Manger MSW Transducer
           Copyright 2011 Troels Gravesen

THE MANGER TRANSDUCER     MEASUREMENTS     CABINET     CROSSOVER     STORAGE (!)     


Left: Manger Zerobox from Manger website. Right: The MSW drivers as delivered from Manger for diy.

Link to Manger website

My website may be an exercise in well-trodden paths into loudspeaker building. At least one reader thought so and as I couldn't promise him projects on electrostatic or planar speakers, he offered me a pair of Manger MSW transducers for loan. In return I would document my findings, hence this article.

These MSW drivers are one of a kind and the result of years of development by Josef W. Manger in Germany. To learn about the ideas and principles behind these drivers, I suggest visiting the German Manger website: www.manger-msw.de

I've been well aware of these drivers for decades but never had the chance of hearing what they could do. In principle this driver should be the ideal solution to having an extended range unit covering all of the midrange and treble. Xmax is limited (3.5 mm), thus requires a high-pass filter and a bass driver to handle lower octaves up to e.g. 200 Hz. The suggested high-pass filter should be 1st order and recommended are 60-100 uF for the 8 ohms version. Due to the high impedance of the driver I found 66 uF (high quality Jantzen Superior Z-cap) suitable for mating ScanSpeak 25W/8567-01 alu bass driver. In fact, this bass driver does really well in my Jenzen TL design and might pop up in some future Jenzen design.

As all of the sound emanates from the same flat diaphragm, this should present a sound stage free of any phase distortion in all of the midrange and treble range. No (passive) crossover in the troublesome upper-mid/lower treble range. How about that?
As can be seen from measurements below we have an overall balanced presentation and as Richard Vandersteen points out: The human ear is less sensitive to linear distortion when we do not have sudden phase shifts, thus we can have e.g. +/- 3 dB variation in amplitude without noticing too much.
What struck me the most is the extremely linear response from 10-25 kHz. Flat! Remarkably indeed. Getting a 3 inch voice coil to perform this way is quite an achievement. What to look for in frequency response graphs are peaks superseding dips as these most often indicate serious phase changes. No such thing could be found in the performance of the Manger drivers although there are some problems around 1.5 kHz (- the mechanical crossover....)

My expectations were high, really high, so what did I hear?
Well, not only is the MSW transducer one of a kind technically, also so sonically. This driver really does deliver a balanced presentation, very much to my liking and regardless of musical genre, I couldn't point out any particular preference for any kind of music, being classical, jazz, pop or rock. The presentation is speedy and dynamic and despite extremely limited dispersion in the 10-20 kHz range I didn't find them particularly difficult in setting up and toeing in.
Moving one seat in the sofa immediately reduce airiness due to the lack of dispersion in upper octaves, but still, a credible soundstage was apparent from a wide dispersion in upper-mid/lower-treble.

Now to the troublesome parts: The MSW driver doesn't handle significant sound levels well. Soon the sound becomes congested and details are smeared - and I'm not talking really loud, only loud, e.g. peak 95 dB @ 1 meter.
Despite the lack of crossover in the troublesome upper-mid/lower treble range it did not handle Siri's Killer Note well. This was very disappointing. I had great hopes for this. At the same time I was doing a new crossover for an old Dali 310 speaker (Vifa P17 + OEM tweeter) and even with modest quality components, this speaker handles this trouble note better!
Next, my expectations regarding sound stage depth were sky high and I was seriously disappointed. These drivers have peculiar presence quality that is not due to any elevated frequency band as such, but nevertheless something that makes this driver one of a kind. I'm intrigued by this as I can't find any possible explanation except the diaphragm being flat compared to most other transducers. Again the vintage Dali 310 did better in revealing the depth of the room in which a recording had taken place. It's not that the Mangers lack transparency as such, only the depth of the sound image seems quite limited. Really strange - and in accordance with what my supplier of the Manger units had noticed. I didn't know his views before I tried the drivers, it has to be said, so I wasn't biased. Nor had a read any of the numerous reviews available from Manger website. I tried other cabs for the Mangers and the results were the same, so I'm sure this is not due to the Jenzen TL mid cab not being suitable for these drivers.

These drivers are easy to install and if you're not a head banger and if you're fed up with mating midrange drivers and tweeters, give them a try. They're not particularly demanding on baffle size and shape and finding a 86-87 dB bass driver to handle lower octaves is easy too. Give the bass driver a 2nd order filter and reverse polarity of the Mangers - and you're flying. By the way: "Listening from another room" is good despite lack of treble. I would like to hear what the Mangers can do with two additional units placed on the sides of the mid cabinet as can be seen from the bigger commercial versions, but buying six Mangers is serious money. One driver is 700 . Click here.

Many hours later: 
Hmm.... Looking again at the dispersion characteristics, I feel more and more certain this is where to look for an explanation on the lack of perceived soundstage depth. 

  
Left: Manger at 0-5-10-15-20-25o. Right: SP44 up to 40o off axis.

Very early we have a significant reduction of treble dispersion compared to e.g. SP44, which may be unusually good with regard to this, but nevertheless. Listening to the Mangers at low level and a bit off-axis, the lack of dispersion becomes more apparent and it's a bit like listening to a "transistor" with a deeply recessed speaker like seen on ghettoblasters. The sound is closed in and we miss the highs that are part of rendering room information.
Next: The Manger is like a gigantic ring-radiator and from the Manger website we can see images of which parts of the membrane vibrate the most at various frequences. Regardless of this, the Mangers will to some extent suffer the same fate as large fullrange drivers; it starts beaming as soon as the wavelength supersedes the diameter of the cone. Beaming means smearing of detail and we loose sense of depth. Every single time I've added a tweeter to a fullrange 8" driver at 3-4 kHz, the result is increased sense of depth and perspective. We see fullrange aficionados stuffing their fullrange drivers with gigantic mushrooms, light bulbs or whatever to overcome the intrinsic problems of having a large cone doing it all. It's hard to fool physics here and trying so is full of compromises.
After these experiences I took the Mangers to the workshop again to do distortion measurements as can be viewed below. I should have done this in the first place. The drivers at hand have been reconed at the factory and used very little since then and considering the consistency in frequency response and impedance I believe these drivers are working properly. Nevertheless they display significant levels of distortion. 

CONCLUSION

These Manger drivers do not get my full-hearted recommendation. Price is fairly high, soundstage depth is limited, power handling is limited and distortion soon a problem. 
The inability to present a transparent soundstage with good depth is what I rate the most serious shortcoming here. Three drivers as seen from the larger commercial variants may solve power handling problem and well, we may easily pay 6 x 700 for good commercial speakers, so I don't consider them overpriced as such. Making a Manger driver probably takes hours and even from these old units, pair matching is nothing short of excellent. 
At the end of the day my AT-SW speakers will for the same price (two MSW units) beat the crap out of the Mangers. You may find this inappropriate self-praise, but I'll stick my neck out.

Post scriptum:
After finishing the article I started a google search on "Manger MSW distortion" and found this article on the Manger Zerobox 109. I was kind of relieved to find an article very much confirming my measurements and to some extent my evaluation. In particular with regard to distortion. Quote: "However, this transient accuracy is achieved at the expense of frequency response and nonlinear distortion, both of which lie outside the specifications of most monitor loudspeakers".

THE MSW DRIVER
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CABINET
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Jenzen Cabinet with ScanSpeak 25W/8567-01 (alu)

 Go to: Jenzen Cabinet


A few quick Sony snapshots from my living room.


MEASUREMENTS
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Left: Response of both drivers mounted in Jenzen TL mid cab. Right: SPL from applying 0 (red), 66 (green) and 99 uF (blue) series capacitor.
Due to intrinsic high impedance only modest uF are needed.


Here the Manger response graph for comparison. What we may call a smoothed marketing presentation but generally, not too far off reality.
The suggested 91 dB sensitivity goes for the 4 ohms version. At 8 ohms we're down to ~87 dB/2.8 volts according to my measurements.


Left: Horizontal dispersion at 0, 5, 10, 15, 20 and 25o. Right: Impedance of MSW driver.


Left: Impulse response. Right: Step response (MSW unit only).


CSD @ 25 dB scaling. MSW only (no woofer connected).

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DISTORTION MEASUREMENTS

All measurements were performed at 0.25 meter distance, 1/48 octave intervals and 2.8 and 5.6 volts input. Distortion rise 15 dB.

 
Left: Manger at 2.8 volt and 5.6 volts equivalent to 87 dB and 93 dB at 1 meter. Some serious problems at 1.6 kHz.
Right
: The QUATTROs were at hand this day in the workshop. This speaker delivers some additional 3 dB for the same input.

Let's increase THD scaling to 10%:

 
It seems we have an explanation for some of the sonic experiences. More than 10% harmonic distortion at ~1.7 kHz! 
No wonder the Mangers can't handle Siri's Killer Note.


CROSSOVER
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LCR circuit is optional (flattens impedance when mounted in Jenzen TL cab) and may increase power handling.


LAST BUT NOT LEAST -
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Like magnesium, neodymium is prone to oxidation and if drivers must
be stored for longer periods, they need a bag of silica to keep moisture low. 

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