I've been listening to my DIY armboard and thought I'd try to give some of my impressions. Since it's totally DIY in nature, there's really nothing to compare it to.
The materials are 3 layers consisting of: the top plate is 1/2" Purpleheart (a very dense hardwood), the 2nd layer, which I bonded to the top layer, is 3'8" Baltic birch plywood, the bottom interface, (which I view as a combination of isolation/damping), is a 1/4" sheet of engineered wood flooring underlayment. (I purposely didn't bond this layer in order to have a way to evaluate other materials in this situation). I have no idea what the actual materials are but I'm sure it's a recycled product. I experimented with it when I was constructing my motor enclosure.
I'm a self-described "shade tree mechanic" of the audio world. I don't have any scientific means of evaluating materials, just soaking in everything I've seen, heard and read about over the years, then somehow, coming up with my own variations of the above.
I'm going to try and post pictures of it temporarily on my virtual systems page, just to let you get an idea of it visually. Since it's a prototype, I didn't go for a visually pleasing product overall.
The overall sound is very, very good. I realize that there are several changes here, one is the absence of the stock tonearm/armboard interface plate. I really wanted to get rid of anything that could be a resonance inhibitor.
I'm sure you all are aware of evaluating changes in your system and how they are 'recording dependant'.
Let's start with my standby recording in which I use to evaluate any changes I make. Shawn Colvin "Steady On". I can't say it's a reference recording but it meets my criteria not only as a damn good record, but it has most of all of the aspects one would need to evaluate every aspect of a recording, IMO.
The vocals on this @ (every lp I've heard since) are spot on. No hint of any unnatural element. Actually, the vocals seem noticeably more well integrated into the whole picture. I hear no loss of detail or inner detail. What seems to be of any concern at all is, on some familiar records, there could be a slight, "rounding off or softening" of bass, though no loss of bass lines. Upon listening to Van Morrison "Moondance" Direct Disk Labs, it sounds pretty awesome! I'm wondering, given all of the unknown changes here, if this may be a factor due to the removal of the factory plate mentioned above? I realize there's more going on here than that however.
I'm really intrigued by the end result of this project, given the unknown scientific nature of the differences I'm hearing.