No Strum hollow
It seems to me that the strum hollow was "invented" by either Charles Prichard in Huntington, WV or by Ed Thomas in Bath, KY, long after dulcimers were being built, as Ken said. If you look at old Virginia dulcimers, for example, you'll see many scratch marks on their flat fretboards, where the strum hollow would normally be.
A great many of the olde dulcimers from the 1800s had no strum hollow. In part the function of the hollow is to reduce the weight of that massive brace that runs from end to end which we call a fretboard. If you have decent strum technique you won't hit the fretboard, regardless of a strum hollow or not.
The "mathematically correct" place to strum is half way between the fret being pressed and the bridge; which of course changes with each note. Most of us find ourselves strumming somewhere up around fret 12-14. Changing the location of the strum can be used to good effect depending on the song.
As Dusty says, learning to strum both ways is good (it took me 15 years to 'get it'). Learning to strum 'up and out' and 'in and down' will help emphasize the melody string sounds, not lose them in the hum of the drones.
Enjoy the journey!
You don't need a strum hollow. You can strum or pick anywhere you want. I usually tell beginners to strum wherever their hand and arm feel most comfortable. Eventually, as you have discovered, you will learn to move toward the bridge to get a sharper tone and tighter strings and toward the middle of the dulcimer to get a warmer tone and looser strings.
Adding a strum hollow will not change the tone of your dulcimer. The only exception would be if you use a flatpick and sometimes hit the fretboard, creating a clicking sound. (I sometimes have that issue, unfortunately.) Good technique can avoid that problem, and strumming over the strum hollow does as well, obviously.
It sounds like you are off to a great start. My advice would be to eventually begin strumming both in and out, alternating in a steady pattern, but don't worry about that right away. Take your time.
Dusty T., Northern California
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie
updated by @dusty-turtle: 02/07/19 01:25:20AM
Hi, I bought my cardboard dulcimer used, already put together. It looks like any other cardboard dulcimer, except it has round holes instead of hearts. The box is a rectangle, no tapering toward the tuners, i’ve seen both kinds of boxes, nothing too odd there. But the thing that seems a little strange is it doesn’t have a strum hollow at all.
I’m wondering what the purpose of the strum hollow is? I don’t use a pick, only my fingers and rarely my nails, so does it matter that there isn’t one?
I think I read or saw a video somewhere that you wherever you fret your string, you double that distance and strum there. I don’t know if that’s true or correct, I watch a lot of videos, that could be info for a completely different instrument and I’m, mixed up. Anyhow, to my ears, it sounds more like an electric guitar when I strum closer to the bridge, and more of a normal, warm, acoustic sound higher up, so i usually strum all over the place for whatever effect I want to hear at the moment. I also strum toward myself, not away, or pluck the strings with three fingers at the same time, or I sometimes try to fingerpick a little bit. I mostly just strum toward myself at an angle, not straight across the strings, holding my fingers really flat, so I’m not using only the pads. I sometimes try to accent the string(s) I’m fretting a little bit more than the other one or two. I know my technique is terrible, a real train wreck, but I really enjoy the sounds I’m making.
I really like how it sounds now, and also wonder if the tone would change a lot if I were to take a Dremel to it, and carve out a strum hollow.
I’ll most likely leave it as is, but just wanted to understand what the strum hollow is all about, and make sure I’m not missing out on some major tone improvement or the notes having longer sustain because the fretboard is one straight piece.