My 1990 Martin D16M tops my 2013 D18
 

I hate to admit it but the 2013 D18 I have had for four years still isn't the equal to my D16M. Maybe it's the age and quality of the wood, not sure, but the D16M sounds like a martin dread should IMO. Big, bold and NOT plinky. The D18 while being very nice is just a wee bit too polite and bright. Don't get me wrong the D18 is a great guitar but the D16M is special.

For those who don't know about these guitars they were short run NAMM show guitars that came in a few varieties from 1986 to 1991 if I'm correct. Nothing like the latest D16 series. They were Martin's first attempt to get back to pre-war specs. Set neck, forward shifted scalloped bracing, small bridge plate etc. Very light build. Over at the UMGF they are referred to as a "poor man's D18V". The only difference being RW fretboard and bridge as opposed to ebony. Martin was obviously concerned about the light build as evidenced by the warning in the sound hole to use mediums or lighter strings. The only mods I've done is a bone uncompensated saddle, ebony pins, changed the Grover buttons to butterbean style and polished the headstock. If you can find one with a good neck angle I highly recommend.

The D16M..
https://i.imgur.com/HcW8gta.jpg
https://i.imgur.com/tDbXxNg.jpg
https://i.imgur.com/m5DwRPZ.jpg
https://i.imgur.com/IxEooRA.jpg
and with the D18 on the right.
https://i.imgur.com/3ZInVLh.jpg

Yep, those special runs were great and if you prefer the 1 11/16 nut neck, you're all set.

Unfortunately, most people want 1 3/4 these days.

Enjoy!

Sitka and mahogany can make a heck of an instrument, can't it? The silking on your D16M is pretty amazing! I've never played one, but no doubt that is a boss of a guitar. As to your D18, I've played some of the newer ones that were stellar, many that were good, and a few that didn't do it for me, though it's still my favorite Martin model by far. If you have all you need in that D16, I'd move the 18 and get something else, or go on a trip!

Enjoy!

16 series
 

I just sold my 1990 000-16M. Unfortunately I just did not bond with it. These are very special instruments and, as you say, not at all what the current 16 series is.

Mine must have been custom because it was 1 3/4" nut width with 2 1/4" spacing, so ever odder that the "average" 16 from that period.

Great guitars though.

Being an electric player I adapt pretty easily to different size and shaped necks. I do like 1-3/4" for fingerpicking, but 1-11/16" still works fine. Having J45's with 1.725" nuts going back and forth is easy, plus the D16M neck has a much more traditional depth to it over the new D18 neck which makes it very comfortable. I know a lot of people say that the Spanish Cedar is just as good as Mahogany but I disagree, you have to be way more careful with capos with SC than with a good hard piece of hog.

Wow, thanks for sharing this info on your D-16M made of beautiful woods and in extremely fine condition. That neck looks as hard as a rock too (good!) I like the 1 11/16” nut size also - that dimension seems to allow for an easy fit of neck carve to my hand.

I had one of these models. Sold it to a buddy who still plays it and loves it. BTW, the warning about string gauge is common in Martins.

Rb

Maybe you just got an exceptional D-16 and a more common D-18 (?)...

They changed the D-18 and got it a forward-shifted bracing, around these years -2012 I believe...I could have bought one of the new ones, but didn't quite like the ones with the standard bracing at the time (much preferred D-28s)...
Forward-shifted braces give a rounder tone with richer more bassy overtones I think.
Did you get your guitar in 2013, or was it actually made this year ?

It took 4 or 5 years before I noticed a real tone improvement on my (vintage style) D-28, so maybe a bit more time..?

My D18 is a 2013 with the new specs. I bought it used in late 2014 if I remember right. Don't get me wrong it sounds very good and compares well with other D18's I've played with the new specs. It just doesn't sound as rich and full as the D16m. It's more of the case of the D16m being exceptional than the D18 being an inferior example. It seems that most Martin dreads I've played that have a few decades on them have similar qualities. I'm also wondering if this "select hardwood" that Martin is using on some necks is having a detrimental effect on the tone produced. Spanish Cedar seems a little punkier and soft than Mahogany.

I told you of a possible explanation that had come to my mind ; but since this wasn't the right one, I can't help you much more I'm afraid. I had my guitar for about 5 years and a half when I found it had become noticeably better in fact (so maybe you are close bu now :) ).
If your D-16 is from among the runs that were Martin's first attemps to go back to pre-war specs it's no surprise than your D-18 finds it hard to compete...As those specs are something rather special in my experience
I find the mahogany used for the back on the D-16 very nice looking too...Seems like very good wood. Can't tell about the D-18's neck, but yes I think the neck does have some incidence on the overall tone or feel...
But I'm not familiar enough with spanish cedar and mahogany use for necks to know much about it..
Do you really think you have a spanish cedar neck on your D-18 ? Sounds very unusual to me.

I feel the same about my 1991 D16H which is very similar to the D16M. This Dreadnought surpasses the sound/tone/balance/volume of my 2005 D18V. My 91 D16H sounds very much like an old 40's D18 with that dry, articulate tone while the 2005 D18V has that modern contemporary Martin sound. The D16H is a very light build and weighs only 3 lb 10 oz and projects a very very loud, open, dry sound.

No explanation is necessary. A great guitar is a great guitar. The D-18 may be a great guitar and the 16 exceptional. Congrats on a couple of excellent guitars.

I picked up my 1989 000-16M from Craigslist around 10 years ago. It complimented my 1968 D-28 quite well. Now I have three Martin Sitka/hogs.
The 89 feels more delicate, though it only weighs one ounce less than D-18.

1976 000-18 3lbs 12.7oz
1975 D-18 3lbs 15oz
1989 000-16M 3lbs 14oz

https://i.imgur.com/QVImleR.jpg

https://i.imgur.com/EPeW0Sh.jpg

And the 000-16 has a pretty back side too.

https://i.imgur.com/c6Z4T4N.jpg

https://i.imgur.com/8BwM9gP.jpg