Why are is one Gibson Rosewood brighter sounding than the other?

[J185-4Me]

The J-45 likely has an overall bigger soundbox than the Songbird, moves more air, and besides the short scale, has a different bracing pattern from the Songbird model, which was developed originally in the late '90s by Ren Ferguson as a slightly smaller dreadnought model, the "CL" line of models. It is braced differently, so that, along with differences in the body geometry and scale length -- and the guitar-to-guitar differences that are inevitable between models -- will result in different tonal qualities.

Fred

[printer2]

Originally Posted by 62burst

printer2- that image is in no way a good representation of a J-45 bridge plate; the massive bracing, hellaciously thick, oversized plywood bridge plate looks to be from one of the train wreck 1970's square shouldered J-45's from Gibson's Norlin dark era, showing the inserts for an ADJ saddle.

A more common look under the hood of a old J-45:



The OP's observation of his long scale rosewood Songwriter sounding brighter than his J-45 R is counterintuitive, and underscores how Gibsons, and acoustic guitars in general, do vary. Yes, the Songwriter may have a bone saddle, to the J-45's Tusq, but variations occur in builds, and even in the same variety of wood; where it's cut on the log, wood sourced from different regions, altitudes, growing conditions, aging processes, etc.

In the end, yes, they do vary. You actually have to listen to them, and see if the guitar's sound matches what you're looking for. And I wouldn't have it any other way.

I don't know too much of Gibsons, found a couple of pictures and posted them. I know they and Martin were building lighter way back when, are they building as they did in the 40's, I don't know.

[Bronsky]

I think the design elements that make a guitar brighter or darker sounding are pretty well known by makers, designers, luthiers, repair techs, and experienced players who have played (and looked inside) hundreds of guitars in their time.

I am not one of the above, so I can't help OP with his question.

I think you'll find that video about Gibson's bracing patterns interesting, even though it doesn't answer your question directly.