I combined both your thread questions here...

I play a 2-up/2-down double bass Ludwig kit. It is a mixture of three and six-ply drums: 12", 13" (6-ply), 16", 18" (3-ply), 26" (both a 3 and a 6 ply variant). The 26's are the easiest to compare as they are the same diameter/depth. There is a sonic difference between them, the 6-ply has more attack and overtones, which can seem louder than the 3-ply. I typically use the 3-ply as the main bass, but have periodically swapped it for the 6-ply. I can't tune these to be the exact same sound, and there is a clear difference in timbre (due to mass and bearing edge). Now of course this matters only when played together, as separate or solo instruments, it doesn't really matter.

I would say the 12" & 13" have more attack characteristics than the 16" & 18", but I don't think when all are played together one would attribute the sonic difference between the drums as boiling down to a smaller/greater number of plys. I consider them as a set of higher and lower voices. And maybe because the sizes/plys are paired so closely together the difference is less obvious than my bass drums (and the difference in bass drums could be interpreted as a tuning related).

I also have a three-ply 14" tom that I haven't played in years due to the height of the drum over the 26" bass drums. I recall it being a great sounding drum, and only briefly paired it with the 12" (to have a 12/14/16/18 run of toms), but quickly exchanged it in/out of the kit in prefernce fo the smaller footprint of the 13". Unfortunatley, I can't recall any impression of the sound with that combination of drums as I was more interested in chasing the ergonomics.

So, to sum up my opinion, is there a sonic difference between the 3-ply and 6/7-ply? Yes there will be some timbre difference due to a difference in overall mass and the bearing edge cuts. However, you may not notice it as much with a larger spread of drums. If you have the option of trying before buying, I would strongly suggest bringing the 12" tom to hear how it pairs with the 13" to make sure you like it, because the bottom line is only your ears matter in this case.

Just as a side note, there are manufacturers that have drum lines that feature a mixture of ply numbers and bearing edges (i.e. as the drum get bigger the ply numbers increase and the bearing edge changes). So mixing drums can and does work.

Thankyou for that info your kit sounds very interesting they would sound absolutely awsome so you are saying it really doesn't matter they should be ok sonicly together i have a 15 7ply and a 16 3ply floor toms and they sound great together.