There is just so much rubbish written about "tone wood" for solid bodied instruments with zero scientific proof to back it up. Simply opinion dressed up as facts.
I don't deny that the choice of woods can make a difference to the tone of a solid instrument, although IMO when you factor in all the other things that define the sound of the instrument, their contribution is fairly negligible. What I do dispute is that their properties can be absolutely defined as a constant characteristic.
And here is why.
Just looking at "Ash" as a body wood. For starters there are over 40 different species of Ash, and the density of the wood can vary from 540kg/m3 to 710kg/m3 which is a lot of variation. The distribution of the trees covers much of the northern hemisphere and soil types, climatic conditions and growing season day length will all contribute to different growth characteristics of the trees and consequently the characteristics of the wood produced from those trees.
Do we know exactly which species of Ash is used for guitar bodies? Is it always the same species of Ash? Is a guitar made in the US made from the same species sourced from the same geographical location as one made in Europe, or Asia? I can't see any information from the big manufacturers, and without that information I can only assume that while the manufacturers will have certain specifications for the wood they buy, there is still going to be significant variation from one batch to another.
So having added in a lot of variables, here are a lot more.
If solid bodied instruments were made of a single piece of wood for the body, a single piece for the neck and headstock and a single piece for the fingerboard, we might have some consistency between instruments to start making some useful observations about the woods used and the tone of the instrument. But they are not. Most bodies are made from 2 or 3 separate pieces of wood glued together. Glue is not the same as wood. It adds in another variable. If the body is made of 2 equally sized pieces of wood there are 8 different ways they can be glued together, each of which is going to give a potentially different tonal result.
As soon as you glue two or more pieces of wood together you change the way the wood behaves compare with a single piece of the same total size. If it didn't there would be no point in multi-laminate necks.
And for a two-piece body on a Fender bass is the join always in the same place? From what I have seen the answer is a resounding "no". And on a 3-piece body it is even less consistent. More unaccounted for variables.
And of course a Fender style neck with a maple board will sound different to one with a rosewood board, but not because of the board material, but because they are constructed in completely different ways. The neck with the maple board is a single piece of maple with the truss rod inserted from the back of neck and held in place with the "skunk stripe", while the rosewood board is a separate piece of wood glued onto the maple neck, with the truss rod fitted either from behind or underneath the fingerboard. IMO it is these differences in construction and lamination of woods that is going to have an effect on the tone not the actual wood used for the fingerboard.
And there's the electrics. Even on passive bass there is lots of potential for variation.
Pickups. Do they have the same DC resistance? Have they been wound with the same gauge of wire with the same number of turns in the same way (scatter winding or even winding)? Are the magnets of the same material and magnetic strength? All these factors can change the characteristic of the pickup and the sound it produces.
Even the humble potentiometers and capacitors in a passive circuit have lots of potential for variation. A good quality potentiometer like CTS will still have ±20% tolerance which means that a pot specified at 500kΩ can be anywhere between 400 and 600kΩ. The same with capacitors. And these components always have an impact on the sound of the instrument, even at maximum settings - full volume, full tone; as can be demonstrated by connecting the pickup directly to the output jack as opposed to going through the passive volume and tone circuit.
With all these variables in play, trying to pin-point tonal characteristics of an instrument to the type of wood used for the body, neck or fingerboard is completely and utterly futile. When people try and do comparisons their methodology is so poor and their sample sizes so small that the results have no means whatsoever.