The Mundorf MA30 Anniversary Speaker Kit - In Theory

In case you're not familiar with it, the MA30 is a sealed two way speaker using one of the smallest Mundorf AMT19CM1.1C for $255 each mated with the 6.5" Accuton C158-8-085 which runs around $275 each. Given normal margins, if this speaker had a brand name this would be a $10,000 speaker for the drivers alone. With the premium Mundorf crossover parts you could easily drop another $2,000 to $4,000 on a comparable speaker system.  Compare that to the minimum full kit of $2,500 and you can see what a huge bargain this kit could be for you.


At the current time the speaker kit appears to only be available through Grant Fidelity. An e-mail from Madisound on May 12, 2016 confirmed they are selling the kit but do not yet have the web page for it online.

The speaker kits come with your choice of pre-assembled crossovers, all made by Mundorf. Not a brand to be scoffed at, they also provide the parts and assembly for several very high-end brands.

At the Munich 2016 High End Show, Gryphon and Kharma, two of the most expensive speaker brands there, included drivers from either Accuton or Mundorf. The MA30 has no reason to feel shy around either brand.

I personally have measured a larger sibling of the Mundorf AMT's and found it literally beyond reproach. Frequency response, distortion, and linearity (freedom from compression) of the Mundorf AMT tweeters is among the very best in the world, technically and audibly. You can spend more money, but you can't actually build a better tweeter, diamond or otherwise.  You can also get far worse AMT tweeters than Mundorf makes by the way.

Accuton also has a very strong following, and rightly so for their quality and technical advancements but not from this particular author.  Sorry, I don't find them that interesting compared to other driver makers. My personal tastes aside, I think this is a great kit worth promoting.  Like ANY speaker, it has to do oo-mox to your ears, not mine, and for many Accuton does just that.

In any event, it's time to get to the heart of this discussion. The title of this article says it all.  This is a theoretical analysis based on the driver measurements and crossover design as can be gleaned over the internet. I have not measured them directly, and am guessing the acoustical distance from the phase matching.

While I had a great time meeting Norbert Mundorf at the 2015 California Audio Show but the electronics, room acoustics and source material was out of our hands and I never had the chance to listen to these beautiful looking speakers in a good environment.

Still, we can say a lot about them based on simulations and parts.

The Crossover

You would be surprised how many manufacturers skimp on parts quality, as well as include tricks in their design to make speaker sound different, more exciting than they would otherwise. Some even go to great lengths to make the speakers hard to drive, so they appear to be more discerning, or deliberately mismatch the crossover points to leave a dip and enhance "imaging." And don't get me started on how many juice the treble one way or another.

So, let's talk about the crossover. Grant Fidelity lists specs that just can't be correct, so I'll put what are more likely true, based on published board designs:

• Crossover point: 2.5 kHz
• Filter types: 3rd Order
• Driver polarity: In Phase

Based on the designs I have put together a crossover network, which I will not show here, but I did derive some frequency and impedance plots.

The frequency response is exactly what I would expect from an honest design. Below 2kHz it's flat to +- about 2.5 dB. After this there's a plateau where the response dips (a good thing) about 2 dB after which it's even flatter.

I would have dipped before then, but meh. The one bit of criticism, is that there is an overlapping bump in response at around 3.7kHz. The overall effect is small, around 2.5 dB. A notch filter could fix it at the expense of the driver phase matching which would have been a terrible trade-off indeed.

My point is, based on driver specs and crossover parts, its' a very solid crossover design without  tricks or gimmicks. Far too good a frequency response to appear in a magazine and a lot of so-called audiophiles probably won't like such an honest and well balanced speaker.

The Korean site Full Range has a write up on the MA30. Sadly among Asian languages I only can read a little Chinese but they do include what I presume is a measured frequency response. As you can see, it aligns closely with the simulation.


Of course, the other important factor is how easy is it to drive?

The answer is, it's pretty easy actually. The Accuton driver does have a very high peak. This simulation does not adequately simulate the cabinet effects, but if this peak remains, I would consider putting a 60 Ohm resistor across the inputs if driven by a tube amplifier. It will help keep that impedance peak normal. The minimum impedance (above 20 Hz) is 4.6 Ohms at around 1.2 kHz, not a place where amps usually have to huff and puff.

Conclusion

The MA30 kit has top quality parts everywhere. The makers are making money by bundling as a kit, but it's a pittance compared to what a branded, pre-built speaker would cost. The bass is going to be exactly what you expect from a small speaker. The MA30 will need reinforcement and a subwoofer to be close to full-range. However if you are good with that, you are going to have a very difficult time finding any speaker under $10,000 with these drivers and crossover components. If you listen to them and like them, get them, they are an absolute steal and a great start to a high end system, not to mention speaker building. The $300 crossover upgrade makes this an incomparable bargain.

Judge the value with your own ears but do not listen to them in haste. These speakers do not run to impress anybody. There is no fake modesty, blushing or seductive batting of the eyes in this design. Listen, breathe deeply and take your time to discover their sublime talents.

A Top Tier Alternative

For about the same amount of money, an alternative speaker kit is the Klang-Tong NADA design runs around $1,800 for parts plus $800 for cabinets from Taylor Speakers. Price and parts quality are comparable and both are available with pre-built crossovers. I personally prefer the ScanSpeak woofer to the Accuton, but I'm completely in love with the Mundorf AMT line, so I would say it's a bit of a toss-up. The Scanspeak will be warmer, and have more bass, it's also a much larger cabinet which is hard to tell from the images. Also, the dome tweeter has better dispersion.  Best for listening in well treated rooms, or when you need your stereo speakers to serve as background listening in addition to critical listening. If you need a full-range speaker and have the room for it then it's no contest. The NADA is  your top-tier speaker kit.

A Bargain Alternative

The MA30 and NADA  speakers are all expensive, and to many out of reach, so if you are looking for a well balanced speaker that costs under $500 / pair to build please consider the LM-1 speakers. They share a similar tonal balance to the MA30, but of course use much less expensive drivers, and can be built using off-the-shelf cabinets.