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Positive Feedback ISSUE 20


The Marantz 10B FM Tuner and the Magnum Dynalab MD-108 Reference Tuner: Forty Years of Progress, Sort Of!
by Robert H. Levi


During the last forty years, FM has become a mature medium. FM stereo was first approved by the FCC in 1959, when the first licenses were issued. The earliest FM tuners were mono. Then, around 1961, the first stereo FM tuners came out, from Scott, Fisher, Mac, Sherwood, Dynaco, and others. Marantz sat on the sidelines until 1964, when it built the Marantz 10. That tuner would not hold its IF alignment, and was only built for a year. A much-improved design, the 10B, was built between 1965 and 1969 and sold for $650 to $700. It cost much more than, say, the McIntosh MR-71, and was considered ridiculously expensive, but was dubbed a classic from day one. It was the ultimate in 1960s tuner technology. Sol Marantz imbued his gear with the magic of music.

I am the third owner of a 10B that was built around 1967. It was restored by Brooks Berdan, Ltd. in Monrovia, California (, which I recommend to 10B owners who want the best restoration at a reasonable price. It was retubed, aligned, cleaned, and adjusted to top specs or better. Do you own a 10B that has muddy bass, a thick midrange, and rolled highs? I have the solution: Reverse the power plug. This is not an issue with modern components, which have three-pin plugs, but it makes a major difference on the 10B! With correct polarity, the 10B's frequency range is more even, its performance is much improved at the frequency extremes, and it has better overall definition. Try it! 

Excellent-sounding FM tuners are very scarce these days. I don't think it's the fault of the technology as much as taste levels. You can lie with specs, and many giant tuner manufacturers do so. The specs rarely tell you how the tuner will sound! Also, few manufacturers seem to listen to their products. Outside of Magnum Dynalab and a few British manufacturers, most of the tuners on the market are ordinary. One problem is CDs. We like them for their signal-to-noise ratio and convenience, but musically, things are more complicated. Great audio systems have become much quieter and more dynamic, with vastly higher definition. Transistors and digital tuning made tuner acceptability in high-end systems more predictable. I put my well-tweaked vintage Scott 300B tuner in my primary system, and the music was glorious, but so was the noise between the notes. With the problems of noise and radio station variability, not to mention poor antennas, it's no wonder tuners have become sources for background music. Hardly anyone really listens to FM as a primary source, but you can. Magnum Dynalab has proved it.

In 1996, Magnum Dynalab, who had made a major splash with the Etude tuner, put all of its knowledge and experience into a cost-no-object reference tuner, the MD-108. It had the works—it was fully balanced, with four antenna inputs, large, helpful meters, a pair of 12AX7s in the output stage, five (!) IF stages, and more. The MD-108 quickly became the benchmark by which audiophiles judged the state of the art. When I bought mine in 2004, it was supplied with Svetlana 12AX7s. I have not done any tube rolling, but it might be better with NOS tubes. Svetlana's small-signal tubes are pretty good if carefully selected, but not as good as even ordinary NOS RCAs from the 80s. I'll let you know.

Forty years is a long time in technological terms, but since I own both an MD-108 and a 10B, which represent the pinnacles of tuner design at both ends of the time line, I am in a unique position to determine what, if anything, we have gained (aside from a lot of cheap, average-sounding tuners). Here is a quick comparison of the two units:


Marantz 10B

Capture 1.5 dB

2.0 dB

S/N 80 dB

70 dB

Weight 40 lbs

38 lbs.

Tubes 2

19 (20 with oscilloscope)

IF stages 5


Inputs 2 x 75-ohm

1 x 300-ohm

Price $5500-5850


Remote $350 extra

No remote

I used an AudioPrism 7500 antenna on the MD-108 and a Magnum Dynalab ST-2 antenna on the 10B. Cables were Kimber Select—balanced on the 108 and single-ended on the 10B. Both were plugged into the same Monster Power Conditioner in the filtered analog positions. These two flagship tuners weigh nearly the same, and are both analog in design. Both come from talented designers attempting to produce a primary music source. Has there been progress?

Here are the gains. The MD-108 has more flexibility and is easier to use. The cat's eye tuning (a 1950s technology) is terrific, and channel changing is quick and ultra precise. I don't really recommend the 108 single-ended. Its balanced output has superior sound quality and allows superbly quiet long cable runs. The unit benefits from great power cords and interconnects. I like the multiple antenna inputs and the way the muting works. It's also shielded like crazy from digital sources in the room. It sounds robust, detailed, smooth, silky, and airy. It has a front-hall sound, with some emphasis of frequencies over 2500Hz. It has lovely extension at the frequency extremes. It is the best-sounding tuner that has been produced by anyone in quite a while. Its lack of crispies and its great quietude make for long, wonderful listening sessions. It tunes in everything, but it's only sonically superior in wide mode (it has three). It sounds like a great CD or SACD.

Here are the losses. It's as if no one has ever heard an LP or a great reel-to-reel tape—the 10B captures much of that musical delicacy and textural nuance, and does a better job at this than ALL other classic tuners. The 10B has a mid-hall sound, and is even top to bottom, without any obvious frequency emphases. The bass is very good, but less defined than the MD-108's. The highs are silky, delicious, and quite realistic. The overall definition is close to the 108's, but it is not as emphasized. It makes you want to turn up the volume. It sounds very involving, with a midrange that constantly entices the ear. I hear less of this wondrous textural naturalness in today's top tuners. We've lost it somehow.

I am surprised by how quiet my forty-year-old 10B is. It's almost silent. The MD-108's background is only slightly blacker. There's no shielding in the 10B, just a walnut cabinet, so digital sources must be turned off. I thought I heard a birdie, but it went away when I turned off my DAC. The 10B is much quieter than my Scott or my old MR-71. It has six IF stages—only the new Magnum Dynalab 109 has that many! It's 95 percent as quiet as the 108, and that's amazing. It replicates the 108's huge soundstage, so no real gain there for modernity. Where the 108 trumps the 10B is in playing jazz or rock. The added drive makes the sound more realistic and alive. Cymbals are a bit more silvery with the 108, and that's a good thing. The 108 is a bit more airy, and goes lower, too. This makes the pace of jazz and rock closer to what you expect to hear.

The years have been less kind to tuners than just about any other pieces of audio gear. Forty years have brought us precision, flexibility, and compactness. There were few real competitors to the Marantz 10B then, and there are few real competitors to the MD-108 today. I own both and am quite happy! Magnum Dynalab has doubled the number of tubes to four in the new 109, and perhaps this will capture more of the elusive charm of the 10B while retaining the numerous benefits of the 108. At $3000-$3500 for a 10B in pristine shape, many must truly believe in the Marantz magic. With the 109 at $8500 and the 108 at $6000, belief in Magnum Dynalab also has to be backed by big money.

With respect to modern tuners, I can only truly recommend the top Magnum Dynalabs and maybe the Fanfare, though it has been a while since I've heard one. These can be bought with confidence and enjoyed as a full-fledged listening source. For the truly adventurous, there's the Marantz 10B, a beacon of musicality and quiet that has rarely been equaled. Maybe next year, your new digital tuner will come with a satellite dish and we'll have perfect sound forever. I saw these at the Home Entertainment Show in New York, so I'm not kidding. I'm also not holding my breath!

Addendum to 10B and Magnum Dynalab 108 Comparison

I finally pulled the screws from the MD-108 and opened the cabinet. Inside were the two 12AX7s—only they were inexpensive Sovtek WXT+s, not the better Svetlanas as advertised! I replaced them with a pair of GE NOS 5751s from the 1980s, graded for low noise phono use. These are readily available very good sounding tubes (though finer NOS European types are also everywhere, they are getting way too expensive.). By the way, Cary and Manley use the GEs in their best gear.

The results of the tube rolling were mind-boggling. The Sovteks are OK as emergency tubes, but are NOT of audiophile grade. With the GEs, the MD 108 became dramatically better in every way. Etch and glare had vanished! The tuner was now much sweeter and more musical. It very nearly matches the 10B’s ravishing midband, and in comparison, is more accurate in the highs and lows. The majority of the listening panel I had over for a listen, actually thought the 108 surpassed the 10B in overall performance as fitted with the GE tubes. It was a close call …very close. The 10B wins by a whisker to the tube rolled 108. If I had a pair of black plates or Mullards around, well who knows?

I have never read a review of the 108 that recommended tube rolling. No doubt, this is why I never tried it, and I’ve owned the unit for two years! If you own a 108, tube roll immediately! This is an Emergency Audiophile Alert! Good NOS American and European small signal tubes can best 95% of the currently manufactured small signal tubes sonically. This is a fact!

With the 108 fitted with the GEs, it clearly bested a Day Sequerra Reference Tuner and an Audio Classic modified Mac MR78 in musicality and overall performance! Without the GEs, the 108 came in 4th place to the three other tuners for listenability. The pecking order of premier tuners is as follows:

1. Marantz 10B [perfect stock condition throughout]

2. Magnum Dynalab MD-108 [with GE 5751s]

3. Day Sequerra Reference Tuner [updated just before company folded in 1999]

4. Macintosh MR78 [with Modafferi Modification by Audio Classics]

As noted, two members of the three-person panel would have listed the retubed 108 first. The Marantz’s luxurious mid band tips the order of things listed above. Since the Marantz is tough to find and is always in need of alignment with its 19 tubes and 6 IF stages (try Brooks Berdan LTD, Monrovia, Ca.), the 108 looks really good here and is highly recommended.

Great FM listening to all!