It's what you were referring to when you said: "...that I could just count up a few frets to make that tab work"

(The +3 tab conversion really works best)  Sorry, but what does that mean?

Use a DAd tab & count up 3 frets on melody? So, if it's a 2 I would play a 5? Same as a DAA tab

or - use a DAA tab & count up 3 frets, so a 3 I would play on a 6?

1)  No- the standard 'reverse tuning' of DAA would be ADA... reversing the middle and bass strings, NOT doing anything to the melody string. In both DAA and ADA, your tonic note would still be the note of D. (found on one of the drone strings and on the melody string at 3rd fret.)

2)  I don't know what you consider to 'standard tab'... for what tuning? 
Easiest way to test all this: Play it while doing your counting up thing and see if it sounds right, and if you have all the notes you need for the tune. My bet is that it won't translate well if you are fretting on all strings and chording. If that's the case, then retuning to an optimal tuning for the tune and the tab will be the easiest solution.

The +3 tab conversion really works best if you only or mostly play/fret on the melody string (drone style playing). It's more complicated when you fret notes on all strings and/or play chords. You can try it, but I have no idea how it'll sound.

A tuning can often play tunes in more than 1 mode. That's why we are not technically correct in saying "dorian tuning" for instance. What I try to say these days, which is more correct, is that "this tuning is great for playing dorian tunes". The purpose of 'tunings' is to make it easier to play various kinds of tunes. A particular tune might be easier to play in DAG than DAC, for example. You'd have all the notes you need in places that are easily available depending on your style of playing. This is particularly important on non-chromatic instruments like the dulcimer, which is typically 'missing' certain frets.

Hope this helps!

Strumelia,

Looking at your Noter & Drone Blog - Lots of info - could reversing tuning of DAA be the same as AAd 

(Tonic/home note which is on fret #4.) means d is 4 up from A - I still don't understand whats standard tab i have that I could just count up a few frets to make that tab work

Hi

I just ran across a tab (from Carolyn Brodgnisku 'St. Kilba's Lullaby' playing with 'Send in the Music') I tuned to this and tried it out, easy to tune my bass down to 'A. It did sound like bagpipe tuning. 

I usually play melody/chord in DAd/DAA/DGd/CGc etc.. Lately I have been learning how to strum down & much on the melody in AEA (the 50yr. old red dulcimer, I just finished working on) 

As I was just starting to try different tabs, I played a DAA tab on the bass string & again on the middle. 

(Tonic/home note which is on fret #4.)   If I can take my DAd tab & count up 3 & turn it into a DAA tab - does this mean I would count up to 4 for this tuning and would I need to play on the A string, or could I play on the d string?

(dorian tunes) Is that what this tuning is - Dorian?

Thanks, Strumelia - I love how I keep discovering new ways in playing the dulcimer

Marg that appears to me to be a tuning one would use to play in the lonesome-sounding Dorian mode.

Are you playing the melody on the melody (d) string when in that tuning? And... are you playing in chording style, or in drone style? (drone style meaning you are not fretting the middle or bass string). 
I do have a couple of tabs on my noter drone blog for dorian tunes.  Basically, it's like playing in aeolian except further up the fretboard, and thus you have several extra available notes below the Tonic/home note which is on fret #4.

If I am tune to say AEA I can play DAd tabs, does anyone know if there are any standard tabs for an A'Ad tuning? (Just tuned the D in my DAd down - base D down to A')