 drivers. They are designed and engineered by Harman in California but manufactured in China to keep costs down. The P363’s employ Infinity’s patented MMD “Metal Matrix Diaphragm” which is just a fancy name for a coated aluminum cone. I examined the cones and found them to be extremely stiff (good thing) while also being well damped to ensure a gradual break up mode. The dual 6.5” drivers produce the bass in this speaker up to around 350Hz where the mid frequencies are handed off to a 4” MMD midrange driver. These drivers employ stamped baskets with no venting and also use bucking magnets adding unnecessary weight and cost. If this were just for those still using a CRT display, it would be a waste, but more and more manufacturers are claiming that these magnets redirect flux back into the pole piece. The drivers employ 1” voice coils and a rather stiff suspension and spider to prevent excessive cone movement. There is not a lot of motor force here, but a speaker at this price isn’t expected to produce gobs of bass at meaningful output levels. The tweeter is an MMD ¾” hard dome with a rather anemic-looking neodymium motor structure. Luckily it is crossed over fairly high (around 3.3kHz) so it’s not tasked with producing the lower treble frequencies at high power, which it’s simply incapable of doing. Infinity also incorporated a wave guide or shallow horn to increase tweeter sensitivity and control directivity in an effort to better integrate the frequency response between the midrange and tweeter. I am a fan of the MMD cone material Infinity uses on these drivers, but would have liked to see the shielded magnets dropped in favor of allocating that budget towards beefing up the motor structures and voice coils a bit.

Infinity P363 Crossover

There is nothing particularly special about the parts Infinity chose in these crossovers. They are the same crossover boards from the P360 predecessor employing a 2^nd order network on the bass drivers (consisting of an iron core choke and electrolytic caps), 2^nd order high pass filter on the midrange and a 4^th order response between the midrange and the tweeter at 3.3kHz utilizing an air core inductor. While the parts usage was arguably ho-hum, it was nice to see that Infinity paid attention to proper bandwidth limiting on the drivers. We’ve seen more expensive speakers run with nothing but a padding resistor on their tweeter and no crossover at all on the midrange driver which introduces a host of performance problems. This was NOT the case with the P363’s. Personally I’d like to see Infinity replace the electrolytic with mylar caps as they not only offer a performance advantage, but also a longevity one as well. The crossover board was mounted on the back of the cabinet and connected to a single pair of 5-way binding posts on the rear bottom end of the cabinet.

          

Infinity P363 Internal View thru front baffle: driver mounts (left pic), bottom cabinet (right pic)

The cabinet is constructed of 5/8” MDF but the front baffle is thinner due to the cutouts for the silver plastic driver covers that are presumably meant to increase the speaker’s visual appeal. Harman marketing didn’t get the memo on how front baffle rigidity is the most important part to make thick on a cabinet. I’d prefer to see Infinity ditch these silver driver covers and just stick to an entirely black and thicker front baffle with the drivers all flush mounted. I measured areas that were less than ½” thick right where the drivers mount. Luckily, Infinity was smart and employed thick stick bracing framed around the circumference of the cabinet in those areas to add rigidity. The cabinet was conservatively lined with rather thin gray insulation along the walls but was completely hollow at the bottom of the cabinet where sound foam is needed most to help dampen standing waves. The cabinet is vented with a 1” deep, 2“ circumference port on the front baffle below the bottom driver. The midrange driver was encased in its own plastic cup and was heavily insulated.

Infinity P363 Binding Posts

The P363’s came with rather generic style connectors. It also had annoying plastic plugs glued into the back of the binding posts making it impossible for me to use banana plug cables. After spending nearly 15 minutes trying to pry them out, I had to use my drill to drill them out of the binding posts. This was very frustrating to me as it was the first time I’ve ever seen plastic protecting caps glued into a binding post so snugly. Harman told me they do this to be compliant with a European CE regulation. The ¾” spacing between the posts means the Euro AC plug with its two round prongs can be plugged directly into a speaker’s binding posts. The plastic plugs prevent this. Why anyone in Europe would ever think of plugging their AC cord into a speaker is a question no one has ever been able to answer. But, I’d venture to guess there’s a less tumultuous way Infinity could have accomplishing this since I’ve never encountered this problem before on other review speakers.

Infinity P363 Grille Covers

The grilles of the Infinity P363 towers are constructed of flimsy plastic but the cloth is wound tight around the frame to minimize losses. They cover almost the entire front baffle (including the port) and wrap around the top edge of the cabinet. The grilles aren’t the magnetic type that’s becoming more popular these days with speakers, and the plastic pegs make for a very snug fit onto the front baffle. In fact, you really have to give quite a tug to remove them.

The P363’s are currently only offered in the pictured black vinyl finish, which is rather pedestrian looking but serves its purpose. With the grilles on, the Infinity P363 won’t draw much attention to itself.

Set-Up

I tested the Infinity P363 speakers in the following two scenarios:

• Audioholics Showcase Theater room - two-channel utilizing the reference gear and premier listening space in the Audioholics Showcase home

• Friend’s House to compare to his EMP E55Ti speakers

Listening Scenario #1 Audioholics Showcase Theater Room

For the first listening session, I positioned the P363 towers about 5ft from sidewalls and around 8ft from the back walls and spread apart about 10ft from each other which was about two feet shy of the distance from my primary listening position. After experimenting, I found they sounded their best with moderate toe-in. I used my Marantz PM-11S2 200wpc integrated stereo amplifier and the Denon DVD-A1UDCI Universal Blu-ray player as the source connected via balanced cables. All interconnects were furnished by Blue Jeans Cables (1694A Coax) and Kimber 8PR speaker cables with WBT compression banana plugs. The speakers in this case were run full-range with no bass management. For comparative purposes I also used my Denon AVP-A1HDCI A/V processor, Denon POA-A1HDCI 10 channel amplifier to run the P363’s bass managed to my reference Velodyne DD-15+ subwoofers crossed over at 80Hz.

Listening Scenario #2: Friend's Home Infinity P363 vs EMP E55Ti

I directly compared the Infinity P363 and EMP E55Ti speakers side by side on a Harman/Kardon HK 3490 stereo receiver using SPK A and SPK B outputs to switch between speaker pairs. Volume was properly adjusted each time to ensure the speaker pairs were level matched during the comparison. The cables were Kimber 8PR's and the source was the Denon DVD-1920CI connected via Sonicwave toslink to the HK 3490.

Infinity Primus P363 Floorstanding Loudspeaker Listening Tests

Listening Scenario #1: Audioholics Showcase Theater Room

I pulled out one the Audioholics demo CD's I created for critical listening tests to begin my assessment of the Infinity P363's using key tracks from this disc as noted below.

Dianne Reeves - Never too Far

Bass emanating from this track was punchy and tight. I detected a bit of overhang or upper bass bloom but it did add a bit of warmth to the recording. Dianne Reeves’ voice sounded very articulate and I wasn’t expecting this level of midrange clarity given the price and driver compliment of the P363s. I did find the vocals to be a bit bright but not offensively so. Trust me, I’ve auditioned tower speakers costing 2X the retail of the P363’s that didn’t maintain as good a tonal balance.

Fourplay - Chant

The resonance in the kick drums was well pronounced in the Infinity P363 tower speakers. I use this song to test how prone a speaker is to bottoming out. It wasn’t until I really pushed these speakers to their limits that I heard the woofers straining but they NEVER bottomed out. I was quite taken back at how loud I was able to play this track on these speakers. I expected them to simply whimper out but they proved me wrong. The P363’s did a great job extracting all the nuances of this song. From the vocal overlays to the rain sticks, everything was crystal clear.

Pat Metheny / John Scofield - Say the Brother's Name

I love the reverb of Pat Metheny’s guitar in this song. A really good speaker system will instantly transport you into a small jazz club in NY. The Infinity P363’s put forth a valiant effort at placing me there. The brushes on the high hats were very detailed and forward and the reverb from the guitar was good though it didn’t quite pop out at you like I remember hearing on other systems. The P363’s did a good job separating all of the musical instruments, perhaps better than I’ve heard from other budget minded systems.

Next, I deviated a bit from my reference disc and just hand selected some great tunes off my Yamaha MXC-2000 MusicCast media server. I cued up a few Marc Anthony tracks next, starting with “Ahora Quien”. The P363’s showed off their uncanny ability to image and really involve you into the landscape of the song. Marc’s voice came through loud and clear, though with perhaps a tad of excessive sibilance overemphasizing the “sss” in his voice. The trumpets sounded a bit edgy as well but overall the Infinity’s kept my attention on the pure enjoyment of this awesome song. “Tu Amor Me Hace Bien”, another classic Marc Anthony song showcased the abilities of the P363’s to extract all of the subtle details of the recording. The percussion in this track sounded fabulous and I didn’t fear cranking the volume up as the Infinity’s proved they could take it. The stereo separation of the trumpets and shakers was particularly excellent.

CD: Spock’s Beard – Snow

I took a liking to this band after my brother told me to take a listen to their concept album called Snow. They have clear influenced progressive roots from the likes of 70’s era Genesis and Yes along with very spiritual and deep lyrics to compliment their extraordinary musicianship. “Solitary Soul” is my favorite track on the double disc set. This track builds on the constant theme in the album about a young albino priest with special healing powers struggling to find his way into the world. The acoustical guitars were reproduced with excellent separation on the P363’s. The P363’s portrayed good tonal characteristics of the piano, but didn’t quite produce the depth in the soundstage as I’ve heard on more expensive speaker systems. Vocal quality was fluid and absent of chestiness I’ve heard on lesser systems. Hearing the singer repeat the hook “love beyond words” just sent chills down my spine. What a moving song and the P363’s made you really feel the emotion. This 7:34 minute masterpiece just flew by listening to it on these speakers.

I experimented playing the P363’s on my Denon rig, bass managing them at 80Hz to my dual Velodyne DD-15+ reference subs. This definitely added much needed low end extension and helped balance out the somewhat bright character that these speakers conveyed. Anyone integrating these speakers into a multi channel home theater system is encouraged to do the same.

Listening Scenario #2: Friend’s House to Compare

Again, using the Audioholics demo CD, I conducted some brief listening comparisons with my friend between the Infinity P363 and EMP E55Ti (rev1) towers. The EMP’s ($795/pr) carry a slightly higher retail price than the Infinity P363’s but both brands are regarded as producing high value oriented products so I thought it would be good measure to directly face them off in a controlled blind listening test. I found the Infinity’s were only 1dB more efficient than the EMP speakers despite they were spec’d to be 5dB more efficient! Levels were matched each time the switching occurred between the two speakers.

Listening to Fourplay “Chant” revealed that the Infinity P363’s dug a bit deeper than the EMP’s and had more sparkle on the top end. Although the Infinity’s won points on bass extension, the bass response wasn’t quite as tight or snappy as the EMPs. This became more apparent as volume level increased. Both speakers did a great job of achieving high output levels without causing woofer bottoming which this track will often do to speakers not well damped to prevent this undesirable nasty from occurring.

As we listened to more jazz-oriented music such as Pat Metheny/Scofield “Say a Brother’s Name”, we both clearly preferred the sonic attributes of the EMP speakers. The Infinity’s were able to convey more detail in the top end, but the reverb in the guitars just popped better on the EMPs. Listening to Sade “Hang on to your Love” showcased the strengths and weaknesses of both speakers. The EMP’s sounded a bit flat in the bass but the vocals were very natural and open sounding. The Infinity’s put forth more flavor to the sound but also made Sade’s vocals sound more electronic. We moved on to Santana’s “Put your Lights On” and started cranking the juice. High listening levels is where the biggest audible differences between the speakers presented themselves. Both speakers were able to play loudly without complaint, but the EMP’s seemed to be better behaved. The Infinity’s just sounded more busy in direct comparison but this was not surprising given how much more cone area the larger EMP speakers had. Quite frankly at low to modest listening levels the sonic differences between the two speakers were subtle and highly dependent on program material. Music favoring female vocals and brass instruments really highlighted the positive attributes of the EMP speakers while music favoring bass intense or high frequency effects showcased the product positives of the Infinity’s. Both speakers sounded great in their own respects as we were amazed by the level of performance achievable of such modestly priced products. The casual listener favoring more electronic or rock music would likely prefer the Infinity’s while the more discerning listener who appreciates Jazz and vocal intense music would likely gravitate towards the EMPs. If price were the key determining issue for making a purchasing decision and you’re able to get the Infinity P363’s for less than half the price of the EMP E55Ti’s, then I’d say go for the Infinity’s. If you don’t mind spending a little more for a speaker that can play more effortlessly at high SPL and also offers better build quality and cosmetics, then go for the EMPs. Both speakers will play fine as full-range towers though the EMP’s would benefit even more by supplementing their rather anemic low end bass output with a powered subwoofer.

Infinity Primus P363 Floorstanding Loudspeaker Measurements and Analysis

 

Impedance / Phase Measurements of the Infinity P363

Although Harman rates the Infinity Primus P363 as 8-ohm speakers, what I measured tells a much different story. These are clearly 4-ohm speakers. They appear to be tuned just below 50Hz, but the saddle points are quite asymmetric. This indicates a system tuning too low for the available box size needed to produce a more optimal response. The 4 ohm dip between 100Hz to 200Hz is a bit concerning for those wanting to use these speakers with budget A/V receivers. Even if bass managed, these speakers can present a rather strenuous load if the amplifiers in the A/V receiver don’t take kindly to 4-ohm loads. I found that Infinity employed a 4-ohm tweeter as evident by the impedance dip above 10kHz. I believe they did this in attempt to increase speaker sensitivity.

Impedance Measurement Comparison of the Infinity P363 Left/Right Speakers

I was a bit perplexed at how differently the two P363 samples I received measured, as can be seen in the magnitude of the impedance spikes 30Hz and 80Hz respectively. I believe this was a combination of loose driver tolerances possibly combined with a leaky transmission path in one of the cabinets. It’s not atypical for budget minded speakers to show variances in impedance measurements, though this example was a bit more extreme than I am used to seeing.

Harman’s marketing is not only taking liberty with impedance ratings with the P363, but they are also doing the same with sensitivity ratings too. I found the sensitivity of the P363’s was around 90dB at 2.83V at 1 meter which is 3dB less than what Infinity claims. If you want to scale this back to 1 watt (remember the P363 is a 4 ohm speaker) that means its real 1 watt / 1 meter sensitivity is 87dB.

All frequency response measurements were taken with the grilles removed unless otherwise noted.

Infinity P363 In-room 1/2 meter Listening Window Response Spliced 1 Meter GP at 1kHz

I took a total of seven measurements (on-axis +-15 & +-30 deg horizontal and +-15 deg vertical) at ½ meter on the midrange axis and averaged the response to more accurately represent what the listener will actually hear. I then spliced this data with a 1 meter outdoor groundplane measurement for 1kHz and below. The combined response tracks very closely with the anechoic data Harman sent me for comparative purposes. As you can see, the frequency response is fairly linear with a slight tilt in bass response below 500Hz and treble response above 5kHz. These results don’t surprise me as the P363’s have a lot of top end energy and a good deal of bass punch and depth for a speaker of its size.

Infinity P363 In-room 1/2 meter SPL vs Frequency Response (1/12^th octave smoothed)
orange trace: on-axis; red trace: 15 deg off-axis hor; blue trace: 30 deg off-axis hor
green trace: 15 deg off-axis vert up; purple trace: 15 deg off-axis vert down

The P363 maintained well behaved dispersion characteristics off-axis which is of no surprise since that is a design hallmark of all Harman based loudspeakers. Well-behaved horizontal dispersion is an agreeably-predictable result from vertically-aligned drivers operating well within their wide-dispersion bandwidths, while the good vertical response within the 15 degree window comes from closely-spaced drivers and well-chosen crossover points.

Infinity P363 On-Axis Frequency Response Comparison ( red: no grille, yellow: with grille)

The grille covers weren’t quite as transparent as we’d like to see, though no speaker we’ve ever measured produces exactly the same results with their grille covers installed. The fairly significant dip in the 5kHz area with the grille cover installed is an extremely audible frequency range. I recommend critical listening to be done without grilles installed and to reserve using them only in the presence of small children or disrespectful house guests.

Infinity P363 In-Room THD Distortion Measurement (1/2 meter)

Using the OmniMic system, I positioned the mic about ½ meter away from the P363’s midrange to do a frequency vs distortion sweep. This is a similar test to how the NRC does distortion. In my opinion this doesn’t come close to giving you the whole picture on actual audible distortion since it’s a single tone sweep and doesn’t account for modulation distortion, if for example, a midrange driver is running full-range without a HPF (like this speaker has). This measurement does tell you of any obvious flaws or problems with the speaker system. I drove the P363’s at fairly high output (more than my ears could take for any duration of time) and they produced nice clean results as you can see above. If you want to convert the THD to physical #’s, you can subtract the SPL sweep (black) from the distortion sweep (blue) at corresponding frequencies and convert the numerical # to a percentage as follows:

dB Below Test Tone	% Distortion
-5 dB	56.2%
-10 dB	31.6%
-15 dB	17.8%
-20 dB	10.0%
-25 dB	5.62%
-30 dB	3.16%
-35 dB	1.78%
-40 dB	1.00%
-45 dB	.562%
-50 dB	.316%
-55 dB	.178%
-60 dB	.100%
-65 dB	.056%
-70 dB	.032%
-75 dB	.018%
-80 dB	.01%

For example at 1kHz, the P363 SPL was roughly 90dB while the THD level was 35dB. 90dB – 35dB = 55dB or 0.178% THD.

The Downside

Like any budget-minded speaker, compromises are always made in order to hit a certain price point. The Infinity P363 tower speaker system is far from perfect, but it does many things right. For one, the almost unremovable plastic plugs on the binding posts were simply ridiculous. The overall fit and finish on these speakers is unremarkable. They certainly won’t win any beauty contests. I feel the P363’s were deliberately voiced a bit hot in the treble and upper bass regions to stand out on a noisy showroom floor. I wouldn’t characterize these speakers as being particularly neutral (expect maybe for the mids), but few if any speakers in this price class are. I would imagine the typical consumer shopping for a speaker system like this would actually appreciate the little tonal color these speakers add to the presentation however. Totally neutral speakers are unpalatable for most listeners, despite it sounding like a good design goal to aspire to.

Recommendations

The Infinity P363 floorstanding speaker system is not quite as sensitive or as easy of an amplifier load as Harman spec’d them to be. They are truly a 4-ohm speaker, so care must be taken when pairing them with modestly priced A/V receivers, especially when trying to achieve high output levels in medium to larger sized rooms. These speakers would greatly benefit from external amplification; Emotiva and Outlaw Audio come to mind as great performance/value solutions. You can run these speakers full-range but in a multi-channel setup, I’d recommend bass managing them and allowing a separate powered subwoofer to handle the bass notes below 80Hz. Only moderate toe-in is recommended on these speakers since they exhibit very uniform off-axis horizontal dispersion and produce a rather lively top end response as is.

Infinity Primus P363 Floorstanding Loudspeaker Conclusion

It’s been a long time since I’ve had my hands on a pair of Infinity speakers. In fact, the last time was prior to Harman’s acquisition of the brand. Infinity is obviously a different company now. Their focus is more mainstream and budget conscious. This doesn’t mean that there isn’t some solid engineering behind these speakers. It’s far more challenging to make a budget product sound good than a costlier ones. That being said, I’d love to see what Harman could do with Infinity on a higher end line-up to bridge the price gap between Infinity and Revel.

Infinity seems to have taken a well-balanced approach in designing the Primus P363 speaker system. Sure I had some nits to pick, but the fact that these speakers were able to hit high SPL levels in my nearly 6,000 ft³ room without bottoming out or sounding completely shrill was truly amazing. I’ve had tower speakers costing $4k/pair that couldn’t play as loud. I felt the true strength in these speakers was in their fairly neutral and very fluid midrange response. It was obvious to me the midrange driver was the true workhorse and really shaped the overall sound of the system. I was impressed with the vocal clarity I was hearing coming from a single 4” driver. The P363’s produced great high frequency detail, though they were a bit sibilant at times depending on source material. The P363's sounded very consistent when I moved my head side to side thanks to the good driver integration and attention to off-axis performance Harman engineers paid when designing these speakers.  At the retail price of $758/pair, there are certainly other options to consider. But, realizing the P363’s can usually be had for $400/pr on sale (sometimes even cheaper), they are truly a remarkable value. If you can catch the local deal Fry’s often offers for $200/pair for these babies, RUN out and get them even if they are for a remote system or office. There are currently no floorstanding speakers on the planet for that price that could compete in my opinion. Recommended!

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Build Quality
Appearance
Treble Extension
Treble Smoothness
Midrange Accuracy
Bass Extension
Bass Accuracy
Dynamic Range
Performance
Value