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How would deep body OM sound?

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Total Posts: 273
I'm just starting an Ovangkol OM guitar and I've got end/neck blocks for a dread depth guitar. How exactly would it sound if I were to use those blocks and not cut them down to dimensions for an OM? I do not know if that is a common thing or not, I've seen deep body OM but I didn't know how deep they actually were.


Feb 13, 10 | 7:03 pm
Ken Cierp

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Total Posts: 2262
Generally for smaller body guitars the difference in depth from standard is about 1/4" for the large body guitars M/J as an example, the difference is 5/8". Because the internal volume is increased a little more bass projection is expected. It can be related size wise to hi-fi speakers, tweeters, mid-range, woofers (bass).


Kenneth Michael guitars est. 1978

Feb 14, 10 | 6:43 am
Ken Hundley

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Total Posts: 2169
I have the plans for the (LMI) Martin OM, Dan... The Tail from top to back is 4.13", and the neck is 3.34". The Lion and the Lamb, when I first built it, was very tight, very mid and treble oriented, almost shimmeringly high. Later, I put a sound port in it, and the bass really opened up. I got every bit as much bass out of the OM as the jumbo, though some can be attributed to slightly more aggressive scalloping. THe biggest difference was that the OM recorded better. The bass tone was as deep as the jumbo, but it wasn't Boomy, overwhelming the microphones response range. Hope that helps.

Feb 14, 10 | 9:59 am

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Total Posts: 509
Dan, the OLF OM plan has leaves the neck block taller than a Martin OM. If you're interested, I'll drag the plans out and post the dimension.

Kent Everett says a deeper body may help the bass somewhat but more gives it a deeper, more canyon like response. The deeper the box, the less coupling there will be between the top and back which could be good or bad depending on what you want.

Ken, really interesting to read how the sound of your OM changed after adding the sound port. I had originally went with a smaller soundhole on my OM like was used on the Norman Blake OM. I'm close to glueing the soundboard to the rims and I've decided to open the soundhole up to 4.25" (the size it will be if I cut past the inside rosette ring). Mario Proulx uses a 4 3/8" diameter soundhole on his OMs and even uses 4 1/2" at times. I think he uses 4 1/2" - 4 9/16" on his dreadnaughts.

Per Al Carruth opening the soundhole will raise the main air resonance and usually give the resonance more power.

Feb 14, 10 | 3:31 pm
Ken Cierp

Total Topics: 58
Total Posts: 2262
Be careful when thinking about changing the designed size of the soundhole there is much to consider -- this is excellent and the results of actual test not opinions.


Kenneth Michael Guitars est. 1978

Feb 14, 10 | 3:52 pm

Total Topics: 27
Total Posts: 668
My OM sized 12 string is a deeper body. I wanted a smaller overall guitar to better balance the mid and treble courses, yet wanted to keep a big bass (I downtune two or three semi tones).

Compared to my 12 dread, it is a much better balanced guitar, but it still has a pretty good thump - here it is with my standard depth 000

one thing to remember is that if you make it too deep it probably won't fit in a standard OM case. Cedar Creek makes some really nice custom ones....

Feb 15, 10 | 7:29 am

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