Isophon PH2132e Coxaial Drivers

OK I just want to state upfront at the beginning, these are outstanding sounding speaker drivers! Really just exceptional on every plane, these old 50'-60’s German coaxials bring the whole package to the table. Once in a while there is treasure and these drivers qualify.

With that out of the way….

Here we have a somewhat rarer bird, a pair of Isophon PH2132e, 1950s-60’s coaxial drivers made in West Germany and sold primarily in Canada housed in Noresco boxes. These 12 inch oval speakers feature big alnico magnets and a single capacitor acting as crossover to a round 4 inch paper tweeter. Between the two, these drivers paint one of the most satisfying aural pictures out there. When its really right you know it within the first few seconds, and these drivers energize the room and dive right in with a huge immersive sound.

Extremely efficient, the Isophon PH2132e allows even the micro amps to open up and bloom, with lots of texture and expansive space. Placement and imaging are precise. They have a thick but fast sound that is a rare treat. And while not bright, they don't miss anything and feel really alive and vibrant. Very complete. And perhaps most importantly for me, they serve up the emotion in the program material.

One of my test tracks is J.J. Cale’s The Old Man and Me. This is a tough track. It has pulsating bass tones with a very ethereal overlay of voice and guitar, and there is a sort of weird vibration that throws a lot of wide band drivers off. The Isophon glides right through, still showing off the weirdness but not getting thrown off by it. It doesn't sound “wrong”, as many drivers tend to on this track.

Another tough one is Indian music. The Isophons present the “sheen” of this program material really well; richly textured and contoured, and still buzzing with an electrified feeling.

Back to back against some of the heavyweights, the Isophon holds its own and doesn't give up anything. Compared to the Altec 755a, the Isophon are more open and airy but not as low midrange focused. Voice is better on the Altec but music is the Isophon. After so many hours of play, the Rullit Aero 8 have opened up so much that they do still eclipse the Isophon in pretty much every way, but the Isophon are close enough in flavor and performance to still have their days in the rotation.

As you can see, I’m enthusiastic about these drivers. For the $250 or so I paid in 2023, I don't see how they can be bettered. I hesitate to recommend things that just cant be found, but I do see these for sale on eBay with some frequency, so there are still a few out there. If you are a DIY speaker builder these are a great place to be. And I haven’t even recapped mine yet. Super highly recommended.

Update Summer 2025: I’ve had these drivers for about 3 years now, and that’s given me time to put them up against quite a barrage of competition. Folks, these are perhaps my favorite “fullrange” driver solution so far. They sound absolutely magnificent in an open panel, and they are efficient enough for a true flea watt amp to light up while still gracefully handling the 30 watts from my McIntosh MC30 and A116. They have a presence factor that is just remarkable, and they still sound warm and inviting. I purchased a backup pair, and recently have been using one of those drivers in a mono system at a small second home. The Isophon clearly outperform everything else I’ve put up against it in mono, and it’s not even been close. It's a little frustrating to sideline so many other choices, but that Isophon just sounds too good. These aren’t terribly common but are not unobtainable either. If you find a pair, they are well worth your time. Good luck!

Most of the drivers I favor are single cone full or wide banders. These coaxials of course have a big advantage in that each of their cones can be made to optimize a specific part of the audio band, while that single cone driver needs to cover it all on their own. Coaxial drivers are a smart solution, and in this case Isophon really nailed it. I also think there may be some kind of advantage to the oval shape.

Nice heavy duty construction. These are big drivers and with their oval shape and rectangular frames, they are unlike anything I’ve handled before.

These drivers are naturals for open baffle, and work perfectly in the Telefunken cabinets.

Here is one of my “backup” PH2132 drivers in a smallish mono system. Also on tap is a Wharfedale SFB, a 12 inch Capeheart field coil and an un-mounted early alnico ElectroVoice 12TRXB, all powered by a 1954 McIntosh A116. I’m using an ipad and a beautiful Dual 1019 both run into a Bellari preamp and then into a mono converter. The Isophon absolutely smokes everything here, and these days it sits alone in the room.