Since a lot of the TV music I compose uses acoustic guitars, I need to have a variety of them on hand. From detuned 12 strings and resonators to high-strung Nashville dreads to small-bodied 0-series guitars, they all have their purpose. But what I didn’t have was that classic sound of Americana, which for many is a Martin D Series instrument.
Recently, I purchased a D-18 and, while at the Martin factory in Nazareth, PA, I caught up with the highly knowledgeable Dick Boke, who runs its museum archives and special projects department.
Rich: First, let’s start by discussing the different Martin models. Fundamentally speaking, the smaller guitars are going to resonate less. The larger guitars will resonate more.
Dick: Typically that’s true. Larger guitars will have more bass response, smaller guitars will have more treble. Mahogany guitars typically have a brighter, crisper, cleaner treble response whereas the rosewood guitars have a deep, more resonant, rich, thick bass response.
Now get more specific in the Martin line.
Well, specifically the dreadnought—the big guitar—has a big, boomier bass response.
Which is the D Series.
Yes, the D Series. But when you build the dreadnought guitar with mahogany back and sides, you still have strong bass, but you have a crisp, clean treble response, very nicely balanced. Generally, I think the mahogany guitars, like the D-18 or any of the mahogany guitars built in the smaller sizes as well, are typically better for recording in the studio.
Studio engineers constantly are telling me that in the studio, the D-28, which is rosewood, produces such a strong bass response they can’t subtract the bass response out of the recording. They can add warmth, but they can’t subtract it. They prefer the warm, mahogany back and side instruments.
We did a project with George Martin, who said he specifically ran into this problem in the studio. Designing the guitar as his signature model, we were trying to create the quintessential recording studio model. We actually chose the M size. The M size is one size larger than the Triple O. It has a very tight waist. The tight-waisted M guitars were initiated as a result of David Bromberg. He was having problems with guitars because he was playing notes so quickly that they would resonate, but they wouldn’t go away. They had too much resonance. He wanted a guitar that would play, resound, resonate and decay quickly enough for the next note. So he gravitated towards this M size, which was actually an arch top Martin guitar known as the F series. Somebody had smashed the top of one of them, and it was re-topped with a flat top, and Bromberg got a hold of it. He brought it to us and showed us what he was looking for, and we made the M model, which became the favorite of folk musicians playing onstage and studio musicians in the studio because it wasn’t producing feedback like the big dreadnoughts were. It was really really good in studio, and really really good on stage. Guthrie, Bromberg, Steve Howe, etc., are all proponents of the M models. Of course, nowadays with the pick-up technology, you can install a piezo and they’ve evolved very nicely. You can play Madison Square Garden with a soundhole cover and not worry too much about feedback.
What is the classic Martin bluegrass instrument?
That would be the D-28. Though you can’t discount the D-18. Both of them have their role in bluegrass. Peter Rowan, Lester Flatt, Elvis Presley, Neil Young, McCartney— everybody, regardless of the genre, has gravitated toward the D-28 because it’s so good for vocal accompaniment.
Talk briefly about the tops of the instrument.
The Sitka tops—Sitka spruce which grows between Oregon and Alaska—is probably the most prevalent wood for guitar tops. The Sitka spruce produces a deep, low boom when you tap the top. It’s quite low, like a rumble. Of course, when you build a guitar and string it up, it can produce a very nice balance, but the other types of spruce that we use are Engelmann spruce, Italian Alpine spruce, German spruce, Carpathian spruce and historically, we’ve used Adirondack spruce. Roosevelt made a huge state park out of the Adirondacks, so logging was discontinued in the 1940s. Our supply of Adirondack spruce got more and more difficult, so we switched in the 50’s to German and Sitka spruce. Recently, Adirondack spruce has become more available though, from personal stock.
So conversely with regards to Sitka spruce, which has low tap tone, I was selecting guitar tops for Laurence Juber, who played with McCartney and Wings. These were Adirondack tops, and he wanted me to pick them out. They had a much wider grain, but they were producing a very high pitch, noticeably about half an octave higher. I equate this type of thing to banjoes. If you stretch a banjo head and start adjusting the lugs around the banjo head, the more you tighten them, the higher the pitch. So I’m equating the higher pitch top with a stiffer membrane. And of course, the Adirondack is highly prized for that reason. That’s not to say you can’t build a guitar with any variety of spruce and get a great sound. So overall, you’ve got Adirondack with a higher pitch, Sitka with a lower pitch. The rest of the spruces tend to fall between them.
The D-18 records so well. How about the classic D-18 top?
The D-18 uses a Sitka spruce top. These tops are the most available [for] us, so there’s great quality of the grain, with the straightness of the grain and the medullary rings, which run exactly perpendicular to the grain rings.
Can you explain medullary rings?
Medullary rings run perpendicular outwards. When you hand split a cant of spruce, you’re in effect creating a pie section of the log. First, you’re cutting out cylinders, and then you’re using a wedge to cut out pie sections of the tree. Those are put on a saw that swings and allows you to cut perfectly vertical grain. The grain rings, as you’re viewing the end of the spruce, the grain rings are showing up as perfect vertical lines. They’re extremely strong, but also very stiff and vibrant.
The classic recording instruments, the D-18 and the D-28, have the same tops but different backs and sides.
Yes, the primary difference is the back and sides. The D-28 has East Indian rosewood back and sides, which produces a warmer resonant tone than the D-18. The D-18 has a clearer, more focused bass response. Laurence Juber started to compare tone to wine. Maybe this is a good way of thinking of it, that the mahogany—the D-18 has a chardonnay effervescence—whereas the D-28 is more of a cabernet, more aromatic in its tone. And there are other tone woods like Koa wood, which is used for back and sides, and maple. I would consider maple more of a vodka. The Koa wood is falling somewhere between the mahogany and rosewood—maybe like a Malbec or something. Ah, let’s go have lunch!