Moving from my previous vehicle, a Subaru Legacy, to my current one, the very practical Mitsubishi Chariot, presented me with an opportunity to explore new car audio equipment possibilities. This was due to it being inappropriate for a number of reasons to transfer the Boston Pro 6.5 components used in my old Liberty to the new Nimbus. So the opportunity arose to find a suitable set of speakers to fill the shoes of the newer cars’ factory 4” speakers located on top of the dashboard.

This is where the Infinity Kappa 42.5i speakers enter the picture. These speakers were bought to my attention after I had auditioned five other models of good quality 4” coaxial speakers. Whilst these were all respectable in performance, they were still found wanting because as you can imagine, after living for two years with the famous Boston Pro’s I was now rather particular about what would replace them. It was decided that I would outlay more than originally budgeted to get the 42.5i speaker set.

Impressions
These speakers come well packaged in a compact but “fairly heavy for it’s size” box. Once opened and the contents revealed, it was easy to understand the reason for the heft. The quality of build is impressive. The cones use what Infinity call Plus 1 sizing. The cone and surround goes right up to the very edge of the basket giving a claimed 30% greater area for the stated size. These speakers are almost as deep as they are wide with quite a decent magnet stack contributing significantly to the weight. The magnets are almost the same width across as the cone’s basket. The basket material is a cast polymer material and is again quite substantial. Infinity claims that this is superior to metal baskets as it means that the magnetic field is concentrated where it should be…around the coils. All in all, these are very chunky and solid speakers.

The crossovers are an external affair each about the size of two matchboxes laid end to end. A peek inside them reveals what seem to be fairly high grade components on a good quality printed circuit board with decent sized copper tracks. No microscopic capacitor in the back of the tweeter stalk here.

Infinity have invested heavily in what they call CMMD technology. All the Kappa series drivers, including tweeters, are made from a Ceramic Metal Matrix (Aluminium and Ceramic) material. Claims of ideal stiffness to mass ratios leading to true pistonic motion are made here. While all this sounds pretty impressive, the listening test was to prove the real test.

Listening
Once installed into the dash facing straight up into the windscreen and with a few hours run in time, serious listening could begin. I’d like to point out that these speakers did benefit from this run in time. They became less constricted and more open sounding after a few hours of music. Another point I’d like to make is that they also benefit from a few minutes of music to “warm them up” before each listening session. This is not the first time I have experienced this from speakers using metal cones. Whether this is in fact because of the metal cones I cannot say for sure.

Initial listening was done with the 42.5i’s run straight off my Pioneer 9750 head unit. This unit employs internal amplification that Pioneer quote at 45w x 4 peak. Not huge figures but this was to prove quite effective for good quality, dynamic sound. For those not familiar with this unit, it’s the predecessor to the 9350/9450 but with looks that would have some mistaking it for the DEX-P1. Quite a nice unit.

Serious listening was done with my Clarion DRX-9675z 24 bit pre-amp only head unit feeding its signals via Monster Cable M-850i interconnects to my Alpine MRV-F407 amplifier. This a 60wrms x 4 (@12v where most listening was done) amplifier, running stereo for my front stage and bridged to mono for my Infinity Beta 10 ten inch sub in the rear of the cabin. The sub is housed in a 14 litre sealed enclosure. Speaker cables were a mix of 12 gauge Live Lines and Monster Cable MCX (the MCX ran from the crossovers to the driver tabs). I used them running full range (i.e. not high passed).

Did I like ‘em?
Straight up, without mucking around, these small speakers absolutely ROCKED! Especially when run off the Alpine amplifier, which would afford them much greater dynamic power reserves for the music’s transients. Bass was solid, fairly hard hitting and tuneful. On hard house and trance tracks, the leading edge of many bass notes helped to bring the bass forward into the windscreen so that it wasn’t dragged back by the sub. This meant that the impact of bass notes on CD’s like Virus’ Lab 4 live mix was in my face, where it should be. Wendy Mathews’ laid back sounding “Lily” album uses more natural instruments and the bass was again tuneful and easy to follow. There were still limitations due to the small size of the driver though. Infinity quote a lower response of 75hz but I found that I needed to boost things by about 3dB at 100hz to avoid a hole between the mid and the boot mounted sub.

It was the treble though that was the real surprise. A lot of people like to put metal dome/ring tweeters in the cold and bright sounding box. Listen to a set of these though and you could be forgiven for thinking silky smooth thoughts. Infinity claim that their ceramic coating has a lot to do with this. Whilst nowhere as smooth as some of the best silk domes by any means, they were still very enjoyable and I found myself wanting to play more music rather than turning things down or loosing interest and switching to the next tack. This I feel is the ultimate test of a tweeter. Referring again to Wendy Mathews’ Lily album, her “S’s” and “T’s” were quite accurate with only a very small amount of smear.

Some of my listening was also done at pretty high levels and these speakers coped very well. This would continue until the scowling face of my loved one appeared at my garage window. She could hear it all at these times from inside our house despite our garage being detached from the house down the back of my property. The thing is, it didn’t sound too loud inside the car until I tried to yell. Again a testament to good sound. It was possible though to drive them into compression before the amplifier clipped but all hope of good listening and enjoying things long term had vanished by this stage.

Criticisms
Even though I obviously enjoy these speakers, as I have already mentioned they don’t delve into the deepest realms of bass, as they are after all only a 4” speaker. This means that extra attention needs to be paid to gain and cross over settings to allow a seamless blend if you use a sub woofer and to maintain a natural bass reproduction in front of you.

Whilst I also rate the treble highly, there still seems to be an annoying peak between 10-12kHz. I didn’t use an RTA for measures but found that a small amount of attenuation on the EQ in my head unit cured things somewhat. It didn’t remove the last small traces of smearing that were present but certainly made things nicer to listen to. Apart from that, these speakers are physically very deep for their size, which means that care must be taken to making sure that they’ll fit the space intended.

The Nutshell
These are the best 4” speakers I have heard so far. They will work well without a sub and with enough power, will provide good SPL as well. If you desire a high quality sound without having to modify things heavily to fit a 5.25” or 6.5” speaker set and don’t mind the NZ$249 recommended retail price tag, these could well be the speakers for you. Whilst still not as good as the Boston’s, they do come highly recommended.

Specifications
Power Handling, RMS: 50 Watts
Power Handling, Peak: 150 Watts
Frequency Response (± 3dB): 75Hz - 21kHz
Sensitivity: 90dB
Impedance: 4 Ohms

Ceramic Metal Matrix Diaphrams (CMMD) with Plus One sizing (30% larger), external crossover, and cast polymer basket.

For your information, the other coaxial speakers auditioned were from the following companies: Rockford Fosgate, Alpine, MTX, Cerwin Vega, and Infinity (Reference series).

About the author Stephen (Winno) has been involved in the mid to higher end home audio industry for the last eighteen years with the last two years in the car audio industry at a retail level. He was NZ’s Pro Street Sound Quality Champion at the 2002 Auto Salon before the demise of IASCA in NZ.

This entry was posted on Wednesday, June 30th, 2004 at 10:44 am and is filed under Product Reviews. You can trackback from your own site.